Abstract:The rapid identification of cereulide-producing Bacillus cereus by matrix-assisted laser desorption ionization time-off-light mass spectrometry was investigated. The characteristic peak was located and the sensitivity was determined through analyzing the standard substances. The differences between the test results under different culture conditions were analyzed by the orthogonal test, and the specificity of 49 wild B. cereus and 3 standard strains were tested under the optimized culture conditions. The results showed that MALDI-TOF MS could detect the characteristic peaks of [M+Na]+ and [M+K]+ adducts with 1 175 and 1 191 m/z values respectively, corresponding to the cereulide produced in B. cereus, with a high sensitivity (0.01 μg/mL). The range analysis showed that the typical colony cultured in MYP medium at 30 ℃ for 12 hours could lead to the most stable test result with the highest response value (>104). The method application verification revealed that among 49 wild strains, 2 Bacillus cereus strains containing ces gene were detected, whilst the other strains without the ces gene were not detected. The MALDI-TOF MS detection method established in this study can directly, rapidly and accurately detect cereulide-producing B. cereus. This method has strong specificity (100%) and high sensitivity (0.01 μg/mL). Thus, it is of great significance for rapid and accurate analysis and judgment of food safety accidents.
