Prevalence, molecular identification and characterization of Bacillus cereus isolated from beef burgers
Résumé
The 3-component hemolysin BL (Hbl) and non-hemolytic enterotoxin (Nhe) are probably associated with Bacillus cereus diarrheal outbreaks. In this study, toxin transcription of 18 biochemically positive isolates isolated from 80 beef burgers containing different percentage of meat (30, 60, and 90%) were evaluated using PCR method. Bacterial growth curves were further obtained by Bioscreen C to predict B.cereus population of uncooked and fried burgers kept at refrigerator and at room temperatures. The results showed that 22.5% of beef burgers (18 of 80 burgers) were contaminated with B.cereus where 14/18 and 5/18 of the samples contaminated to B.cereus with Nhe and Hbl genes, respectively. No significant growth was observed in burgers stored at 4 degrees C, although after 8 hr the uncooked burgers and within 10 hr the fried burgers stored at 20 degrees C were considered as spoiled by reaching B.cereus counts of >10(6) cfu/g. Practical applicationsBacillus cereus is recognized as a causative agent of emetic and diarrheal foodborne poisoning. To differentiate the encoding chromosomal genes of Nhe (i.e., nheA, nheB, and nheC) and Hbl (i.e., hblC, hblD, and hblA), multiplex PCR was quite selective to perform.