Physiological responses of Escherichia coli exposed to different heat-stress kinetics |
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Authors: | Stéphane Guyot Laurence Pottier Eric Ferret Laurent Gal Patrick Gervais |
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Institution: | 1. Laboratoire de Génie des Procédés Microbiologiques et Alimentaires-AgroSup Dijon, Université de Bourgogne, 1, Esplanade Erasme, 21000, Dijon, France 2. UMR Microbiologie du Sol et de l’Environnement, INRA, 17 rue Sully, BP 86510, 21065, Dijon Cedex, France
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Abstract: | The effects of heat-stress kinetics on the viability of Escherichia coli were investigated. Cells were exposed to heat-stress treatments extending from 30 to 50°C, with either a slope (40 min) or
a shock (10 s), both followed by a 1-h plateau at 50°C in nutritive medium. A higher survival rate was observed after the
slope than after the shock, when both were followed by a plateau, so the heat slope induced a certain degree of thermotolerance.
This tolerance was partly (i) linked to de novo protein synthesis during the subsequent plateau phase, and (ii) abolished
after rapid cooling from 50 to 30°C, which means that cellular components with rapidly reversible thermal properties are involved
in this type of thermotolerance. The heat-slope-induced thermotolerance was chiefly linked to the maintenance of the plasma
membrane integrity (preservation of structure, fluidity, and permeability), and not to GroEL or DnaK overexpression. Moreover,
the high level of cell mortality induced by the heat shock could be related to changes in the membrane integrity. |
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