Biohydrogenation of unsaturated fatty acids. Hydrogenation by cell-free preparations of Butyrivibrio fibrisolvens.

Hydrogenation of cis-9,trans-11-octadecadienoic acid to yield trans-11-octadecenoic acid by cell-free preparations of Butyrivibrio fibrisolvens has been obtained under strictly anaerobic conditions. Reduced methyl viologen, NADH, and an endogenous electron donor each can serve as a reductant. Inhibition studies and gel filtration patterns reveal the presence of at least two hydrogenation systems, one of which is coupled through a flavin, possibly FMN. Although the enzymes comprising the biohydrogenation pathway, the fatty acid reductases and linoleic acid isomerase, are part of the bacterial membrane, they do not appear to be constituted as a multienzyme complex.