Wang Yu, Delettre Jérôme, Guillot Alain, Corrieu Georges, Béal Catherine
UMR Génie et Microbiologie des Procédés Alimentaires, INA P-G, INRA, 78850 Thiverval-Grignon, France.
Cryobiology. 2005 Jun;50(3):294-307. doi: 10.1016/j.cryobiol.2005.03.001. Epub 2005 Apr 18.
The effect of different cooling temperatures and durations on resistance to freezing and to frozen storage at -20 degrees C in Lactobacillus acidophilus RD758 was studied, by using a central composite rotatable design. A cold adaptation was observed when the cells were maintained at moderate temperature (26 degrees C) for a long time (8h) before being cooled to the final temperature of 15 degrees C. These conditions led to a low rate of loss in acidification activity during frozen storage (0.64 minday(-1)) and a high residual acidification activity after 180 days of frozen storage (1011 min). The experimental design allowed us to determine optimal cooling conditions, which were established at 28 degrees C during 8h. Adaptation to cold temperatures was related to an increase in the unsaturated to saturated fatty acid ratio and in the relative cycC19:0 fatty acid concentration. Moreover, an increased synthesis of four specific proteins was observed as an adaptive response to the optimal cooling conditions. They included the stress protein ATP-dependent ClpP and two cold induced proteins: pyruvate kinase and a putative glycoprotein endopeptidase.
采用中心复合旋转设计，研究了不同冷却温度和持续时间对嗜酸乳杆菌RD758在-20℃下的抗冻性及冻存抗性的影响。当细胞在冷却至最终温度15℃之前，在适中温度（26℃）下长时间（8小时）维持时，观察到冷适应性。这些条件导致冻存期间酸化活性的损失率较低（0.64毫单位/天），并且在冻存180天后具有较高的残余酸化活性（1011毫单位）。实验设计使我们能够确定最佳冷却条件，即在28℃下维持8小时。对低温的适应性与不饱和脂肪酸与饱和脂肪酸的比例增加以及相对环丙烷脂肪酸C19:0浓度增加有关。此外，观察到作为对最佳冷却条件的适应性反应，四种特定蛋白质的合成增加。它们包括应激蛋白ATP依赖性ClpP和两种冷诱导蛋白：丙酮酸激酶和一种假定的糖蛋白内肽酶。
