Composition of cecal bile acids in ex-germfree mice inoculated with human intestinal bacteria

Germfree (CF) mice were orally inoculated with human fecal suspension or va rious components of human fecal microbiota. Three weeks after the inoculati on, cecal bile acid composition of these mice was examined. More than 80% o f total bile acids was deconjugated in the cecal contents of ex-GF mice ass ociated with human fecal dilutions of 10(-2) or 10(-6), or anaerobic growth from a dilution of 10-6. In these ex-GF mice, deoxycholic acid accounted f or about 20% of total bile acids. In the cecal contents of ex-GF mice assoc iated only with clostridia, unconjugated bile acids made up less than 40% o f total bile acids, about half of those in other ex-GF groups. How ever, th e percentage of deoxycholic acid in these mice was the same as that in the other groups. These results indicate that dominant anaerobic bacterial comb ination is efficient for de-conjugation of primary bile acids, and that clo stridia in the human feces may play an important role in 7 alpha-dehydroxyl ation of unconjugated primary bile acids in the intestine.