MF研究者総覧

研究者データベース

詳細
田島　健次(タジマ　ケンジ)
工学研究院　応用化学部門　生物工学分野
准教授
researchmap個人ページ
Last Updated :2024/05/15

基本情報

所属

  • 工学研究院　応用化学部門　生物工学分野

職名

  • 准教授

学位

  • 博士（工学）（北海道大学）

ホームページURL

科研費研究者番号

  • 00271643

ORCID ID

Researcher ID

  • B-1379-2012

J-Global ID

研究キーワード

  • ナノセルロース   セルロース   甜菜   糖   多糖   再生可能資源   生分解性ポリマー   環境循環型高分子材料   バイオマス   高分子   バイオポリマー   微生物   発酵工学   生合成機構   酢酸菌   ナノマテリアル   遺伝子工学   分子生物学   

研究分野

  • ものづくり技術（機械・電気電子・化学工学） / バイオ機能応用、バイオプロセス工学
  • ライフサイエンス / 分子生物学
  • ナノテク・材料 / 高分子化学

担当教育組織

職歴

  • 2010年04月 - 現在 北海道大学 大学院工学研究院 准教授
  • 2007年04月 - 2010年03月 北海道大学 大学院工学研究科 准教授
  • 2002年10月 - 2007年03月 北海道大学 大学院工学研究科 助教授
  • 1997年04月 - 2002年09月 北海道大学 大学院工学研究科 助手
  • 1995年04月 - 1997年03月 北海道大学 工学部 助手
  • 1993年04月 - 1995年03月 日本学術振興会 特別研究員DC1

学歴

  • 1993年04月 - 1995年03月   北海道大学   大学院工学研究科   応用化学専攻 博士後期課程
  • 1991年04月 - 1993年03月   北海道大学   工学研究科   応用化学専攻 修士課程
  • 1988年04月 - 1991年03月   北海道大学   工学部   応用化学科
  • 1983年04月 - 1988年03月   沼津工業高等専門学校   工業化学科

所属学協会

  • ナノセルロースジャパン   日本生物工学会   日本農芸化学会   セルロース学会   高分子学会   日本化学会   

研究活動情報

論文

  • Yuki Kugo, Satoshi Nomura, Takuya Isono, Shin-ichiro Sato, Masashi Fujiwara, Toshifumi Satoh, Hirofumi Tani, Tomoki Erata, Kenji Tajima
    Carbohydrate Polymers 332 121907 - 121907 2024年05月 [査読有り][通常論文]
  • Iyoka Ota, Ryota Suzuki, Yuta Mizukami, Xiaochao Xia, Kenji Tajima, Takuya Yamamoto, Feng Li, Takuya Isono, Toshifumi Satoh
    Macromolecules 2024年04月11日 [査読有り][通常論文]
  • Chaehun Lee, Brian J. Ree, Kai Chen, Ryoya Komaki, Satoshi Katsuhara, Takuya Yamamoto, Redouane Borsali, Kenji Tajima, Hsin-Lung Chen, Toshifumi Satoh, Takuya Isono
    Giant 17 100211 - 100211 2024年03月 [査読有り][通常論文]
  • Satoshi Katsuhara, Yuki Tsuji, Naoki Sunagawa, Kiyohiko Igarashi, Kenji Takahashi, Takuya Yamamoto, Feng Li, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    ACS Sustainable Chemistry & Engineering 2024年02月14日 [査読有り][通常論文]
  • Yuki Kugo, Satoshi Nomura, Takuya Isono, Masashi Fujiwara, Toshifumi Satoh, Hirofumi Tani, Tomoki Erata, Kenji Tajima
    Polymer Journal 2024年02月13日 [査読有り][通常論文]
  • Yuta Mizukami, Yuto Kakehi, Feng Li, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    ACS Macro Letters 252 - 259 2024年02月09日 [査読有り][通常論文]
  • Minami Ebe, Asuka Soga, Kaiyu Fujiwara, Brian J. Ree, Hironori Marubayashi, Katsumi Hagita, Atsushi Imasaki, Miru Baba, Takuya Yamamoto, Kenji Tajima, Tetsuo Deguchi, Hiroshi Jinnai, Takuya Isono, Toshifumi Satoh
    Angewandte Chemie International Edition 135 35 e202304493  2023年07月 [査読有り][通常論文]
     
    Abstract Rotaxanes consisting of a high‐molecular‐weight axle and wheel components (macro‐rotaxanes) have high structural freedom, and are attractive for soft‐material applications. However, their synthesis remains underexplored. Here, we investigated macro‐rotaxane formation by the topological trapping of multicyclic polydimethylsiloxanes (mc‐PDMSs) in silicone networks. mc‐PDMS with different numbers of cyclic units and ring sizes was synthesized by cyclopolymerization of a α,ω‐norbornenyl‐functionalized PDMS. Silicone networks were prepared in the presence of 10–60 wt % mc‐PDMS, and the trapping efficiency of mc‐PDMS was determined. In contrast to monocyclic PDMS, mc‐PDMSs with more cyclic units and larger ring sizes can be quantitatively trapped in the network as macro‐rotaxanes. The damping performance of a 60 wt % mc‐PDMS‐blended silicone network was evaluated, revealing a higher tan δ value than the bare PDMS network. Thus, macro‐rotaxanes are promising as non‐leaching additives for network polymers.
  • Katsuhara, S., Sunagawa, N., Igarashi, K., Takeuchi, Y., Takahashi, K., Yamamoto, T., Li, F., Tajima, K., Isono, T., Satoh, T.
    Carbohydrate Polymers 316 120976 - 120976 2023年05月 [査読有り][通常論文]
  • Hiroyuki Kono, Yoichiro Sogame, Uugan-Erdene Purevdorj, Makoto Ogata, Kenji Tajima
    ACS Applied Nano Materials 6 6 4854 - 4863 2023年03月02日 [査読有り][通常論文]
  • Ryohei Sato, Atsuo Utagawa, Koji Fushimi, Feng Li, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Hiroshi Hirata, Yoshihiro Kikkawa, Takuya Yamamoto
    Polymers 15 3 666 - 666 2023年01月28日 [査読有り][通常論文]
     
    The redox behaviors of macrocyclic molecules with an entirely π-conjugated system are of interest due to their unique optical, electronic, and magnetic properties. In this study, defect-free cyclic P3HT with a degree of polymerization (DPn) from 14 to 43 was synthesized based on our previously established method, and its unique redox behaviors arising from the cyclic topology were investigated. Cyclic voltammetry (CV) showed that the HOMO level of cyclic P3HT decreases from –4.86 eV (14 mer) to –4.89 eV (43 mer), in contrast to the linear counterparts increasing from –4.94 eV (14 mer) to –4.91 eV (43 mer). During the CV measurement, linear P3HT suffered from electro-oxidation at the chain ends, while cyclic P3HT was stable. ESR and UV–Vis–NIR spectroscopy suggested that cyclic P3HT has stronger dicationic properties due to the interactions between the polarons. On the other hand, linear P3HT showed characteristics of polaron pairs with multiple isolated polarons. Moreover, the dicationic properties of cyclic P3HT were more pronounced for the smaller macrocycles.
  • Takuya Isono, Ema Baba, Shunma Tanaka, Ken Miyagi, Takahiro Dazai, Feng Li, Takuya Yamamoto, Kenji Tajima, Toshifumi Satoh
    Polymer Chemistry 14 22 2675 - 2684 2023年 [査読有り][通常論文]
     
    We present the polystyrene block post-polymerization modification of PS-b-PMMA through Friedel–Crafts alkylation with adamantanols to modulate its microphase-separated morphology and dimensions.
  • Yamato Ebii, Yoshinobu Mato, Feng Li, Kenji Tajima, Takuya Yamamoto, Takuya Isono, Toshifumi Satoh
    Polymer Chemistry 14 26 3099 - 3109 2023年 [査読有り][通常論文]
     
    Macromolecules with cyclic topologies have attracted significant attention because of their unique structures. Herein, we report the systematic synthesis of multicyclic polystyrene (mc-PS) via cyclopolymerization of α,ω-dinorbornenyl end-functionalized PS macromonomers...
  • Wang, Y., Quinsaat, J.E.Q., Li, F., Isono, T., Tajima, K., Satoh, T., Sato, S.-I., Yamamoto, T.
    Polymers 14 21 4535 - 4535 2022年10月26日 [査読有り][通常論文]
     
    Silver nanoparticles (AgNPs) are used in a wide range of applications, and the size control and stability of the nanoparticles are crucial aspects in their applications. In the present study, cyclized poly(ethylene glycol) (c-PEG) with various molecular weights, along with linear PEG with hydroxy chain ends (HO–PEG–OH) and methoxy chain ends (MeO–PEG–OMe) were applied for the Tollens’ synthesis of AgNPs. The particle size was significantly affected by the topology and end groups of PEG. For example, the size determined by TEM was 40 ± 7 nm for HO–PEG5k–OH, 21 ± 4 nm for c-PEG5k, and 48 ± 9 nm for MeO–PEG5k–OMe when the molar ratio of PEG to AgNO3 (ω) was 44. The stability of AgNPs was also drastically improved by cyclization; the relative UV–Vis absorption intensity (A/A0 × 100%) at λmax to determine the proportion of persisting AgNPs in an aqueous NaCl solution (37.5 mM) was 58% for HO–PEG5k–OH, 80% for c-PEG5k, and 40% for MeO–PEG5k–OMe, despite the fact that AgNPs with c-PEG5k were much smaller than those with HO–PEG5k–OH and MeO–PEG5k–OMe.
  • Tianle Gao, Xiaochao Xia, Kenji Tajima, Takuya Yamamoto, Takuya Isono, Toshifumi Satoh
    Macromolecules 55 21 9373 - 9383 2022年10月21日 [査読有り][通常論文]
  • Takuya Isono, Ryoya Komaki, Nao Kawakami, Kai Chen, Hsin-Lung Chen, Chaehun Lee, Kazushige Suzuki, Brian J. Ree, Hiroaki Mamiya, Takuya Yamamoto, Redouane Borsali, Kenji Tajima, Toshifumi Satoh
    Biomacromolecules 23 9 3978 - 3989 2022年09月12日 [査読有り][通常論文]
     
    Carbohydrates are key building blocks for advanced functional materials owing to their biological functions and unique material properties. Here, we propose a star-shaped discrete block co-oligomer (BCO) platform to access carbohydrate nanostructures in bulk and thin-film states via the microphase separation of immiscible carbohydrate and hydrophobic blocks (maltooligosaccharides with 1-4 glucose units and solanesol, respectively). BCOs with various star-shaped architectures and saccharide volume fractions were synthesized using a modular approach. In the bulk, the BCOs self-assembled into common lamellar, cylindrical, and spherical carbohydrate microdomains as well as double gyroid, hexagonally perforated lamellar, and Fddd network morphologies with domain spacings of ∼7 nm. In thin films, long-range-ordered periodic carbohydrate microdomains were fabricated via spin coating. Such controlled spatial arrangements of functional carbohydrate moieties on the nanoscale have great application potential in biomedical and nanofabrication fields.
  • Ryota Suzuki, Xiaochao Xia, Tianle Gao, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    Polymer Chemistry 13 38 5469 - 5477 2022年08月 [査読有り][通常論文]
     
    Hyperbranched polyesters (HBPEs) are well-known interesting materials used in many fields.
  • Hashim, H.B., Emran, N.A.A.B., Isono, T., Katsuhara, S., Ninoyu, H., Matsushima, T., Yamamoto, T., Borsali, R., Satoh, T., Tajima, K.
    Composites Part A: Applied Science and Manufacturing 158 106978 - 106978 2022年05月 [査読有り][通常論文]
  • Taiki Nishimura, Satoshi Katsuhara, Chaehun Lee, Brian Ree, Redouane Borsali, Takuya Yamamoto, Kenji Tajima, Toshifumi Satoh, Takuya Isono
    Nanomaterials 12 10 1653 - 1653 2022年05月 [査読有り][通常論文]
     
    Block copolymers (BCPs) have garnered considerable interest due to their ability to form microphase-separated structures suitable for nanofabrication. For these applications, it is critical to achieve both sufficient etch selectivity and a small domain size. To meet both requirements concurrently, we propose the use of oligosaccharide and oligodimethylsiloxane as hydrophilic and etch-resistant hydrophobic inorganic blocks, respectively, to build up a novel BCP system, i.e., carbohydrate-inorganic hybrid BCP. The carbohydrate-inorganic hybrid BCPs were synthesized via a click reaction between oligodimethylsiloxane with an azido group at each chain end and propargyl-functionalized maltooligosaccharide (consisting of one, two, and three glucose units). In the bulk state, small-angle X-ray scattering revealed that these BCPs microphase separated into gyroid, asymmetric lamellar, and symmetric lamellar structures with domain-spacing ranging from 5.0 to 5.9 nm depending on the volume fraction. Additionally, we investigated microphase-separated structures in the thin film state and discovered that the BCP with the most asymmetric composition formed an ultrafine and highly oriented gyroid structure as well as in the bulk state. After reactive ion etching, the gyroid thin film was transformed into a nanoporous-structured gyroid SiO2 material, demonstrating the material’s promising potential as nanotemplates.
  • Tomohisa Watanabe, Yubo Wang, Tomoko Ono, Satoru Chimura, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Daichi Ida, Takuya Yamamoto
    Polymers 14 9 1823 - 1823 2022年04月29日 [査読有り][通常論文]
     
    The topology effects of cyclization on thermal phase transition behaviors were investigated for a series of amphiphilic Pluronic copolymers of both hydrophilic–hydrophobic–hydrophilic and hydrophobic–hydrophilic–hydrophobic block sequences. The dye solubilization measurements revealed the lowered critical micelle temperatures (TCMT) along with the decreased micellization enthalpy (ΔHmic) and entropy (ΔSmic) for the cyclized species. Furthermore, the transmittance and dynamic light scattering (DLS) measurements indicated a block sequence-dependent effect on the clouding phenomena, where a profound decrease in cloud point (Tc) was only found for the copolymers with a hydrophilic–hydrophobic–hydrophilic block sequence. Thus, the effect of cyclization on these critical temperatures was manifested differently depending on its block sequence. Finally, a comparison of the linear hydroxy-terminated, methoxy-terminated, and cyclized species indicated the effect of cyclization to be unique from a simple elimination of the terminal hydrophilic moieties.
  • Takahama, R., Kato, H., Takayama, G., Tajima, K., Kondo, T.
    Cellulose 29 6 3239 - 3251 2022年03月07日 [査読有り][通常論文]
  • Kono, H., Tsujisaki, H., Tajima, K.
    Nanomaterials 12 3 537 - 537 2022年02月04日 [査読有り][通常論文]
     
    Nanofibrillated bacterial cellulose (NFBC), a type of cellulose nanofiber biosynthesized by Gluconacetobacter sp., has extremely long (i.e., high-aspect-ratio) fibers that are expected to be useful as nanofillers for fiber-reinforced composite resins. In this study, we investigated a composite of NFBC and poly(methyl methacrylate) (PMMA), a highly transparent resin, with the aim of improving the mechanical properties of the latter. The abundant hydroxyl groups on the NFBC surface were silylated using 3-(methacryloyloxy)propyltrimethoxysilane (MPTMS), a silane coupling agent bearing a methacryloyl group as the organic functional group. The surface-modified NFBC was homogeneously dispersed in chloroform, mixed with neat PMMA, and converted into PMMA composites using a simple solvent-casting method. The tensile strength and Young’s modulus of the composite increased by factors of 1.6 and 1.8, respectively, when only 0.10 wt% of the surface-modified NFBC was added, without sacrificing the maximum elongation rate. In addition, the composite maintained the high transparency of PMMA, highlighting that the addition of MPTMS-modified NFBC easily reinforce PMMA. Furthermore, interactions involving the organic functional groups of MPTMS were found to be very important for reinforcing PMMA.
  • Takaaki Fujiwara, Ayumi Fujishima, Yui Nakamura, Kenji Tajima, Min Yao
    Acta Crystallographica Section D Structural Biology 78 2 228 - 237 2022年02月01日 [査読有り][通常論文]
     
    Bacterial cellulose (BC), which is produced by bacteria, is a biodegradable and biocompatible natural resource. Because of its remarkable physicochemical properties, BC has attracted attention for the development and manufacture of biomedical and industrial materials. In the BC production system, the enzyme endo-β-1,4-glucanase, which belongs to glycoside hydrolase family 8 (GH8), acts as a cleaner by trimming disordered cellulose fibers to produce high-quality BC. Understanding the molecular mechanism of the endo-β-1,4-glucanase would help in developing a reasonable biosynthesis of BC. Nevertheless, all of the steps in the reaction of this endo-β-1,4-glucanase are not clear. This study confirms the BC hydrolytic activity of the endo-β-1,4-glucanase from the BC-producing bacterium Enterobacter sp. CJF-002 (EbBcsZ) and reports crystal structures of EbBcsZ. Unlike in previously reported GH8 endo-β-1,4-glucanase structures, here the base catalyst was mutated (D242A) and the structure of this mutant bound to cellooligosaccharide [EbBcsZ(D242A)CPT] was analyzed. The EbBcsZ(D242A)CPT structure showed two cellooligosaccharides individually bound to the plus and minus subsites of EbBcsZ. The glucosyl unit in subsite −1 presented a distorted 5 S 1 conformation, a novel snapshot of a state immediately after scissile-bond cleavage. In combination with previous studies, the reaction process of endo-β-1,4-glucanase is described and the β-1,4-glucan-trimming mechanism of EbBcsZ is proposed. The EbBcsZ(D242A)CPT structure also showed an additional β-1,4-glucan binding site on the EbBcsZ surface, which may help to accept the substrate.
  • Onyinyechukwu Justina Oziri, Yubo Wang, Tomohisa Watanabe, Shuya Uno, Masatoshi Maeki, Manabu Tokeshi, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Yutaka Miura, Takuya Yamamoto
    Nanoscale Advances 4 2 532 - 545 2022年 [査読有り][通常論文]
     
    Cyclic PEG without any chemical inhomogeneity was physiosorbed onto AgNPs to PEGylate and drastically enhance the dispersion stability against a physiological condition, white light, and high temperature, while its linear counterparts could not.
  • Tajima, K., Imai, T., Yui, T., Yao, M., Saxena, I.
    Cellulose 29 5 2755 - 2777 2022年 [査読有り][通常論文]
  • Onyinyechukwu Justina Oziri, Masatoshi Maeki, Manabu Tokeshi, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Takuya Yamamoto
    Langmuir 38 17 5286 - 5295 2021年12月08日 [査読有り][通常論文]
     
    Unique physical and chemical properties arising from a polymer topology recently draw significant attention. In this study, cyclic poly(ethylene glycol) (c-PEG) was found to significantly interact with bovine serum albumin (BSA), suggested by nuclear magnetic resonance, dynamic light scattering, and fluorescence spectroscopy. On the other hand, linear HO-PEG-OH and MeO-PEG-OMe showed no affinity. Furthermore, a complex of gold nanoparticles and c-PEG (AuNPs/c-PEG) attracted BSA to form aggregates, and the red color of the AuNPs dispersion evidently disappeared, whereas ones with linear PEG or without PEG did not demonstrate such a phenomenon. The interactions among BSA, AuNPs, and PEG were investigated by changing the incubation time and concentration of the components by using UV-Vis and fluorescence spectroscopy.
  • Hiroyuki Kono, Eiki Tsukamoto, Kenji Tajima
    ACS Omega 6 49 34107 - 34114 2021年12月01日 [査読有り][通常論文]
  • Saburo Kobayashi, Mayoh Ashiya, Takuya Yamamoto, Kenji Tajima, Yasunori Yamamoto, Takuya Isono, Toshifumi Satoh
    Polymers 13 23 4168 - 4168 2021年11月28日 [査読有り][通常論文]
     
    Herein, we report the Suzuki–Miyaura catalyst-transfer polycondensation (SCTP) of triolborate-type carbazole monomers, i.e., potassium 3-(6-bromo-9-(2-octyldodecyl)-9H-carbazole-2-yl)triolborate (M1) and potassium 2-(7-bromo-9-(2-octyldodecyl)-9H-carbazole-2-yl) triolborate (M2), as an efficient and versatile approach for precisely synthesizing poly[9-(2-octyldodecyl)-3,6-carbazole] (3,6-PCz) and poly[9-(2-octyldodecyl)-2,7-carbazole] (2,7-PCz), respectively. The SCTP of triolborate-type carbazole monomers was performed in a mixture of THF/H2O using an initiating system consisted of 4-iodobenzyl alcohol, Pd2(dba)3•CHCl3, and t-Bu3P. In the SCTP of M1, cyclic by-product formation was confirmed, as reported for the corresponding pinacolboronate-type monomer. By optimizing the reaction temperature and reaction time, we successfully synthesized linear end-functionalized 3,6-PCz for the first time. The SCTP of M2 proceeded with almost no side reaction, yielding 2,7-PCz with a functional initiator residue at the α-chain end. Kinetic and block copolymerization experiments demonstrated that the SCTP of M2 proceeded in a chain-growth and controlled/living polymerization manner. This is a novel study on the synthesis of 2,7-PCz via SCTP. By taking advantage of the well-controlled nature of this polymerization system, we demonstrated the synthesis of high-molecular-weight 2,7-PCzs (Mn = 5–38 kg mol−1) with a relatively narrow ÐM (1.35–1.48). Furthermore, we successfully synthesized fluorene/carbazole copolymers as well as 2,7-PCz-containing diblock copolymers, demonstrating the versatility of the present polymerization system as a novel synthetic strategy for well-defined polycarbazole-based materials.
  • Ryo Takahama, Honami Kato, Kenji Tajima, Satomi Tagawa, Tetsuo Kondo
    Biomacromolecules 22 11 4709 - 4719 2021年11月08日 [査読有り][通常論文]
     
    Naturally occurring polysaccharides, such as cellulose, hemicellulose, and chitin, have roles in plant skeletons and/or related properties in living organisms. Their hierarchically regulated production systems show potential for designing nanocomposite fabrication using engineered microorganisms. This study has demonstrated that genetically engineered Gluconacetobacter hansenii (G. hansenii) individual cells can fabricate naturally composited nanofibrils by simultaneous production of hyaluronan (HA) and bacterial cellulose (BC). The cells were manipulated to contain hyaluronan synthase and UDP-glucose dehydrogenase genes, which are essential for HA biosynthesis. Fluorescence microscopic observations indicated the production of composited nanofibrils and suggested that HA secretion was associated with the cellulose secretory pathway in G. hansenii. The gel-like nanocomposite materials produced by the engineered G. hansenii exhibited superior properties compared with conventional in situ nanocomposites. This genetic engineering approach facilitates the use of G. hansenii for designing integrated cellulose-based nanomaterials.
  • Yoshinobu Mato, Maho Sudo, Hironori Marubayashi, Brian J. Ree, Kenji Tajima, Takuya Yamamoto, Hiroshi Jinnai, Takuya Isono, Toshifumi Satoh
    Macromolecules 54 19 9079 - 9090 2021年10月12日 [査読有り][通常論文]
  • Satoshi Katsuhara, Yasuko Takagi, Naoki Sunagawa, Kiyohiko Igarashi, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    ACS Sustainable Chemistry & Engineering 9 29 9779 - 9788 2021年07月08日 [査読有り][通常論文]
     
