Survival and growth of enterotoxin-positive and enterotoxin-negative Clostridium perfringens in laboratory media.

The survival and growth characteristics of enterotoxin-positive and enterotoxin-negative Clostridium perfringens were compared. Spores of C. perfringens were heated and incubated in laboratory media to simulate the cooking and inadequate storage of cooked food. In our experiment, enterotoxin-positive and enterotoxin-negative spores were heated and incubated individually and it was found that spores of enterotoxin-positive strains were more heat-resistant than spores of the enterotoxin-negative strains. In another experiment, cocktails of enterotoxin-positive and enterotoxin-negative spores were heated and incubated. At the time of inoculation, the ratio of enterotoxin-positive spores to enterotoxin-negative spores was about 1:100. In the case of high-temperature heat treatment, the number of enterotoxin-negative spores decreased to below that of enterotoxin-positive spores after heating, and enterotoxin-positive strains grew to high levels during incubation. In the case of low-temperature heat treatment, the number of enterotoxin-negative spores remained almost unchanged after heating and enterotoxin-positive strains did not grow to high CFU levels during incubation.