Alteration of Bile Salts by Bacteria. ∗

Abstract

Summary

The ability of a variety of common intestinal microrganisms to grow in bile salt-containing media and to alter the structure of those bile salts was studied. Strains of Escherichia coli, Proteus vulgaris, and Streptococcus faecalis were adapted by serial transfer in cholate-containing media to grow more rapidly in high concentrations of cholate and to alter the composition of the cholate more rapidly than unadapted cultures. E. coli was also shown to alter the structure of deoxycholate. Low concentrations of linoleic or palmitic acids when added to cholate-containing media partially overcame the inhibition of growth and cholate-altering capacity of E. coli. 7-Ketodeoxycholate was the principal metabolite of cholate in continuously aerated cultures of E. coli. The conditions used for transfer of mixed cultures and the isolation of one apparently pure culture of organisms from rat cecum which was capable on 2 first transfers, but not subsequently, of converting cholic acid to deoxycholic acid were described.