Atmospheric cold plasma inactivation of Escherichia coli in liquid media inside a sealed package

Abstract

Aims: The main objective of this study was to determine the inactivation efficacy of dielectric barrier discharge atmospheric cold plasma (DBD-ACP) generated inside a sealed package for Escherichia coli ATCC 25922.

Methods and results: A plasma discharge was generated between two circular aluminium electrodes at 40 kV. E. coli suspensions (10(7) CFU ml(-1)) in either maximum recovery diluent (MRD) or phosphate buffered saline (PBS) were treated in a 96-well microtitre plate inside a sealed package. The effects of treatment time, post-treatment storage time, either direct or indirect samples exposure to the plasma discharge and suspension media were studied. Regardless of the media tested, 20 s of direct and 45 s of indirect plasma treatment resulted in complete bacterial inactivation (7 log CFU ml(-1)). At the lower plasma treatment times (10-30 s) investigated, the effects of suspension media and mode of exposure on the inactivation efficacy were evident. The inactivation efficacy was also influenced by the post-treatment storage time.

Conclusions: It was demonstrated that the novel DBD-ACP can inactivate high concentrations of E. coli suspended in liquids within sealed packages in seconds.

Significance and impact of the study: A key advantage of this in-package nonthermal novel disinfection approach is the elimination of post-processing contamination.