A study of oxidative stress induced by non-thermal plasma activated water for bacterial damage

Abstract

Summary form only given. Recently, the study of plasma activated water (PAW) disinfection has attracted increasing researchers' attention. However, many questions of PAW disinfection still remain unanswered, especially for the mechanism of bacterial cell damage caused by PAW. More in-depth studies of the PAW disinfection are expected. In this study, we produced the PAW by Alternating Current Cold Plasma Jet. The disinfection activities of PAW stored at different time against Staphylococcus aureus were evaluated by plate counting method. The Oxidation Reduction Potential (ORP) of PAW stored at different time was detected by standard electrode method. Morphologies of bacteria treated with PAW were observed by transmission electron microscopy (TEM). The staphyloxanthin damage was analyzed by measuring the cell color change, and the integrity and the permeabilities of the cell membranes were investigated by determining release of cellular contents: the release of DNA and Protein was determined by absorbs at 260 nm and 280 nm respectively; the release of Ca <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> , K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> , Na <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> and Mg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> was determined by atomic absorption spectrometry (AAS). In addition, X-ray photoelectron spectroscopy (XPS) was used to study the interaction of PAW with cell wall. Results showed that PAW could effectively disinfect bacteria and the disinfection efficiency was associated strongly with the ORP of PAW. The morphologies of the bacterial and the ratio of cell wall component were changed after PAW treatment. Moreover, PAW increased the permeability of the cell membraes, ultimately disrupted bacterial cell membranes, with the release of cellular contents. In conclusion, the bacteria cells were badly damaged by PAW and these damages were probably caused by the oxidative stress of PAW. Detailed study will be discussed at the conference.