Biohydrogenation of C20 polyunsaturated fatty acids by anaerobic bacteria

The PUFAs include many bioactive lipids. The microbial metabolism of C-18 PUFAs is known to produce their bioactive isomers, such as conjugated FAs and hydroxy FAs, but there is little information on that of C-20 PUFAs. In this study, we aimed to obtain anaerobic bacteria with the ability to produce novel PUFAs from C-20 PUFAs. Through the screening of similar to 100 strains of anaerobic bacteria, Clostridium bifermentans JCM 1386 was selected as a strain with the ability to saturate PUFAs during anaerobic cultivation. This strain converted arachidonic acid (cis-5, cis-8, cis-11, cis-14-eicosatetraenoic acid) and EPA (cis-5, cis-8, cis-11, cis-14, cis-17-EPA) into cis-5, cis-8, trans-13-eicosatrienoic acid and cis-5, cis-8, trans-13, cis-17-eicosatetraenoic acid, giving yields of 57% and 67% against the added PUFAs, respectively. This is the first report of the isolation of a bacterium transforming C-20 PUFAs into corresponding non-methylene-interrupted FAs. We further investigated the substrate specificity of the biohydrogenation by this strain and revealed that it can convert two cis double bonds at the omega 6 and omega 9 positions in various C-18 and C-20 PUFAs into a trans double bond at the omega 7 position. jlr This study should serve to open up the development of novel potentially bioactive PUFAs.