    Herein, we compared the microphase-separation behavior and mechanical properties of cellulose- and amylose-based block copolymers (BCPs). Various cellooligosaccharide triacetate-b-poly(δ-decanolactone)-b-cellooligosaccharide triacetates (AcCeln-b-PDL-b-AcCelns), which are cellulose-based ABA-type BCPs, with PDL molecular weights of approximately 5, 10, and 20 kg mol-1and PDL volume fractions of 0.65, 0.77, and 0.87, were synthesized from α,ω-diazido-end-functionalized PDLs and propargyl-end-functionalized cellooligosaccharide triacetates via click chemistry. We adopted the cellodextrin-phosphorylase-mediated oligomerization of α-glucose-1-phosphase in the presence of a propargyl-end-functionalized cellobiose primer to synthesize the functional cellooligosaccharide segment. The maltooligosaccharide triacetate-b-poly(δ-decanolactone)-b-maltooligosaccharide triacetate (AcMaln-b-PDL-b-AcMalns) amylose counterparts were also synthesized in a similar manner. Small-angle X-ray scattering experiments and atomic force microscopy revealed that AcCeln-b-PDL-b-AcCelns are more likely to microphase-separate into ordered nanostructures compared to AcMaln-b-PDL-b-AcMalns, despite their comparable chemical compositions and molecular weights. Furthermore, AcCeln-b-PDL-b-AcCelns exhibited significantly superior mechanical performance compared to their amylose counterparts under tensile testing, with Young’s modulus and stress at break of AcCeln-b-PDL10k-b-AcCelnbeing 2.3 and 1.8 times higher, respectively, than those of AcMaln-b-PDL10k-b-AcMaln. The enhanced microphase-separation and mechanical properties of AcCeln-b-PDL-b-AcCelns were found to be attributable to the stiffness and crystalline nature of the AcCelnsegments. These results demonstrate the advantages of using cellulose derivatives to synthesize novel biofunctional materials.
  • Kodai Watanabe, Noya Kaizawa, Brian J. Ree, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    Angewandte Chemie International Edition 60 33 18122 - 18128 2021年07月08日 [査読有り][通常論文]
  • Hidenori Ando, Takashi Mochizuki, Amr S. Abu Lila, Shunsuke Akagi, Kenji Tajima, Kenji Fujita, Taro Shimizu, Yu Ishima, Tokuo Matsushima, Takatomo Kusano, Tatsuhiro Ishida
    Nanomaterials 11 7 1697 - 1697 2021年06月28日 [査読有り][通常論文]
     
    Natural materials such as bacterial cellulose are gaining interest for their use as drug-delivery vehicles. Herein, the utility of nanofibrillated bacterial cellulose (NFBC), which is produced by culturing a cellulose-producing bacterium (Gluconacetobacter intermedius NEDO-01) in a medium supplemented with carboxymethylcellulose (CMC) that is referred to as CM-NFBC, is described. Recently, we demonstrated that intraperitoneal administration of paclitaxel (PTX)-containing CM-NFBC efficiently suppressed tumor growth in a peritoneally disseminated cancer xenograft model. In this study, to confirm the applicability of NFBC in cancer therapy, a chemotherapeutic agent, doxorubicin (DXR), embedded into CM-NFBC, was examined for its efficiency to treat a peritoneally disseminated gastric cancer via intraperitoneal administration. DXR was efficiently embedded into CM-NFBC (DXR/CM-NFBC). In an in vitro release experiment, 79.5% of DXR was released linearly into the peritoneal wash fluid over a period of 24 h. In the peritoneally disseminated gastric cancer xenograft model, intraperitoneal administration of DXR/CM-NFBC induced superior tumor growth inhibition (TGI = 85.5%) by day 35 post-tumor inoculation, compared to free DXR (TGI = 62.4%). In addition, compared with free DXR, the severe side effects that cause body weight loss were lessened via treatment with DXR/CM-NFBC. These results support the feasibility of CM-NFBC as a drug-delivery vehicle for various anticancer agents. This approach may lead to improved therapeutic outcomes for the treatment of intraperitoneally disseminated cancers.
  • Tomohisa Watanabe, Satoru Chimura, Yubo Wang, Tomoko Ono, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Daichi Ida, Takuya Yamamoto
    Langmuir 37 23 6974 - 6984 2021年05月28日 [査読有り][通常論文]
  • Shunsuke Akagi, Hidenori Ando, Kenji Fujita, Taro Shimizu, Yu Ishima, Kenji Tajima, Tokuo Matsushima, Takatomo Kusano, Tatsuhiro Ishida
    International Journal of Biological Macromolecules 174 494 - 501 2021年03月 [査読有り][通常論文]
  • Li-Che Hsu, Takuya Isono, Yan-Cheng Lin, Saburo Kobayashi, Yun-Chi Chiang, Dai-Hua Jiang, Chih-Chien Hung, Ender Ercan, Wei-Chen Yang, Hui-Ching Hsieh, Kenji Tajima, Toshifumi Satoh, Wen-Chang Chen
    ACS applied materials & interfaces 13 2 2932 - 2943 2021年01月20日 [査読有り]
     
    The mechanical properties and structural design flexibility of charge-trapping polymer electrets have led to their widespread use in organic field-effect transistor (OFET) memories. For example, in the electrets of polyfluorene-based conjugated/insulating block copolymers (BCPs), the confined fiberlike polyfluorene nanostructures in the insulating polymer matrix act as effective hole-trapping sites, leading to controllable memory performance through the design of BCPs. However, few studies have reported intrinsically stretchable charge-trapping materials and their memory device applications, and a practical method to correlate the thin-film morphology of BCP electrets with their charge-trapping ability has not yet been developed. In this study, a series of new conjugated/insulating BCPs, poly(9,9-di-n-hexyl-2,7-fluorene)-block-poly(δ-decanolactone)s (PF-b-PDL x , x = 1-3), as stretchable hole-trapping materials are reported. The linear and branched PDL blocks with comparable molecular weights were used to investigate the effect of polymer architecture on morphology and device performance. Moreover, the coverage area of the polyfluorene nanofibers on the BCP films was extracted from atomic force microscopy images, which can be correlated with the trapping density of the polymer electrets. The branched PDL segments not only improve stretchability but also tailor crystallinity and phase separation of the BCPs, thus increasing their charge-trapping ability. The OFET memory device with PF-b-PDL3 as the electret layer exhibited the largest memory window (102 V) and could retain its performance at up to 100% strain. This research highlights the importance of the BCP design for developing stretchable charge-trapping materials.
  • Takuya Uto, Yuki Ikeda, Naoki Sunagawa, Kenji Tajima, Min Yao, Toshifumi Yui
    Journal of Chemical Theory and Computation 17 1 488 - 496 2020年12月31日 [査読有り][通常論文]
  • Yubo Wang, Jose Enrico Q. Quinsaat, Tomoko Ono, Masatoshi Maeki, Manabu Tokeshi, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Shin-ichiro Sato, Yutaka Miura, Takuya Yamamoto
    Nature Communications 11 1 2020年11月30日 [査読有り][通常論文]
     
    Abstract Nano-sized metal particles are attracting much interest in industrial and biomedical applications due to the recent progress and development of nanotechnology, and the surface-modifications by appropriate polymers are key techniques to stably express their characteristics. Herein, we applied cyclic poly(ethylene glycol) (c-PEG), having no chemical inhomogeneity, to provide a polymer topology-dependent stabilization for the surface-modification of gold nanoparticles (AuNPs) through physisorption. By simply mixing c-PEG, but not linear counterparts, enables AuNPs to maintain dispersibility through freezing, lyophilization, or heating. Surprisingly, c-PEG endowed AuNPs with even better dispersion stability than thiolated PEG (HS–PEG–OMe). The stronger affinity of c-PEG was confirmed by DLS, ζ-potential, and FT-IR. Furthermore, the c-PEG system exhibited prolonged blood circulation and enhanced tumor accumulation in mice. Our data suggests that c-PEG induces physisorption on AuNPs, supplying sufficient stability toward bio-medical applications, and would be an alternative approach to the gold–sulfur chemisorption.
  • Kono, H., Uno, T., Tsujisaki, H., Matsushima, T., Tajima, K.
    ACS Omega 5 45 29561 - 29569 2020年11月17日 [査読有り][通常論文]
  • Saburo Kobayashi, Kaiyu Fujiwara, Dai-Hua Jiang, Takuya Yamamoto, Kenji Tajima, Yasunori Yamamoto, Takuya Isono, Toshifumi Satoh
    Polymer Chemistry 11 42 6832 - 6839 2020年10月09日 [査読有り][通常論文]
     

    In this study, we demonstrated that the Suzuki–Miyaura catalyst transfer polycondensation (SCTP) of the triolborate-type fluorene monomer, viz. potassium 2-(7-bromo-9,9-dihexyl-9H-fluorene-2-yl)triolborate, can be an efficient and versatile approach to the precise...

  • Takuya Isono, Ryoya Komaki, Chaehun Lee, Nao Kawakami, Brian J. Ree, Kodai Watanabe, Kohei Yoshida, Hiroaki Mamiya, Takuya Yamamoto, Redouane Borsali, Kenji Tajima, Toshifumi Satoh
    Communications Chemistry 3 1 2020年10月09日 [査読有り][通常論文]
     
    Abstract Discrete block co-oligomers (BCOs) are gaining considerable attention due to their potential to form highly ordered ultrasmall nanostructures suitable for lithographic templates. However, laborious synthetic routes present a major hurdle to the practical application. Herein, we report a readily available discrete BCO system that is capable of forming various self-assembled nanostructures with ultrasmall periodicity. Click coupling of propargyl-functionalized sugars (containing 1–7 glucose units) and azido-functionalized terpenoids (containing 3, 4, and 9 isoprene units) afforded the discrete and monodisperse BCOs with a desired total degree of polymerization and block ratio. These BCOs microphase separated into lamellar, gyroid, and cylindrical morphologies with the domain spacing (d) of 4.2–7.5 nm. Considering easy synthesis and rich phase behavior, presented BCO systems could be highly promising for application to diverse ~4-nm nanofabrications.
  • Kaoru Takojima, Hiroshi Makino, Tatsuya Saito, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    Polymer Chemistry 11 39 6365 - 6373 2020年09月07日 [査読有り][通常論文]
     

    Highly regioselective ring-opening polymerization of optically active methylglycolides was achived using P2-t-Bu/alcohol system to produce alternating copolymer of lactic acid and glycolic acid.

  • Kono, H., Uno, T., Tsujisaki, H., Anai, H., Kishimoto, R., Matsushima, T., Tajima, K.
    ACS Applied Nano Materials 3 8 8232 - 8241 2020年08月14日 [査読有り][通常論文]
  • Kodai Watanabe, Satoshi Katsuhara, Hiroaki Mamiya, Yukihiko Kawamura, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    Nanoscale 12 31 16526 - 16534 2020年08月13日 [査読有り][通常論文]
     
    The highly asymmetric lamellar (A-LAM) nanostructure is one of the most important template geometries for block copolymer (BCP) lithography. However, A-LAM is unattainable from conventional BCPs, and there is no general molecular design strategy for A-LAM-forming BCP. Herein, a nanoparticle-linear hybrid BCP system is reported, which is designed based on the intramolecular crosslinking technique, as a remarkably effective platform to obtain the A-LAM morphology. The hybrid BCPs consisting of polystyrene single-chain nanoparticles and linear polylactide segments show a remarkable capability to form the A-LAM morphology in bulk, where a maximum width ratio of 4.1 between the two domains is obtained. This unusual phase behavior is attributed to the bulky and rigid characteristics of the nanoparticle block. Furthermore, the thin films of these hybrid BCPs show perpendicularly oriented A-LAM morphology on a chemically modified Si substrate, allowing promising application in the fabrication of asymmetric line-and-space nanopatterns.
  • Yoshinobu Mato, Kohei Honda, Brian J. Ree, Kenji Tajima, Takuya Yamamoto, Tetsuo Deguchi, Takuya Isono, Toshifumi Satoh
    Communications Chemistry 3 1 2020年08月04日 [査読有り][通常論文]
  • Mumtaz, M., Takagi, Y., Mamiya, H., Tajima, K., Bouilhac, C., Isono, T., Satoh, T., Borsali, R.
    European Polymer Journal 134 109831 - 109831 2020年07月 [査読有り][通常論文]
  • Takuya Isono, Saki Nakahira, Hui-Ching Hsieh, Satoshi Katsuhara, Hiroaki Mamiya, Takuya Yamamoto, Wen-Chang Chen, Redouane Borsali, Kenji Tajima, Toshifumi Satoh
    Macromolecules 53 13 5408 - 5417 2020年06月16日 [査読有り][通常論文]
  • Kenji Tajima, Koutaro Tahara, Junya Ohba, Ryo Kusumoto, Ryota Kose, Hiroyuki Kono, Tokuo Matsushima, Koji Fushimi, Takuya Isono, Takuya Yamamoto, Toshifumi Satoh
    Biomacromolecules 21 2 581 - 588 2020年02月10日 [査読有り][通常論文]
     
    Nanofibrillated bacterial cellulose (NFBC) is produced by culturing a cellulose-producing bacterium under agitated aerobic conditions in a carboxymethylcellulose (CMC)-supplemented medium. Detailed structural analyses revealed that NFBC fiber widths varied with the degree of substitution of the CMC used, and zeta potential values decreased with the increment of CMC concentration in the medium. Transmission electron microscopy observation after immunostaining demonstrated that CMC molecules were present on the NFBC microfibril surfaces. We tested NFBC for utility as a binder for a display device that uses electrochromic (EC) material. Introduction of a quaternary ammonium group into the EC molecules enhanced their interactions with the negatively charged NFBC microfibrils. A casting process homogeneously adsorbed the EC molecules onto the surface of a transparent electrode with NFBC. A homogeneous color change was successfully observed upon applying an electric field, suggesting that NFBC could be used as a binder material for uniform surface adsorption.
  • Kaoru Takojima, Tatsuya Saito, Cedric Vevert, Viko Ladelta, Panayiotis Bilalis, Jun Watanabe, Shintaro Hatanaka, Takashi Konno, Takuya Yamamoto, Kenji Tajima, Nikos Hadjichristidis, Takuya Isono, Toshifumi Satoh
    Polymer Journal 52 1 103 - 110 2020年01月 [査読有り][通常論文]
  • Satoshi Katsuhara, Hiroaki Mamiya, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    Polymer Chemistry 11 17 2995 - 3002 2020年 [査読有り][通常論文]
     

    The novel high-χ BCPs comprising poly(vinyl ferrocene) and oligosaccharides formed hexagonal cylinder morphology with d values of ∼8 nm. Lamellar morphology with d values of ∼9 nm was also realized by mixing these polymers and glucose.

  • Numata, Y., Kono, H., Mori, A., Kishimoto, R., Tajima, K.
    Food Hydrocolloids 92 233 - 239 2019年07月 [査読有り][通常論文]
  • Yoshida, K., Yamamoto, T., Tajima, K., Isono, T., Satoh, T.
    Polymer Chemistry 10 24 3390 - 3398 2019年06月 [査読有り][通常論文]
     

    Various functional groups were incorporated into the inherently inactive ω-chain end of polymethacrylate-based polymers by terminal-selective transesterification.

  • Tatsuya Saito, Kaoru Takojima, Takafumi Oyama, Shintaro Hatanaka, Takashi Konno, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    ACS Sustainable Chemistry & Engineering 7 9 8868 - 8875 2019年05月06日 [査読有り][通常論文]
  • Takafumi Oyama, Shingo Kobayashi, Tetsuo Okura, Shunsuke Sato, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    ACS Sustainable Chemistry & Engineering 7 8 7969 - 7978 2019年04月15日 [査読有り][通常論文]
  • Kodai Watanabe, Satoshi Katsuhara, Hiroaki Mamiya, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    Chemical science 10 11 3330 - 3339 2019年03月21日 [査読有り][通常論文]
     
    A novel strategy for downsizing the feature of microphase-separated structures was developed via the intramolecular crosslinking reaction of block copolymers (BCPs) without changing the molecular weight. A series of BCPs consisting of poly[styrene-st-(p-3-butenyl styrene)] and poly(rac-lactide) (SBS-LA) was subjected to Ru-catalyzed olefin metathesis under highly diluted conditions to produce intramolecularly crosslinked BCPs (SBS(cl)-LAs). Small-angle X-ray scattering measurement and transmission electron microscopy observation of the SBS(cl)-LAs revealed feature size reduction in lamellar (LAM) and hexagonally close-packed cylinder (HEX) structures in the bulk state, which was surely due to the restricted chain dimensions of the intramolecularly crosslinked SBS block. Notably, the degree of size reduction was controllable by varying the crosslink density, with a maximum decrease of 22% in the LAM spacing. In addition, we successfully observed the downsizing of the HEX structure in the thin film state using atomic force microscopy, indicating the applicability of the present methodology to next-generation lithography technology.
  • Isono, T., Kawakami, N., Watanabe, K., Yoshida, K., Otsuka, I., Mamiya, H., Ito, H., Yamamoto, T., Tajima, K., Borsali, R., Satoh, T.
    Polymer Chemistry 10 9 1119 - 1129 2019年03月 [査読有り][通常論文]
     

    Star-block copolymers consisting of polycaprolactone and maltotriose segments with three, four, and six arms were synthesized to achieve sub-10 nm microphase-separated structures.

  • Yoshinobu Mato, Kohei Honda, Kenji Tajima, Takuya Yamamoto, Takuya Isono, Toshifumi Satoh
    Chemical science 10 2 440 - 446 2019年01月14日 [査読有り][通常論文]
     
    Cage-shaped polymers, or "macromolecular cages", are of great interest as the macromolecular analogues of molecular cages because of their various potential applications in supramolecular chemistry and materials science. However, the systematic synthesis of macromolecular cages remains a great challenge. Herein, we describe a robust and versatile synthetic strategy for macromolecular cages with defined arm numbers and sizes based on the intramolecular consecutive cyclization of highly reactive norbornene groups attached to each end of the arms of a star-shaped polymer precursor. The cyclizations of three-, four-, six-, and eight-armed star-shaped poly(ε-caprolactone)s (PCLs) bearing a norbornenyl group at each arm terminus were effected with Grubbs' third generation catalyst at high dilution. 1H NMR, SEC, and MALDI-TOF MS analyses revealed that the reaction proceeded to produce the desired macromolecular cages with sufficient purity. The molecular sizes of the macromolecular cages were controlled by simply changing the molecular weight of the star-shaped polymer precursors. Systematic investigation of the structure-property relationships confirmed that the macromolecular cages adopt a much more compact conformation, in both the solution and bulk states, as compared to their linear and star-shaped counterparts. This synthetic approach marks a significant advance in the synthesis of complex macromolecular architectures and provides a platform for novel applications using cage-shaped molecules with polymer frameworks.
  • Yoshida, K., Tanaka, S., Yamamoto, T., Tajima, K., Borsali, R., Isono, T., Satoh, T.
    Macromolecules 51 21 8870 - 8877 2018年11月13日 [査読有り][通常論文]
  • Takuya Yamamoto, Masaaki Hosokawa, Minato Nakamura, Shin-ichiro Sato, Takuya Isono, Kenji Tajima, Toshifumi Satoh, Masamichi Sato, Yasuyuki Tezuka, Akinori Saeki, Yoshihiro Kikkawa
    Macromolecules 51 22 9284 - 9293 2018年11月 [査読有り][通常論文]
  • Yoshida, K., Tian, L., Miyagi, K., Yamazaki, A., Mamiya, H., Yamamoto, T., Tajima, K., Isono, T., Satoh, T.
    Macromolecules 51 20 8064 - 8072 2018年10月23日 [査読有り][通常論文]
  • Tomoki Shingu, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    Polymers 10 8 877  2018年08月06日 [査読有り][通常論文]
     
    Cyclic polymers exhibit unique physical and chemical properties because of the restricted chain mobility and absence of chain ends. Although many types of homopolymers and diblock copolymers possessing cyclic architectures have been synthesized to date, there are relatively few reports of cyclic triblock terpolymers because of their synthetic difficulties. In this study, a novel synthetic approach for μ-ABC tricyclic miktoarm star polymers involving t-Bu-P₄-catalyzed ring-opening polymerization (ROP) of glycidyl ethers and intramolecular copper-catalyzed azido-alkyne cycloaddition (CuAAC) was developed. First, the t-Bu-P₄-catalyzed ROP of decyl glycidyl ether, dec-9-enyl glycidyl ether, and 2-(2-(2-methoxyethoxy) ethoxy) ethyl glycidyl ether with the aid of functional initiators and terminators was employed for the preparation of a clickable linear triblock terpolymer precursor possessing three azido and three ethynyl groups at the selected positions. Next, the intramolecular CuAAC of the linear precursor successfully produced the well-defined tricyclic triblock terpolymer with narrow dispersity in a reasonable yield. The present strategy is useful for synthesizing model polymers for studying the topological effects on the triblock terpolymer self-assembly.
  • Takuya Isono, Tetsuya Sasamori, Kohei Honda, Yoshinobu Mato, Takuya Yamamoto, Kenji Tajima, Toshifumi Satoh
    Macromolecules 51 10 3855 - 3864 2018年05月22日 [査読有り][通常論文]
     
    A novel synthesis of multicyclic polymers that feature ultradense arrays of cyclic polymer units has been developed by exploiting the cyclopolymerization of α,ω-norbornenyl end-functionalized macromonomers mediated by the Grubbs third-generation catalyst (G3). Owing to the living polymerization nature, the number of cyclic repeating units in these multicyclic polymers was controlled to be between 1 and approximately 70 by varying the initial macromonomer-to-G3 ratio. The ring size was also tuned by choosing the molecular weight of the macromonomer in this way we successfully prepared multicyclic polymers that possess cyclic repeating units composed of up to about 500 atoms, which by far exceeds those prepared to date by cyclopolymerization. Specifically, cyclopolymerizations of α,ω-norbornenyl end-functionalized poly(l-lactide)s (PLLAs) proceeded homogeneously under highly dilute conditions (∼0.1 mM in CH2Cl2) to give multicyclic polymers that feature cyclic PLLA repeating units on the polynorbornene backbone. The cyclic product architectures were confirmed not only by structural characterization based on NMR, MALDI-TOF MS, and SEC analyses but also by comparing their glass transition temperatures, viscosities, and hydrodynamic radii with their acyclic counterparts. The cyclopolymerization strategy was applicable to a variety of α,ω-norbornenyl end-functionalized macromonomers, such as poly(ϵ-caprolactone), poly(ethylene glycol) (PEG), poly(tetrahydrofuran), and PLLA-b-PEG-b-PLLA. The successful statistical and block cyclocopolymerizations of the PLLA and PEG macromonomers gave amphiphilic multicyclic copolymers.
  • Tatsuya Saito, Yusuke Aizawa, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    Macromolecules 51 3 689 - 696 2018年02月13日 [査読有り][通常論文]
     
