Restoration of culturability of starvation-stressed and low-temperature-stressed Escherichia coli O157 cells by using H2O2-degrading compounds |
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Authors: | Y Mizunoe S N Wai Akemi Takade Shin-ichi Yoshida |
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Institution: | (1) Department of Bacteriology, Faculty of Medicine, Kyushu University, Fukuoka 812–8582, Japan e-mail: ymizunoe@bact.med.kyushu-u.ac.jp Tel.: +81-92-642-6130; Fax: +81-92-642-6133, JP |
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Abstract: | Late-exponential-phase cells of Escherichia coli O157:H- strain E32511/HSC became nonculturable in sterilized distilled water microcosms at 4 °C. Plate counts declined from
3 × 106 to less than 0.1 CFU/ml in about 21 days. However, when samples of microcosms at 21 days were inoculated onto an agar medium
amended with catalase or nonenzyme peroxide-degrading compounds such as sodium pyruvate or α-ketoglutaric acid, plate counts
increased to 104–105 CFU/ml within 48 h. The proposed mode of action of the catalase or pyruvate is via the degradation of the metabolic by-product
H2O2, rather than through supplementation of a required nutrient in the recovery of nonculturable cells. Our studies were based
on the assumption that E32511/HSC strain responds to starvation and a low temperature by entering a nonculturable state and
that the correction of oxidative stress upon the inoculation of bacteria on agar plates promotes recovery of nonculturable
cells.
Received: 15 January 1999 / Accepted: 8 April 1999 |
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Keywords: | Escherichia coli O157 Nonculturable cells Restoration of culturability H2O2-degrading compounds |
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