Bacterial 7-dehydroxylation of Cholic Acid and Allocholic Acid

An obligate anaerobic organism capable of dehydroxylating cholic acid to deoxycholic acid and allocholic acid to allodeoxycholic acid was isolated from feces of the rabbit. It was a member of the bacteroides group (Gram-variable, nonsporulating anaerobes). The growth of the organism was inhibited by neomycin, 10-20 micro g/ml. The existence of this organism affords a satisfactory explanation for the development of gallstones in the cholestanol-fed rabbit and for their absence in rabbits simultaneously treated with neomycin.