Inactivation of Aeromonas hydrophila in water by dielectric barrier discharge plasma: Efficiency, mechanism, and application safety

Aeromonas hydrophila (A. hydrophila) is a typical zoonotic pathogen that commonly found in water environments, capable of infecting various aquatic animals and causing different diseases in both animals and humans. In this study, the dielectric barrier discharge plasma (DBDP) is used to inactivate the A. hydrophila in water. The efficiency and mechanism of A. hydrophila inactivation by DBDP were investigated, and the application safety of DBDP also were examined. The results demonstrate that DBDP treatment for 8 min can reduce the concentration of A. hydrophila from 108 CFU/mL to 0 CFU/mL under optimal conditions. Higher discharge voltage and lower concentration is beneficial for the inactivation of A. hydrophila, and O2 as carrier gas and alkaline environment can improve the inactivation efficiency. Reactive oxygen species (ROS) produced in the DBDP system play a significant role in A. hydrophila inactivation. However, molecules like O3 and H2O2 long-lived are likely the main forces responsible for the initial destruction of cell membranes. Subsequently, ROS penetrates the cell membrane, and result in the destruction of main virulence genes of A. hydrophila and the loss of bacterial infectivity. The silver carp challenge experiment indicates that mortality rates and septicemia symptoms in silver carp are not significantly different from the control group when treated with DBDP. Moreover, the total bacterial count in the main organs can be reduced to a safe level. These findings suggest that DBDP is a safe and reliable method for inactivating A. hydrophila in water bodies.