Growth and survival of Clostridium botulinum type E in pasturized oysters

The risk of toxin production by Clostridium botulinum type E in pasteurized oysters was evaluated. Thermal death time studies for type E spores in a oyster homogenate showed that the spores survived pasteurization at 550 C; D-values ranged from 65 to 100 min at 700 C and 880 to 1300 min at 550 C. When tubes of oyster homogenate were inoculated with 1x103 type E spores/ml and stored at 3, 6, 12, and 30oC, no growth was observed; however, when the inocculum was increased to 1x104 spores/ml, toxin was produced during storage at 30oC, but not at lower temperatures. For containers of whole oysters inoculated with a low spore level, toxin production occurred during incubation at 6, 12, and 30oC.