Antibacterial effect and mechanism of shorter ultraviolet light (222 nm) combined with slightly acidic electrolyzed water against Escherichia coli

Abstract

The impact and mechanism of the combination of Slightly acidic electrolyzed water (SAEW) and shorter UV-C wavelengths at 222 nm (UV222) disinfection (SAEW + UV222) on Escherichia coli (E. coli) were evaluated. A reduction of 6.77 log CFU/mL of E. coli was observed after the combination treatment at an available chlorine concentration (ACC) of 30 mg/L for 120 s. A constructed model (R2 = 0.99) indicated the bactericidal effect of SAEW + UV222 was positive and nonlinearly correlated between time and ACC and their interactions (P < 0.05). Moreover, the SAEW + UV222 treatment required a longer time (120 s) to achieve similar bactericidal effects as the combination of SAEW and UV-C wavelengths at 254 nm treatment. Additionally, UV222 treatment (60 s) alone did not affect the intracellular ROS and ATP of E. coli. In contrast, SAEW + UV222 treatment (30 mg/L, 60 s) induces the accumulation of intracellular ROS and the reduction of ATP of E. coli and destroys the cell membranes. Our study indicates that SAEW + UV222 is a combination disinfection method with great potential.