The growth, physiology and toxigenic potential of Bacillus cereus in cooked rice during storage temperature abuse

The effect of storage temperature abuse on the growth and physiology of Bacillus cereus in cooked rice was examined using plate counting and flow cytometry (FCM). Concurrently, toxigenic potential was measured through recording phosphatidylcholine-specific phospholipase C (PC-PLC) activity. Rice spiked with endospores was incubated at 4 °C, 10 °C or 18 °C for 6 days. Growth was not recorded at 4 °C, whereas >1.0 × 106 CFU g−1 were detected at 10 °C and 18 °C. PC-PLC activity was temperature dependent and was not destroyed by microwaving. FCM population profiling complemented plate count data, providing novel physiological data e.g. on the membrane integrity, redox or intracellular activities of cells over time during low temperature incubation.