Effects of nisin and temperature on survival, growth, and enterotoxin production characteristics of psychotropic Bacillus cereus in beef gravy

The growth of four strains of psychotropic Bacillus cereus strains were cultured in a brain heart infusion (BHI) broth and beef gravy with nisin supplementation. The repair of cytoplasmic membrane dysfunction in heat injured Bacillus cereus cells was inhibited by nisin which acted as a voltage-dependent polarizer that prevented the restoration of membrane integrity. The growth and enterotoxin synthesis by Bacillus cereus in BHI was also attenuated by nisin compared to microbial cultures in beef gravy.