Sterol requirement for the growth of Treponema hyodysenteriae.

The addition of cholesterol to a liquid medium containing bovine serum albumin (BSA) fraction V or acetone-delipidized BSA fraction V instead of serum stimulated the growth of Treponema hyodysenteriae, a serum-requiring spirochaete associated with swine dysentery. As little as 1.25 micrograms cholesterol ml-1 increased viable counts about 1000-fold. Sitosterol and cholestanol, but not pregnenalone, cholestenone or stigmasteriol, produced a growth response comparable to that of cholesterol. The results suggest that T. hyodysenteriae requires a sterol for growth.