HEAT AND RADIATION RESISTANCE AND ACTIVATION OF SPORES OF CLOSTRIDIUM WELCHII

Spores of‘classical’strains of Clostridium welchii were more sensitive to heat (D90° 3–5 min) than spores of‘food poisoning’strains (D90° 15–145 min) from the same sporulation media. The z values of‘classical’strains (z=11–14°F) were lower than for‘food poisoning’strains (z= 16–29°F). 30–50% of spores of‘classical’strains grew without heating, and no heat activation was detected. Only 0.13‐3.6% of spores of‘food poisoning’strains grew without heating, heat activation being generally detected at 75–80°, and on one occasion at 75–100°. Spores of‘food poisoning’strains were more resistant to γ radiation (D=0.26‐0.34 Mrad) than spores of‘classical’strains (D=0.12‐0.21 Mrad). Copyright © 1968, Wiley Blackwell. All rights reserved