AIMS: To study the influence of growth temperature on the resistance of Escherichia coli to three agents of different nature: heat, pulsed electric field (PEF) and hydrogen peroxide. METHODS AND RESULTS: Escherichia coli cells were grown to stationary phase at 10 degrees C, 20 degrees C, 30 degrees C, 37 degrees C and 42 degrees C. Survival curves to a heat treatment at 57.5 degrees C, to a PEF treatment at 22 kV cm(-1) and to 40 mmol l(-1) hydrogen peroxide were obtained and fitted to a model based on the Weibull distribution to describe and compare the inactivation. Time to inactivate the first log cycle of the population at 57.5 degrees C of cells grown at 42 degrees C was sixfold higher than that corresponding to cells grown at 10 degrees C. On the contrary, cells grown at 10 degrees C and 20 degrees C were more resistant to PEF and hydrogen peroxide treatments. CONCLUSIONS: The influence of growth temperature on bacterial resistance depends on the stress applied. Cells grown at higher temperatures were more heat resistant, but more sensitive to PEF and hydrogen peroxide. SIGNIFICANCE AND IMPACT OF THE STUDY: Results obtained in this investigation help in understanding the physiology of bacterial resistance and the inactivation mechanisms of different technologies.
AIMS: To study the influence of growth temperature on the resistance of Escherichia coli to three agents of different nature: heat, pulsed electric field (PEF) and hydrogen peroxide. METHODS AND RESULTS:Escherichia coli cells were grown to stationary phase at 10 degrees C, 20 degrees C, 30 degrees C, 37 degrees C and 42 degrees C. Survival curves to a heat treatment at 57.5 degrees C, to a PEF treatment at 22 kV cm(-1) and to 40 mmol l(-1) hydrogen peroxide were obtained and fitted to a model based on the Weibull distribution to describe and compare the inactivation. Time to inactivate the first log cycle of the population at 57.5 degrees C of cells grown at 42 degrees C was sixfold higher than that corresponding to cells grown at 10 degrees C. On the contrary, cells grown at 10 degrees C and 20 degrees C were more resistant to PEF and hydrogen peroxide treatments. CONCLUSIONS: The influence of growth temperature on bacterial resistance depends on the stress applied. Cells grown at higher temperatures were more heat resistant, but more sensitive to PEF and hydrogen peroxide. SIGNIFICANCE AND IMPACT OF THE STUDY: Results obtained in this investigation help in understanding the physiology of bacterial resistance and the inactivation mechanisms of different technologies.