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=Volume 12 - 2021

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=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 s, 300 s and 900 s (pre-treatment time), after which the bacterial biofilm was exposed to the PTW for 1 min, 3 min 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.