2003 年 22 巻 4 号 p. 133-137
The effects of Escherichia coli on the transformation of bile acids were examined in aerobic and anaerobic culturing systems for 4 days. Bile acids were converted to methyl ester dimethylethylsilyl ether derivatives and determined by capillary gas liquid chromatography. E. coli oxidized cholic acid (CA) and chenodeoxycholic acid (CDCA) to 3α, 12α-dihydroxy- 7-oxo-5β-cholanoic acid (3α12α 7=O) and 3a-hydroxy-7-oxo-5β-cholanoic acid (3α7=O), and reduced these oxo-bile acids to CA and CDCA, respectively. These oxidation and reduction reactions occurred in both aerobic and anaerobic cultures, finally attaining certain equilibrium values. The values, or oxidation/reduction ratios, were 9 or more in the aerobic culture, and about 1 in the anaerobic culture. E. coli also oxidized taurocholic acid in the aerobic culture, but not in the anaerobic culture.
