title: Comparative study on the high pressure inactivation behavior of the Shiga toxin-producing Escherichia coli O104:H4 and O157:H7 outbreak strains and a non-pathogenic surrogate.
abstract: Enterohemorrhagic Escherichia coli strains cause each year thousands of illnesses, which are sometimes accompanied by the hemolytic uremic syndrome, like in the 2011 outbreak in Germany. For preservation thermal pasteurization is commonly used, which can cause unwanted quality changes. To prevent this high pressure treatment is a potential alternative. Within this study, the 2011 outbreak strain O104:H4, an O157:H7 and a non-pathogenic strain (DSM1116) were tested. The cells were treated in buffer (pH 7 and pH 5) and carrot juice (pH 5.1) in a pressure temperature range of 0.1-500 MPa and 20-70 °C. Flow cytometry was used to investigate the pressure impact on cell structures of the strain DSM1116. Both pathogenic strains had a much higher resistance in buffer and carrot juice than the non-pathogenic surrogate. Further, strains cultivated and treated at a lower pH-value showed higher pressure stability, presumably due to variations in the membrane composition. This was confirmed for the strain DSM1116 by flow cytometry. Cells cultivated and treated at pH 5 had a stronger ability to retain their membrane potential but showed higher rates of membrane permeabilization at pressures <200 MPa compared to cells cultivated and treated at pH 7. These cells had the lowest membrane permeabilization rate at around 125 MPa, possibly denoting that variations in the fatty acid composition and membrane fluidity contribute to this stabilization phenomenon.
authors.affiliation: Quality and Safety of Food and Feed, Leibniz Institute for Agricultural Engineering (ATB), Potsdam, Germany. Electronic address: kreineke@atb-potsdam.de.
authors.forename: Kai
authors.initials: K
authors.lastname: Reineke
authors.affiliation: Department of Food Biotechnology and Food Process Engineering, Technische Universitaet Berlin, Berlin, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Sevenich
authors.affiliation: Quality and Safety of Food and Feed, Leibniz Institute for Agricultural Engineering (ATB), Potsdam, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Hertwig
authors.affiliation: Centre for Infection Medicine, Institute of Microbiology and Epizootics, Veterinary Faculty, Freie Universitaet Berlin, Berlin, Germany.
authors.forename: Traute
authors.initials: T
authors.lastname: Janßen
authors.affiliation: Quality and Safety of Food and Feed, Leibniz Institute for Agricultural Engineering (ATB), Potsdam, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Fröhling
authors.affiliation: Department of Food Biotechnology and Food Process Engineering, Technische Universitaet Berlin, Berlin, Germany.
authors.forename: Dietrich
authors.initials: D
authors.lastname: Knorr
authors.affiliation: Centre for Infection Medicine, Institute of Microbiology and Epizootics, Veterinary Faculty, Freie Universitaet Berlin, Berlin, Germany.
authors.forename: Lothar H
authors.initials: LH
authors.lastname: Wieler
authors.affiliation: Quality and Safety of Food and Feed, Leibniz Institute for Agricultural Engineering (ATB), Potsdam, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Schlüter
mesh_terms: D001628:Beverages / Q000032:analysis / Q000382:microbiology*; D004196:Disease Outbreaks; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000737:chemistry / Q000254:growth & development; D005858:Germany / Q000453:epidemiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D050296:Microbial Viability; D011312:Pressure; D054323:Shiga-Toxigenic Escherichia coli / Q000737:chemistry / Q000254:growth & development*
keywords: EHEC; Flow cytometry; High pressure; Inactivation mechanisms; Kinetic modeling