title: Inactivation of Shiga toxin-producing Escherichia coli O104:H4 using cold atmospheric pressure plasma.
abstract: From cultivation to the end of the post-harvest chain, heat-sensitive fresh produce is exposed to a variety of sources of pathogenic microorganisms. If contaminated, effective gentle means of sanitation are necessary to reduce bacterial pathogen load below their infective dose. The occurrence of rare or new serotypes raises the question of their tenacity to inactivation processes. In this study the antibacterial efficiency of cold plasma by an atmospheric pressure plasma-jet was examined against the Shiga toxin-producing outbreak strain Escherichia coli O104:H4. Argon was transformed into non-thermal plasma at a power input of 8 W and a gas flow of 5 L min(-1). Basic tests were performed on polysaccharide gel discs, including the more common E. coli O157:H7 and non-pathogenic E. coli DSM 1116. At 5 mm treatment distance and 10(5) cfu cm(-2) initial bacterial count, plasma reduced E. coli O104:H4 after 60 s by 4.6 ± 0.6 log, E. coli O157:H7 after 45 s by 4.5 ± 0.6 log, and E. coli DSM 1116 after 30 s by 4.4 ± 1.1 log. On the surface of corn salad leaves, gentle plasma application at 17 mm reduced 10(4) cfu cm(-2) of E. coli O104:H4 by 3.3 ± 1.1 log after 2 min, whereas E. coli O157:H7 was inactivated by 3.2 ± 1.1 log after 60 s. In conclusion, plasma treatment has the potential to reduce pathogens such as E. coli O104:H4 on the surface of fresh produce. However, a serotype-specific adaptation of the process parameters is required.
authors.affiliation: Leibniz Institute for Agricultural Engineering, Max-Eyth-Allee 100, 14469 Potsdam-Bornim, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Baier
authors.affiliation: Centre for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany.
authors.forename: Traute
authors.initials: T
authors.lastname: Janssen
authors.affiliation: Centre for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163 Berlin, Germany.
authors.forename: Lothar H
authors.initials: LH
authors.lastname: Wieler
authors.affiliation: Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Straße 2, 17489 Greifswald, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Ehlbeck
authors.affiliation: Department of Food Biotechnology and Food Process Engineering, Berlin University of Technology, Königin-Luise-Straße 22, 14195 Berlin, Germany.
authors.forename: Dietrich
authors.initials: D
authors.lastname: Knorr
authors.affiliation: Leibniz Institute for Agricultural Engineering, Max-Eyth-Allee 100, 14469 Potsdam-Bornim, Germany. Electronic address: oschlueter@atb-potsdam.de.
authors.forename: Oliver
authors.initials: O
authors.lastname: Schlüter
mesh_terms: D001274:Atmospheric Pressure; D003080:Cold Temperature; D004927:Escherichia coli Infections / Q000382:microbiology; D019453:Escherichia coli O157 / Q000254:growth & development; D005516:Food Microbiology; D059022:Food Safety / Q000379:methods*; D006801:Humans; D050296:Microbial Viability; D058626:Plasma Gases; D022621:Shiga Toxin / Q000096:biosynthesis; D054323:Shiga-Toxigenic Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D003313:Zea mays / Q000382:microbiology
chemical_list: D058626:Plasma Gases; D022621:Shiga Toxin
keywords: Antibacterial treatment; Corn salad; Escherichia coli O157:H7; Food safety; Fresh produce; Plasma-jet