Inactivation efficacy and mechanisms of plasma activated water on bacteria in planktonic state

Abstract

Aims: The study aimed to investigate the inactivation efficacy and mechanisms of plasma activated water (PAW) on selected bacteria in planktonic state. Methods and Results: Plasma activated water was generated using an atmospheric cold plasma jet at 15, 22 and 30 kV for 5 min. Escherichia coli, Listeria innocua, Staphylococcus aureus, Aeromonas hydrophila, Pseudomonas fluorescens and Shewanella putrefaciens were selected as the representative bacterial species. Each bacterial suspension was inoculated into PAW immediately after generation, and the viable counts at different exposure times of 0Á5, 1, 3, 5 and 24 h during 4°C storage were measured to determine the inactivation efficacy. Scanning electron microscopy images of the bacteria were conducted to examine the structural changes. Physicochemical properties of PAW, including pH, conductivity, oxidation reduction potential (ORP), and reactive species of H 2 O 2 , NO 2 À and NO 3 À were measured. The results demonstrated that inactivation efficacy was in positive correlation with voltage and exposure time. Gram-negative bacteria were more susceptible to PAW than Gram-positive bacteria. Morphology damage was observed for all the bacterial species. PAW was significantly acidified, conductivity and ORP were significantly increased, and reactive species were detectable after 48 h. Conclusions: This study offered a better understanding of the inactivation mechanisms of PAW, and the inactivation efficacy can be affected by voltage, exposure time and bacterial species. Significance and Impact of the Study: This study demonstrated the potential usage of PAW as an alternative disinfectant.

Plasma‐activated water: Physicochemical properties, microbial inactivation mechanisms, factors influencing antimicrobial effectiveness, and applications in the food industry

“…While more than 5 log reduction was obtained for the Gram‐negative bacteria within 15 min. Similarly, Zhao, Ojha, Burgess, Sun, and Tiwari (2020b) investigated the inactivation efficacy of PAW on six bacteria, including Gram‐negative and Gram‐positive bacterial species. Based on the exposure time needed to get 5 log reduction, the bacteria were classified into three categories.…”

Antimicrobial Effect of Plasma-Activated Tap Water on Staphylococcus aureus, Escherichia coli, and Candida albicans

“…According to Q. Xiang et al [46,47], the ORP increased from 546 to 552 mV after the G Arc treatment of 200 mL of SWD at discharge power of 750 W and a compressed air flux of 30 L min −1 for 30 s without stirring. Zhao et al [48], using an atmospheric cold plasma jet (ACPJ), treated 30 mL of SWD for 5 min in static mode. They observed an increase in PAW's ORP value to 546.77, 558.57, and 565.40 mV at 15, 22, and 30 kV, respectively, showing that the voltage had a significant impact on the oxidation-reduction potential.…”

Inactivation of Dermatophytes Causing Onychomycosis and Its Therapy Using Non-Thermal Plasma

“…NTP is widely used in many areas of human activity including the modification of the surface of various materials (surface termination, increasing of wettability), the food industry (food decontamination, increase of seed wettability), biotechnology (microbial decontamination), wastewater treatment, biology, and medicine (wound and skin infection healing, blood coagulation); for a more detailed description of its applications, reviews by Tendero et al (2006) [20], Julák and Scholtz (2020) [21], Zhao et al (2020) [22], or the comprehensive book by Metelmann et al (2018) [23] may be recommended. Medical applications mainly include disinfection processes, but also acceleration of blood coagulation and improved wound healing, dental applications, or cancer therapy [24,25].…”