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. (April 2015)

• Record Type: Journal Article
• Authors: Reineke, Kai; Sevenich, Robert; Hertwig, Christian; Janßen, Traute; Fröhling, Antje; Knorr, Dietrich; Wieler, Lothar H.; Schlüter, Oliver
• Is Part Of: Food microbiology. Volume 46(2015:Apr.)
• Page Start: 184
• Page End: 194
• Publication Date: 2015-04
• Subjects: High pressure -- EHEC -- Kinetic modeling -- Flow cytometry -- Inactivation mechanisms; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2014.07.017
• Languages: English
• ISSNs: 0740-0020

Abstract

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. Highlights: Escherichia coli O157:H7 and O104:H4 showed a much higher pressure resistance than other E. coli strains. The pressure resistance increased if strains were incubated and treated at lower pH. Cells, cultivated at pH 5, showed higher ability to retain its membrane potential. E. coli cells showed higher resistance towards pore formation, if cultivated at pH7. Loss of culturability did not correlate with loss of membrane potential or permeabilization.