The biohydrogenation of α-linolenic acid and oleic acid by rumen micro-organisms

Abstract

[alpha]-[U-C14]Linolenic acid was incubated with the rumen contents of sheep and the metabolic products were characterized by thin-layer chromatography, gas-liquid chromatography and absorption spectroscopy in the ultraviolet and infrared. A tentative scheme for the biohydrogenation route to stearic acid is presented. The main pathway is through diconjugated cis-cis-cis-octadecatrienoic acid, non-conjugated trans-cis (cis-trans)-octadecadienoic acid and trans-octadecenoic acid, but other pathways are apparent. Washed rumen microorganisms possessed only a limited capacity to hydro-genatea-linolenic acid and oleic acid but the rate was greatly stimulated by a factor(s) present in the supernatant rumen liquor. Pure cultures of Clostridium periringens, Streptococcus faecalis, Escherichia coli and a coliform organism isolated from sheep feces possessed negligible ability to hydrogenate unsaturated fatty-acids compared with a mixed population of rumen micro-organisms. Butyrivibriofibrisolvens slowly converted linoleic acid into octadecenoic acid.