    Alkali metal carboxylates were discovered as efficient and simple catalysts for the ring-opening polymerization of cyclic esters that are alternatives to conventional metal-based catalysts and organocatalysts. In our system using an alcohol initiator and this simple catalyst, biodegradable and biocompatible aliphatic polyesters, such as poly(lactide), poly(e-caprolactone), poly(δ-valerolactone), and poly(trimethylene carbonate), were obtained with predictive molecular weights ranging from 3500 to 22-600 and narrow dispersities. A kinetic experiment for the ROP of l-lactide confirmed the controlled/living nature of the present ROP system, which allowed the precise synthesis of end-functionalized polyesters as well as multihydroxyl-containing polyesters, including α,hydroxy telechelic and star-shaped polyesters. Furthermore, a block copolymer containing the poly(l-lactide) segment was successfully synthesized using a macroinitiator possessing a hydroxyl group at the chain end. The tunability of the alkali metal carboxylates by the appropriate choice of the alkyl moiety and countercation enables not only control of the polymerization behavior but also expansion of the scope of the applicable monomers. Given the low cost, easy handling, and low toxicity of the alkali metal carboxylates, the present ROP system can be highly promising for both laboratory- and industrial-scale polyester productions.
  • Takuya Isono, Brian J. Ree, Kenji Tajima, Redouane Borsali, Toshifumi Satoh
    Macromolecules 51 2 428 - 437 2018年01月23日 [査読有り][通常論文]
     
    Microphase-separated structures of block copolymers (BCPs) have attracted considerable attention for their potential application in the bottom-up fabrication of 10 nm scale nanostructured materials. To realize sustainable development within this field, the creation of novel BCP materials from renewable biomass resources is of fundamental interest. Thus, we herein focused on maltoheptaose-b-poly(δ-decanolactone)-b-maltoheptaose (MH-b-PDL-b-MH) as a sustainable alternative for nanostructure-forming BCPs, in which both constitutional blocks can be derived from renewable biomass resources, in the case, δ-decanolactone and amylose. Well-defined MH-b-PDL-b-MHs with varying PDL lengths were synthesized through a combination of controlled/living ring-opening polymerization and the click reaction. The prepared MH-b-PDL-b-MHs successfully self-assembled into highly ordered hexagonal cylindrical structures with a domain-spacing of ∼12-14 nm in both the bulk and thin film states. Interestingly, the as-cast thin films of MH-b-PDL-b-MHs (with PDL lengths of 9K and 13K) form horizontal cylinders, with thermal annealing (180 °C, 30 min) resulting in a drastic change in the domain orientation from horizontal to vertical. Thus, the results presented herein demonstrated that the combination of oligosaccharides and biomass-derived hydrophobic polymers appears promising for the sustainable development of nanotechnology and related fields.
  • Shingo Nojima, Ayumi Fujishima, Koji Kato, Kayoko Ohuchi, Nobutaka Shimizu, Kento Yonezawa, Kenji Tajima, Min Yao
    Scientific reports 7 1 13018 - 13018 2017年10月12日 [査読有り][通常論文]
     
    Bacterial cellulose (BC) is synthesized and exported through the cell membrane via a large protein complex (terminal complex) that consists of three or four subunits. BcsC is a little-studied subunit considered to export BC to the extracellular matrix. It is predicted to have two domains: a tetratrico peptide repeat (TPR) domain and a β-barrelled outer membrane domain. Here we report the crystal structure of the N-terminal part of BcsC-TPR domain (Asp24-Arg272) derived from Enterobacter CJF-002. Unlike most TPR-containing proteins which have continuous TPR motifs, this structure has an extra α-helix between two clusters of TPR motifs. Five independent molecules in the crystal had three different conformations that varied at the hinge of the inserted α-helix. Such structural feature indicates that the inserted α-helix confers flexibility to the chain and changes the direction of the TPR super-helix, which was also suggested by structural analysis of BcsC-TPR (Asp24-Leu664) in solution by size exclusion chromatography-small-angle X-ray scattering. The flexibility at the α-helical hinge may play important role for exporting glucan chains.
  • Kenji Tajima, Ryo Kusumoto, Ryota Kose, Hiroyuki Kono, Tokuo Matsushima, Takuya Isono, Takuya Yamamoto, Toshifumi Satoh
    Biomacromolecules 18 10 3432 - 3438 2017年10月09日 [査読有り][通常論文]
     
    Nanofibrillated bacterial cellulose (NFBC) is produced by culturing a cellulose-producing bacterium (Gluconacetobacter intermedius NEDO-01) with rotation or agitation in medium supplemented with carboxymethylcellulose (CMC). Despite a high yield and dispersibility in water, the product immediately aggregates in organic solvents. To broaden its applicability, we prepared amphiphilic NFBC by culturing strain NEDO-01 in medium supplemented with hydroxyethylcellulose or hydroxypropylcellulose instead of CMC. Transmission electron microscopy analysis revealed that the resultant materials (HE-NFBC and HP-NFBC, respectively) comprised relatively uniform fibers with diameters of 33 ± 7 and 42 ± 8 nm, respectively. HP-NFBC was dispersible in polar organic solvents such as methanol, acetone, isopropyl alcohol, acetonitrile, tetrahydrofuran (THF), and dimethylformamide, and was also dispersible in poly(methyl methacrylate) (PMMA) by solvent mixing using THF. HP-NFBC/PMMA composite films were highly transparent and had a higher tensile strength than neat PMMA film. Thus, HP-NFBC has a broad range of applications, including as a filler material.
  • Yukari Numata, Hiroyuki Kono, Minato Tsuji, Kenji Tajima
    CARBOHYDRATE POLYMERS 173 67 - 76 2017年10月 [査読有り][通常論文]
     
    This study explores the structural and mechanical properties of bacterial cellulose-polyethylene glycol diacrylate (BC-PEGDA) composite gels. The molecular dynamics results obtained by solid-state (13) C nuclear magnetic resonance analyses suggested that BC and PEGDA molecules were incompatible as composite gels, though BC fibers and PEGDA interact with each other. The mechanical strength of the gels depended on the amount of PEGDA, becoming softer and more stretchable when a tensile force was applied, but for a large amount of PEGDA, they became brittle. The BC-3% and 5% PEGDA gels had similar viscoelastic behaviors as a BC gel, and these composite gels could stick to human skin. Since BC-PEGDA composite gels are composed of BC and PEGDA-both of which are biocompatible, it is thought that these composite gels also have excellent biocompatibility. Taken together, we concluded that the BC-3% and 5% PEGDA gels have great potential for use in medical and cosmetic fields. (C) 2017 Elsevier Ltd. All rights reserved.
  • Ryoto Tanaka, Kodai Watanabe, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    POLYMER CHEMISTRY 8 23 3647 - 3656 2017年06月 [査読有り][通常論文]
     
    The effect of intramolecular cross-linking in an amphiphilic block copolymer (BCP) system was systematically investigated in terms of its thermal properties, critical micelle concentration (CMC), and aqueous self-assembly. A series of linear BCPs consisting of poly(ethylene glycol) (PEG) as a hydrophilic block and poly(epsilon-caprolactone-co-7-allyloxepan-2-one) (P(CL-co-ACL)) as a hydrophobic block were prepared by the ring-opening copolymerization of epsilon-caprolactone (CL) and 7-allyloxepan-2-one (ACL) using poly (ethylene glycol) monomethyl ether as an initiator. The intramolecular olefin metathesis reaction in the P(CL-co-ACL) block was subsequently carried out under various conditions to prepare the cross-linked BCPs with different degrees of cross-linking. The thermal analysis confirmed that the linear P(CL-co-ACL) block was found to crystallize, while the cross-linked one showed no crystallinity. In addition, glass transition temperature of the P(CL-co-ACL) block increased upon cross-linking. On the other hand, the intramolecular cross-linking had no significant influence on the CMC. The self-assembled micelles were prepared from the obtained BCPs and their size and morphology were investigated. For the BCPs with relatively short PEG chains, the micellar size decreased from 36.6 nm to 16.7 nm as the degree of cross-linking of the P(CL-co-ACL) block increased. On the other hand, the BCPs with relatively long PEG chains showed a change in the micellar morphology from spherical micelles to short worm and large compound micelles upon cross-linking.
  • Hiroyuki Kono, Sayaka Fujita, Kenji Tajima
    CARBOHYDRATE POLYMERS 157 728 - 738 2017年02月 [査読有り][通常論文]
     
    Methylcellulose samples with different degrees of substitution were prepared by a heterogeneous reaction of cellulose. Two-dimensional NMR spectroscopy provided complete assignment of the H-1 and C-13 chemical shifts of the un-, 2-mono-, 3-mono-, 6-mono-, 2,3-di-, 2,6-di-, 3,6-di-, and 2,3,6-tri-substituted anhydroglucose units (AGUs). Comparative analysis of the chemical shift data revealed the relationship between the methyl substituents at the 2-, 3-, and 6-positions and the 1H and 13C chemical shifts of the AGUs; additivity could be applied to the H-1 and C-13 chemical shifts of methylcellulose. Quantitative C-13 NMR spectra of the samples determined the composition of the eight AGUs and the substituent distribution at the 2-, 3-, and 6-positions of cellulose. This provided estimations of the hydroxyl group reactivity toward methylation and the interactions between the substituent groups within the same AGU. (C) 2016 Elsevier Ltd. All rights reserved.
  • Yusuke Satoh, Hirohiko Matsuno, Takuya Yamamoto, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    MACROMOLECULES 50 1 97 - 106 2017年01月 [査読有り][通常論文]
     
    This paper describes a novel synthetic approach for three- and four-armed cage-shaped polymers based on the topological conversion of the corresponding trefoil- and quatrefoil-shaped precursors. The trefoil- and quatrefoil-shaped polymers were synthesized by the following three reaction steps: (1) the t-Bu-P-4-catalyzed ring-opening polymerization of butylene oxide using multiple hydroxy- and azido-functionalized initiators to produce the three- or four-armed star-shaped polymers possessing three or four azido groups at the focal point, respectively, (2) the omega-end modification to install a propargyl group at each chain end, and (3) the intramolecular multiple click cyclization of the clickable star-shaped precursors. The topological conversion from the trefoil- and quatrefoil-shaped polymers to the cage-shaped polymers was achieved by the catalytic hydrogenolysis of the benzyl ether linkages that had been installed at the focal point. The amphiphilic cage-shaped block copolymers together with the corresponding trefoil- and quatrefoil-shaped counterparts were synthesized in a similar way using 2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether as a hydrophilic monomer and decyl glycidyl ether as a hydrophobic monomer. Interestingly, significant changes in the critical micelle concentration and micellar morphology were observed for the amphiphilic block copolymers upon the topological conversion from the trefoil- and quatrefoil-shaped to cage-shaped architectures.
  • Naoki Sunagawa, Kenji Tajima, Masahiro Samejima, Kiyohiko Igarashi
    Kobunshi 66 6 288 - 289 2017年 [査読有り][通常論文]
     
    Cellulose is one of the major carbohydrate on the earth and is utilized in humankind life as a major component of plant materials. Most of terrestrial cellulose is produced by land plant, however it is also found in some algae, tunicates and various bacteria species. Since cellulose biosynthetic process is a complicated system, details are still unknown. To solve this issue, we attempt to make a heterogonous expression system and trying a dynamic visualization of this synthesis process. In this paper, to carry out the approaches, we will report the construction of the recombinant expression system of bacterial cellulose synthase (GrCeSAB) and plant cellulose synthase (AtCeSA1) in the yeast Pichia pastoris.
  • Kenji Tajima, Xuerong Han, Yoshiki Hashimoto, Yasuharu Satoh, Toshifumi Satoh, Seiichi Taguchi
    Journal of bioscience and bioengineering 122 6 660 - 665 2016年12月 [査読有り][通常論文]
     
    Thermostable enzymes are required for the rapid and sustainable production of polyhydroxyalkanoate (PHA) in vitro. The in vitro synthesis of PHA using the engineered thermostable synthase PhaC1(SG)(STQK) has been reported; however, the non-thermostable enzymes acetyl-CoA synthetase (ACS) and CoA transferase (CT) from mesophilic strains were used as monomer-supplying enzymes in this system. In the present study, acs and ct were cloned from the thermophilic bacteria Pelotomaculum thermopropionicum JCM10971 and Thermus thermophilus JCM10941 to construct an in vitro PHA synthesis system using only thermostable enzymes. ACS from P. thermopropionicum (ACS(Pt)) and CT from I thermophilus (CTTt) were confirmed to have high thermostability, and their optimal temperatures were around 60 degrees C and 75 degrees C, respectively. The in vitro PHA synthesis was successfully performed by ACS(Pt), CTTt, PhaC1(SG)(STQK), and poly(3-hydroxybutyrate) [P(3HB)] was synthesized at 45 degrees C. Furthermore, the yields of P(3HB) and P(lactate-co-3HB) at 37 degrees C were 1.4-fold higher than those of the in vitro synthesis system with non-thermostable ACS and CT from mesophilic strains. Overall, the thermostable ACS and CT were demonstrated to be useful for the efficient in vitro PHA synthesis at relatively high temperatures. (C) 2016, The Society for Biotechnology, Japan. All rights reserved.
  • Hiroyuki Kono, Kazuhiro Oshima, Hisaho Hashimoto, Yuuichi Shimizu, Kenji Tajima
    CARBOHYDRATE POLYMERS 150 241 - 249 2016年10月 [査読有り][通常論文]
     
    The chemical shifts of the substituent groups of sodium carboxymethyl cellulose (CMC) were assigned by examining a series of CMC samples with different degrees of substitution. Comparative analysis of the H-1-C-13 heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) spectra allowed the complete assignment of the substituent groups at the 2-, 3-, and 6 -positions of the seven substituted monomers comprising the CMC chains, namely, 2 -mono-, 3 -mono-, 6-mono, 2,3 -di-, 2,6 -di-, 3,6 -di-, and 2,3,6-tri-substituted anhydroglucose units (AGUs). In addition, the mole fractions of the monomers were determined by lineshape analysis of the carbonyl carbon resonances. The comparison between the chemical shifts of the substituents revealed strong interactions between 2 and 3-substituents in the same AGU, and showed that the steric hindrance by a substituent at the 2- or 3-position suppresses subsequent substitution at the adjacent position. (C) 2016 Elsevier Ltd. All rights reserved.
  • Hiroyuki Kono, Kazuhiro Oshima, Hisaho Hashimoto, Yuuichi Shimizu, Kenji Tajima
    CARBOHYDRATE POLYMERS 146 1 - 9 2016年08月 [査読有り][通常論文]
     
    A series of sodium carboxymethyl cellulose (CMC) samples with degrees of substitution (DS) from 0.68 to 2.84 were prepared from cellulose by multistep carboxymethylation. Two-dimensional NMR spectroscopic analyses allowed complete assignment of the H-1 and C-13 chemical shifts of the eight anhydroglucose units (AGUs) found in CMC: 2,3,6-tri-, 2,3-di-, 2,6-di-, 3,6-di-, 2-mono-, 3-mono-, 6-mono-, and unsubstituted AGUs. A comparative analysis of the chemical shift data revealed the substituent effects of the carboxymethyl groups at the 2-, 3-, and 6-positions on the H-1 and C-13 chemical shifts of the AGUs and that additivity could be applied to the H-1 and C-13 chemical shifts of CMC. Quantitative C-13 NMR spectra of the CMC samples allowed determination of the AGU composition, as well as the substituent distribution at the 2-, 3-, and 6-positions of cellulose, which allowed estimation of the reactivity of the hydroxyl groups toward the carboxymethylation. (C) 2016 Elsevier Ltd. All rights reserved.
  • Takuya Isono, Kana Miyachi, Yusuke Satoh, Ryosuke Nakamura, Yao Zhang, Issei Otsuka, Kenji Tajima, Toyoji Kakuchi, Redouane Borsali, Toshifumi Satoh
    MACROMOLECULES 49 11 4178 - 4194 2016年06月 [査読有り][通常論文]
     
    This paper describes the systematic investigation into the aqueous self-assembly of a series of block copolymers (BCPs) consisting of maltoheptaose (MH; as the A block) and poly(e-caprolactone) (PCL; as the B block), i.e., linear AB-type diblock copolymers with varied PCL molecular weights (MH-b-PC1-(2.5(k,3.3k,5k10k))), AB(y)-type = 2, MH-b(PCL5k) 2; y = 3, MH-b-(PCL3.3k)(3)), A(2)B(2)-type ((MH)(2)-b(PCL(5)k)(2)), and AxB-type miktoarm star polymers (x = 2, (MH)2-b-PCL10k; x = 3, (MH)(3)-b-PCLiok), which had been precisely synthesized via the combination of the living ring opening polymerization and click reaction. Under similar conditions, the nanoprecipitation method was employed to self -assemble them in an aqueous medium. Imaging and dynamic light scattering techniques indicated the successful formation of the carbohydrate -decorated nanoparticles via self -assembly. The MH-b-PCLs formed regular core shell micellar nanoparticles with the hydrodynamic "radius (Rh) of 17-43 nm. MH-b-(PCL5k)2 and MH-b-(PCL3.3k)(3), which have an NPCL comparable to MH-b-PCLiok, were found to form large compound micelles with relatively large radii (Rh of 49 and 56 nm, respectively). On the other hand, (MH),-b-(PCL5k),, (MH),-b-PCLiok, and (MH)3-bPCLiok predominantly formed the regular core shell micellar nanoparticles (Rh = 29-39 nm) with a size smaller than that of MH-b-PCLiok (Rh = 43 nm).
  • Kenji Tajima, Kosuke Iwamoto, Yasuharu Satoh, Ryosuke Sakai, Toshifumi Satoh, Tohru Dairi
    APPLIED MICROBIOLOGY AND BIOTECHNOLOGY 100 10 4375 - 4383 2016年05月 [査読有り][通常論文]
     
    Polyhydroxyalkanoates (PHAs) incorporating vinyl-bearing 3-hydroxyalkanoates were prepared in 8.5-12.9 g L-1 yield. The molar ratios (0-16 mol%) of the vinyl-bearing 3-hydroxyalkanoate derivatives were controlled by the continuous feeding of undecylenate at various concentrations. Subsequently, the PHAs were functionalized by UV-initiated thiol-ene click reaction and chemical modification. H-1 NMR spectra suggested that 3-mercaptopropionic acid and 2-aminoethanethiol were successfully introduced into the vinyl-bearing PHA. Subsequently, chemical modification using fluorescein or a fibronectin active fragment (GRGDS) was attempted. The former yielded a PHA derivative capable of emitting fluorescence under UV irradiation, which was useful for determining the miscibility of PHA in a composite film comprising poly-EY-lactic acid (PLLA) and PHA. In the latter case, PHA bearing GRGDS peptides exhibited cell adhesiveness, suggesting that its biocompatibility was improved upon peptide introduction. Taken together, the UV-initiated thiol-ene click reaction was demonstrated to be useful in PHA modification.
  • Yukari Numata, Shiro Masaki, Kenji Tajima
    POLYMER JOURNAL 48 3 317 - 321 2016年03月 [査読有り][通常論文]
  • Yusuke Satoh, Kana Miyachi, Hirohiko Matsuno, Takuya Isono, Kenji Tajima, Toyoji Kakuchi, Toshifumi Satoh
    MACROMOLECULES 49 2 499 - 509 2016年01月 [査読有り][通常論文]
     
    A comprehensive set of amphiphilic star-shaped block copolyethers with a fixed molecular weight and composition was synthesized via the t-Bu-P-4-catalyzed ring opening polymerization (ROP) of 2-(2-(2-methoxyethoxy)-ethoxy)ethyl glycidyl ether as a hydrophilic monomer and decyl glycidyl ether as a hydrophobic monomer. The three and four-armed star-block copolyethers, i.e., the (AB)(3)-, (BA)(3)-, (AB)(4)-, and (BA)(4)-type star-block copolyethers, where A and B represent hydrophilic and hydrophobic blocks, respectively, were synthesized by the sequential t-Bu-P-4-catalyzed block copolymerization using tri- and tetra-alcohol initiators, respectively, according to the core-first method. The homogeneous growth of each arm was confirmed by cleaving the linkages between the initiator residue and polyether arms. The synthesis of the A(2)B(2)-, AB(2)-, and A(2)B-type miktoarm star copolyethers was achieved by the combination of the t-Bu-P-4-catalyzed ROP and azido-alkyne click chemistry. The azido- and ethynyl-functionalized precursor polyethers with the predicted molecular weights were separately prepared by the t-Bu-P-4-catalyzed ROP with the aid of functional initiators as well as a terminator. The intermolecular click reaction of the precursors provided the desired miktoarm star copolyethers. All the obtained star-shaped block copolyethers had a comparable monomer composition (degree of polymerization = 50:50) and total molecular weight (ca. 22 200 g mol(-1)) with a narrow dispersity (<1.05). The hydrodynamic diameter and the cloud point analyses for the aqueous micellar solution of the amphiphilic star-shaped block copolyethers revealed that the self-assembly properties were affected by the block arrangements and branched architectures of the amphiphilic polymers.
  • Kodai Watanabe, Ryoto Tanaka, Kenji Takada, Myung-Jin Kim, Jae-Suk Lee, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    POLYMER CHEMISTRY 7 29 4782 - 4792 2016年 [査読有り][通常論文]
     
    A comprehensive examination of the synthesis of single-chain nanoparticles (SCNPs) from statistical copolymers of n-butyl methacrylate (BMA) and 3-butenyl methacrylate (3BMA), i.e., P(BMA-co-3BMA)s, via the intramolecular olefin metathesis reaction under high dilution conditions is described. The olefin metathesis reaction of P(BMA-co-3BMA) using Grubbs' 2nd generation catalyst in CH2Cl2 efficiently gave the corresponding SCNPs under mild conditions. We achieved the size-controlled synthesis of the SCNPs by adjusting the following factors: (1) the olefin content in the precursor, (2) the molecular weight of the precursor, and (3) the solvent quality of the reaction medium. The hydrodynamic radius and the intrinsic viscosity of the resultant SCNPs were investigated by DLS and viscometric measurements, respectively, which provided further evidence of SCNP formation with controlled diameters. Furthermore, the above-established intramolecular olefin metathesis approach was successfully applied to poly(acrylate), poly(styrene), and poly(ester) precursors, which proved that the present approach could be applied to a wide range of olefin-containing precursors to give SCNPs with various functional groups.
  • Ju Fang, Shin Kawano, Kenji Tajima, Tetsuo Kondo
    BIOMACROMOLECULES 16 10 3154 - 3160 2015年10月 [査読有り][通常論文]
     
