Effect of centrifugation on the pressure resistance of exponential phase cells of Escherichia coli 8164

Authors


Dr M. A. Casadei, Institute of Food Research, Earley Gate, Whiteknights Road, Reading RG6 6BZ, UK (e-mail: casadeim@bbsrc.ac.uk).

Abstract

M.A. casadei and B.M. mackey. 1997. Exponential phase cells of Escherichia coli NCTC 8164 that were centrifuged at 2000g for 20 min at 4 °C were more resistant to subsequent pressure treatment than cells grown in trypticase soya broth (TSB) and treated without any centrifugation steps. The effects of mild pressure stress (200 kPa for 20 min) and temperature stress (a shift from 37 °C to 4 °C) involved in the centrifugation procedure were analysed separately. It appeared that the increase in pressure resistance obtained following centrifugation was mainly due to the gradual temperature decrease during centrifugation, while the mild pressure stress seemed to play a smaller role in the response.

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