Investigation of plasma-activated water inactivation mechanisms of E.coli

Plasma-activated water (PAW), produced through the interaction of low-temperature plasmas with water, demonstrates significant biochemical activity, with potential applications across a wide range of fields, from biomedical to agricultural. [1] In this study, we investigate the potential of PAW for decontamination, using E. coli as a model organism. The goal of this project is to enhance the understanding of the bacterial inactivation mechanisms by PAW to aid in the development of safe PAW-based technologies, and to optimize PAW production. We introduce an in-house designed portable PAW reactor that employs a surface dielectric barrier discharge to activate water through the diffusion of reactive oxygen and nitrogen species (RONS) into the liquid phase. [2]

The chemistry of the plasma and liquid phase is characterized by Fourier transform infrared spectroscopy and colorimetric methods. Different techniques are employed for the study of E. coli inactivation mechanisms: fluorescence flow cytometry, single cell time-lapse microscopy, scanning electron microscopy, RNA sequencing and proteomics. The results of this investigation suggest that after exposure to PAW, bacteria do not lyse and keep an intact membrane. The proteomics results indicate that E. coli become unable to duplicate and dye because of internal damage to proteins and RNA. These findings point towards PAW efficacy associated to the diffusion of RONS inside of the cell wall rather than membrane disruption, opening new frontiers for the understanding and improvement of PAW based technologies.

[1] Zhou Renwu et al. “Plasma-activated water: generation, origin of reactive species and biological applications.” Journal of Physics D: Applied Physics 53 (2020), 303001

[2] Rita Agus et al., “Implementing water recirculation in a novel portable plasma-activated water reactor enhances antimicrobial effect against Escherichia coli”, Chemical Engineering Journal 486 (2024), 149915