engleski

Determination of oxidative stress upon high voltage electrical discharge (HVED) plasma on Escherichia coli MG 1655

High voltage electrical discharge (gas and liquid) plasmas are new rapidly developing techniques used for food and water decontamination [1]. Though, one of the main questions to answer are effectiveness of this method and full understanding of cell inactivation mechanisms after plasma treatments. This study investigates the influence of high voltage gas phase plasma treatment on several parameters: inactivation rate of Escherichia coli K12 MG1655, cells recovery, cellular leakage, biofilm formation and influence of pH and generated H2O2 species on inactivation of the Gram negative bacteria. Bacterial solution of Escherichia coli K12 was treated in a glass reactor with a point-to- plate electrode configuration. Four independent variables: electrical conductivity, polarity, time and frequency were chosen in order to determine their influence on listed parameters. Statistical analyses were obtained to optimize conducted treatments. Treated samples gave positive reaction to catalase activity, as a response to oxidative stress. Biofilm formation was not completely reduced, as all the samples gave increase in percentage of recovery. Also with a longer treatment time increase in cellular leakage was observed. Synergistic effects of polarity, treatment time, solution conductivity, pH and concentration of free radicals could have influence on inactivation rate of E. coli, but further optimization of method is needed to understand why the recovery of cell occurs.

Escherichia coli, cold plasma, oxidative stress

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