Rapid detection of Bacillus cereus from foods by PCR analysis

Bacillus cereus a well known food poisoning organism, has been identified as the causative agent in a number of food poisoning outbreaks many of which unreported because confused with those of other pathogens. Improving microbial safety and extending the shelf-life of industrial food products has always been an important concern to the food industry. There is still confusion regarding how many different enterotoxins are produced by B. cereus. In fact it produces a high variety of toxins. Furthermore enterotoxins could be produced also by non- B. cereus species. isolates of B. circulars. B. lentos, B. mycoses and B. thuringiensis, which are strictly related to B. cereus demonstrated positive results using RPLA assay. Some authors proved difficulties to distinguish between B. cereus, B. mycoses and B. thuringiensis because they referred as B. cereus also the B. mycoses and B. thuringiensis. in this work we developed a couple of specific primers for B. cereus and specific DNA extraction techniques to obtain PCR products from food without any previous enrichment. Salad, meat, rice, coffee and mll samples were used to verify the procedure. The gyro gene used as target for the primer design was useful to obtain amplified products only for B. cereus also in the presence of low number of B. cereus cells and a high number of other natural contaminant microorganisms. Moreover positive results were obtained using the PCR detection of B. cereus directly in food samples, and the data are confirmed by classical microbiological analyses.