Biosynthesis of androgen from cortisol by a species of Clostridium recovered from human fecal flora.

A hitherto unknown species of Clostridium, provisionally designated strain 19, was isolated from the fecal flora of a healthy human adult. This strain synthesizes a constitutive desmolase that cleaves the side chain of cortisol to form 11 beta-hydroxy-4-androstene-3,17-dione. The enzymatic conversion is best demonstrated in supplemented peptone broth and in prereduced brain-heart infusion broth. The fecal concentration of strain 19 is 10(7)-10(8) cells/g. The strain adapts with difficulty to growth on Mueller-Hinton agar and Columbia agar base; colony formation is enhanced by the addition of 5% sheep blood. The organism is sensitive to penicillin G and resistant to tetracycline, chloramphenicol, clindamycin, and erythromycin.