AUTHOR=Handorf Oliver , Pauker Viktoria Isabella , Weihe Thomas , Schäfer Jan , Freund Eric , Schnabel Uta , Bekeschus Sander , Riedel Katharina , Ehlbeck Jörg 

TITLE=Plasma-Treated Water Affects Listeria monocytogenes Vitality and Biofilm Structure

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.652481

DOI=10.3389/fmicb.2021.652481

ISSN=1664-302X

ABSTRACT=<p><bold>Background:</bold> 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 <italic>Listeria monocytogenes</italic>, a common foodborne pathogen.</p><p><bold>Results:</bold> 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 log<sub>10</sub> ± 0.29 log<sub>10</sub>, 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.</p><p><bold>Conclusion:</bold> These results indicate a promising antimicrobial impact of plasma-treated water on <italic>Listeria monocytogenes</italic>, which may lead to more targeted applications of plasma decontamination in the food industry in the future.</p>