Novel <scp> C ₂₀ </scp> Conjugated Fatty Acids as Biohydrogenation Intermediates in <i>Paraclostridium bifermentans</i>

ABSTRACT In this paper, we report a detailed characterization of the eicosapentaenoic acid (EPA) hydrogenation pathway in Paraclostridium bifermentans JCM 1386 T , including the identification of novel intermediates of conjugated EPAs, cis ‐5, cis ‐8, cis ‐11, trans ‐13, cis ‐17‐20:5 (CEPA1) and cis ‐5, cis ‐8, trans ‐11, trans ‐13, cis ‐17‐20:5 (CEPA2) by nuclear magnetic resonance spectroscopy (NMR). EPA was converted to CEPA1 then subsequently to CEPA2. Moreover, the conversion from CEPA1 to CEPA2 was observed as an irreversible reaction. The saturation of CEPA1 and CEPA2 to cis ‐5, cis ‐8, trans ‐13, cis ‐17‐20:4 appeared to occur sequentially, from CEPA1 to CEPA2 and then to cis ‐5, cis ‐8, trans ‐13, cis ‐17‐20:4. The other C 20 fatty acids, arachidonic acid (AA), was hydrogenated in the same way by P. bifermentans JCM 1386 T , producing novel conjugated AAs of cis ‐5, cis ‐8, cis ‐11, trans ‐13‐20:4 (CAA1) and cis ‐5, cis ‐8, trans ‐11, trans ‐13‐20:4 (CAA2). C 18 and C 20 PUFAs with cis ‐ω6 and cis ‐ω9 double bonds were also converted to two corresponding conjugated fatty acid with trans ‐ω7 and cis ‐ω9 as well as trans ‐ω7 and trans ‐ω9 structures, which were further saturated (ω9 saturation) to trans ‐ω7 structures.