Production and Stability of Hemolysin, Phospholipase C, and Lethal Toxin of Bacillus cereus in Foods.

Production of hemolysin, phospholipase C, and (mouse) lethal toxin by two strains of Bacillus cereus in beef, pea, and banana was assayed. Both strains produced hemolysin, phospholipase C, and lethal toxin in beef, hemolysin and phospholipase C in pea, and only lethal toxin in banana, although growth was excellent in each food. In each instance the metabolites were produced at characteristic levels for the food in which the organism was grown and the time of incubation. Foods containing these products were subjected to heating, refrigeration, and freezing. At 65 C lethal toxin in beef was substantially inactivated in 3 min, but hemolysin and phospholipase C retained 50% of their activities after 30 min and about 13% after 120 min. Activity of the three substances in the different foods was decreased by approximately 50% at 4 C after 24 h, but in several instances was still substantially retained after 48 h. Freezing, holding at -37 C, and then thawing generally was less destructive of the activity of the three metabolites in the different foods although decreases of 50% or slightly more occurred in 48 h in most instances. Stability of the different metabolites was much the same with both strains of B. cereus . The influence of particular foods upon stability of hemolysin and phospholipase C was greater than upon lethal toxin.