M Hosokawa, CT Hou, D Weisleder
APPLIED AND ENVIRONMENTAL MICROBIOLOGY 69 (7) 3868 - 3873 0099-2240 2003
[Refereed][Not invited] Previously, it was reported that a newly isolated microbial culture, Clavibacter sp. strain ALA2, produced trillydroxy unsaturated fatty acids, diepxoy bicyclic fatty acids, and tetrabydroxyfuranyl fatty acids (THFAs) from linoleic acid (C. T. Hou, J. Am. Oil Chem. Soc. 73:1359-1362,1996; C. T. Hou. and R. J. Forman III, J. Ind. Microbiol. Biotechnol. 24:275-276, 2000; C. T. Hou, H. Gardner, and W. Brown, J. Am. Oil Chem. Soc. 75:14831487,1998; C. T. Hou, H. W. Gardner, and W. Brown, J. Am. Oil Chem. Soc. 78:1167-1169,2001). In this study, we found that Clavibacter sp. strain ALA2 produced novel THFAs, including 13,16-dihydroxy-12-THFA, 15epoxy-9(Z)-octadecenoic acid (13,16-dihydroxy-THFA), and 7,13,16-trihydroxy-12, 15-epoxy-9(Z)-octadecenoic acid (7,13,16-trihydroxy-THFA), from alpha-linolenic acid (9,12,15-octadecatrienoic acid). The chemical structures of these products were determined by gas chromatography-mass spectrometry and proton and C-13 nuclear magnetic resonance analyses. The optimum incubation temperature was 30degreesC for production of both hydroxy-THFAs. 13,16-Dihydroxy-THFA was detected after 2 days of incubation, and the concentration reached 45 mg/50 ml after 7 days of incubation; 7,13,16-trihydroxy-THFA was not detected after 2 days of incubation, but the concentration reached 9 mg/50 ml after 7 days of incubation. The total yield of both 13,16-dihydroxy-THFA and 7,13,16-trihydroxy-THFA was 67% (wt/wt) after 7 days of incubation at 30'C and 200 rpm. In previous studies, it was reported that Clavibacter sp. strain ALA2 oxidized the C-7, C-12, C-13, C-16, and C-17 positions of linoleic acid (n-6) into hydroxy groups. In this case, the bond between the C-16 and C-17 carbon atoms is saturated. In ot-linolenic acid (n-3), however, the bond between the C-16 and C-17 carbon atoms is unsaturated. It seems that enzymes of strain ALA2 oxidized the C-12-C-13 and C-16-C-17 double bonds into dihydroxy groups first and then converted them to hydroxy-THFAs.