Detection of emetic bacillus cereus by real-time PCR in foods

Abstract

The simplex real-time PCR assays based on the TaqMan probe and SYBR green I, which target cereulide synthetase genes (ces genes) were used for rapidly, reliably and sensitively identifying the emetic strains from among Bacillus cereus strains isolated from different sources. Only the emetic strains showed positive reactions to the real-time PCR assays, but all examined strains of diarrheal B. cereus, other Bacillus species and other gram positive and negative bacteria gave negative results. The final identification of emetic B. cereus was possible within 1 to 1.5 h in both simplex real-time PCR procedures. The detection limit of emetic strains in food was suggested to be 104 - 105 cfu/g. Both simplex real-time PCR assays were found to be rapid, sensitive and reliable diagnostic tools that complement the different cellular, immunological and chemical detection methods for cereulide-producing B. cereus, even if a relatively expensive device is required for the assays.