[The significance of the bacterial steroid degradation for the etiology of large bowel cancer. VIII. Transformation of cholic-, chenodeoxycholic-, and deoxycholic acid by lecithinase-lipase-negative clostridia].

In order to examine their bile acid transforming capacities, lecithinase-lipase-negative Clostridia, 40 strains, isolate from the feces of patients with large bowel cancer, were cultivated in Schaedler broth containing either cholic, chenodeoxycholic or deoxycholic acid (250 muM). Gas chromatographic analysis of bile acids as hexafluoroisopropylester-trifluoroacetates [on QF-1] showed that 14 strains (35%) attacked cholic acid and 13 strains (32%) chenodeoxycholic acid. Deoxycholic acid, however, was not attacked. About half of the strains transformed cholic and chenodeoxycholic acids as well to one or two products respectively. The metabolites were identified as 3 alpha, 12 alpha-dihydroxy-7-keto-5 beta-cholanoic acid, 3 alpha, 7 beta, 12 alpha -trihydroxy-5 beta-cholanoic acid resp. 3 alpha-hydroxy-7-keto-5 beta-cholanoic acid, and 3 alpha, 7 beta-dihydroxy-5 beta-cholanoic acid (ursodeoxycholic acid) by gas chromatography an combined gas chromatography-mass spectrometry. The Clostridial strains tested here are the first which have proved able to epimerize the 7 alpha-hydroxyl groups of bile acids. We could, however, find no relevance to the etiology of large bowel cancer.