Characterizations of Environmental Factors in Conjugated Linoleic Acid Production by Mixed Rumen Bacteria

Abstract

Conjugated linoleic acid (CLA) production by rumen bacteria is closely related to biohydrogenation of linoleic acid (LA) and affected by various environmental factors. Ruminal biohydrogenation and isomerization were characterized in view of incubation conditions using a mixed culture of microorganisms obtained from surgically prepared cows. Free-floating bacteria (FFB) produced more CLA than particle-attached bacteria (PAB). Some major factors affecting the ruminal environment such as diet, concentrations of fat substrates, incubation time, pre-incubation, and the presence of glucose in the medium were found to be important determinants for the ruminal production of CLA and in a close relationship with biohydrogenation. The mixed bacterial culture, which was pre-exposed to LA, produced more CLA than an unexposed control in a medium containing 30% rumen fluid. The rate of conversion of fat substrate (LA) to hydrogenated products (trans-C18:1, C18:0) was negatively correlated with the initial LA concentration. Overall, the present study showed that CLA accumulation can be increased by modification of diet-induced environmental conditions, which affect changes in ruminal microflora.