Cooperative formation of omega-muricholic acid by intestinal microorganisms.
Three anaerobic bacteria, isolated from the ceca of rats and mice, converted, through a concerted mechanism, beta-muricholic acid, the predominant bile acid in germfree rats, into omega-muricholic acid. One isolate was a Eubacterium lentum strain; the second and third isolates were tentatively identified as atypical Fusobacterium sp. strains. The conversion of beta-muricholic acid into omega-muricholic acid proceeded in two steps: E. lentum oxidized the 6 beta-hydroxyl group of beta-muricholic acid to a 6-oxo group, which was reduced by either of the two other species to a 6 alpha-hydroxyl group, yielding omega-muricholic acid. This transformation occurred both in vitro and in gnotobiotic rats. Monoassociation of germfree rats with the E. lentum strain gave rise to an unidentified fecal bile acid, probably a derivative of beta-muricholic acid having a double bond in the side chain.
D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism; D001711:Biotransformation; D002432:Cecum / Q000382:microbiology*; D002793:Cholic Acids / Q000378:metabolism*; D005051:Eubacterium / Q000378:metabolism*; D005673:Fusobacterium / Q000378:metabolism*; D005856:Germ-Free Life; D008297:Male; D051381:Rats
D001647:Bile Acids and Salts; D002793:Cholic Acids; C004821:muricholic acid