Damages of biological components in bacteria and bacteriophages exposed to atmospheric non-thermal plasma

Abstract

Mechanism of inactivation of bio-particles exposed to dielectric barrier discharge, DBD, has been studied using E. coli and bacteriophages. States of different biological components were monitored during the course of inactivation. Analysis of green fluorescent protein, GFP, introduced into E.coli cells proved that Non-thermal Plasma, NTP causes a prominent protein damages without cutting peptide bonds. We have developed a biological assay which evaluates in vitro DNA damage of the bacteriophages. Bacteriophage λ having double stranded DNA was exposed to DBD, then DNA was purified and subjected to in vitro DNA packaging reactions. The re-packaged phages consist of the DNA from discharged phages and brand-new coat proteins. Survival curves of the re-packaged phages showed extremely large D value (D = 25 s) compared to the previous D value (D = 3 s) from the discharged phages. The results indicate that DNA damage hardly contributed to the inactivation, and the damage in coat proteins is responsible for inactivation of the phages. M13 phages having single stranded DNA were also examined with the same manner. In this case, damage to DNA was as severe as that of the coat proteins. © 2012 Springer Science+Business Media B.V.