    Bacterial cellulose pellicle produced by Gluconacetobacter xylinus (G. xylinus) is one of the best biobased materials having a unique supernetwork structure with remarkable physiochemical properties for a wide range of medical and tissue-engineering applications. It is still necessary to modify them to obtain materials suitable for biomedical use with satisfactory mechanical strength, biodegradability, and bioactivity. The aim of this research was to develop a gene-transformation route for the production of bacterial cellulose/Curdlan (beta-1,3-glucan) nanocomposites by separate but simultaneous in vivo synthesis of cellulose and Curdlan. Modification of the cellulose-nanofiber-producing system of G. xylinus enabled Curdlan to be synthesized simultaneously with cellulose nanofibers in vivo, resulting in biopreparation of nanocomposites. The obtained Curdlan/cellulose composites were characterized, and their properties were compared with those of normal bacterial cellulose pellicles, indicating that Curdlan mixed with the cellulose nanofibers at the nanoscale without disruption of the nanofiber network structure in the pellicle.
  • Takuya Isono, Shunsuke Asai, Yusuke Satoh, Toshimitsu Takaoka, Kenji Tajima, Toyoji Kakuchi, Toshifumi Satoh
    MACROMOLECULES 48 10 3217 - 3229 2015年05月 [査読有り][通常論文]
     
    The combination of t-Bu-P-4 and alcohol was found to be an excellent catalytic system for the controlled/living ring-opening polymerization (ROP) of N,N-disubstituted glycidylamine derivatives, such as N,N-dibenzylglycidylamine (DBGA), N-benzyl-N-methylglycidylamine, N-glycidylmorpholine, and N,N-bis(2-methoxyethyl)glycidylamine, to give well-defined polyethers having various pendant tertiary amino groups with predictable molecular weights and narrow molecular weight distributions (typically M-w/M-n, < 1.2). The tBu-P-4-catalyzed ROP of these monomers in toluene at room temperature proceeded in a living manner, which was confirmed by a MALDI-TOF MS analysis, kinetic measurement, and postpolymerization experiment. The well-controlled nature of the present system enabled the production of the block copolymers composed of the glycidylamine monomers. The polyethers having pendant primary and secondary amino groups, i.e., poly(glycidylamine) and poly(glycidylmethylamine), respectively, were readily obtained by the debenzylation of poly(DBGA) and poly(BMGA), respectively, through the treatment with Pd/C in THF/MeOH under a hydrogen atmosphere. To the best of our knowledge, this report is the first example of the controlled/living polymerization of glycidylamine derivatives, providing a rapid and comprehensive access to the polyethers having primary, secondary, and tertiary amino groups.
  • Yukari Numata, Tadanori Sakata, Hidemitsu Furukawa, Kenji Tajima
    MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS 47 57 - 62 2015年02月 [査読有り][通常論文]
     
    A composite structure was formed between polyethylene glycol diacrylate (PEGDA) and bacterial cellulose (BC) gels swollen in polyethylene glycol (PEG) as a solvent (BC/PEG gel) to improve the mechanical strength of the gels. The mechanical strength under compression and the rheostatic properties of the gels were evaluated. The compression test results indicated that the mechanical strength of the gels depended on the weight percent of cross-linked PEGDA in the gel, the chain length between the cross-linking points, and the cross-linking density of PEGDA polymers. The PEGDA polymers around the cellulose fibers were resistant to pressure; thus, the BC/PEG-PEGDA gel was stronger than the BC/PEG gel under compression. The results of transmittance measurements and thermomechanical analysis showed that the rheostatic properties of the gels were retained even after composite structure formation. BC/PEG-PEGDA gels, which are expected to be biocompatible, may be useful for clinical applications as a soft material. (C) 2014 Elsevier B.V. All rights reserved.
  • Tatsuya Saito, Yusuke Aizawa, Kenji Tajima, Takuya Isono, Toshifumi Satoh
    POLYMER CHEMISTRY 6 24 4374 - 4384 2015年 [査読有り][通常論文]
     
    The ring-opening polymerizations (ROPs) of epsilon-caprolactone (epsilon-CL), delta-valerolactone, 1,5-dioxepan-2-one, trimethylene carbonate, and L-lactide were performed in the bulk using an organophosphate, such as diphenyl phosphate, bis(4-nitrophenyl)phosphate, and di(2,6-xylyl)phosphate, as the catalyst. The ROPs proceeded in a well-controlled manner even under the bulk conditions to afford well-defined aliphatic polyesters, polyester-ether, and polycarbonate with relatively low dispersities. Notably, the amount of the loaded catalyst was successfully reduced when compared to the conventional organophosphate-catalyzed ROP in solution. A kinetic study revealed the controlled/living nature of the present bulk ROP system, which allowed us to produce the block copolymers composed of polyesters, polyester-ether, and polycarbonate in one pot. Syntheses of the end-functionalized poly(epsilon-caprolactone)s (PCLs) and poly(trimethylene carbonate) were successfully demonstrated using alcohol initiators possessing highly reactive functional groups. Furthermore, the alpha,beta-dihydroxy telechelic PCL-diol as well as the three-and fourarmed star-shaped PCL-polyols were also easily obtained by using the polyols as an initiator. Finally, the one-pot synthesis of polyurethane via the ROP of epsilon-CL and a subsequent urethane forming reaction was demonstrated by taking advantage of the dual catalytic abilities of the organophosphate for both the ROP and polyurethane synthesis.
  • Xuerong Han, Yasuharu Satoh, Yumi Kuriki, Teruyuki Seino, Shinji Fujita, Takanori Suda, Takanori Kobayashi, Kenji Tajima
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 118 5 514 - 519 2014年11月 [査読有り][通常論文]
     
    We successfully isolated one microorganism (UMI-21) from Ulva, a green algae that contains starch. The strain UMI-21 can produce polyhydroxyalkanoate (PHA) from starch, maltotriose, or maltose as a sole carbon source. Taxonomic studies and 16S rDNA sequence analysis revealed that strain UMI-21 was phylogenetically related to species of the genus Massilia. The PHA content under the cultivation condition using a 10-L jar fermentor was 45.5% (w/w). This value was higher than that obtained after cultivation in a flask, suggesting the possibility of large-scale PHA production by UMI-21 from starch. A major issue for the industrial production of microbial PHAs is the very high production cost. Starch is a relatively inexpensive substrate that is also found in abundant seaweeds such as Ulva. Therefore, the strain isolated in this study may be very useful for producing PHA from seaweeds containing polysaccharides such as starch. In addition, a 3.7-kbp DNA fragment containing the whole PHA synthase gene (phaC) was obtained from the strain UMI-21. The results of open reading frame (ORF) analysis suggested that the DNA fragment contained two ORFs, which were composed of 1740 (phaC) and 564 bp (phaR). The deduced amino acid sequence of PhaC from strain UMI-21 shared high similarity with PhaC from Ralstonia eutropha, which is a representative PHA-producing bacterium with a class I PHA synthase. This is the first report for the cloning of the PHA synthase gene from Massilia species. (C) 2014, The Society for Biotechnology, Japan. All rights reserved.
  • Takuya Isono, Yohei Kondo, Shun Ozawa, Yougen Chen, Ryosuke Sakai, Shin-ichiro Sato, Kenji Tajima, Toyoji Kakuchi, Toshifumi Satoh
    MACROMOLECULES 47 20 7118 - 7128 2014年10月 [査読有り][通常論文]
     
    Random and block copolymerizations of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) macromonomers having an exo-norbornene group at the alpha- or pi-chain end (D/L ratio = 1/1, M-n = ca. 5000 g mol(-1)) were performed via ring-opening metathesis polymerization to produce the brush random and block copolymers consisting of parallel or antiparallel aligned PLLA and PDLA side chains on a poly(norbornene) backbone. The molecular weight and polydispersity index of the brush copolymers were in the range of 40 300-458 000 g mol(-1) and 1.031.14, respectively. Despite such high molecular weights, these brush copolymers formed a stereocomplex without homochiral crystallization. The melting temperature (T-m) and crystallinity (X) of the resulting stereocomplex varied depending on the backbone length, relative chain direction, and distribution of the PLLA/PDLA side chains. The parallel brush copolymers showed significantly higher T-m and X values than the antiparallel ones.
  • Akira Inoue, Kohei Takadono, Ryuji Nishiyama, Kenji Tajima, Takanori Kobayashi, Takao Ojima
    MARINE DRUGS 12 8 4693 - 4712 2014年08月 [査読有り][通常論文]
     
    A major alginate lyase, FlAlyA, was purified from the periplasmic fraction of an alginate-assimilating bacterium, Flavobacterium sp. strain UMI-01. FlAlyA showed a single band of similar to 30 kDa on SDS-PAGE and exhibited the optimal temperature and pH at 55 degrees C and pH 7.7, respectively. Analyses for substrate preference and reaction products indicated that FlAlyA was an endolytic poly(mannuronate) lyase (EC 4.2.2.3). A gene fragment encoding the amino-acid sequence of 288 residues for FlAlyA was amplified by inverse PCR. The N-terminal region of 21 residues except for the initiation Met in the deduced sequence was predicted as the signal peptide and the following region of six residues was regarded as propeptide, while the C-terminal region of 260 residues was regarded as the polysaccharide-lyase-family-7-type catalytic domain. The entire coding region for FlAlyA was subjected to the pCold I-Escherichia coli BL21(DE3) expression system and similar to eight times higher yield of recombinant FlAlyA (recFlAlyA) than that of native FlAlyA was achieved. The recFlAlyA recovered in the periplasmic fraction of E. coli had lost the signal peptide region along with the N-terminal 3 residues of propeptide region. This suggested that the signal peptide of FlAlyA could function in part in E. coli.
  • Takuya Isono, Yusuke Satoh, Kana Miyachi, Yougen Chen, Shin-ichiro Sato, Kenji Tajima, Toshifumi Satoh, Toyoji Kakuchi
    MACROMOLECULES 47 9 2853 - 2863 2014年05月 [査読有り][通常論文]
     
    This paper describes the synthesis of systematic sets of figure-eight- and tadpole-shaped amphiphilic block copolyethers (BCPs) consisting of poly(decyl glycidyl ether) and poly[2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether], together with the corresponding cyclic counterparts, via combination of the t-Bu-P-4-catalyzed ring-opening polymerization (ROP) and click cyclization. The clickable linear BCP precursors, with precisely controlled azido and ethynyl group placements as well as a fixed molecular weight and monomer composition (degree of polymerization for each block was adjusted to be around 50), were prepared by the t-Bu-P-4-catalyzed ROP with the aid of functional initiators and terminators. The click cyclization of the precursors under highly diluted conditions produced a series of cyclic, figure-eight-, and tadpole-shaped BCPs with narrow molecular weight distributions of less than 1.06. Preliminary studies of the BCPs self-assembly in water revealed the significant variation in their cloud points depending on the BCP architecture, though there were small architectural effects on their critical micelle concentration and morphology of the aggregates.
  • Ryota Kose, Naoki Sunagawa, Makoto Yoshida, Kenji Tajima
    CELLULOSE 20 6 2971 - 2979 2013年12月 [査読有り][通常論文]
     
    A major by-product of biodiesel production is waste glycerol, which has numerous potential applications. In this study, we isolated a novel bacterium capable of producing cellulose from waste glycerol, and identified it as a novel strain (named NEDO-01) of Gluconacetobacter intermedius. Scanning electron microscopy revealed that the morphology of the pellicle produced by NEDO-01 was similar to that of cellulose produced by Gluconacetobacter hansenii ATCC23769. Furthermore, X-ray diffraction and solid-state nuclear magnetic resonance spectroscopic analyses suggested that cellulose produced by NEDO-01 had molecular and crystalline structures similar to those of cellulose produced by ATCC23769. After the optimization of cultivation conditions, NEDO-01 mediated the one-step production of nanofibrillated bacterial cellulose (NFBC) from waste glycerol in a medium supplemented with carboxymethyl cellulose. Transmission electron microscopic analysis revealed that the NFBC was composed of relatively uniform fibers with diameters of approximately 20 nm. NFBC was produced as uniform water suspensions, the yield of which was 3.4 g/L from cultivation in 7.5 L medium in a 10-L jar fermenter. The bioconversion of waste glycerol to NFBC, which has superior fluidity, moldability, and miscibility, has a wide variety of applications, including potential uses in the medical and materials engineering fields.
  • Naoki Sunagawa, Takaaki Fujiwara, Takanori Yoda, Shin Kawano, Yasuharu Satoh, Min Yao, Kenji Tajima, Tohru Dairi
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 115 6 607 - 612 2013年06月 [査読有り][通常論文]
     
    The cellulose complementing factor (Ccp) is known to be involved in cellulose production in the Acetobacter species. However, its precise functions remain unclear. In the current study, we identified the coding region of the ccpAx gene (ccp gene from Acetobacter xylinum) and the localization of the CcpAx in cells by generating fusion proteins tagged to an enhanced green fluorescent protein (EGFP). From the results of N-terminal sequencing of CcpAx-EGFP-fusion protein, which recovered 65% of cellulose-producing abilities of the wild-type to the ccpAx gene-knockout mutant, the ccpAx gene was determined to encode a protein with the molecular weight of 8 kDa. The amino acid sequence deduced had high similarities with the C-terminal regions of Ccp proteins from other Acetobacter species. Fluorescence microscopy analysis showed that CcpAx was longitudinally localized along with one side of the cell membrane. Additionally, the localization of AxCeSD, which is thought to be a member of the cellulose synthase complex [terminal complex (TC)] in A. xylinum, was determined in the same manner as CcpAx. Fluorescence microscopy analysis showed that AxCeSD had a localization pattern similar to that of CcpAx. Pulldown assays and isothermal titration calorimetry analysis clearly showed a significant interaction between CcpAx and AxCeSD. Taken together, these data strongly suggest that CcpAx functions as a member of the TC in A. xylinum. (C) 2013, The Society for Biotechnology, Japan. All rights reserved.
  • Takaaki Fujiwara, Keisuke Komoda, Naofumi Sakurai, Kenji Tajima, Isao Tanaka, Min Yao
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 431 4 802 - 807 2013年02月 [査読有り][通常論文]
     
    In some Proteobacteria and Firmicutes such as Pseudomonas aeruginosa, Vibrio cholerae, Xanthomonas campestris, and Clostridium difficile, cyclic dimeric guanosine monophosphate (c-di-GMP) is known to regulate cellular processes, including motility, biofilm formation, and virulence, as a second messenger. Cellulose production in Acetobacter xylinum, a model organism of cellulose biosynthesis, also depends on by cellular c-di-GMP level. In cellulose-synthesizing bacteria, a terminal complex localized in the cell membrane synthesizes cellulose and regulates the production of cellulose sensed by c-di-GMP. Although previous studies indicated that the PilZ domain conserved in cellulose synthase subunit A (CeSA) was part of a receptor for c-di-GMP, the recognition mechanism by PilZ domain of CeSA remains unclear. In the present study, we studied the interaction between c-di-GMP and the PilZ domain of CeSA from a structural viewpoint. First, we solved the crystal structure of the PilZ domain of CeSA from A. xylinum (AxCeSA-PilZ) at 2.1 angstrom resolution. Then, comparison of the sequence and structure of AxCeSA-PilZ to those of known structures of PilZ, such as VCA0042, PP4397, and PA4608, indicated the involvement of Lys573 and Arg643 of AxCeSA-PilZ in the recognition of c-di-GMP besides the RxxxR motif. Finally, the binding characteristics of c-di-GMP to AxCeSA-PilZ and mutants were determined with isothermal titration calorimetry, indicating that the residues corresponding to Lys573 and Arg643 in AxCeSA-PilZ generally contribute to the binding of c-di-GMP to PilZ. (C) 2013 Elsevier Inc. All rights reserved.
  • Naoki Sunagawa, Kenji Tajima, Mariko Hosoda, Shin Kawano, Ryota Kose, Yasuharu Satoh, Min Yao, Tohru Dairi
    CELLULOSE 19 6 1989 - 2001 2012年12月 [査読有り][通常論文]
     
    Enterobacter sp. CJF-002, which had been isolated as a cellulose producer with saccharides as a carbon source, was shown to efficiently produce cellulose from beet molasses (B-Mol) and biodiesel fuel by-product (BDF-B), renewable non-edible and inexpensive biomasses. The cellulose production rates of Enterobacter sp. CJF-002 using B-Mol and BDF-B as carbon sources were faster than those of Acetobacter xylinum (A. xylinum) ATCC23769, a representative cellulose producing bacterium. To clarify the biosynthetic machinery of cellulose in the strain, genes responsible for cellulose biosynthesis were cloned. Six open reading frames (ORFs) were suggested to be clustered and their amino acid sequences had high similarities with those of BcsA, BcsB, BcsZ (endoglucanase), BcsC, YhjQ, and YhjK from Escherichia coli, respectively. Of these, the former four genes showed low similarities to corresponding orthologs in a cellulose biosynthetic gene cluster of A. xylinum. A bcsC-knockout mutant produced no cellulose, confirming that the gene is essential for cellulose production of Enterobacter sp. CJF-002. The predicted three-dimensional structure of BcsZ(En) from Enterobacter sp. CJF-002 had high similarity with that of CMCax (endoglucanase) from A. xylinum ATCC23769 in spite of the low similarity in their amino acid sequences. Taken together, A. xylinum and Enterobacter sp. CJF-002 might produce cellulose via a similar synthetic mechanism.
  • Yasuharu Satoh, Kenji Tajima, Masanobu Munekata, Jay D. Keasling, Taek Soon Lee
    METABOLIC ENGINEERING 14 6 603 - 610 2012年11月 [査読有り][通常論文]
     
    The hydroxylation of tyrosine is an important reaction in the biosynthesis of many natural products. The use of bacteria for this reaction has not been very successful due to either the over-oxidation to ortho-quinone when using tyrosinases from bacteria or plants, or the lack of the native cofactor, tetrahydrobiopterin (BH4), needed for the activity of tyrosine hydroxylases (TH). Here, we demonstrate that an Escherichia coli cofactor, tetrahydromonapterin (MH4), can be used as an alternative cofactor for TH in presence of the BH4 regeneration pathway, and tyrosine hydroxylation is performed without over-oxidation. We used this platform for biosynthesis of one of the most powerful antioxidants, hydroxytyrosol. An endogenous aromatic aldehyde oxidase was identified and knocked out to prevent formation of the side product, and this resulted in nearly exclusive production of hydroxytyrosol in engineered E. coli. Finally, hydroxytyrosol production from a simple sugar as a sole carbon source was demonstrated. Published by Elsevier Inc.
  • Kenji Tajima, Xuerong Han, Yasuharu Satoh, Ayako Ishii, Yuji Araki, Masanobu Munekata, Seiichi Taguchi
    APPLIED MICROBIOLOGY AND BIOTECHNOLOGY 94 2 365 - 376 2012年04月 [査読有り][通常論文]
     
    Recently, we succeeded in isolating a thermotolerant bacterium, Pseudomonas sp. SG4502, which is capable of accumulating polyhydroxyalkanoate (PHA) even at 55 A degrees C, as a source of thermostable enzymes. In this study, we cloned a pha locus from the bacterium and identified two genes encoding PHA synthases (PhaC1(SG) and PhaC2(SG)). Two mutations, Ser324Thr and Gln480Lys, corresponding to those of a lactate (LA)-polymerizing enzyme (LPE) from mesophilic Pseudomonas sp. 61-3 were introduced into PhaC1(SG) to evaluate the potential of the resulting protein as a "thermostable LPE". The mutated PhaC1(SG) [PhaC1(SG)(STQK)] showed high thermal stability in synthesizing P(LA-co-3HB) in an in vitro reaction system under a range of high temperatures. Requirement of 3HBCoA as a priming unit for LA polymerization by the LPE has been suggested in both of the in vitro and in vivo experiments. Based on the finding, the PhaC1(SG)(STQK)-mediated synthesis of a LA-based copolymer with a block sequence was achieved in the in vitro system by sequential feeding of the corresponding two substrates. This in vitro reaction system using the thermostable LPE provides us with a versatile way to synthesize the various types of LA-based copolymers with desired sequence patterns, random or block, depending on the way of supplying hydroxyalkanoates (mixed or sequential feeding).
  • Yasuharu Satoh, Kenji Tajima, Masanobu Munekata, Jay D. Keasling, Taek Soon Lee
    JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 60 4 979 - 984 2012年02月 [査読有り][通常論文]
     
    Metabolic engineering was applied to the development of Escherichia coli capable of synthesizing tyrosol hydroxyphenyl)ethanol), an attractive phenolic compound with great industrial value, from glucose, a renewable carbon source. In this strain, tyrosine, which was supplied not only from the culture medium but also from the central metabolism, was converted into tyrosol via three steps: decarboxylation, amine oxidation, and reduction. The engineered strain synthesized both tyrosol and 4-hydroxyphenylacetate (4HPA), but disruption of the endogenous phenylacetaldehyde dehydrogenase gene shut off 4HPA production and improved the production of tyrosol as a sole product. The engineered mutant strain was capable of producing 0.5 mM tyrosol from 1% (w/v) glucose during a 48 h shake flask cultivation.
  • Xuerong Han, Yasuharu Satoh, Toshifumi Satoh, Ken&apos, ichiro Matsumoto, Toyoji Kakuchi, Seiichi Taguchi, Tohru Dairi, Masanobu Munekata, Kenji Tajima
    APPLIED MICROBIOLOGY AND BIOTECHNOLOGY 92 3 509 - 517 2011年11月 [査読有り][通常論文]
     
    A previously established improved two-phase reaction system has been applied to analyze the substrate specificities and polymerization activities of polyhydroxyalkanoate (PHA) synthases. We first analyzed the substrate specificity of propionate coenzyme A (CoA) transferase and found that 2-hydroxybutyrate (2HB) was converted into its CoA derivative. Then, the synthesis of PHA incorporating 2HB was achieved by a wild-type class I PHA synthase from Ralstonia eutropha. The PHA synthase stereoselectively polymerized (R)-2HB, and the maximal molar ratio of 2HB in the polymer was 9 mol%. The yields and the molecular weights of the products were decreased with the increase of the (R)-2HB concentration in the reaction mixture. The weight-average molecular weight of the polymer incorporating 9 mol% 2HB was 1.00 x 10(5), and a unimodal peak with polydispersity of 3.1 was observed in the GPC chart. Thermal properties of the polymer incorporating 9 mol% 2HB were analyzed by DSC and TG-DTA. T (g), T (m), and T (d) (10%) were observed at -1.1A degrees C, 158.8A degrees C, and 252.7A degrees C, respectively. In general, major components of PHAs are 3-hydroxyalkanoates, and only engineered class II PHA synthases have been reported as enzymes having the ability to polymerize HA with the hydroxyl group at C2 position. Thus, this is the first report to demonstrate that wild-type class I PHA synthase was able to polymerize 2HB.
  • Y. Satoh, K. Tajima, S. Nakamoto, H. Xuerong, T. Matsushima, T. Ohshima, S. Kawano, T. Erata, T. Dairi, M. Munekata
    JOURNAL OF APPLIED MICROBIOLOGY 111 4 811 - 817 2011年10月 [査読有り][通常論文]
     
