ABSTRAKT

Nonthermal plasmas (NTPs) represent a new class of sterilizing agents. A full set of NTP bioactive factors includes electric components (E, charged particles and electric field), neutral active particles (R), and UV. A specific construction of the direct current (DC) corona source was used that allowed dissection of NTP bioactive factors and quantitative evaluation of their individual and combined action on bacterial pathogens Pseudomonas aeruginosa and Staphylococcus aureus. 10 and 120 s were required for the positive and negative coronas, respectively, to kill 10⁵ colony-forming units (CFU) P. aeruginosa. 10 s was required for both positive and negative coronas to kill 10⁵ CFU S. aureus. For the positive corona, the bactericidal activity of components decreased as R+UV>E+UV>>UV and E+UV>R+UV>>UV for P. aeruginosa and S. aureus, respectively. For the negative corona, the bactericidal activity decreased as R+UV>>E+UV=UV=0 and R+UV>>E+UV>UV~0 for P. aeruginosa and S. aureus, respectively. Despite low, if any, activity of electric components in the negative corona, the whole plasma effect was much higher than the effect of neutral particles and UV alone. The obtained results demonstrated that different combinations of bioactive plasma components exerted diverse species-specific bactericidal effects. It is synergy among plasma bioactive factors that supplies high bactericidal activity of NTP.