The hydrogenation of the series of methylene-interrupted cis,cis-octadecadienoic acids by pure cultures of six rumen bacteria.

The hydrogenation of all the methylene-interrupted cis,cis-octadecadienoic acids was examined using pure cultures of six rumen bacteria able to hydrogenate linoleic acid to stearic acid or its immediate precursor, trans-11-octadecenoic acid, after first conjugating the linoleic acid to cis,trans-9,11-octadecadienoic acid. Only the delta 14-cis,17-cis-isomer was not hydrogenated by at least one of the bacteria and no evidence was found that conjugation was necessary before hydrogenation except for the delta 2-cis,5-cis- and delta 9-cis,12-cis-isomers. Several isomers were hydrogenated to an extent close to that achieved with linoleic acid (delta 9-cis,12-cis). Those bacteria only able to hydrogenate linoleic to trans-11-octadecenoic acid gave only octadecenoic acid products and those bacteria able to hydrogenate linoleic acid to stearic gave variable yields of octadecenoic acids and stearic acid except with the isomers delta 12-cis,15-cis and delta 13-cis,16-cis when only octadecenoic acids were detected. At the substrate levels used (20 micrograms/ml), both inhibition and stimulation of growth were found but no common pattern emerged, nor was the growth consistently related to the extent of hydrogenation.