Steady-state rates of linoleic acid biohydrogenation by ruminal bacteria in continuous culture.

Ruminal biohydrogenation of linoleic acid was determined in fermenters with a continuous culture of microorganisms. Rates of biohydrogenation and changes of fatty acids in culture were measured during steady-state concentration of linoleic acid that was achieved by continuous infusion of linoleic acid into the fermenters. A number of trans and cis isomers were identified using a GLC equipped with an infrared detector. The infusion of linoleic acid resulted in a substantial increase in the content of trans-C18:1 and a lesser increase in cis-C18:1. the major trans peak consisted of a mixture of n-9 and n-7 isomers. Biohydrogenation of infused linoleic acid averaged 77%. There was evidence of fatty acid loss, as determined by a decrease in the recovery of linoleic acid after 8 h of infusion. Addition of C18:2n-6 had no major effect on the VFA production by ruminal microorganisms. The results were similar to those measured in vivo, indicating that artificial fermenters were reliable predictors of fatty acid metabolism in vivo.