Gliding Arc Discharge in the Potato Pathogen Erwinia carotovora subsp. atroseptica: Mechanism of Lethal Action and Effect on Membrane-Associated Molecules

ABSTRACT Gliding arc (glidarc) discharge is a physicochemical technique for decontamination at atmospheric pressure and ambient temperature. It leads to the destruction of bacterial phytopathogens responsible for important losses in industrial agriculture, namely, Erwinia spp., without the formation of resistant forms. We investigated the effect of a novel optimized prototype allowing bacterial killing without lag time. This prototype also decreases the required duration of treatment by 50%. The study of the time course effect of the process on bacterial morphology suggests that glidarc induces major alterations of the bacterial membrane. We showed that glidarc causes the release of bacterial genomic DNA. By contrast, an apparent decrease in the level of extractible lipopolysaccharide was observed; however, no changes in the electrophoretic pattern and cytotoxic activity of the macromolecule were noted. Analysis of extractible proteins from the outer membrane of the bacteria revealed that glidarc discharge induces the release of these proteins from the lipid environment, but may also be responsible for protein dimerization and/or aggregation. This effect was not observed in secreted enzymatic proteins, such as pectate lyase. Analysis of the data supports the hypothesis that the plasma generated by glidarc discharge is acting essentially through oxidative mechanisms. Furthermore, these results indicate that, in addition to effectively destroying bacteria, glidarc discharge should be used to improve the extraction of bacterial molecules.