여러 조건에 따른 Bacillus cereus 포자 형성과 포자의 열저항성 평가

Abstract

Bacillus cereus is a gram-positive spore-forming bacterium and produces an emetic or diarrheal syndrome induced by an emetic toxin and an enterotoxin, respectively. In this study, the effect of different types of media, temperature, and time on the sporulation of B. cereus, and thermal resistance of B. cereus spores produced in various temperatures were evaluated. The highest levels of spores were detected when they are produced at 25oC. There were no significant differences in levels of spores produced at 25oC among culture media and times while levels of spores produced at 43oC were significantly reduced with the increase of time. However, thermal resistance of B. cereus spores could be affected by incubation temperature. In fact, higher D-values (12.0, 10.1, and 5.9 min for 2, 4, and 6 weeks, respectively) of spores produced at 43oC were observed than did in samples produced at other temperatures (25 and 37oC). D-values of spores were 7.7, 8.2, and 12.0 min when they were produced at 25, 37, and 43oC for 2 weeks, respectively. The sporulation of B. cereus at 25oC could result in high amounts of spores however the sporulation at 43oC for 2 weeks could be effective to produce thermal resistant spores.