Effect of electrolyzed water produced using carbon electrodes on HeLa cell proliferation

Inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on stainless steel by synergistic effects of tap water-based neutral electrolyzed water and lactic acid

Contaminated food contact surface is one of the most important transmission routes for foodborne pathogens. Stainless steel is one such food-contact surface that is widely used in food-processing environments. The present study aimed to evaluate the synergistic antimicrobial efficacy of a combination of tap water-based neutral electrolyzed water (TNEW) and lactic acid (LA) against the foodborne pathogens Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on stainless steel. The results revealed that simultaneous treatment with TNEW (ACC of 4.60 mg/L) and 0.1% LA (TNEW-LA) for 5 min resulted in 4.99-, 4.34-, and >5.4- log CFU/cm² reductions in E. coli O157:H7, S. Typhimurium, and L. monocytogenes on stainless steel, respectively. Of these, 4.00-, 3.57-, and >4.76-log CFU/cm² reductions in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively were exclusively attributed to the synergistic action of the combined treatments after factoring out the reductions due to individual treatments. Furthermore, five mechanistic investigations revealed that the key mechanisms underlying the synergistic antibacterial effect of TNEW-LA were reactive oxygen species (ROS) production, cell membrane damage resulting from membrane lipid oxidation, DNA damage, and inactivation of intracellular enzymes. Overall, our findings suggest that the TNEW-LA combination treatment could be effectively used in the sanitization of food processing environments, especially the food contact surfaces, to control major pathogens and enhance food safety.

Electrolyzed water produced using carbon electrodes promotes the proliferation of normal cells while inhibiting cancer cells

We previously developed electrolyzed water (EW) using carbon electrodes and estimated its ability to inhibit the proliferation of human cervical carcinoma HeLa cells. In this study, we found that EW-containing media could not only inhibit HeLa cell proliferation, but were also capable of promoting the proliferation of normal human dermal fibroblasts (NHDF). In addition, the developed EW could reduce cytochrome c, as demonstrated by the cytochrome c reduction assay. Interestingly, EW with a greater pH, which was unable to inhibit HeLa cell proliferation, completely lost the ability to reduce cytochrome c. Our results indicate that EW has opposite effects on cancer and normal cell proliferation and has the ability to reduce cytochrome c. Based on our findings, we suggest the possibility that the reducing capacity of our developed EW may be involved in the significant inhibition of HeLa cell proliferation.

Synergistic interaction of tap water-based neutral electrolyzed water combined with UVA irradiation to enhance microbial inactivation on stainless steel

As an emerging electrolyzed water (EW) technology, tap water-based neutral electrolyzed water (TNEW) is an attractive alternative to other types of conventional EW for sterilization of food contact surfaces. In this study, we sought to identify strategies for improving TNEW inactivation efficiencies of major foodborne pathogenic bacteria. We investigated the synergistic antimicrobial effect of TNEW and ultraviolet-A light (UVA) combination treatment against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on stainless steel. The data confirmed that simultaneous TNEW and UVA treatment for 60 min reduced E. coli O157:H7, S. Typhimurium, and L. monocytogenes population by 2.15, 1.55, and 2.65 log CFU/cm², respectively. The synergistic cell count reductions in E. coli O157:H7, S. Typhimurium, and L. monocytogenes in the combination treatment group were 1.17, 0.59, and 1.62 log units, respectively. Additionally, the mechanisms of the synergistic bactericidal effects of TNEW and UVA were identified through several approaches. Mechanistic investigations suggested that the synergistic effect was associated with intracellular reactive oxygen species generation, bacterial cell membrane damage, and inactivation of dehydrogenase. These findings demonstrate that treatment with TNEW and UVA light can enhance the microbiological safety of food contact surfaces during food processing.