Lethal effect of the gliding arc discharges on Erwinia spp.

Aims: To compare the decontamination performances of glidarc on strains of Erwinia of industrial interest. Methods and Results: Cultures of Erwinia carotovora carotovora, Erwinia carotovora atroseptica and Erwinia chrysanthemi taken in stationary phase were exposed to the plasma generated by electric discharges in a gliding arc reactor prototype. The kinetics of destruction of bacteria were followed by direct platting. All bacterial strains presented a three-phase destruction kinetics leading to an apparent sterilization within 10 min. Epifluorescent observations using life/dead probes revealed the absence of viable but not cultivable resistant forms. Measurement of the physical parameters of the medium confirmed that the technique was nonthermal but that reactive species responsible for a decrease of the pH were generated. However, even after neutralization the medium did not allow bacterial growth. Conclusions: The results demonstrate that glidarc allows a rapid and complete destruction of planctonic strains of Erwinias without formation of resistant forms. Significance and Impact of the Study: The reduction rate obtained by this technique shows the great industrial interest of glidarc for decontamination and suggests that it can be used for sterilization of industrial water effluents.