Mechanisms behind tailing in the pressure inactivation curve of a clinical isolate of Escherichia coli O157:H7

Seiji Noma, Daiki Kajiyama, Noriyuki Igura, Mitsuya Shimoda, Isao Hayakawa

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The tailing in pressure inactivation curve of clinically isolated Escherichia coli O157:H7 was investigated. A typical tailing was observed after the treatment period for 30 min when 107 CFU/ml of the cell suspension was subjected to pressure treatment at 300 MPa and 25 °C. There was no effect on the tailing profiles by the addition of pressure-killed cells and released cellular components. When cells survived at a tail portion were re-propagated (tail-culture) and subjected to second pressure treatment, the cells of the tail-culture exhibited eminently higher barotolerance compared to those of the original-culture, suggesting that the presence of genetically pressure-resistant subpopulation was responsible for the tailing. The cytoplasmic membrane of the tail-culture cells had higher stability to a pressure treatment at 100 MPa for 10 min than that of the original-culture, which was evidenced by lower permeability to ethidium bromide. The addition of non-ionic surfactants including 0.5 μl/ml polyoxyethylene p-t-octylphenyl ester (Triton X-100) and 0.53 mg/ml lauric sugar ester dramatically reduced the level of tailing and made the inactivation curve linear.

Original languageEnglish
Pages (from-to)103-108
Number of pages6
JournalInternational Journal of Food Microbiology
Volume109
Issue number1-2
DOIs
Publication statusPublished - May 25 2006

All Science Journal Classification (ASJC) codes

  • Food Science
  • Microbiology

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