Carmelo V, Santos R, Viegas C A, Sá-Correia I
Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Lisboa, Portugal.
Int J Food Microbiol. 1998 Jul 21;42(3):225-30. doi: 10.1016/s0168-1605(98)00089-0.
Thermotolerance was induced in cells of Saccharomyces cerevisiae YPH499 pre-exposed, during 10 min and in the presence of glucose, to a mild acid-stress with HCl at pH 3.5. Thermotolerance was not induced in cells exposed to a severe acid stress by 50 mM acetic acid at pH 3.5, or HCl at pH 2.5 or pH 2.0. Yeast cells pre-incubated under glucose starvation were found to be more tolerant to a lethal heat stress than cells pre-incubated in glucose-supplemented media, despite the pH value of the media (range 2.0-6.5) and the type of acidulant used (HCl or acetic acid). Moreover, the high thermotolerance exhibited by cells pre-incubated at pH 6.5 for 10 min under glucose starvation was not significantly modified by the acidification of the pre-incubation medium. Results are discussed based on the effect that glucose and a mild or severe acid stress have on plasma membrane H+-ATPase activity and on cytosolic pH values, estimated in a previous work.
在葡萄糖存在的情况下，酿酒酵母YPH499细胞预先暴露于pH 3.5的HCl轻度酸胁迫10分钟，从而诱导热耐受性。在pH 3.5下暴露于50 mM乙酸、pH 2.5或pH 2.0的HCl严重酸胁迫的细胞中未诱导出热耐受性。发现预先在葡萄糖饥饿条件下孵育的酵母细胞比在补充葡萄糖的培养基中预先孵育的细胞对致死热胁迫更具耐受性，无论培养基的pH值（范围为2.0 - 6.5）以及所用酸化剂的类型（HCl或乙酸）如何。此外，在葡萄糖饥饿条件下于pH 6.5预先孵育10分钟的细胞所表现出的高热耐受性，不会因预孵育培养基的酸化而发生显著改变。基于先前工作中估计的葡萄糖以及轻度或严重酸胁迫对质膜H⁺ - ATP酶活性和胞质pH值的影响，对结果进行了讨论。
