title: Isolation and characterization of thirteen intestinal microorganisms capable of 7 alpha-dehydroxylating bile acids.
abstract: Thirteen anaerobic bacteria capable of performing the 7 alpha-dehydroxylation of both cholic acid and chenodeoxycholic acid were isolated from human feces and also from sewage. Ten organisms from heat-treated samples were species of Clostridium identical or closely related to the Clostridium bifermentans-C. sordellii group and consisted of four strains elaborating 7 alpha-dehydroxylase alone and six strains capable of catalyzing both 7 alpha-dehydrogenation and 7 alpha-dehydroxylation. The remaining three organisms, recovered from fresh human feces, were gram-positive, nonflagellated, nonsporeforming, anaerobic rods and comprised two distinct species. Strain HD-17, still unidentified, had both activities, but was unique in that it exclusively 7 alpha-dehydroxylated cholic acid while biotransforming chenodeoxycholic acid, preferably though 7 alpha-dehydrogenation. Two unclassified strains, b-8 and c-25, metabolized both acids though 7 alpha-dehydroxylation and 7 alpha-dehydrogenation. Except for strains b-8 and c-25, all of th 7 alpha-dehydroxylating bacteria split the conjugated bile acid series, and hydrolases were detected in cell-free filtrates of early stationary-phase broth cultures.
mesh_terms: D001419:Bacteria / Q000201:enzymology* / Q000302:isolation & purification; D001647:Bile Acids and Salts / Q000378:metabolism*; D002635:Chenodeoxycholic Acid / Q000378:metabolism; D002793:Cholic Acids / Q000378:metabolism; D003013:Clostridium / Q000201:enzymology* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology*; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases; D010088:Oxidoreductases; D012722:Sewage; D013250:Steroid Hydroxylases / Q000378:metabolism*
chemical_list: D001647:Bile Acids and Salts; D002793:Cholic Acids; D012722:Sewage; D002635:Chenodeoxycholic Acid; D010088:Oxidoreductases; D006913:Hydroxysteroid Dehydrogenases; C025376:7 alpha-hydroxysteroid dehydrogenase; D013250:Steroid Hydroxylases