Mechanism of inactivation of Pseudomonas fluorescens by plasma-activated water based on active substances

The physicochemical properties of plasma-activated water (PAW) and the mechanism of PAW on the inactivation of Pseudomonas fluorescens were investigated. The results demonstrated that as activation time and output voltage increased, the electrical conductivity (EC) and oxidation-reduction potential (ORP) of PAW increased, while its pH decreased. When the activation condition was 20 kV for 30 min (PAW30), the content of active substances of the PAW was the highest (P < 0.05). The concentrations of NO₂⁻, NO₃⁻, and H₂O₂ were high as 0.43 μg/mL, 2.46 μg/mL, and 0.837 μg/mL, respectively. After the PAW30 treatment for 30 min, the population of P. fluorescens was decreased by 2.27 log₁₀ CFU/mL when the initial inoculation volume was 4.38 log₁₀ CFU/mL. PAW oxidative stress disrupted the balance of the intracellular redox, ion concentration, and pH, leading to the breakdown of cell wall and membrane integrity, ultimately causing bacterial inactivation. These are important mechanisms by which PAW exerts its bactericidal effect.

Industrial relevance

The aim of this study was to clarify the optimal preparation conditions for PAW, and its mechanism of killing P. fluorescens. These results contribute to our understanding of the control of spoilage organisms in aquatic products by PAW. In the raw material treatment stage of aquatic product processing, PAW can be used to clean and soak raw materials to kill microorganisms on their surfaces of raw materials. Therefore, PAW can be applied as a green cleaning technology to improve the hygienic quality of aquatic products.