    Aims: The aim of this study was to isolate a thermotolerant micro-organism that produces polyhydroxyalkanoates (PHAs) composed of medium-chain-length (mcl) HA units from a biodiesel fuel (BDF) by-product as a carbon source. Methods and Results: We successfully isolated a thermotolerant micro-organism, strain SG4502, capable to accumulate mcl-PHA from a BDF by-product as a carbon source at a cultivation temperature of 45 degrees C. The strain could also produce mcl-PHA from acetate, octanoate and dodecanoate as sole carbon sources at cultivation temperatures up to 55 degrees C. Taxonomic studies and 16S rRNA gene sequence analysis revealed that strain SG4502 was phylogenetically affiliated with species of the genus Pseudomonas. This study is the first report of PHA synthesis by a thermotolerant Pseudomonas. Conclusions: A novel thermotolerant bacterium capable to accumulate mcl-PHA from a BDF by-product was successfully isolated. Significance and Impact of the Study: A major issue regarding industrial production of microbial PHAs is their much higher production cost compared with conventional petrochemical-based plastic materials. Especially significant are the cost of a fermentative substrate and the running cost to maintain a temperature suitable for microbial growth. Thus, strain SG4502, isolated in this study, which assimilates BDF by-product and produces PHA at high temperature, would be very useful for practical application in industry.
  • Jumiarti Agus, Prihardi Kahar, Manami Hyakutake, Satoshi Tomizawa, Hideki Abe, Takeharu Tsuge, Yasuharu Satoh, Kenji Tajima
    POLYMER DEGRADATION AND STABILITY 95 12 2250 - 2254 2010年12月 [査読有り][通常論文]
     
    This study aimed to investigate the factors affecting molecular weight of poly[(R)-3-hydroxybutyrate] [P(3HB)] when polyhydroxyalkanoate (PHA) synthase (PhaRC(Bsp)) from Bacillus sp. INT005 was used for P(3HB) synthesis in Escherichia coli JM109. It was found that the molecular weight of P(3HB) decreased with time in mid- and late-phase of culture and was strongly affected by culture temperature. At 37 degrees C culture temperature, the molecular weight of P(3HB) rapidly decreased from 4.4 x 10(5) to 4.8 x 10(4) with culture time, whereas it was almost unchanged at 25 degrees C. Kinetic analysis suggested that the decrease in molecular weight of P(3HB) was due to random scission of the polymer chain. The decrease in molecular weight of P(3HB) was not observed when PHA synthases other than PhaRC(Bsp) were expressed. This study sheds light on the unique behaviour in molecular weight change of P(3HB) that is synthesized by E. coli expressing PhaRCB(sp). (C) 2010 Elsevier Ltd. All rights reserved.
  • Song-Qing Hu, Yong-Gui Gao, Kenji Tajima, Naoki Sunagawa, Yong Zhou, Shin Kawano, Takaaki Fujiwara, Takanori Yoda, Daisuke Shimura, Yasuharu Satoh, Masanobu Munekata, Isao Tanaka, Min Yao
    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 107 42 17957 - 17961 2010年10月 [査読有り][通常論文]
     
    The cellulose synthesizing terminal complex consisting of subunits A, B, C, and D in Acetobacter xylinum spans the outer and inner cell membranes to synthesize and extrude glucan chains, which are assembled into subelementary fibrils and further into a ribbon. We determined the structures of subunit D (AxCeSD/AxBcsD) with both N- and C-terminal His(6) tags, and in complex with cellopentaose. The structure of AxCeSD shows an exquisite cylinder shape (height: similar to 65 angstrom, outer diameter: similar to 90 angstrom, and inner diameter: similar to 25 angstrom) with a right-hand twisted dimer interface on the cylinder wall, formed by octamer as a functional unit. All N termini of the octamer are positioned inside the AxCeSD cylinder and create four passageways. The location of cellopentaoses in the complex structure suggests that four glucan chains are extruded individually through their own passageway along the dimer interface in a twisted manner. The complex structure also shows that the N-terminal loop, especially residue Lys6, seems to be important for cellulose production, as confirmed by in vivo assay using mutant cells with axcesD gene disruption and N-terminus truncation. Taking all results together, a model of the bacterial terminal complex is discussed.
  • Satoshi Funai, Yumi Satoh, Yasuharu Satoh, Kenji Tajima, Teruoki Tago, Takao Masuda
    TOPICS IN CATALYSIS 53 7-10 654 - 658 2010年06月 [査読有り][通常論文]
     
    Conversion of coliform-fermented residue to useful chemicals such as ketone was carried out by a new conversion process consisting of hydrothermal treatment and catalytic reaction using ZrO2-FeO (X) , resulting in the selective production of acetone. Moreover, catalytic reactions using a model compounds were carried out to clarify the reaction mechanism and kinetics for the fermentation residue conversion.
  • Xuerong Han, Yasuharu Satoh, Kenji Tajima, Tokuo Matsushima, Masanobu Munekata
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 108 6 517 - 523 2009年12月 [査読有り][通常論文]
     
    In our previous paper, we synthesized poly-3-hydroxybutyrate [P(3HB)] by using the water-organic solvent two-phase reaction system (TPRS), in which thiophenyl (R)-3-hydroxybutyrate [(R)-3HBTP] was used as a precursor of 3HBCoA. We have developed an improved TPRS for the chemo-enzymatic synthesis of polyhydroxyalkanoate (PHA). In this method, acetyl thioester of ethyl thioglycolate (AcETC) was used as a precursor of acetylCoA (AcCoA), which was a donor of CoA. The AcCoA was formed by the ester exchange reaction between CoA in the water phase and AcETC in the organic solvent phase. The AcCoA and free 3-hydroxybutyrate (3HB) in the water phase were converted into 3HBCoA and acetate by a CoA transfer reaction of propionylCoA transferase (PCT). The synthesized 3HBCoA was polymerized sequentially by PHA synthase, and P(3HB) was successfully formed. The maximal yield of P(3HB) was 1.2 g/l under the optimal reaction condition; this is comparable to that of in vivo PHA production. Furthermore, the number of enzymes was reduced and enzyme preparation was simplified by the construction of a fusion protein, PCT-PhaC. The chemo-enzymatic synthesis of P(3HB-co-3-hydroxypropionate) and P(3HB-co-3-mercaptopropionate) was also achieved by the improved TPRS using the fusion protein. (C) 2009, The Society for Biotechnology, Japan. All rights reserved.
  • Kenji Tajima, Yasuharu Satoh, Toshifumi Satoh, Rumi Itoh, Xuerong Han, Seiichi Taguchi, Toyoji Kakuchi, Masanobu Munekata
    MACROMOLECULES 42 6 1985 - 1989 2009年03月 [査読有り][通常論文]
     
    In our previous paper, we synthesized poly-3-hydroxybutyrate [P(3HB)] by using the water-organic-solvent two-phase reaction system (TPRS), in which (R)-3-hydroxybutyrylCoA [(R)-3HBCoA] was continuously supplied to PHA synthase by the ester exchange reaction between CoA and thiophenol in thiophenyl (R)-3HB [(R)-3HBTP]. By applying TPRS to the screening, we found a lactate- (LA-) polymerizing enzyme from PHA synthases. The enzyme was an engineered PHA synthase, which stereoselectively copolymerized (R)-LA together with (R)-3HB. NMR and GPC revealed that the TPRS successfully synthesized poly(lactate-co-(3-hydroxybutyrate)) [P(LA-co-3HB)] using the LA-polymerizing enzyme as a catalyst. The molar ratios of LA in the copolymers were controllable in the range of 0 to 36 mol% by varying the ratio of (R)-LATP and (R)-3HBTP fed into the TPRS. The number-average molecular weight and the polydispersity of P(36 mol%-co-3HB) were 1.1 x 10(4) and 1.4, respectively. This is the first report on the chemo-enzymatic synthesis of P(LA-co-3HB) by a LA-polymerizing enzyme.
  • 佐藤 康治, 田島 健次
    環境技術 38 14 - 18 2009年
  • Ken'ichiro Matsumoto, Fumi Shozui, Yasuharu Satoh, Kenji Tajima, Masanobu Munekata, Seiichi Taguchi
    POLYMER JOURNAL 41 3 237 - 240 2009年 [査読有り][通常論文]
  • Yukari Numata, Kazumi Muromoto, Hidemitsu Furukawa, Jian Ping Gong, Kenji Tajima, Masanobu Munekata
    POLYMER JOURNAL 41 7 524 - 525 2009年 [査読有り][通常論文]
  • Seiichi Taguchi, Miwa Yamadaa, Ken'ichiro Matsumoto, Kenji Tajima, Yasuharu Satoh, Masanobu Munekata, Katsuhiro Ohno, Katsunori Kohda, Takashi Shimamura, Hiromi Kambe, Shusei Obata
    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 105 45 17323 - 17327 2008年11月 [査読有り][通常論文]
     
    Polylactate (PLA) is synthesized as a representative bio-based polyester by the chemo-bio process on the basis of metal catalyst-mediated chemical polymerization of lactate (LA) supplied by microbial fermentation. To establish the one-step microbial process for synthesis of LA-based polyesters, we explored whether polyhydroxyalkanoate (PHA) synthase would exhibit polymerizing activity toward a LA-coenzyme A (CoA), based on the fact that PHA monomeric constituents, especially 3-hydroxybutyrate (3HB), are structurally analogous to LA. An engineered PHA synthase was discovered as a candidate by a two-phase in vitro polymerization system previously developed. An LA-CoA producing Escherichia coli strain with a CoA transferase gene was constructed, and the generation of LA-CoA was demonstrated by capillary electrophoresis/MS analysis. Next, when the engineered PHA synthase gene was introduced into the resultant recombinant strain, we confirmed the one-step biosynthesis of the LA-incorporated copolyester, P(6 mol% LA-co-94 mol% 3HB), with a number-average molecular weight of 1.9 x 10(5), as revealed by gel permeation chromatography, gas chromatography/MS, and NMR.
  • Shin Kawano, Kenji Tajima, Hiroyuki Kono, Yukari Numata, Hitomi Yamashita, Yasuharu Satoh, Masanobu Munekata
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 106 1 88 - 94 2008年07月 [査読有り][通常論文]
     
    Although cellulose is the most abundant biopolymer in nature, the detailed mechanisms of cellulose biosynthesis remain unknown. Acetobacter xylinum is one of the best-studied model organisms for cellulose biosynthesis. Interestingly, the over-expression of the cmcax gene cause enhancement of cellulose production in A. xylinum, while its product (CMCax) has cellulose degradation activity. The addition of CMCax into medium also promotes cellulose production, suggesting that CMCax is involved in cellulose synthetic pathway. In the present study, we reveal the regulation mechanism of cmcax expression in A. xylinum. First, we treated cells with four kinds of beta-glucodisaccharide. Using an enzyme assay and real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), we observed an increase in CMCax activity and an induction of cmcax expression by gentiobiose treatment. Therefore, we concluded that gentiobiose induced cmcax expression. Although gentiobiose does not originally exist in the cultivation medium, we have revealed that membrane and intra-cellular proteins extracted from A. xylinum produce gentiobiose from glucose, which is one of the components in the cultivation medium. Furthermore, we confirmed that cmcax expression in a wild-type strain increased gradually after 5 d cultivation using real-time qRT-PCR. These results have led us to conclude that the increase in cmcax expression after 5 d cultivation is caused by the increase in gentiobiose, which could be synthesized by a condensation reaction in A. xylinum. Since CMCax plays a pivotal role in the cellulose production system, our results will contribute to the elucidation of mechanisms of cellulose biosynthesis.
  • SongQing Hu, YongGui Gao, Kenji Tajima, Min Yao, Takanori Yoda, Daisuke Shimura, Yasuharu Satoh, Shin Kawano, Isao Tanaka, Masanobu Munekata
    PROTEIN AND PEPTIDE LETTERS 15 1 115 - 117 2008年01月 [査読有り][通常論文]
     
    AxCesD protein required for bacterial cellulose biosynthesis in Acetobacter xylinum was overexpressed in E. coli, purified and crystallized. Single crystals of SeMet-substituted AxCesD were obtained by the sitting-drop vapor-diffusion method. The crystal belongs to the primitive trigonal space group P3(2), with unit-cell parameters a = b = 77.7 angstrom, and c = 213.9 angstrom. The asymmetric unit in the crystal was assumed to contain 8 protein molecules giving the Matthews coefficient (V(M)) of 2.54 angstrom(3) Da(-1). Se-MAD data were collected to 2.3 angstrom resolution using synchrotron radiations.
  • Nobuhiro Nagai, Kazuo Mori, Yasuharu Satoh, Noritaka Takahashi, Shunji Yunoki, Kenji Tajima, Masanobu Munekata
    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A 82A 2 395 - 402 2007年08月 [査読有り][通常論文]
     
    Marine-derived collagen is expected to be a much safer alternative to calf collagen, which in medical applications carries the risk of bovine spongiform encephalopathy. In this study, acid-soluble collagen was extracted from salmon skin and crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide during fibril formation to produce a crosslinked salmon collagen (SC) gel. The growth rates and the differentiated functions of human periodontal ligament fibroblasts (HPdLFs) cultured on the SC gel were investigated. Growth was faster on the SC gel than on porcine collagen (PC) gel. In addition, the HPdLFs cultured on the SC gel exhibited higher alkaline phosphatase (ALP) activity than those cultured on the PC gel. Quantitative RT- PCR revealed higher mRNA expression of type I collagen, ALP, and osteocalcin in the HPdLFs cultured on the SC gel. HPdLFs had a flat shape on the SC gel and a spindle shape on the PC gel, as revealed by observation with scanning electron microscopy and immunostaining with cytoskeletal protein and vinculin. The results showed that HPdLFs could grow and show highly differentiated activity on the SC gel as well as on the PC gel. (c) 2007 Wiley Periodicals, Inc.
  • Nobuhiro Nagai, Shunji Yunoki, Takeshi Suzuki, Yasuharu Satoh, Kenji Tajima, Masanobu Munekata
    CELL TECHNOLOGY FOR CELL PRODUCTS 321 - + 2007年 [査読有り][通常論文]
     
    Salmon atelocollagen (SAC) has not been used as biomaterials due to its low denaturation temperature (19 degrees C). In the present study, we succeeded in preparation of SAC fibrillar gel stable at an actual physical temperature of human by cross-linking during fibril formation, and in cultivating human periodontal ligament cells on the cross-linked SAC fibrillar gel.
  • Yoshiaki Yasutake, Shin Kawano, Kenji Tajima, Min Yao, Yasuharu Satoh, Masanobu Munekata, Isao Tanaka
    PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS 64 4 1069 - 1077 2006年09月 [査読有り][通常論文]
     
    Previous studies have demonstrated thatendoglucanase is required for cellulose biosynthesis both in bacteria and plants. However, it has yet to be elucidated how the endoglucanases function in the mechanism of cellulose biosynthesis. Here we describe the crystal structure of the cellulose biosynthesis-related endo-beta-1,4-glucanase (CMCax; EC 3.2.1.4) from the cellulose-producing Gram-negative bacterium, Acetobacter xylinum (= Gluconacetobacter xylinus), determined at 1.65-angstrom resolution. CMCax falls into the glycoside hydrolase family 8 (GH-8), and the structure showed that the overall fold of the CMCax is similar to those of other glycoside hydrolases belonging to GH-8. Structure comparison with Clostridium thermocellum Ce1A, the best characterized GH-8 endoglucanase, revealed that sugar recognition subsite +3 is completely missing in CMCax. The absence of the subsite +3 leads to significant broadness of the cleft at the cellooligosaccharide reducing-end side. CMCax is known to be a secreted enzyme and is present in the culture medium. However, electron microscopic analysis using immunostaining clearly demonstrated that a portion of CMCax is localized to the cell surface, suggesting a link with other known membrane-anchored endoglucanases that are required for cellulose biosynthesis.
  • Nobuhiro Nagai, Takafumi Anzawa, Yasuharu Satoh, Takeshi Suzuki T, Kenji Tajima, Masanobu Munekata
    Journal of Bioscience and Bioengineering 101 6 511 - 514 2006年06月 [査読有り][通常論文]
     
    We investigated the effect of gamma-irradiation on the activities of MC3T3-E1 cells cultured on gamma-irradiated salmon atelocollagen (SAC) scaffolds. SAC-cultured samples were irradiated at doses of 10, 15, and 25 kGy. gamma-Irradiation had a significant impact on the activities of MC3T3-E1 cells. The proliferation rates and alkaline phosphatase activities of MC3T3-E1 cells increased with gamma-irradiation dose.
  • Y Satoh, F Murakami, K Tajima, M Munekata
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 99 5 508 - 511 2005年05月 [査読有り][通常論文]
     
    We succeeded in developing a novel method for in vitro poly(3-hydroxybutyrate-co-4-hydroxy-butyrate) [P(3HB-co-4HB)] synthesis with CoA recycling using polyhydroxyalkanoate synthase and an acyl-CoA synthetase. Using this method, the monomer compositions in P(3HB-co-4HB)s could be controlled strictly by the ratios of the monomers in the reaction mixtures.
  • S Kawano, Y Yasutake, K Tajima, Y Satoh, M Yao, Tanaka, I, M Munekata
    ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY AND CRYSTALLIZATION COMMUNICATIONS 61 Pt 2 252 - 254 2005年02月 [査読有り][通常論文]
     
    The cellulose biosynthesis-related protein CMCax from Acetobacter xylinum was overexpressed in Escherichia coli, purified and crystallized. Single crystals of selenomethionine (SeMet) substituted CMCax were obtained by the hanging-drop vapour-diffusion method at 293 K, primarily using polyethylene glycol 4000 as a precipitant. The crystals belong to the primitive hexagonal space group P6(1) or P6(5), with unit-cell parameters a = b = 89.1, c = 94.2 A. The predicted Matthews coefficient (V-M) value is 3.0 angstrom(3) Da(-1) for one CMCax monomer in the asymmetric unit. A single-wavelength anomalous dispersion (SAD) data set was collected to a resolution of 2.3 angstrom using synchrotron radiation.
  • N Nagai, S Yunoki, Y Satoh, K Tajima, M Munekata
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 98 6 493 - 496 2004年12月 [査読有り][通常論文]
     
    We prepared a cell sheet by using collagenase treatment to digest salmon atelocollagen fibrillar gel (SAC gel) on which human periodontal ligament (HPDL) cells had been cultured. The SAC gel was found to be digested completely within 2 h at a concentration of 50 U of collagenase per mg of collagen. The SAC gel on which HPDL cells were cultured for 10 d was treated with collagenase, resulting in the formation of a detached and shrunken cell sheet. Immunostaining results showed that the cytoskeleton and fibronectin matrix level of the cell sheet were maintained after collagenase treatment. In addition, collagenase treatment had almost no effect on the activities of HPDL Cells.
  • K Tajima, Y Satoh, K Nakazawa, H Tannai, T Erata, M Munekata, M Kamachi, RW Lenz
    MACROMOLECULES 37 12 4544 - 4546 2004年06月 [査読有り][通常論文]
     
    We succeeded in developing of a new method for in vitro poly(3-hydroxybutyrate) (P(3HB)) synthesis with coenzyme A (CoA) recycling. Thiophenyl (R)-3-hydroxybutyrate was used as a precursor for the monomer, (R)-3-hydroxybutylCoA ((R)-3HBCoA). The (R)-3HBCoA was synthesized by the ester exchange reaction between thiophenyl (R)-3-hydroxybutyrate and CoA. Although the polymerization reaction in the buffer (water phase) was performed, the reaction did not occurred. The results of a PHA synthase assay in the presence of thiophenol suggested that the reaction was inhibited by a small amount of thiophenol. To avoid the inhibition of PHA synthase by thiophenol, a water-organic solvent two-phase reaction system was developed for the polymerization reaction. The water-organic solvent two-phase reaction system has been used previously for the bioconversion of substrates with low solubility in water; it was used to remove thiophenol released during the ester exchange reaction from the water phase. Thiophenyl (R)-3-hydroxybutyrate and PHA synthase were dissolved in the organic solvent and water phases, respectively. Ester exchange between thiophenol and CoA occurs at the interface of water and the organic solvent phase, and the (R)-3HB 3-hydroxybutylCoA synthesized was polymerized sequentially by PhaC. The organic solvents with high a logP(ow) of more than 3.9 such as hexane, octane, decane, or dodecane were found to be suitable for the organic solvent phase in the two-phase system. The polymerization reaction mixture showed signs of turbidity in 2 h, after which white precipitates formed. The structural analyses by H-1 NMR spectroscopy indicated that the product was P(3HB). The weight-averaged molecular weight and molecular weight distribution of P(3HB) synthesized were found to be 1.6 x 10(6) and 2.9, respectively. The maximum yield of P(3HB) based on thiophenyl (R)-3-hydroxybutyrate was 47%.
  • N Nagai, S Yunoki, T Suzuki, M Sakata, K Tajima, M Munekata
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 97 6 389 - 394 2004年06月 [査読有り][通常論文]
     
    The purpose of this study was to investigate the application of salmon atelocollagen (SAC) to a scaffold. SAC has a low denaturation temperature and needs to be cross-linked before being used as a scaffold. In the present study, SAC was cross-linked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) or dehydrothermal treatment (DHT). The material properties (degree of cross-linking and solubility in phosphate-buffered saline) of the SAC scaffolds crosslinked by EDC (EDC-SAC) and DHT (DHT-SAC) were evaluated. It was found that EDC-SAC had a high degree of cross-linking and high stability compared with DHT-SAC. Human periodontal ligament (HPDL) cells were cultured in the scaffolds for 2 weeks in vitro, and the activities (proliferation rate and alkaline phosphatase [ALP] activity) of HPDL cells cultured in EDC-SAC and DHT-SAC were compared with those cultured in bovine atelocollagen (BAC) scaffolds crosslinked by EDC (EDC-BAC) and DHT (DHT-BAC), respectively. The proliferation rate of HPDL cells cultured in EDC-SAC was equivalent to that in EDC-BAC, and the ALP activity in EDC-SAC was found to be significantly higher than that in EDC-BAC. In the cross-linking by DHT, the cell proliferation rate and the ALP activity in DHT-SAC were lower than those in DHT-BAC. DHT seemed to provide insufficient cross-linking, and DHT-SAC was found to be breakable and contractile, resulting in less cell activity. In contrast, there was no difference in the thermal stability, porous structure, and cell proliferation rate between EDC-SAC and EDC-BAC. In addition, the collagen helix of EDC-SAC was found to be partially denatured, and this structure resulted in the enhancement of ALP activity of HPDL cells compared with that using EDC-BAC. In conclusion, our results indicate that EDC-SAC could be used as a scaffold for in vitro culture.
  • Y Satoh, K Tajima, H Tannai, M Munekata
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 95 4 335 - 341 2003年04月 [査読有り][通常論文]
     
