L. monocytogens exhibited less cell membrane damage, lipid peroxidation, and intracellular reactive oxygen species accumulation after plasma-activated water treatment compared to E. coli O157:H7 and S. Typhimurium

Abstract

This study investigated the bactericidal activity of plasma-activated water (PAW) generated with a remote discharge reactor against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes. PAW-40, -80, and -120, prepared by activating distilled water for 40, 80, and 120 min, respectively, showed inactivation activity against pathogenic bacteria, which increased as the activation time increased due to decrease in pH and increase in oxidation-reduction potential and reactive oxygen/nitrogen species (RONS) of PAW. In addition, Gram-positive bacteria L. monocytogenes showed superior resistance to PAW than Gram-negative bacteria E. coli O157:H7 and S. Typhimurium. Compared with E. coli O157:H7 and S. Typhimurium, L. monocytogens exhibited less cell membrane damage, lipid peroxidation, and intracellular ROS accumulation after PAW treatment, which indicated that L. monocytogenes exhibited greater resistance because the thick cell wall buffered RONS diffusion into the cell. PAW also showed a control effect on the pathogenic bacteria on cherry tomato, and the effect was maintained throughout five repeated applications; thus, proposing high reusability of PAW. The results of this study propose that PAW generated with a remote discharge reactor can be utilized for pathogen control and provides basic data for related research and practical industrial applications.

Keywords: Bactericidal activity; Fresh produce; Inactivation mechanism; Plasma-activated water; Remote discharge reactor.