Although the cell death mechanism in pulsed electric field (PEF) sterilization has traditionally been attributed primarily to cell membrane dielectric breakdown—which causes pore formation and the subsequent leakage of cytoplasmic contents—a phenomenon has been observed where cell viability decreases even under low-intensity PEF treatment without the detection of propidium iodide (PI), a dye used to detect small pore formation in the membrane. Consequently, a hypothesis was proposed that reactive oxygen species (ROS), generated through electrical discharges or biochemical reactions, contribute significantly to cell death in parallel with physical membrane destruction.In this study, we evaluated the survival rate and ROS generation of Saccharomyces cerevisiae subjected to PEF treatment at an electric field strength of a sufficiently low voltage of 7.5 kV/cm that does not cause membrane disruption. We compared conditions with and without the addition of dimethyl sulfoxide (DMSO: an OH radical scavenger), EGTA and BAPTA-AM (extracellular and intracellular calcium ion chelators, respectively), and apocynin (an NADPH oxidase [NOX] inhibitor).The addition of these ROS scavengers and inhibitors significantly reduced ROS generation compared to the untreated control group (Fig. 1). Furthermore, the survival rate increased in the presence of ROS scavengers (Fig. 2). These results suggest that the mechanism of PEF sterilization involves not only physical cell membrane destruction (electroporation) but also a ROS-induced biochemical stress response that promotes cell death.
 

Paluse electic field,Sterilization,ROS