    We established a novel enzyme-catalyzed poly(3-hydroxybutyrate) [P(3HB)] synthesis system capable of recycling CoA on the basis of the P(3HB) biosynthetic pathway in Ralstonia eutropha. The system includes purified beta-ketothiolase (PhaA), NADPH-dependent acetoacetyl-CoA reductase (Phabeta), PHA synthase (PhaC), acetyl-CoA synthetase (Acs) and glucose dehydrogenase (GDH). In this system, acetyl-CoA was synthesized from acetate and CoA by Acs and ATP, and then two molecules of acetyl-CoA were condensed by PhaA to synthesize acetoacetyl-CoA, which was converted to (R)-3-hydroxybutyryl-CoA (3HBCoA) by PhaB and NADPH. The 3HBCoA was polymerized by PhaC and converted to P(3HB). In this system, the CoA molecules that were released during the condensation and polymerization reactions catalyzed by PhaA and PhaC, respectively, were reused successfully for the synthesis of acetyl-CoA. In addition, NADPH, which was consumed in the reduction of acetoacetyl-CoA, was regenerated by the action of GDH. In this system, the yield of P(3HB) synthesized from acetate as the substrate was 5.6 mg in a 5-ml reaction mixture, and the weight-average molecular weight and polydispersity were 6.64x10(6) and 1.36, respectively. Furthermore, CoA was reused at least 26 times, and NADPH was also regenerated at least 26 times during 24 h of reaction.
  • K Tajima, H Tannai, Y Satoh, M Munekata
    POLYMER JOURNAL 35 4 407 - 410 2003年 [査読有り][通常論文]
  • K Tajima, T Igari, D Nishimura, M Nakamura, Y Satoh, M Munekata
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 95 1 77 - 81 2003年01月 [査読有り][通常論文]
     
    A gram-positive bacterium (designated strain INT005) that accumulated polyhydroxyalkanoate (PHA) was isolated from gas field soil. From its morphological and physiological properties and the partial nucleotide sequence (about 500 bp) of its 16S rDNA, it was suggested that strain INT005 was similar to several species of the genus Bacillus. We confirmed that strain INT005 is a Bacillus sp. The PHA productivities of strain INT005 were higher than those of Bacillus megaterium and Ralstonia eutropha at 37-45degreesC reported to date, and it was suggested that the PHA synthase of INT005 may exhibit moderate thermostability. The bacterium had the ability to produce poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-3-hydroxyhexanoate), and poly(3-hydroxybutyrate-co-6-hydroxyhexanoate-co-3-hydroxyhexanoate) from the appropriate carbon sources. The PHA synthase from INT005 showed similar substrate specificity to those of class I and III PHA synthases and strain INT005 produced PHAs with various monomer compositions. From the analysis of monomer composition and PHA accumulation in the presence of acrylic acid, it was suggested that de novo fatty acid synthesis and P-oxidation are involved in the PHA synthesis of Bacillus sp. INT005. Since Bacillus sp. INT005 could synthesize PHA even at 45degreesC and PHAs with various monomer compositions, and only one report on the cloning of the synthesis-related genes from a Bacillus species (B. megaterium) has been published; Bacillus sp. INT005 is thought to be very valuable source of PHA synthesis-related genes.
  • S Kawano, K Tajima, Y Uemori, H Yamashita, T Erata, M Munekata, M Takai
    DNA RESEARCH 9 5 149 - 156 2002年10月 [査読有り][通常論文]
     
    About 14.5 kb of DNA fragments from Acetobacter xylinum. ATCC23769 and ATCC53582 were cloned, and their nucleotide sequences were determined. The sequenced DNA regions contained endo-beta-1,4-glucanase, cellulose complementing protein, cellulose synthase subunit AB, C, D and beta-glucosidase genes. The results from a homology search of deduced amino acid sequences between A. xylinum ATCC23769 and ATCC53582 showed that they were highly similar. However, the amount of cellulose production by ATCC53582 was 5 times larger than that of ATCC23769 during a 7-day incubation. In A. xylinum ATCC53582, synthesis of cellulose continued after glucose was consumed, suggesting that a metabolite of glucose, or a component of the medium other than glucose, may be a substrate of cellulose. Oil the other hand, cell growth of ATCC23769 was twice that of ATCC53582. Glucose is the energy source in A. xylinum as well as the substrate of cellulose synthesis, and the metabolic pathway of glucose in both strains may be different. These results suggest that the synthesis of cellulose and the growth of bacterial cells are contradictory.
  • Y Satoh, N Minamoto, K Tajima, M Munekata
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 94 4 343 - 350 2002年10月 [査読有り][通常論文]
     
    A polyhydroxyalkanoate (PHA) biosynthesis gene locus from Bacillus sp. INT005 strain, which had been isolated from a gas field, was cloned and analyzed at the molecular level. We found that a 3.8-kbp DraI-digested fragment of genomic DNA of Bacillus sp. INT005 conferred PHA-producing ability to Escherichia coli, which was PHA-negative. The DNA fragment contained three genes, phaR, -B and -C. The activity of 3-ketoacyl-CoA reductase with NADPH was detected in the lysate from recombinant E. coli carrying the phaB gene. Although PHA synthase activity could be detected in the extract from E. coli carrying phaR, -B and -C genes, no such activity could be detected in that from E. coli carrying only the phaC gene. However, the mixture of the crude extracts of E. coli expressing phaR or phaC revealed very high PHA synthase activity. Furthermore, when His-tagged PhaC was purified by Ni-affinity chromatography from the mixture of crude extracts containing His-tagged PhaC or native PhaR, the eluate contained His-tagged PhaC and native PhaR. On the other hand, PhaR did not bind to the column directly. This purified PhaC with PhaR had 160-fold higher specific activity of PHA synthase than that without PhaR. In addition, the kinetics of the purified PhaC with PhaR revealed a lag phase that preceded the linear phase. It has been known that class III PHA synthase is composed of two different subunits, PhaC and PhaE, and phaC and phaE genes are directly linked in the genomes. Furthermore, the PHA synthase has no lag phase. We hence concluded that the PHA synthase of Bacillus sp. INT005 consists of PhaC and PhaR, and has characteristics different from class III PHA synthase.
  • S Kawano, K Tajima, H Kono, T Erata, M Munekata, M Taka
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 94 3 275 - 281 2002年09月 [査読有り][通常論文]
     
    Endo-beta-1,4-glucanase (CMCax; EC 3.2.1.4) from Acetobacter xylinum ATCC23769 was expressed as a 6xHis-tagged fusion protein in Escherichia coli. The optimal temperature, pH, K. and V-max of the purified His-tagged CMCax toward carboxymethyl cellulose were 50degreesC, 4.5, 20 mg/ml and 37.2 muM/min, respectively. The number of recognition residues of cello-oligosaccharide by this enzyme were five (cellopentaose) or longer, and the stereochemical course of hydrolysis was of the inverting type. Addition of a small amount (1.5 mg/l) of His-tagged CMCax into a culture medium enhanced cellulose production 1.2-fold. CMCax overproduction in A. xylinum also enhanced the yield of cellulose production. Transmission electron microscopic analysis revealed that the cellulose ribbons secreted from the CMCax overproducing strain were dispersed compared with those from the wild type strain in the same manner as by carboxymethyl cellulose addition. These results could suggest that CMCax from A. xylinum influences in cellulose ribbon assembly, which is considered to be a rate-determined process in cellulose synthesis.
  • K Tajima, K Nakajima, H Yamashita, T Shiba, M Munekata, M Takai
    DNA RESEARCH 8 6 263 - 269 2001年12月 [査読有り][通常論文]
     
    The beta-glucosidase gene (bglxA) was cloned from the genomic DNA of Acetobacter xylinum ATCC 23769 and its nucleotide sequence (2200 bp) was determined. This bglxA gene was present downstream of the cellulose synthase operon and coded for a polypeptide of molecular mass 79 kDa. The overexpression of the beta-glucosidase in A. xylinum caused a tenfold increase in activity compared to the wild-type strain. In addition, the action pattern of the enzyme was identified as G3ase activity. The deduced amino acid sequence of the bglxA gene showed 72.3%, 49.6%, and 45.1% identity with the beta-glucosidases from A. xylinum subsp. sucrofermentans, Cellvibrio gilvus, and Mycobacterium tuberculosis, respectively. Based on amino acid sequence similarities, the beta-glucosidase (BglxA) was assigned to family 3 of the glycosyl hydrolases.
  • K Tajima, T Tanio, Y Kobayashi, H Kohno, M Fujiwara, T Shiba, T Erata, M Munekata, M Takai
    DNA RESEARCH 7 4 237 - 242 2000年08月 [査読有り][通常論文]
     
    The levansucrase gene (lsxA) was cloned from the genomic DNA of Acetobacter xylinum NCI 1005, and the nucleotide sequence of the lsxA gene (1,293 bp) was determined. The deduced amino acid sequence of the lsxA gene showed 57.4% and 46.2% identity with the levansucrases from Zymomonas mobilis and Erwinia amylovora, respectively, while only 35.2% identity with that from Acetobacter diazotrophicus. The gene product of lsxA (LsxA) that was overproduced in E. coli coded for a polypeptide of molecular mass 47 kDa. The LsxA released glucose and produced polysaccharide from sucrose, the structure of which was analyzed by nuclear magnetic resonance spectroscopy and determined to be a beta-(2,6)-linked polyfructan. From these results, it can be concluded that the lsxA gene encodes A. xylinum levansucrase.
  • H Kono, S Kawano, K Tajima, T Erata, M Takai
    GLYCOCONJUGATE JOURNAL 16 8 415 - 423 1999年08月 [査読有り][通常論文]
     
    A new beta-glucosidase was partially purified from Trichoderma viride cellulase. This beta-glucosidase catalyzed a transglycosylation reaction of cellobiose to give beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 4)-D-Glc (1, yield: 18.8%) and beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 4)-D-Glc (2, 3.7%), regioselectively. Furthermore, the enzyme regioselectively converted laminaribiose and gentiobiose into beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 3)-D-Glc (3, 15.3%) and beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 6)-D-Glc (4, 20.2%), respectively. The structures (1-4) of the products were determined by H-1 and C-13 NMR spectroscopies. This high regio- and stereoselectively of the beta-glucosidase could be applied for oligosaccharide synthesis. [GRAPHICS]
  • K Tajima, N Uenishi, M Fujiwara, T Erata, M Munekata, M Takai
    CARBOHYDRATE RESEARCH 305 1 117 - 122 1997年12月 [査読有り][通常論文]
     
    A new water-soluble polysaccharide (WSP) was isolated from a culture of Acetobacter xylinum NCI 1005 grown on sucrose. The structure of the WSP was analysed by nuclear magnetic resonance spectroscopy and determined to be a beta-(2-->6)-linked polyfructan, which is structurally different from the polymer synthesized from glucose instead of sucrose by the same strain. The discovery of this new polysaccharide has revealed that the bacterium is able to synthesize two different kinds of water-soluble polysaccharides. (C) 1998 Elsevier Science Ltd.
  • K Tajima, N Uenishi, M Fujiwara, T Erata, M Munekata, M Takai
    MACROMOLECULAR SYMPOSIA 120 19 - 28 1997年07月 [査読無し][招待有り]
     
    A new polysaccharide was isolated from the culture of Acetobacter aceti subsp. xylinum (A. xylinum) NCl 1005 grown on sucrose. The structure of the polymer was analyzed by nuclear magnetic resonance (NMR) spectroscopy, The water-soluble polysaccharide (WSP) was determined to be beta(2, 6) linked polyfructan, which was structurally different from the polymer synthesized from glucose instead of sucrose by the same strain. The discovery of the new polysaccharide has elucidated that the bacterium has the ability to synthesize two different kinds of water-soluble polysaccharides.
  • K Tajima, M Fujiwara, M Takai, J Hayashi
    MOKUZAI GAKKAISHI 42 3 279 - 288 1996年 [査読有り][通常論文]
     
    Acetobacter aceti subsp. xylinum was cultivated in Hestrin-Schramm (HS) medium containing a water-soluble chitosan oligomer (WSCO) or a water-soluble chitosan derivative (WSCD) to study their effects on bacterial cellulose (BC) productivity. The BC yields in the HS medium with WSCO or WSCD were about 1.3-1.7 times that in normal HS medium. The contents of WSCOs and WSCDs in the bacterial cellulose composites (BCCs) were 0-5(w/w)% and 8-17(w/w)%, respectively. The results of yields, contents and characterizations suggest that WSCO and WSCD enhance BC productivity and that the mechanism of the enhancement are different from each other.
  • K TAJIMA, M FUJIWARA, M TAKAI
    MACROMOLECULAR SYMPOSIA 99 149 - 155 1995年09月 [査読無し][招待有り]
     
    The enhancement of bacterial cellulose (BC) productivity using sucrose as a carbon source has been obtained by the co-cultivation of two different types of acetic acid bacteria BC yields for the given mix ratio of bacteria were larger than that of control. The contents of water-soluble polymer (WSP) in the BC composites (BCCs) are a range of 5-30 wt-%. This will be due to the formation of glucose and fructose through the hydrolysis of sucrose by sucrase secreted from Acetobacter sp.. In addition, this preparation method would be applied to synthesize a new type of BC having both high biodegradability and other functions.
  • K TAJIMA, M FUJIWARA, M TAKAI, J HAYASHI
    MOKUZAI GAKKAISHI 41 8 749 - 757 1995年 [査読有り][通常論文]
     
    Bacterial cellulose (BC) produced by Acetobacter xylinum (A. xylinum) is a very unique and interesting material, because it naturally has both great mechanical strength and biodegradability. We have succeed in controlling these properties by the incorporation of water-soluble polymers (WSPs), such as carboxymethyl cellulose (CMC), methyl cellulose (MC), and so forth. The incorporation was performed by the incubation of A. xylinum in a standard medium containing a WSP. Young's modulus of the obtained BC composite (BCC) was about 1-3 times that of normal BC (NBC) (30-40 GPa). For the enzymatic degradation test, BCC(CMC) was degraded completely by cellulase, while only 20-40% of BCC(MC) were degraded. For degradation test in native soil, all BCC samples were degraded considerably at 30 degrees C for 28 days as well as was normal BC (NBC). This production method will be used to synthesize a new type of BC having both excellent biodegradability and other functions.
  • K. Tajima, H. Ito, M. Fujiwara, M. Takai, J. Hayashi
    Sen'i Gakkaishi 51 7 323 - 332 1995年 [査読有り][通常論文]
     
    We have succeeded in enhancing the bacterial cellulose (BC) productivity using sucrose as a carbon source by the co-cultivation of two different types of Acetobacter species, BC-producing Acetobacter xylinum NCI 1051 and ATCC 10245, which utilize glucose as a carbon source, and branched polysaccharide (BP)-producing Acetobacter aceti subsp. xylinum NCI 1005, which utilizes sucrose as a carbon source. BP-BC composite yields for given mixing ratios of these two species of bacteria were greater than that of control. The contents of BP in the BP-BC composites were 5-30wt%. It was suggested that the BC productivity of Acetobacter xylinum NCI 1051 and ATCC 10245 using sucrose as the carbon source was enhanced by co-cultivation from the increase in the BC production amount. This seems to be due to the formation of glucose and fructose through the hydrolysis of sucrose by sucrase secreted from Acetobacter aceti subsp. xylinum NCI 1005. © 1995, The Society of Fiber Science and Technology, Japan. All rights reserved.
  • Kenji Tajima, Masashi Fujiwara, Mitsuo Takai, Jisuke Hayashi
    Proceedings of the International Conference on Cellulose and Cellulose Derivatives: Physico-Chemical Aspects and Industrial Applications 9 - 14 1993年 [査読無し][招待有り]
  • Tsutomu Nakamura, Kenji Tajima, Masashi Fujiwara, Mitsuo Takai, Jisuke Hayashi
    Proceedings of the International Conference on Cellulose and Cellulose Derivatives: Physico-Chemical Aspects and Industrial Applications 3 - 8 1993年 [査読無し][招待有り]

書籍

  • 田島健次, 松島得雄, 小瀬亮太, 藤田彩華, 甲野裕之, 安藤英紀:石田竜弘 (担当:分担執筆範囲:ナノフィブリル化バクテリアセルロースの生産とその応用)
    エヌ・ティー・エス 2021年11月 (ISBN: 9784860437510) 5, 15, 832, 15p, 図版22p
  • セルロースナノファイバー製造･利用の最新動向
    田島 健次 (担当:分担執筆範囲:発酵ナノセルロースの大量生産とその応用)
    シエムシー出版 2019年
  • セルロースナノファイバーの均一分散と複合化
    田島 健次 (担当:分担執筆範囲:酢酸菌におけるセルロース合成機構と通気撹拌培養によるナノフィブリル化バクテリアセルロース（NFBC）の合成)
    サイエンス＆テクノロジー 2018年
  • セルロースナノファイバーの調製、分散・複合化と製品応用
    田島 健次 (担当:分担執筆範囲:酢酸菌におけるセルロース合成機構と通気撹拌培養によるナノフィブリル化バクテリアセルロース（NFBC）の合成)
    技術情報協会 2015年
  • バイオマス分解酵素の最前線－セルラーゼ・ヘミセルラーゼを中心として－
    田島 健次 (担当:分担執筆範囲:セルロース合成における分解酵素の役割)
    シエムシー出版 2012年
  • Cell Technology for Cell Products
    Nobuhiro Nagai, Shunji Yunoki, Takeshi Suzuki, Yasuharu Satoh, Kenji Tajima, Masanobu Munekata (担当:分担執筆範囲:Preparation of Salmon Atelocollagen Fibrillar Gel and Its Application to the Cell Culture)
    Springer 2007年 (ISBN: 9781402054761) 321-323
  • 木質科学実験マニュアル 日本木材学会編
    田島 健次 (担当:分担執筆範囲:タンパク質の分離，精製，定量)
    文永堂出版 2000年04月
  • セルロースの事典<セルロース学会>
    田島 健次 (担当:分担執筆範囲:セルロースの高次構造)
    朝倉書店 2000年

