SIGNIFICANCE OF BACTERIAL STEROID DEGRADATION FOR ETIOLOGY OF LARGE BOWEL CANCER .6. DEGRADATION OF DEOXYCHOLIC-ACID BY SACCHAROLYTIC BACTEROIDES-SPECIES

  • 1 January 1976
    • journal article
    • research article
    • Vol. 162  (5-6) , 519-527
Abstract
When testing 36 laboratory strains of the strictly anaerobic Bacteroides species B. vulgatus, B. fragilis, B. thetaiotaomicron and B. distasonis, activities for degradation of cholate (3.alpha., 7.alpha., 12.alpha.-trihydroxy-5.beta.-cholanoate) and chenodeoxycholate (3.alpha.,7.alpha.-dihydroxy-5.beta.-cholanoate) were widely, but not universally, distributed in these bacteria. The same strains were also tested for their metabolic activities in regard to deoxycholate (3.alpha.,12.alpha.-dihydroxy-5.beta.-cholanoate). These tests were performed with anaerobically growing cultures and resting cells, incubated aerobically, in media of defined composition previously indicated. After precultivation in a medium containing bile and deoxycholate 22 of 35 strains (63%), growing anaerobically, and 28 of 36 aerobically incubated tests (78%) transformed deoxycholate. The number of active strains was 30 of 36 (83%). All active strains produced 1 metabolite only, all metabolites having the same chromatographic properties as shown by analytical TLC in 2 solvent systems. It must still be decided whether only 1 degradation product is formed from deoxycholate, corresponding to the transformation of chenodeoxycholate, since the chromatographic properties of the metabolites permit the formation of 3.alpha.-hydroxy-12-oxo- and/or 3-oxo-12.alpha.-hydroxycholanoate. Structural evidence could not be demonstrated. Enzyme activity responsible for the metabolism must be induced. It is not identical with the activity oxidizing the 7.alpha.-hydroxyl group. No further details concerning enzyme induction and activity regulation were discovered. The side chain of deoxycholate cannot be degraded by Bacteroides sp., neither by anaerobically growing cultures nor aerobically incubated resting cells.