@article{mbs:/content/journal/micro/10.1099/mic.0.036442-0, author = "McKain, Nest and Shingfield, Kevin J. and Wallace, R. John", title = "Metabolism of conjugated linoleic acids and 18 : 1 fatty acids by ruminal bacteria: products and mechanisms", journal= "Microbiology", year = "2010", volume = "156", number = "2", pages = "579-588", doi = "https://doi.org/10.1099/mic.0.036442-0", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.036442-0", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "CLA, conjugated linoleic acid", keywords = "PUFA, polyunsaturated fatty acid", keywords = "FAME, fatty acid methyl ester", keywords = "DMOX, 4,4-dimethyloxazoline", keywords = "MPE, moles % excess", abstract = "Cultures of ruminal bacteria known to metabolize unsaturated fatty acids were grown in medium containing 50 μg ml−1 of geometric and positional isomers of conjugated linoleic acid (CLA) or 18 : 1 fatty acids and 37.4 % deuterium oxide to investigate the mechanisms responsible for fatty acid metabolism. Butyrivibrio fibrisolvens JW11 converted cis-9,trans-11-18 : 2 and trans-9,trans-11-18 : 2 to trans-11-18 : 1 as the main product, labelled at C-9, and metabolized trans-10,cis-12-18 : 2 to trans-10-18 : 1, labelled at C-13, and smaller amounts of trans-12-18 : 1 and cis-12-18 : 1. Butyrivibrio proteoclasticus P-18 did not grow in the presence of cis-9,trans-11-18 : 2 or trans-10,cis-12-18 : 2, but grew in medium containing trans-9,trans-11-18 : 2, forming 18 : 0. Propionibacterium acnes, a ruminal species that isomerizes linoleic acid to trans-10,cis-12-18 : 2, did not metabolize CLA isomers further. B. fibrisolvens metabolized small amounts of trans-10-18 : 1, trans-11-18 : 1 and cis-9-18 : 1, but the products formed were not detected. B. proteoclasticus, on the other hand, carried out substantial conversion of 18 : 1 substrates to 18 : 0. P. acnes hydrated cis-9-18 : 1 and trans-11-18 : 1 to 10-OH-18 : 0, which was further oxidized to yield 10-O-18 : 0. The deuterium enrichment in the intermediates formed during incubations with 9,11 geometric isomers of CLA was about half that of the products from trans-10,cis-12 CLA and 18 : 1 isomers, suggesting that the reduction of 9,11 geometric isomers CLA by ruminal bacteria occurs via different mechanisms compared with the metabolism of other unsaturated fatty acids.", }