Abstract
Background: Plasma-generated compounds (PGCs) such as plasma-processed air (PPA) or plasma-treated water (PTW) offer an increasingly important alternative for the control of microorganisms in hard-to-reach areas found in several industrial applications including the food industry. To this end, we studied the antimicrobial capacity of PTW on the vitality and biofilm formation of Listeria monocytogenes, a common foodborne pathogen.Results: Using a microwave plasma (MidiPLexc), 10 ml of deionized water was treated for 100, 300, and 900 s (pre-treatment time), after which the bacterial biofilm was exposed to the PTW for 1, 3, and 5 min (post-treatment time) for each pre-treatment time, separately. Colony-forming units (CFU) were significantly reduced by 4.7 log10 ± 0.29 log10, as well as the metabolic activity decreased by 47.9 ± 9.47% and the cell vitality by 69.5 ± 2.1%, compared to the control biofilms. LIVE/DEAD staining and fluorescence microscopy showed a positive correlation between treatment and incubation times, as well as reduction in vitality. Atomic force microscopy (AFM) indicated changes in the structure quality of the bacterial biofilm.Conclusion: These results indicate a promising antimicrobial impact of plasma-treated water on Listeria monocytogenes, which may lead to more targeted applications of plasma decontamination in the food industry in the future.
Highlights
The application of plasma-generated compounds (PGC) such as plasma-treated water (PTW) and plasma-processed air (PPA) is an emerging field of research and development (Andrasch et al, 2017; Schnabel et al, 2018, 2019a)
The aim of this study is to visualize the impact of PTW treatment by the MidiPLexc on L. monocytogenes biofilms in terms of killing the cells to generate a comprehensive model of the antimicrobial spectrum of PTW generated by microwave induced plasma sources
In terms of an optimal treatment window of L. monocytogenes biofilms, the effect on the proliferation ability of the pathogen was investigated, and it was demonstrated at which settings a significant reduction in the proliferation ability could be achieved
Summary
The application of plasma-generated compounds (PGC) such as plasma-treated water (PTW) and plasma-processed air (PPA) is an emerging field of research and development (Andrasch et al, 2017; Schnabel et al, 2018, 2019a). Plasma-generated compounds (PGCs) such as plasma-processed air (PPA) or plasma-treated water (PTW) offer an increasingly important alternative for the control of microorganisms in hard-to-reach areas found in several industrial applications including the food industry. To this end, we studied the antimicrobial capacity of PTW on the vitality and biofilm formation of Listeria monocytogenes, a common foodborne pathogen
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