講演・口頭発表等

  • 寒冷地輪作とてん菜由来の糖蜜から作られる微生物セルロースナノファイバーが世界を変える  [招待講演]
    田島健次
    令和５年度JAつべつ管内における各種実証・研究報告会 2024年01月 口頭発表（基調）
  • Development of Bacterial Cellulose Nano-Fiber;BCNF;and collaboration with companies  [招待講演]
    Kenji Tajima
    OPEN INNOVATION DAY - TECHTRAVERSE 2023 2023年10月 公開講演，セミナー，チュートリアル，講習，講義等
  • 繊維長の異なるセルロースナノファイバーを用いた高強度複合材料の創製  [招待講演]
    田島 健次
    JST新技術説明会 2023年10月 公開講演，セミナー，チュートリアル，講習，講義等
  • 宇宙における微生物を用いたバイオ有機素材（セルロース）合成の試み  [通常講演]
    田島 健次
    セルロース学会第30 回年次大会 2023年09月 口頭発表（一般）
  • 寒地畑輪作の基幹作物であるテンサイと微生物が作るナノセルロースが 世界を変える  [招待講演]
    田島 健次
    アグリシーズセミナー「未来を拓く植物由来の北海道発新素材～シーズ開発から事業化へ」 2023年09月 シンポジウム・ワークショップパネル（指名）
  • 北海道発の新素材「微生物ナノセルロース（NFBC）」  [招待講演]
    田島 健次
    第15回ロバスト農林水産工学「科学技術先導技術研究会」 2023年08月 シンポジウム・ワークショップパネル（指名）
  • テンサイを利用した完全リサイクル可能な新素材（微生物産生セルロースナノファイバー）の開発と利用  [招待講演]
    田島 健次
    グリーンテクノバンク てん菜研究会 第21回技術研究発表会 2023年07月 シンポジウム・ワークショップパネル（指名）
  • バクテリア由来セルロースナノファイバー の構造・物性とその応用例  [通常講演]
    田島 健次
    アカデミックフォーラム＠ファーマラボEXPO 2023年07月 公開講演，セミナー，チュートリアル，講習，講義等
  • 田島健次
    第7回農水産業支援技術展沖縄技術説明会 2022年12月 公開講演，セミナー，チュートリアル，講習，講義等
  • Kenji Tajima
    Association of Bio-based Material Industry (ABbI) Webinar 2022年10月 シンポジウム・ワークショップパネル（指名）
  • Ryo Takahama, Masato Uenishi, Tokuo Matsushima, Takuya Isono, Toshifumi Satoh, Chiaki Ogino, Kenji Tajima
    5th INTERNATIONAL SYMPOSIUM ON BACTERIAL CELLULOSE 2022年09月 口頭発表（一般）
  • Kenji Tajima
    5th INTERNATIONAL SYMPOSIUM ON BACTERIAL CELLULOSE 2022年09月 口頭発表（招待・特別）
  • 田島健次
    ナノセルロースジャパンが開催するナノセルロース塾第五期（2022年度） 2022年09月 公開講演，セミナー，チュートリアル，講習，講義等
  • Hamidah binti Hashim, Nur Aisyah Adlin, binti Emran, 勝原哲, 二之湯寛子, 辻崎晴人, 夏小超, 細川真明, 瀬野修一郎, 可児浩, 磯野拓也, 山本拓矢, 佐藤敏文, 折原宏, 田島健次
    第71回高分子討論会 2022年09月 シンポジウム・ワークショップパネル（指名）
  • Kenji Tajima
    ICRI-BioM (International Centre for Research on Innovative Bio-based Materials) seminor 2022年07月 公開講演，セミナー，チュートリアル，講習，講義等
  • 酢酸菌セルロース合成酵素複合体の構造と機能（シンポジウム：酢酸菌ナノセルロース研究の最前線：合成の分子メカニズムと応用）  [招待講演]
    田島健次
    第73回日本生物工学会大会 2021年10月 シンポジウム・ワークショップパネル（指名）
  • 北海道発の新素材微生物産生セルロー スナノファイバーFibnano®の特⾧とその応用  [招待講演]
    田島 健次
    北海道経済連合会 2020年度 環境・エネルギーセミナー 2021年01月 公開講演，セミナー，チュートリアル，講習，講義等
  • 北海道発の新素材微生物産生セルロースナノファイバー Fibnano(R)の特長と食品応用  [招待講演]
    田島 健次
    CNF実用化事例紹介セミナー CNFによる機能付与の可能性および実現例 2020年11月 公開講演，セミナー，チュートリアル，講習，講義等
  • セルロース合成菌を用いたナノセルロースの大量調製とその構造を活かした応用  [招待講演]
    田島 健次
    2019 年度微粒子工学講演会 2019年11月 シンポジウム・ワークショップパネル（指名）
  • In vitro cellulose synthesis using a recombinant cellulose synthase  [通常講演]
    Kenji Tajima
    4th International Symposium on Bacterial NanoCellulose 2019年10月 口頭発表（一般）
  • Production of nanocellulose using a bacterium and its application  [招待講演]
    田島 健次
    2nd Asian-Franch Workshop on Polymer Science 2019年07月 口頭発表（招待・特別）
  • Production of nanocellulose using a bacterium and its features  [招待講演]
    田島 健次
    Sci-Mix in Kanazawa 2019, Green Innovative Chemistry 2019年06月 公開講演，セミナー，チュートリアル，講習，講義等
  • 酢酸菌におけるセルロース合成メカニズムの解明と産業応用に向けた取り組み  [招待講演]
    田島 健次
    フジッコ株式会社社内講演会 2019年03月 公開講演，セミナー，チュートリアル，講習，講義等
  • バクテリアを用いたナノセルロースの調製とその利用  [招待講演]
    田島 健次
    日本化学会ATP(Advanced Technology Program) 2019年03月 口頭発表（招待・特別）
  • ボトムアップで創るナノセルロースの特長とその特徴を活かした応用  [招待講演]
    田島 健次
    とくしま高機能素材活用促進フォーラム 2018年10月 公開講演，セミナー，チュートリアル，講習，講義等
  • バクテリアを用いたナノセルロースの大量生産とその応用  [招待講演]
    田島 健次
    高分子学会エコマテリアル研究会「バイオベースマテリアルをつくろう・つかおう」 2018年07月 公開講演，セミナー，チュートリアル，講習，講義等
  • セルロース合成菌を用いたナノセルロースのボトムアップ合成とその応用  [招待講演]
    田島 健次
    セルロースナノファイバー in 東北 2018年07月 公開講演，セミナー，チュートリアル，講習，講義等
  • バクテリアを用いた両親媒ナノセルロースの合成とその応用  [通常講演]
    田島 健次
    セルロース学会第25回年次大会 2018年07月 口頭発表（一般）
  • セルロース合成菌を用いたナノセルロースのボトムアップ合成とその応用  [招待講演]
    田島 健次
    島津製作所社内セミナー「セルロースナノファイバーの分析技術セミナー」 2018年07月 公開講演，セミナー，チュートリアル，講習，講義等
  • セルロース合成菌を用いたナノフィブリル化セルロースの大量生産とその応用  [招待講演]
    田島 健次
    nano tech 2018 【特別シンポジウム】ナノセルロースの技術開発最前線 2018年02月 公開講演，セミナー，チュートリアル，講習，講義等
  • One-step production of amphiphilic nano-fibrillated cellulose using a cellulose-producing bacterium  [通常講演]
    田島 健次
    3rd International Symposium on Bacterial NanoCellulose 2017年10月 口頭発表（一般）
  • ナノフィブリル化バクテリアセルロースの大量生産とその応用  [通常講演]
    田島 健次
    セルロース学会第24回年次大会 2017年07月 口頭発表（一般）
  • バクテリアを用いたナノセルロースのボトムアップ生産  [招待講演]
    田島 健次
    第10回ナノセルロースフォーラム技術セミナー・意見交換会 2017年07月 公開講演，セミナー，チュートリアル，講習，講義等
  • 発酵ナノセルロース（NFBC）の事業化について  [招待講演]
    田島 健次
    セルロースナノファイバーサミット in 北海道 2017年03月 公開講演，セミナー，チュートリアル，講習，講義等
  • 低分子バイオマスを原料としたナノフィブリル化バクテリアセルロースの大量生産  [招待講演]
    田島 健次
    2016年度生物工学会北日本支部札幌シンポジウム「低炭素化社会に資する最先端バイオリファイナリー研究」 2016年09月 公開講演，セミナー，チュートリアル，講習，講義等
  • 酢酸菌セルロースの生合成機構と応用  [招待講演]
    田島 健次
    酢酸菌研究会 2015年10月 公開講演，セミナー，チュートリアル，講習，講義等
  • Production and application of nano-fibrillated bacterial cellulose (NFBC)  [招待講演]
    田島 健次
    2nd International Symposium on Bacterial NanoCellulose 2015年09月 口頭発表（招待・特別）
  • ナノフィブリル化バクテリアセルロースの合成と応用  [招待講演]
    田島 健次
    日本木材学会バイオマス変換研究会夏季講演会「バイオマス変換の研究最前線」 2015年07月 公開講演，セミナー，チュートリアル，講習，講義等
  • 酢酸菌によるセルロース合成と発酵ナノセルロース(NFBC)の大量生産  [招待講演]
    田島 健次
    バイオインダストリー協会JBAバイオセミナーシリーズ”未来へのバイオ技術”勉強会 2014年03月 公開講演，セミナー，チュートリアル，講習，講義等
  • 酢酸菌によるセルロース合成と発酵ナノセルロース(NFBC)の大量生産  [招待講演]
    田島 健次
    新化学技術推進協会(JACI)エネルギー・資源技術部会バイオマス分科会講演会 2014年03月 公開講演，セミナー，チュートリアル，講習，講義等
  • 函館マリンバイオフォーラム＆フェスタ2012 函館  [招待講演]
    田島 健次
    函館マリンバイオフォーラム＆フェスタ2012 函館 2012年07月 公開講演，セミナー，チュートリアル，講習，講義等
  • バクテリアを用いた高分子材料の合成  [招待講演]
    田島 健次
    函館工業高等専門学校 物質工学科 学科講演会 2012年 公開講演，セミナー，チュートリアル，講習，講義等
  • バクテリアを用いた非可食バイオマスからの高分子材料の合成  [招待講演]
    田島 健次
    道央バイオ研究交流会講演会 2012年 公開講演，セミナー，チュートリアル，講習，講義等
  • バクテリアによるバイオポリマーの合成と新規材料創製  [招待講演]
    田島 健次
    バイオ産業クラスター・フォーラム・シーズ公開会 2010年 公開講演，セミナー，チュートリアル，講習，講義等
  • 微生物を使って砂糖からプラスチックや紙を作る  [招待講演]
    田島 健次
    日本化学会体験入学講演会 2010年 公開講演，セミナー，チュートリアル，講習，講義等
  • 微生物を用いて再生可能資源からプラスチックや紙を作る  [招待講演]
    田島 健次
    リコー第４回材料フォーラム 2008年 公開講演，セミナー，チュートリアル，講習，講義等
  • 生体を用いた機能性高分子材料の合成  [招待講演]
    田島 健次
    新事業創出に係る技術講演会 2008年
  • 生体を用いた機能性高分子材料の合成  [招待講演]
    田島 健次
    日本化学会北海道支部講演会 2006年 公開講演，セミナー，チュートリアル，講習，講義等
  • 生体を用いた機能性高分子材料の合成  [招待講演]
    田島 健次
    高分子学会北海道支部高分子若手研究会 2005年 公開講演，セミナー，チュートリアル，講習，講義等
  • ２段階バイオリアクター用いた生分解性プラスチックの連続合成  [招待講演]
    田島 健次
    平成11年度ノーステック財団研究開発支援事業成果発表会 2002年 公開講演，セミナー，チュートリアル，講習，講義等
  • 固定化菌体・酵素を用いた生分解性プラスチックの連続合成  [招待講演]
    田島 健次
    平成8年度ホクサイテック財団研究開発支援事業成果発表会 1999年 公開講演，セミナー，チュートリアル，講習，講義等
  • 道内石油・天然ガス採掘土壌からの環境浄化に寄与する菌分離と利用  [招待講演]
    田島 健次
    平成5年度ホクサイテック財団研究開発支援事業成果発表会 1996年 公開講演，セミナー，チュートリアル，講習，講義等
  • 微生物が作る複合材料  [招待講演]
    田島 健次
    高分子学会北海道高分子若手研究会 1995年09月 公開講演，セミナー，チュートリアル，講習，講義等

その他活動・業績

特許

受賞

  • 2015年05月 製糖技術研究会 第112回製糖技術研究会賞
     
    受賞者: 田島健次、他
  • 2010年07月 セルロース学会 林治助賞
  • 2004年08月 International Symposium on Bio Polyesters 2004 Poster award
     
    受賞者: TAJIMA Kenji
  • 2002年09月 高分子化学奨励賞<平成１４年度>

共同研究・競争的資金等の研究課題

  • 文部科学省：科学研究費助成事業
    研究期間 : 2021年10月 -2025年03月 
    代表者 : 磯野拓也, 佐藤敏文, 田島健次
  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    研究期間 : 2021年04月 -2024年03月 
    代表者 : 甲野 裕之, 田島 健次
     
    酢酸菌が作るナノフィブリル化バクテリアセルロース(NFBC)は均一な繊維幅で繊維長が15 μm以上の超高アスペクト比な繊維としての特長を持つ。現在、医薬や生体へ応用可能なCNFとして注目される一方、さらなる機能化のための配向制御や構造体を構築する技術の欠如が課題として残っている。そこで申請者はNFBCを用いたピッカリング乳化が発現可能となれば、乳化剤としてだけでなく、球状の液液界面に沿ったNFBCの三次元組織化が達成できると考えた。そこで本申NFBCによるピッカリング乳化機構の解明と乳化現象を活用した新しい概念に基づく新規中空ナノ粒子の合成を目的とした。 本申請ではエマルジョン形成に伴うNFBC集合状態、ミセル粒径と安定化制御に関する新知見を取得し、中空ナノ粒子の構造設計にフィードバックすることで構造最適化を図る。製剤・樹脂との複合化による特性評価を通じ、その有用性を実証し、ナノ繊維ネットワークが作る多孔性ナノ粒子を創製する。 初年度は乳化技術の構築とそのメカニズムの解明について検討を行った。ホモジナイザーを用いてNFBC水分散液と中鎖脂肪酸トリグリセリドを用いてピッカリングエマルジョンを形成させ、油/水比、NFBC濃度、ホモジナイザー出力/照射時間等をパラメータとして安定な乳化条件とその油滴粒径制御を検討した。現時点では数日安定なピッカエマルジョンが得られておらず、NEBC表層の疎水性制御を実施した。主にシランカップリング剤を用いてナノ繊維構造を有する表層化学修飾法を構築することが可能となった。次年度はこれら表層化学修飾NFBCライブラリーを使用して、ピッカリング乳化技術の達成を目指す。
  • 国立研究開発法人科学技術振興機構：共創の場形成支援プログラム
    研究期間 : 2021年11月 -2024年03月 
    代表者 : 金沢大学, 北海道大学, 東海国立大学機構, 神戸大学, 三井住友信託銀行株式会社, 株式会社ダイセル, 草野作工株式会社, DSP五協フードケミカル株式会社, 日本乳化剤株式会社, マルハニチロ株式会社, 日東電工株式会社
     
    本拠点では多糖類農業廃棄物を資源として捉え、プラスチックごみを生み出さないバイオプラスチック製品を用途に合わせてリデザインする。適切な量だけ生産し、使用後に回収して再生することで無駄なく使い続ける、バイオプラスチック循環プラットフォームを構築する。そのプラットフォームが、様々な世界地域へ、樹木の年輪のように拡大成長し、大量生産、大量廃棄による暗黒の未来を防ぐ。本プラットフォームの運用のため、多糖類農作物を持続的に生産可能な技術を社会実装し、プラスチック生産、消費、リサイクルに関するサプライチェーンを構築し、絶対的デカップリングを達成する。このような社会システム転換の実現のため、インパクトファイナンスを実践する金融機関が協力する。拠点の循環型プラスチック製品の社会実装により、企業と使用者の価値観が変わるイノベーションサイクルを回して、様々な問題解決につながるモデルを示す。これら5つのサイクルを、まるで協奏(共創)曲のように奏でることで、ポストコロナ社会を見据えた資源循環共創社会と「価値観のイノベーション」を実現し、人々を幸せにするSDGs目標達成に、スピード感を持って貢献する。
  • 国立研究開発法人科学技術振興機構：未来社会創造事業
    研究期間 : 2021年10月 -2024年03月 
    代表者 : 田島健次, 折原宏, 甲野裕之, 小瀬亮太, 瀬野修一郎
  • 文部科学省：宇宙航空科学技術推進委託費
    研究期間 : 2021年10月 -2024年03月 
    代表者 : 五十嵐圭日子, 田島健次, 今井友也, 田仲 広明
  • 日本学術振興会：科学研究費助成事業 基盤研究(A)
    研究期間 : 2019年04月 -2023年03月 
    代表者 : 今井 友也, 田島 健次, 姚 閔
     
    酢酸菌のセルロース合成酵素複合体の主要構成サブユニットのうち、ABCDの4サブユニットが一つの複合体中に存在することを支持する生化学的データを得ることに成功した。またその複合体の中で、AB複合体とDタンパク質が直接相互作用している場合と、合成されたセルロース分子を介して間接的に相互作用している場合があることを実験的に証明した。以上から、これら二つの相互作用モードを使い分けることで酵素複合体の状態制御を行っている可能性を示した。さらにこのタンパク質複合体精製実験を進め、クライオ電子顕微鏡法による三次元構造解析への道筋をつけた。具体的には組換え大腸菌および酢酸菌の二つの系を用いて、His-tagあるいはStrep-tagを用いたアフィニティークロマトグラフィー、サイズ排除クロマトグラフィーによる精製条件検討を進めた。 Cサブユニットは、全長タンパク質の取り扱いが難しいことから、C末のβバレル型チャネル部分のタンパク質結晶化を進め、結晶化条件について目途をつけつつある。また、Mass Photometry法により、この部分構造が会合体を形成することを確認した。さらにCタンパク質の機能解析を進めるために、Cサブユニットの遺伝子欠損酢酸菌株を使った実験の条件最適化を進めた。 また機能解析を効率的に進めるために、A遺伝子の機能欠損酢酸菌株の作出を進めた。具体的にはCRISPR-Cas9システムを用いるために新たなプラスミドを構築した。現在このプラスミドにターゲット配列を導入し、ノックインによるA遺伝子欠損株の作出を進めている。さらにセルロース合成に関与している新たな遺伝子を探索するためにランダム変異実験を行い、候補となる遺伝子をいくつか特定することが出来た。これらについて機能解析を行うため、CRISPR-Cas9システムを用いた欠損株の作製を現在行っている。
  • 北海道大学 持続可能社会の実現に向けた 世界トップレベル研究推進・社会実装 「ロバスト農林水産工学国際連携研究教育拠点構想」：コンソーシアム形成型 ロバスト農林水産工学研究プログラム
    研究期間 : 2021年06月 -2022年04月 
    代表者 : 田島健次, 折原宏, 瀬野修一郎, 細川真明
  • 日本学術振興会：科学研究費助成事業 基盤研究(B)
    研究期間 : 2019年04月 -2022年03月 
    代表者 : 田島 健次, 石田 竜弘, 安藤 英紀, 佐藤 敏文, 磯野 拓也, 甲野 裕之, 藤田 彩華
     
    10Lジャーファーメンターに排ガス分析計を溶存酸素計とともにプロセスコントローラーに接続し、得られるデータをもとに酸素移動容量係数（kLa）を決定した。非加圧下と加圧下（0.03 MPa）で、回転数を種々変化させてkLaの測定を行った。非加圧下には、回転数の増加とともにkLaの値も増加する傾向が見られたのに対し、加圧下には回転数に依存せず、kLaが高い値を維持していた。この結果を踏まえ、加圧しながらの培養を行った。非加圧下に比べ菌体の増殖速度が速く、ナノフィブリル化バクテリアセルロース（NFBC）の生産速度、収量ともに増加した。加圧下における生産速度は、2.0g／L／dとなり、非加圧下の2倍に増加させることに成功した。 NFBCの表面の水酸基やカルボキシメチル基を反応点として、塩化グリシジルトリメチルアンモニウムによるカチオン基の導入、アミノプロピルトリメトキシシリルによるアミノプロピルシリル基の導入、εカプロラクトンの開環重合によるグラフト化による表面修飾を行った。それぞれの方法において置換基の導入が確認され、NFBCの表面修飾に成功した。 Paclitaxel（PTX）は胃がん腹膜播種などの腹腔内投与に用いられる抗がん剤である。PTXの腹腔内滞留性向上による治療効果増強と副作用低減を目的に、物理化学的性質の異なる2つのNFBCを用いた新規PTX製剤（PTX/NFBC）の開発を行い、その治療効果を比較検討した。PTX/CM-NFBCおよびPTX/HP-NFBCは、胃がん腹膜播種に対して高い治療効果を示し、PTXの副作用を顕著に低減しうることを明らかにした。その中でも、PTX/CM-NFBCは高い抗腫瘍効果を示すのに対し、PTX/HP-NFBCは毒性を顕著に軽減するということを示し、NFBCの物理化学的性質の違いにより異なる性質を有するPTX製剤の開発に成功した。
  • カーボンニュートラルを目指した オール多糖ガス分離膜の開発
    JST：社会還元加速プログラム（SCORE）大学推進型（拠点都市環境整備型）
    研究期間 : 2021年08月 -2022年03月 
    代表者 : 沼田ゆかり、田島健次、甲野裕之
  • ノーステック財団：研究開発助成事業 イノベーション創出研究支援事業発展・橋渡し研究補助金
    研究期間 : 2019年07月 -2020年03月 
    代表者 : 甲野裕之, 田島健次, 沼田ゆかり, 松島得雄
  • 北海道大学：ロバスト農林水産工学研究プログラム
    研究期間 : 2018年07月 -2020年03月 
    代表者 : 田島健次, 佐藤信一郎
  • ノーステック財団：研究開発助成事業イノベーション創出研究支援事業スタートアップ研究補助金
    研究期間 : 2018年07月 -2019年03月 
    代表者 : 甲野裕之, 田島健次, 沼田ゆかり, 松島得雄
  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    研究期間 : 2016年04月 -2019年03月 
    代表者 : 甲野裕之, 田島健次, 沼田ゆかり, 松島得雄
     
    セルロースナノファイバー（CNF）は繊維径が4～100 nmな高アスペクト比のセルロース繊維を指す。優れた特性を示すため、樹脂との複合化における優れたフィラーとしての応用が期待されている。CNFと樹脂の複合化を達成するには、CNF表層水酸基を他の疎水性置換基に置き換える工夫が必要となる。本研究では水系溶媒下におけるCNF表層シランカップリング改質とその構造評価法について検討を行なった。メチルメトキシシランを用いて反応の最適化をを行い、表層選択的に疎水化可能な条件を決定した。得られた疎水化CNFは反応前後において繊維形態を維持し、クロロホルムに分散可能であることが明らかになった。
  • 経済産業省：戦略的基盤技術高度化支援事業
    研究期間 : 2016年08月 -2018年03月 
    代表者 : 松島得雄, 田島健次
  • 公益財団法人 池谷科学技術振興財団：平成26年度 単年度研究助成
    研究期間 : 2014年04月 -2015年12月 
    代表者 : 田島 健次
  • 函館マリンバイオクラスター～ＵＭＩ（Universal Marine Industry）のグリーンイノベーション
    文部科学省：地域イノベーション戦略支援プログラム
    研究期間 : 2009年04月 -2014年03月 
    代表者 : 高橋 はるみ
  • 国立研究開発法人新エネルギー・産業技術総合開発機構(NEDO)：先導的産業技術創出事業（若手グラント）
    研究期間 : 2011年10月 -2013年09月 
    代表者 : 田島 健次
  • 北海道産非可食原料(糖蜜)からのポリL‐乳酸改質に対応した高品質発酵D‐乳酸の量産技術の開発
    経済産業省：戦略的基盤技術高度化支援事業
    研究期間 : 2009年08月 -2011年03月 
    代表者 : 松島 得雄
  • 日本学術振興会：科学研究費助成事業 基盤研究(B)
    研究期間 : 2009年 -2011年 
    代表者 : 田島 健次, 佐藤 敏文, 佐藤 康治, 堺井 亮介
     
    PHAは、微生物によって再生可能資源から作られるバイオポリマーである。これまでに、様々な構造・物性のPHAが作り出されてきているが、PHAに更なる機能性を付与するためには、新しい構造を有するモノマーユニットを導入する必要がある。本研究では、微生物を用いてまず反応点(官能性置換基)を導入し、その反応点を利用してモノマー構造を変化させ機能性PHAを合成する。研究としては、ベースとなる反応点を有するPHAの微生物合成とクリック反応によるPHAへの化学修飾・機能化と解析の2つに大きく分けることがきる。田島、佐藤康治に関してはPHAの微生物合成を、佐藤敏文、堺井については化学修飾・機能化およびその解析を担当する。平成21年度は、以下のことを行った。 (1) ポロヒドロキシアルカン酸(PHA)の微生物合成:PHA合成を欠失させた微生物(Ralstonia entropha PHB-4、Pseudomonas GPp104)にBacillus由来のPHA合成酵素遺伝子を導入した。ファーメンターを用い、基質をウンデシレン酸にすることによって側鎖に二重結合を有する短鎖長(scl-)PHAの合成に成功した。PHA中における二重結合の導入率は約5mol%程度であった。 (2) 側鎖に二重結合を有する中鎖長(mcl-)PHAに、クリック反応によってメルカプトプロピオン酸を導入した。NMR、FT-IR、GPC等の解析の結果から、ほぼ定量的に二重結合にメルカプトプロピオン酸が導入されていることが確認された。また、カルボキシル基の導入によって、ポリマーの溶解性が変化した。これらの結果から二重結合を有するPHAに対する分子団の導入においてクリック反応が有効であることが確認できた。
  • セルロース合成酵素複合体の立体構造および機能の解析
    サッポロ生物科学振興財団：研究助成
    研究期間 : 2008年10月 -2010年03月 
    代表者 : 田島 健次
  • 日本学術振興会：科学研究費助成事業 若手研究(B)
    研究期間 : 2009年 -2010年 
    代表者 : 佐藤 康治, 田島 健次, 韓 雪容
     
    石油由来プラチックを代替でき、再生可能なマテリアル・ポリヒドロキシアルカン酸(PHA)の新しい発想に基づく生産プロセス開発が望まれている。そこで糖を原料とした無細胞PHA合成法を考案、本研究ではその合成法に適したモノマー供給酵素(R)体特異的NADH依存型還元酵素の開発を行った。(S)体特異的NADH依存型還元酵素の立体選択性の改変、(R)体特異的NADH依存型還元酵素の探索により目的の活性を有する酵素を発見することができた。
  • バイオディーゼル燃料（BDF）製造残渣を原料とする生分解性農業用マルチフィルムの開発試作
    ノーステック財団：イノベーション創出研究支援事業 重点研究・モデル化研究補助金
    研究期間 : 2008年07月 -2009年03月 
    代表者 : 吉田 美樹
  • 日本学術振興会：科学研究費助成事業 基盤研究(B)
    研究期間 : 2005年 -2007年 
    代表者 : 田口 精一, 田島 健次, 岩田 忠久, 島田 浩章
     
