Lethal and Sublethal Effect of a Dielectric Barrier Discharge Atmospheric Cold Plasma on Staphylococcus aureus

The lethal and sublethal effect of a dielectric bather discharge atmospheric cold plasma on Staphylococcus aureus were investigated by nonselective and selective media. The inactivation level and sublethally injured proportions of S. aureus cells by dielectric bather discharge atmospheric cold plasma depended on the treatment times (0, 5, 15, and 45 s), applied input powers (40, 50, and 60 W), and gap distances (2, 4, and 6 mm). Under weak conditions (e.g., 5 s, 40 W, and 6 mm), the occurrence of inactivation and sublethal injury of S. aureus showed a relatively low level. Strong treatment (e.g., 45 s, 60 W, and 2 mm) resulted in highly an inactivated rate, but with small fractions of sublethally injured S. aureus cells. Mild action of cold plasma induced both a large inactivation and a sublethal injury of S. aureus. Therefore, it is significant to optimize the processing of cold plasma sterilization in practice to ensure food safety.