To recognize the risk of Bacillus cereus in pasteurized milk, we investigated the prevalence of B. cereus and the rate of the production of cereulide from B. cereus isolates. B. cereus was found in 66 out of 101 (65.3%) domestically pasteurized milk samples in Japan. The ces gene was identified in 3 out of 90 B. cereus isolates that were isolated from three samples (one product) among the 101 samples. The ces gene positive isolate, the reference strain F4810/72 and a B. cereus isolate collected in a food poisoning incident were shown the productivity of cereulide using an LC-MS/MS analysis. The LC-MS/MS analysis was confirmed the ability of identification and quantification of cereulide produced in the milk samples. In this study, it was shown that B. cereus strains are prevalent in pasteurized milk, some of these strains produce cereulide, and confirmed usefulness of LC-MS/MS analysis to detect cereulide in milk.
Keywords: Bacillus cereus; LC-MS/MS; cereulide; emetic toxin; pasteurized milk.