    資源循環型バイオプラスチック生合成酵素の進化工学的改変により、バイオポリエステルの生産性・物性を積極的に改善する研究を展開してきた。最終年度は、ポリマーの共重合化におけるモノマー分率制御を精密に行ない、かつ分子量変化がダイナミックに実現する進化酵素を多数創出することを目的として、所期の水準に十分達した成果が得られた。 人工進化システムから得られた複数の優良変異部位4箇所(130,325,477,481)のうち、130番目と325番目は酵素活性そのもののに関与し、477番目と481番目は基質特異性に関与することが明らかとなった。この知見に基づき、組換え大腸菌(b酸化系変異株LS5218使用し、C4からCl2までのモノマー基質を供給できる酵素遺伝子(phaA_B_J_)を補強した状態)によって生成されるポリマーの解析から、優良変異の組み合わせから共重合体中の3HB分率が14%から93%の幅で制御できる進化酵素群を取り揃えることができた。さらに、これら優良部位における網羅的アミノ酸置換により、多くの相乗効果をもたらす組み合わせが同定でき、本手法の有効性が実証された。 以上の結果は、側鎖のサイズを系統的に変えたCoA体脂肪酸モノマーを化学合成し、インビトロでの活性試験をした結果とよく符合し、生成ポリマーの解析結果とよい相関を示すことがわかった。これらの結果は、立体構造情報が無くてもPHA重合酵素の機能マッピングができることを始めて示すことができた。 さらに、代表的な進化酵素遺伝子をシロイヌナズナにモノマー供給酵素遺伝子群とともにアグロバクテリウム感染法で導入し、作出されたトランスジェニック植物を野生型酵素遺伝子株と比較したところ、期待どおりポリマー蓄積率が向上する成果を収めつつある。
  • バイオポリエステルの効率的生産系の開発と高機能化
    国立研究開発法人新エネルギー・産業技術総合開発機構(NEDO)：産業技術研究助成事
    研究期間 : 2003年10月 -2006年09月 
    代表者 : 田島 健次
  • バイオプラスチックの微生物から植物への高効率生産系開発
    ノーステック財団：基盤的研究開発育成事業 研究開発シーズ育成補助金
    研究期間 : 2005年07月 -2006年03月 
    代表者 : 田口 精一
  • 皮コラーゲンを用いた人工歯根膜・ゲル培養歯根膜の開発
    ノーステック財団：産業創造技術研究開発支援事業 産業創造技術研究開発補助金
    研究期間 : 2004年07月 -2006年03月 
    代表者 : 棟方 正信
  • バイオポリマーの合成機構解明と遺伝子工学的手法を用いた新規機能性高分子の合成
    日本学術振興会：科学研究費補助金 若手研究(B)
    研究期間 : 2002年04月 -2005年03月 
    代表者 : 田島 健次
  • 日本学術振興会：科学研究費助成事業 基盤研究(A)
    研究期間 : 2002年 -2005年 
    代表者 : 棟方 正信, 田島 健次, 佐藤 康治, 西村 和晃
     
    1.歯周組織再生における理想的な再生療法は,歯周靭帯と歯槽骨の再生がほぼ同時におこることである。従来GTR法などの実際の治療では骨再生が優先し,靭帯の再生はなかなか起こらないのが現状である。我々は,歯プレセメント質に歯周靭帯と歯槽骨をほぼ同時に再生する効果のあることを発見しその有効成分を単離した。DEAE吸着画分をBSA除去後SDS-PAGEにて分離,バンドを切り出し,TOF-MASS分析をおこなった結果トランスフェリン(69kDa)とαプロコラーゲンと同定された。市販品のトランスフェリンを用いてヒト歯周靭帯細胞(hPDL)の走化活性を調べたところアポ体が活性を示した。歯肉線維芽細胞に対してはアポ,ホロ両方に対して走化活性を示したが増殖活性はなかった。 2.γ線照射セメント質による骨性癒着の原因は,hPDL細胞が未照射に高い走化活性を示すのに対し骨芽細胞はγ照射セメント質に高い走化活性を示すことが一因であった。また骨芽細胞のOPG発現抑制を消失することも骨形成バランスを崩し骨再生が優先する原因であると推定された。 3.歯周組織再生因子の徐放化担体,細胞の増殖分化の足場,また手術の際にできた空間のスペース代わりとして,ウシ皮由来ゼラチンスポンジを使用してきたが,BSE問題で使用不可となった。代替物として人獣感染症の報告がない鮭皮コラーゲンの利用について検討を行った。鮭皮コラーゲンは変性温度が19℃と低く,ヒト体温ではゼラチンとなり再生治療用バイオマテリアルとして使用できないが,線維化と化学架橋を同時に行う方法を開発し,架橋後の架橋剤の成分が残らないEDCを用いて変性温度55℃のコラーゲン線維を作成することに成功した。本線維は牛,豚由来のコラーゲン線維に比べ平均太さ70nmと極細で均一であり,さらに強度は豚コラーゲン線維ゲルの5倍あった。歯周組織再生に関与する歯周靭帯細胞,歯槽骨細胞,線維芽細胞すべてに対して豚コラーゲンの1.5倍の増殖性と分化促進活性を有していた。
  • ナノポア制御による歯周組織再生能力を有する人工歯根膜の開発
    ノーステック財団：基盤的研究開発育成事業 研究開発シーズ育成補助金
    研究期間 : 2003年07月 -2004年03月 
    代表者 : 棟方 正信
  • セルロース合成に関与しているセルラーゼの立体構造解析とその機能解明
    秋山記念生命科学振興財団：奨励助成金
    研究期間 : 2003年04月 -2004年03月 
    代表者 : 田島 健次
  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    研究期間 : 2003年 -2004年 
    代表者 : 藤原 政司, 高井 光男, 棟方 正信, 惠良田 知樹, 田島 健次
     
    酢酸菌の一種は培地中に菌体外多糖類としてセルロースを産生する。これはバクテリアセルロースと呼ばれ、高純度・高強度・高生分解性であることから、新規な工業素材として有望であるが、生産性の改善が不可欠である。セルロース収量の大幅な改善を達成するには、原料グルコースの代謝経路の詳細を知る必要がある。そこで、原料にラベル化グルコースを用いて、そのラベルがセルロース中のどの炭素原子に残っているかをNMR法で調べ、グルコースがセルロースに達するまでに通過した代謝経路の割合を調べた。その結果は、直接重合経路が16%、Embden Meyerhof経路が0%、Entner-Doudoroff経路が41%、Pentose phosphate cycle経路が35%、グルコース新生経路が8%であった。次に、エタノールを培地中に1%添加してセルロース収量が1.5倍になったときに代謝経路の割合がどのくらい変化しているかを同様な方法で調べた。その結果、直接重合経路とグルコース新生経路の割合が増えていることがわかった。そのため、エタノールがエネルギー源として菌の増殖に用いられ、その分グルコースが直接セルロース生産に振り向けられるので、セルロース収量が増えたと考えられた。また、培地中の酵母エキスを増量してセルロース収量が2倍になった時の代謝経路について同様に調べた。その結果から、酵母エキスの成分がTCAサイクルを活性化することにより、グルコースがエネルギー源としてではなく、直接セルロース原料として用いられる割合が多くなったと考えられた。また、リグニンスルホン酸を添加してセルロース収量が1.8倍になったときの代謝経路について同様に調べたが、直接重合経路が増えていないので、他とは違う経路が予想できた。
  • 日本学術振興会：科学研究費助成事業 若手研究(B)
    研究期間 : 2002年 -2004年 
    代表者 : 田島 健次
     
    セルロース生産菌Acetobacterxylinum由来のセルロース合成に関与するセルラーゼCMCaxの構造解析を目的として、酵素の単離精製、結晶化、および結晶構造解析を行った.この酵素は糖加水分解酵素のファミリー8(GH-8)に分類されており,すでに解析されていたGH-8に所属するセルラーゼCelA(Clostridium thermocellum由来)と相同な立体構造((α/α)6バレル構造)を形成していることが明らかになった.一方,糖鎖認識部はCelAにおいては6箇所の糖認識サブサイトを持つのに対して,CMCaxはひとつのチロシン残基が欠失していることからサブサイト+3が完全に消えており,この場所で認識クレフトが大きく開いていることが明らかになった.セルロース合成に関わる植物もしくは他のバクテリア由来のセルラーゼは,膜貫通ドメインをN末端側に持っており,膜にアンカーされた状態で細胞表面に存在すると考えられている.一方,CMCaxはN末端にシグナルペプチドを持つ細胞外分泌タンパク質であり,膜貫通ドメインは見られない.ところが,免疫染色法を用いた解析の結果,CMCaxも他のセルラーゼ同様に細胞表面に局在していることが明らかになった.これらの結果から,CMCaxは細胞表面において,合成され細胞から排出されるグルカン鎖と相互作用している可能性が示唆された.
  • 遺伝子組換えによる高機能性セルロース誘導体のin vivo合成
    北海道大学クラーク記念財団：北海道大学クラーク記念財団助成事業 事業化研究助成
    研究期間 : 2002年04月 -2003年03月 
    代表者 : 田島 健次
  • 日本学術振興会：科学研究費助成事業 基盤研究(B)
    研究期間 : 2000年 -2003年 
    代表者 : 山岡 稔, 高橋 悦治, 柴 肇一, 柴 肇一, 田中 仁, 上松 隆司, 恵良田 知樹, 山岡 稔, 田島 健次, 高井 光男, 高橋 悦治, 棟方 正信, 西村 和晃
     
    人工歯根膜開発の基礎研究としてポリリン酸ナトリウムの骨芽細胞に対する作用についてMC3T3-E1細胞を用いて検討した.ポリリン酸による各種骨芽細胞分化マーカー遺伝子の発現誘導では,ポリリン酸処理した細胞ではオステオポンチン,オステオカルシン両遺伝子の発現が誘導され,その発現量は処理後12日目,25日目でそれぞれ最大となった.この結果より,ポリリン酸がこれらの骨芽細胞分化マーカーの発現に関与していることがわかった.アリザリンレッド染色及びvon Kossa染色による細胞石灰化と石灰化結節の観察では,ポリリン酸処理を行わなかった細胞及びリン酸処理した細胞では染色像が観察されなかったのに対し,ポリリン酸処理した細胞では顕著なアリザリンレッド染色像が観察され,染色の程度はβ-グリセロフォスフェート(β-GP)とアスコルビン酸(AA)で処理を行った細胞と比較しても強かった,またvon Kossa染色でもポリリン酸処理を行った細胞で石灰化結節が観察され,ポリリン酸により細胞石灰化が誘導されていることが確認できた.ポリリン酸によるアルカリホスファターゼ活性の誘導では,ポリリン酸処理した細胞ではアルカリホスファターゼ活性が誘導された.β-GPとAAで処理を行った場合と比較するとその活性は若干低くなったが,このことからポリリン酸処理を行った細胞ではアルカリホスファターゼ活性に依存したリン酸供給経路の他に別のリン酸供給経路を持つ可能性が考えられた。以上の結果より、ポリリン酸がMC3T3-E1細胞の石灰化に大きく関わっているということが明らかとなった。
  • 2段階バイオリアクターを用いた生分解性プラスチックの連続合成
    ノーステック財団：基盤的研究開発育成事業 研究開発シーズ育成補助金
    研究期間 : 2001年07月 -2002年03月 
    代表者 : 田島 健次
  • セルロース合成に関与しているセルラーゼの立体構造解析とその機能解明
    北海道大学クラーク記念財団：北海道大学クラーク記念財団助成事業 独創的研究助成
    研究期間 : 2001年04月 -2002年03月 
    代表者 : 田島 健次
  • 固定化菌体・酵素を用いた生分解性プラスチックの連続合成
    ノーステック財団：基盤的研究開発育成事業 研究開発シーズ育成補助金
    研究期間 : 1999年07月 -2000年03月 
    代表者 : 田島 健次
  • 遺伝子組換えによる高機能性セルロース誘導体のin vivo合成
    ゼネラル石油研究医奨励財団：研究助成
    研究期間 : 1999年04月 -2000年03月 
    代表者 : 田島 健次
  • 歯プレセメント質由来糖タンパク質の構造と機能の解明
    日本学術振興会：科学研究費補助金 萌芽研究
    研究期間 : 1997年04月 -1999年03月 
    代表者 : 棟方 正信
  • 固定化菌体を用いた生分解性プラスチックの連続合成
    ノーステック財団：産業化研究開発支援事業 研究開発産業化促進補助金
    研究期間 : 1997年04月 -1999年03月 
    代表者 : 田島 健次
  • 日本学術振興会：科学研究費助成事業 基盤研究(B)
    研究期間 : 1997年 -1999年 
    代表者 : 高井 光男, 柴 肇一, 惠良田 知樹, 棟方 正信, 田島 健次, 藤原 政司
     
    水中離解した精製イカ甲キチンホモジネートから減圧下で均質なイカキチンシートを調製し、代用皮膚材料のべースとした。これにアテロ化した鮭皮コラーゲンをラミネートすることにより代用皮膚試料を調製し、ヒト真皮由来の細胞接着数及び増殖数の測定を行った。キチンシート単体に比べ、鮭皮コラーゲン、仔牛皮コラーゲンをラミネートした試料の接着数が明らかに多いことが確認された。また、増殖能は鮭皮コラーゲンをラミネートしたものは、細胞播種から8日後仔牛皮コラーゲンの1.3倍、イカキチン単体の1.5倍も増殖を活性化した。これは、鮭皮コラーゲンの変性温度が低いため、仔牛皮コラーゲンのような37℃の生理的条件下での繊維化高次構造による細胞増殖の抑制が起こらないためと考えられる。増殖細胞のDNAラベリングインデックスを測定した結果、キチンシート単体、鮭皮コラーゲンおよび仔牛皮コラーゲンをラミネートした試料のいずれも正常ヒト真皮細胞のDNAラベリングインデックスと同様の値であることから、各試料上の皮膚細胞はガン化によって増殖が活性化されているのではなく正常な増殖である事を確認した。従って、鮭皮コラーゲンは、イカ甲キチンシートにラミネート(最適量0.1g/cm^2)することにより細胞接着力、増殖力に優れた高性能代用皮膚材料として利用できる。 更に、本研究では均質な代用皮膚を大量に製造する装置の開発も行った。平成3年度〜4年度科学研究費補助金(試験研究(B)(1))で試作した連続抄紙機を改良した。代用皮膚の通気性を向上させるための穿孔部分と温度制御可能な鮭皮ラミネート部分を具備した構成となっている。本抄紙機の性能は抄紙速度50cm/min,抄紙幅16cm,抄紙長30mで巻き取りボビンでの平均湿度は40%以下である。また、マウス、ラット、兎を使った安全性試験(急性毒性、発熱性、溶血性、皮内反応、移植、抗原性)はいずれも高い適合性を示した。
  • 日本学術振興会：科学研究費助成事業 萌芽的研究
    研究期間 : 1997年 -1998年 
    代表者 : 棟方 正信, 田島 健次, 柴 肇一
     
    本年度は,昨年度報告したヒト歯肉線維芽細胞を走化させるウシ歯根表面プレセメント質由来66KDaタンパクを,HPLCゲル濾過,HPLC陰イオン交換,HPLCハイドロキシアパタイト,HPLC-逆相,SDS-PAGE等にて多量に単離精製し,その走化活性及び増殖活性について既知物質との相違を検討した。歯周組織に存在する歯周靭帯細胞及び歯肉線維芽細胞に対し細胞走化活性がすでに報告されているPDGF-BB,AB,AA等に比べ,66kDaタンパクは約1/100の濃度で歯肉線維芽細胞に対し細胞走化活性を示したが,細胞増殖活性はPDGF-BB,AB,AA等の約10倍濃度を必要とした。すなわち66kDaタンパクは細胞走化活性に特異性がある物質と考えられた。またPDGF-BBとの併用では走化活性の相加効果が認められ,すでに前臨床での効果が報告されているPDGF-BBとIGF-Iの組み合わせより高い走化活性を示し,臨床応用が期待できる結果を得た。 γ線照射したウシ歯セメント質粒子をゼラチン多孔性膜に包埋し,歯肉剥離掻爬手術(in vivo:サル)に用いた場合,歯周靭帯形成がなされず歯槽骨再生のみが進行し,歯槽骨が歯根面に接着する,いわゆるアンキロージスが認められた。γ線照射したウシ歯セメント質粒子のPBS(-)抽出物のHPLCゲル濾過では,全体に抽出物の低分子化認められた。またSDS-PAGEでは,66kDaタンパクは認められなかったことから,66kDaタンパクは歯周靭帯形成(分化)にも関与している可能性が示唆された。
  • 日本学術振興会：科学研究費助成事業 基盤研究(B)
    研究期間 : 1996年 -1997年 
    代表者 : 高井 光男, 田島 健次, 藤原 政司, 柴 肇一, 惠良田 知樹, 棟方 正信
     
    本研究では高い機械的強度と生分解性を合わせ持った新規の機能性バクテリアセルロース(BC)の合成を目的として、種々の水溶性高分子(WSP)を含む培地中で酢酸菌を培養した。メチルセルロース(MC)、カルボキシメチルセルロース(CMC)、ポリエチレングリコール(PEG)を含む培地中で酢酸菌を培養することによってこれらを含んだBC、すなわちBCコンポジット(BCC)を合成した。 MCを添加した場合のBCC収量は最大でコントロール(NBC)の約1.5倍、CMCのBCCについては約1.8倍、PEGについてはNBCとほぼ同じであった。元素分析におけるC%から算出した水溶性多糖の含有率はCMCのBCCで約45wt%、MCのそれではCMCの約半分(約20wt%)であった。BCC中におけるCMCの含有量は培養時間とともに増加し、培養5日目以降で一定値となった。通常、BCの合成は気液の界面で起こり、新しいBCは既に生成したBCの上に作られる。つまりCMC分子が新しくできたセルロースと結合するためには既に合成されたBCCの中を拡散して行かなければならず、培養時間の経過と共にCMCの含有量が一定値となったと考えられる。 BCCの生分解性試験をセルラーゼ酵素標品と土壌埋め込みにより行った。7日間培養BCCのセルラーゼによる分解性試験の結果、BCC(CMC)は6時間で完全に分解され、BCC(MC)は48時間でも20-30%の分解性しか示さなかった。これはCMCとMCのセルラーゼに対する基質特異性によるものと考えられる。また、土壌分解試験の結果、NBC、BCC(CMC)両者とも4週間で完全に分解され、BCC(MC)は僅かに形態を留めていた。この様に分解性の異なる水溶性高分子でBCを複合化することにより生分解性の異なるBCCの調製が可能である。 回転円板型反応器によるBC合成の実験結果をまとめて検討した結果、以下の結論に達した。1)BCを効率的に得るための最適培養条件は、10rpm,2/min、円板枚数10枚であった。2)動的ヤング率の大きいセルロースを得るための最適培養条件は、30rpm,2/minであった。3)pHコントロールは行わない方が良かった。4)液体培地に脱イオン水から蒸留水を用いるとセルロース収量、動的ヤング率共に増加した。5)酵母エキス添加時はグルコースを別滅菌することが望ましく、この時にもセルロース収量、動的ヤング率共に増加した。6)セルラーゼ(Onozuka R-10)添加時には、セルロース収量、動的ヤング率共に最も著しく増大した。
  • 日本学術振興会：科学研究費助成事業 基盤研究(A)
    研究期間 : 1995年 -1996年 
    代表者 : 高井 光男, 田島 健次, 藤原 政司, 柴 肇一, 惠良田 知樹, 棟方 正信
     
    本研究では色々な形状の培養器を用いて効率の良いバイオセルロース(BC)の培養方法について検討し、それに基ずき回転円板型バイオリアクターを試作した。これは横置き円筒型で円筒部分は長さ20cm、直径15cmのガラス製、側面はステンレス製である。モーター駆動部側面には分注及び通気を兼ねた開口部が1箇所、反対側の側面にはpH電極と酸素電極の差し込み口が2箇所とコック付き通気口とドレーンが2箇所備わっている。培養容器下部に温水循環ジャケットを置き、さらに全体をアクリル製カバーで覆い液体培地の温度制御を行った。pHコントロールは1%NaOH水溶液でコントローラーを用いて行った。エアレーションはエア-コンプレッサーからの空気をフィルターに通した後、気相のみに行った。液体培地量はガラス円筒の回転中心部までの1800mlとした。菌体サポーターの形態は円板型(直径14.4cm、アルミ板、ステンレス製金網、6,8,10,12,14,16mesh)で行った。プレカルチャー60mlを植菌し、円板を2〜50rpmで回転させ28℃、6日間培養(通気量2000ml/min)でBC合成を行った。全部で9回の培養実験を行い、円板形態、円板回転速度、メッシュの大きさ、円板枚数、pHコントロール、エアレーション等によるBC収量に与える影響を調べた。その結果、円板形態はステンレス製金網円板が最も効果的であった。円板回転速度については30rpmと50rpmではBC収量に差はほとんど見られなかったが、50rpmでは回転速度があまりにも大き過ぎるため生成セルロースが円板に付かないで培地中で飛散する傾向が見られた。このリアクターは金網円板上に菌体を保持させ円板上でBC合成を行うのが目的であるため、最適回転速度を30rpmとした。メッシュの大きさは14mesh金網円板が最も効果的であった。エアレーションの効果はBCの収量増大と膜質の向上が認められた。

教育活動情報

主要な担当授業

  • 生命分子化学特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 総合化学院
    キーワード : 遺伝情報，タンパク質構造，分子論的理解，生合成機構，動物細胞，二次代謝産物，バイオポリマー，環境浄化
  • 大学院共通授業科目（一般科目）：自然科学・応用科学
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 遺伝情報，タンパク質構造，分子論的理解，生合成機構，動物細胞，二次代謝産物，バイオポリマー，環境浄化
  • 生命分子化学特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 遺伝情報，タンパク質構造，分子論的理解，生合成機構，動物細胞，二次代謝産物，バイオポリマー，環境浄化
  • 分子材料化学特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 総合化学院
    キーワード : 天然高分子分子材料、機能性分子、環境調和型材料、バイオマス由来ポリマー、ポリヒドロキシアルカン酸、ナノファイバー、バクテリアセルロース、コラーゲン
  • 生命分子化学特論
    開講年度 : 2021年
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 遺伝情報，タンパク質構造，分子論的理解，生合成機構，動物細胞，二次代謝産物，バイオポリマー，環境浄化
  • 応用化学学生実験Ⅴ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 有機化学、高分子化学、安全教育、基礎実験、合成実験
  • 物質変換工学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 有機合成，有機材料，化学プロセス，反応器設計，生体材料，高分子材料，分子機能，無機材料，複合材料，電子材料，光機能材料
  • 生物学Ⅰ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 生体高分子，細胞の構造と機能，エネルギー代謝，細胞の成長と分裂，遺伝現象と遺伝子発現制御，分子生物学，遺伝子工学，バイオテクノロジー
  • 高分子化学Ⅱ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 天然高分子、高分子の分子運動、高分子溶液、高分子固体・液晶、分子量測定法
  • 高分子機能化学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 高分子材料、導電性・イオン伝導性材料、光機能材料、分離・認識材料、メディカル機能材料、環境材料

大学運営

委員歴

  • 2021年07月 - 現在   日本生物工学会   北日本支部庶務
  • 2019年07月 - 現在   セルロース学会   理事
  • 1995年04月 - 現在   セルロース学会   北海道・東北支部編集委員   セルロース学会
  • 2009年06月 - 2011年06月   日本生物工学会   代議員
  • 2003年06月 - 2008年06月   日本生物工学会   北日本支部編集委員   日本生物工学会
  • 2003年06月 - 2005年06月   日本生物工学会   北日本支部庶務

社会貢献活動

  • 公益財団法人草野河畔林トラスト財団評議委員
    期間 : 2016年05月 - 現在
    役割 : 助言・指導
    主催者・発行元 : 財団法人草野河畔林トラスト財団

その他

  • 2018年 - 9999年  イムラ・ジャパン株式会社（旧株式会社アイシンコスモス研究所）
  • 草野作工株式会社

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