Effect of pulsed electric field with moderate heat (80°C) on inactivation, thermal resistance and differential gene expression in B. cereus spores

Bacillus cereus spores pose a challenge to the food industry owing to their ability to germinate in food during storage and produce toxins. The objective of the current study was to investigate the effect of pulsed electric field (PEF) at low electric field strength (i.e., 7.3, 8.1, 8.8 and 9.4 kV/cm) and moderate temperatures (65, 70, 75 and 80°C) on B. cereus spores. PEF treatment at 9.4 kV/cm at 80°C (pulse width of 20 μs and frequency of 300 Hz) led to a 3.1 log CFU/ml reduction in the number of B. cereus spores and importantly, the D88°C values of the surviving spores were reduced by 12 min. Differential gene expression revealed the upregulation of the gene (BC1768) encoding for chitooligosaccharide deacetylase involved in peptidoglycan degradation in PEF treated spores. The gene (BC2729) encoding for a penicillin‐binding protein required for septation during sporulation was downregulated in PEF treated spores.