Biological Evaluation of DNA Damage in Bacteriophages Inactivated by Atmospheric Pressure Cold Plasma

Inactivation mechanisms of plasma treated microorganisms are still major subjects. We have developed a biological assay which evaluates in vivo DNA damage of the viruses treated with non-thermal atmospheric pressure plasma in air. Different doses of the plasma were applied to wet state of lambda phage particles under neutral pH and near the room temperature. From each sample of treated lambda phages, DNA was purified and subjected to in vitro DNA packaging reactions. Survival curves of the re-packaged phages showed an extremely large D value (D = 25 s) compared to the previous D value (D = 3 s) obtained from the survival curves of the treated phages. The results indicate the evidence that DNA damage hardly contributed to the inactivation.