Abstract
Clostridium scindens sp. nov., an obligate anaerobe with desmolytic activity, was isolated from human fecal flora. The desmolase, not associated previously with any specific intestinal microorganism, cleaves the carbon-carbon bond of 17-hydroxylated corticoids at C17-C20, thereby converting them to androstans (C19 steroids). In primary cultures on sheep blood agar plates, C. scindens forms minute, nonhemolytic colonies. The gram-positive rods (0.5 to 0.7 by 1 to 2.5 μm) are slightly curved. The rare oval terminal spores (0.8 to 2.0 μm in diameter) are extremely difficult to demonstrate in Gram-stained smears. More than 40% of the cells are fimbriated. Neither a capsule nor flagella are present. d-Fructose, d-glucose, lactose, d-mannose, d-ribose, and d-xylose are fermented. The major fermentation products are acetic acid, ethanol, and hydrogen. The type strain is ATCC 35704 (Bokkenheuser strain 19).