Generation times and modeling of enterotoxin-positive and enterotoxin-negative strains of Clostridium perfringens in laboratory media and ground beef

The growth of two enterotoxin-positive (ent(+)) and two enterotoxin-negative (ent(-)) strains of Clostridium perfringens were examined in two laboratory media, fluid thioglycollate and fluid thioglycollate with beef, and in autoclaved ground beef stored at 37, 41, 43, 46, and 48 degrees C. There was no association between enterotoxigenicity and optimum growth temperature, which varied depending on strain and medium. Experimentally obtained values for generation times at 43 degrees C were as low as 8.7 and 6.3 min in thioglycollate both for ent(+) and ent(-) strains respectively, In autoclaved ground beef the shortest generation times, 7.1 min and 9.2 min, were obtained at 41 and 46 degrees C for two ent(+) strains. For ent(-) strains in autoclaved ground beef a generation time of 6.6 min was observed at 43 degrees C. Temperature optima obtained experimentally were the same as those obtained by the Gompertz model. The rapid growth of the ent(+) strains between 41 and 46 degrees C underlines previous recommendations for proper holding and cooling of protein foods such as meat and poultry known to support the growth of this organism.