Role of the Charged Particles in Bacteria Inactivation by Plasma of a Positive and Negative Corona in Ambient Air

Inactivation of microorganisms by plasma of a positive (PC) and negative corona (NC) discharge in air at atmospheric pressure was investigated. Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Pseudomonas aeruginosa were chosen for the discharge inactivation. PC and NC produce three types of bactericidal agents, which are ultraviolet radiation (UV), neutral reactive species (R), and electric field and charged particles (E), respectively. We elucidated the contribution of each bioactive agent to the inactivation of S. aureus and P. aeruginosa. The influence of the charged particles in PC and NC on the cell inactivation is caused by different electrophysical effects, which lead nevertheless to an identical consequence: the cell membrane becomes more transparent for neutral reactive species. It gives additional possibility for neutral reactive species to increase the inactivation of cell by biochemical mechanisms. Due to that, total UV+R+E bactericidal effect in PC and NC is approximately the same and great - only a few tens of seconds is enough to inactivate completely S. aureus and P. aeruginosa cells.