| Affiliation: | (1) Research Support Services, NCAUR, ARS, USDA, 61604 Peoria, Illinois;(2) Microbial Genomics and Bioprocessing Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, United States Department of Agriculture, 1815 N. University St., 61604 Peoria, IL |
| Abstract: | Clavibacter sp. ALA2 converts linoleic acid into many novel oxygenated products including hydroxy FA and tetrahydrofuranyl unsaturated FA (THFA). One of them was tentatively identified by GC-MS as 12,13,16-trihydroxy-9(Z)-octadecenoic acid (12,13,16-THOA) (Hou, C.T., H.W. Gardner, and W. Brown, J Am. Oil Chem. Soc. 78∶1167–1169, 2001). We have separated and purified 12,13,16-THOA from its isomer, 12,13,17-THOA, by silica gel column chromatography and by preparative TLC. Its structure was then confirmed by proton and 13C NMR analyses. Purified 12,13,16-THOA was used as a substrate to study the biosynthesis of THFA. Within 24 h of incubation, cells of strain ALA2 converted 12,13,16-THOA to both 12-hydroxy-13,16-epoxy-9(Z)-octadecenoic acid (12-hydroxy-THFA) and 7,12-dihydroxy-13,16-epoxy-9(Z)-octadecenoic acid (7,12-dihydroxy-THFA). The relative abundance of 7,12-dihydroxy-THFA increased with incubation time, whereas that of 12,13,16-THOA and of 12-hydroxy-THFA decreased. Therefore, the biosynthetic pathway of THFA from linoleic acid by strain ALA2 is as follows: linoleic acid→12,13-dihydroxy-9(Z)-octadecenoic acid→12,13,16-THOA→12-hydroxy-THEA→7,12-dihydroxy-THFA. |
