Biohydrogenation of unsaturated fatty acids. Presence of dithionite and an endogenous electron donor in Butyrivibrio fibrisolvens.

Two oxygen-consuming substances were isolated from cell-free extracts of the rumen anaerobe, Butyrivibrio fibrisolvens. The major fraction comprising 97% of the total activity was characterized as a three-component mixture of glucose, maltose, and dithionite. The minor activity fraction contained an electron donor for the reduction of cis-9,trans-11-octadecadienoate to trans-11-octadecenoate. After oxidation, the electron donor could be reduced by the dithionite, thereby accounting for the previously observed capacity of cell-free extracts of the bacterium to carry out the biohydrogenation of the conjugated dienoic fatty acid.