Laboratoire de Génie des Procédés Microbiologiques et Alimentaires-AgroSup Dijon, Université de Bourgogne, 1 Esplanade Erasme, 21000 Dijon, France.
Arch Microbiol. 2010 Aug;192(8):651-61. doi: 10.1007/s00203-010-0597-1. Epub 2010 Jun 15.
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 degrees C, with either a slope (40 min) or a shock (10 s), both followed by a 1-h plateau at 50 degrees 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 degrees 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.
研究了热应激动力学对大肠杆菌活力的影响。细胞分别经历斜率（40 分钟）或冲击（10 秒）处理，范围从 30 摄氏度到 50 摄氏度，随后在营养培养基中于 50 摄氏度下保持 1 小时的平台期。与冲击后相比，斜率后观察到更高的存活率，当两者都随后是平台期时，因此热斜率诱导了一定程度的耐热性。这种耐受性部分与后续平台期的新蛋白质合成有关，并且在从 50 摄氏度快速冷却至 30 摄氏度后被消除，这意味着涉及到具有快速可逆热性质的细胞成分。热斜率诱导的耐热性主要与质膜完整性的维持（结构、流动性和通透性的保持）有关，而与 GroEL 或 DnaK 的过表达无关。此外，热冲击引起的细胞高死亡率可能与膜完整性的变化有关。
