Air plasma jet induced bacterial inactivation in dry, aqueous and food environments

An atmospheric pressure resistive barrier air plasma jet is designed to inactivate bacteria in a wide range of media such as dry solid surfaces, aqueous media and in food media such as chicken, egg, vegetables and fruits^{1, 2}. A resistive barrier plasma jet is designed to function at both DC and standard 50-60 Hz low frequency AC power input and the ambient air at 50% humidity level was used as the operating gas. The resistive barrier plasma jet is well characterized¹. The nitric oxides (NO) were observed to be the predominant long lived reactive nitrogen species produced by the plasma. Three different bacteria including S. aureus, E. coli and N. meningitidis were tested in aqueous media and positive bacterial inactivation results were obtained in less than 240 seconds of plasma treatment. Similarly, three different bacteria including S. aureus, E. coli and Pseudomonas were tested on dry solid surfaces and positive bacterial inactivation results were obtained in less than 180 seconds. Correspondingly, the frequent food poisoning bacteria Salmonella infected poultry and produce such as chicken, eggs, vegetables and fruits were tested using our atmospheric pressure resistive barrier air plasma jet and the results show significant outcomes in terms of bacterial inactivation. Plasma induced shifts in gene expression were analyzed using pilC gene expression as a representative gene and the results showed a reduction in the expression of the pilC gene compared to untreated samples suggesting that the observed protection against NO may be regulated by other genes.