Pulsed electric field inactivation of diarrhoeagenic Bacillus cereus through irreversible electroporation

The physical effects of high-intensity pulsed electric fields (PEF) on the inactivation of diarrhoeagenic Bacillus cereus cells suspended in 0.1% peptone water were examined by transmission electron microscopy (TEM). The levels of PEF-induced microbial cell death were determined by enumeration on tryptone soy yeast extract agar and Bacillus cereus-selective agar plates. Following exposure to lethal levels of PEF, TEM investigation revealed irreversible cell membrane rupture at a number of locations, with the apparent leakage of intracellular contents. This study provides a clearer understanding of the mechanism of PEF-induced cellular damage, information that is essential for the further optimization of this emerging food-processing technology.