The effect of acid adaptation on the susceptibility of Bacillus cereus to the stresses of temperature and H2O2 as well as enterotoxin production.

Abstract In the present study, Bacillus cereus 1-4-1, which is capable of causing diarrheal syndrome, was subjected to acid adaptation at pH 5.5 for 2 hours. The effect of acid adaptation on the survival of B. cereus subjected to subsequent lethal challenges at both low (4° and −18°C) and high temperatures (49°C) as well as in the presence of 5 mM H2O2 was investigated. Additionally, enterotoxin production by B. cereus as influenced by acid adaptation was examined. Results revealed that acid adaptation increased the survival of B. cereus during storage at −18°C while a decreased survival was noted for the acid-adapted cells during storage at 4°C. In addition, the acid-adapted cells were less susceptible to high temperature than the nonadapted cells. On the other hand, acid adaptation did not change the susceptibility of test organism to H2O2. It was also found that acid adaptation time affected the enterotoxin production of B. cereus cells. The 1- to 2-hour acid-adapted cells exhibited a reduced level of ...