SPORULATION OF CLOSTRIDIUM PERFRINGENS IN A MODIFIED MEDIUM AND SELECTED FOODS

A modified sporulation medium for C. perfringens was formulated in which a larger number of spores were produced than in SEC broth and in which spores of greater heat resistance were produced than in Ellner''s medium when it was also used as the suspending medium. This modified medium consisted of 1. 5 percent peptone; 3. 0 percent Tryp-ticase; 0. 4 percent starch; 0. 5 percent NaCl; and 0. 02 percent MgSO4 The addition of 0. 1 percent sodium thioglycolate and 0. 0001 percent thiamine hydrochloride was optional. The optimal temperature for sporulation of five strains was 37 C in comparison with 5, 22, and 46 C. Sporulation had occurred by 6 hr. and was essentially complete after 20 hr. at 37 C. Noyes veal broth without glucose also supported the formation of heat-resistant spores but in smaller numbers than did the modified medium. Very low numbers of spores, or none, were produced under the same conditions in pea or tuna slurries.