LAUSR

Abstract The effects of blue light on the promotion of the bactericidal action of plasma-activated water (PAW) against Staphylococcus aureus by inducing the photolysis of staphyloxanthin (STX) were examined. A light-emitting diode (466 nm) and atmospheric-pressure plasma were applied. The degradation of STX pigments extracted through pure methanol was facilitated by increased dosage of blue light (30, 60, 90, and 150 J/cm2). After combined treatment with blue light (150 J/cm2) and PAW (10 min), the surviving population of S. aureus in liquid decreased by 2.70 log CFU/mL, which was about 40 times higher than that of single PAW treatment. Blue light (150 J/cm2) treatment induced leakage of intracellular substances, indicating potential damage to the cell membrane, which was also confirmed as an increase in the SYTOX™ green fluorescence signal. The synergistic bactericidal effect of blue light and PAW was also observed for S. aureus attached to the surface of stainless steel.