Influence of intestinal microorganisms on the metabolism of bile acids in mice

Abstract

In order to investigate the metabolism of bile acids of the mouse by intestinal microorganisms, isolation of the organisms responsible for the transformation of bile acids in the intestinal tract of conventional mice and their activity in vivo in mono- or polycontaminated exgermfree mice were made. Bacteroides, Lactobacillus, Enterococcus and Clostridium perfringens isolated from the intestines of conventional mice converted conjugated bile acids into free acids both in vitro and in vivo, but E. coli, Staphylococcus and Proteus did not. These microorganisms capable of converting conjugates distributed in the whole intestines, also in the cecum and upper small intestine. Among the resident intestinal microorganisms of mice, only E. coli had the ability of converting cholic acid into 7-ketodeoxycholic acid. The role of exogenic microorganisms in the conversion of free bile acids were also investigated compared with resident intestinal flora. Many species of such exogenic bacteria as Shigella, Salmonella and El Tor vibrio had no effect on the conversion of cholic acid. Some of pathogenic E. coli converted cholic acid and some did not. © 1970, The Keio Journal of Medicine. All rights reserved.