Sterilizing Processes and mechanisms of Escherichia coli treated by DBD Plasma

With increasing attention in the novel sterilization methods, the plasma sterilization has gained more and more interest. However, the underlying mechanisms are still unknown. In this paper, we investigated the inactivation of Escherichia coli using DBD plasma in saline water. There are three processes shown in the survival curve, including preparation period, reaction period and saturation period. The observation under transmission electron microscope (TEM) and the detection by Fourier Transform Infrared Spectroscopy (FT-IR) supply adequate details in these processes. Based on these results, we infer that in the preparation period the accumulation of chemical substances is the main process. In the reaction period adequate chemicals decompose and denature cell membranes and macromolecules to kill bacteria in large quantities. In the saturation period the killing effect decreases because the protection of clustered cell and the saturation of pH. This study of sterilizing processes reveals the mechanisms of plasma sterilization systematically. IMPORTANCE Compared with the traditional methods, the plasma sterilization has the advantages of high efficiency, easy operation, and environmental protection. It could be more suitable for air and sewage sterilization in special spaces, such as hospital, laboratory, and pharmaceutical factory. However, the sterilization mechanisms are still relatively immature, especially for the processes of bactericidal activities. The sterilization processes contribute to provide guidance for the practical applications. For example, the bactericidal action mainly occurs in the reaction period, and the treatment time can be set based on the reaction period, which could save a lot of energy. This study would help to improve the efficiency of plasma sterilization device.