Prevalence of oxygen-intolerant microorganisms in primary bile acid 7α-dehydroxylating mouse intestinal microflora

The in vitro 7α-dehydroxylation of cholic and chenodeoxycholic acids by mixed cultures of mouse cecal microorganisms was studied. Conventional anaerobic techniques and rigorous oxygen-free anaerobic experimental conditions were compared. It was found that the total number of anaerobic oxygen-intolerant microorganisms was about 10 times higher than that of anaerobic microorganisms that tolerate oxygen. Among the anaerobic 7α-dehydroxylating microorganisms, the oxygen-intolerant ones are about 1,000 to 10,000 times more numerous than the oxygen-tolerant ones. It can be concluded that the 7α-dehydroxylating activity is more common among oxygenintolerant than oxygen-tolerant anaerobic microorganisms.