Digestion of staphylococcal enterotoxin by Bacillus natto

Cooked rice contaminated with staphylococcal enterotoxin A (SEA) was mixed with 'natto', a Bacillus natto fermented soybean food, and the mixture was incubated at 37 °C for 1 h. Reversed passive latex agglutination (RPLA) tests performed on the mixture revealed that the RPLA titer against SEA was significantly reduced after incubation. Subsequent analytical tests showed that the SEA protein molecule was fragmented to small peptides by an extracellular protease, subtilisin, produced by B. natto. The proteolytic activity of B. natto was also found to be effective against ohter types of staphylococcal enterotoxins.