Development of a PCR assay for identification of the Bacillus cereus group species

Aims: A PCR technique was developed as a reliable and rapid identification method for the Bacillus cereus group species, based on a unique conserved sequence of the motB gene (encoding flagellar motor protein) from B. cereus, Bacillus thuringiensis and Bacillus anthracis. Methods and Results: Primer locations were identified against eight strains of the B. cereus group spp. from nucleotide sequences available in the National Centre for Biotechnology Information database. The PCR assay was applied for the identification of 117 strains of the B. cereus group spp. and 19 strains from other microbial species, with special emphasis on foodborne pathogens. Conclusion: The designed cross-species primers are group specific and did not react with DNA from other Bacillus and non-Bacillus species either motile or not. The primers system enabled us to detect 10³ CFU of B. cereus cells per millilitre of sample. Significance and Impact of the Study: Bacillus cereus group spp. belongs to one of the most prevalent foodborne pathogens. Bacterial growth results in production of different toxins; therefore, consumption of food containing >10⁶ bacteria per gram may result in emetic and diarrhoeal syndromes. A rapid and sensitive bacterial detection method is significant for food safety.