Antibacterial activity and mechanism of slightly acidic electrolyzed water (SAEW) combined with ultraviolet light against Staphylococcus aureus

This study aimed to investigate the antibacterial effect and mechanism of Staphylococcus aureus (S. aureus) by combined treatment with slightly acidic electrolyzed water (SAEW) and ultraviolet light (UV, 253.7 nm) (SAEW + UV). The result shows that about 6.70 logs CFU/mL of S. aureus was inactivated after the SAEW + UV treatment (available chlorine concentration, ACC, 70 mg/L) for 90 s. The SAEW + UV treatment has a higher antimicrobial effect than UV or SAEW alone treatment, and the effect increases with time and ACC (P < 0.05). After treatment with SAEW + UV at ACC of 70 mg/L for 90 s, S. aureus showed a decrease in ATP and an accumulation of ROS, and an increase in the conductivity of its cell membrane, which indicates that the membrane was also damaged, but no evidence of nucleic acid and protein leakage was seen. The results showed that SAEW + UV might damage bacterial cell membranes, leading to the accumulation of intracellular ROS and the reduction of intracellular ATP, which leads to bacterial death. Moreover, the specific mechanisms of ROS production and ATP reduction of SAEW + UV on S. aureus need to be further investigated.