Bactericidal Action Mechanism of Nonthermal Plasma: Denaturation of Membrane Proteins

With increasing attention in indoor air quality for human health, control of microbial contaminants has gained interest. In an attempt to develop an efficient way to control pathogenic microbes in ambient air, an air-purification technology using nonthermal plasma (NTP) has been developed. However, there is no obvious study on bactericidal mechanism even though the NTP irradiation results in bacterial cell death. In this paper, the fluorescent-based bacterial viability assay indicates that the NTP irradiation resulted in the denaturation of bacterial membrane proteins. In addition, the analysis of 2-D electrophoresis and peptide mass fingerprinting reveal that bacterial proteins are denatured by the treatment. Based on these results, we proposed a possible inactivation mechanism of NTP irradiation, emphasizing the important role of the reaction between positive and negative ions generated by NTP and pointing consequent denaturation of bacterial membrane proteins. This paper will contribute to a better understanding of the bactericidal mechanism by the NTP irradiation.