Department of Genetics, Federal University of Pernambuco, Recife, Pernambuco, Brazil.
J Appl Microbiol. 2010 Jul;109(1):116-27. doi: 10.1111/j.1365-2672.2009.04633.x. Epub 2009 Nov 23.
This work aimed to identify the molecular mechanism that allows yeast cells to survive at low pH environments such as those of bioethanol fermentation.
The industrial strain JP1 cells grown at pH 2 was evaluated by microarray analysis showing that most of the genes induced at low pH were part of the general stress response (GSR). Further, an acid-tolerant yeast mutant was isolated by adaptive selection that was prone to grow at low pH in inorganic but weak organic acid. It showed higher viability under acid-temperature synergistic treatment. However, it was deficient in some physiological aspects that are associated with defects in protein kinase A (PKA) pathway. Microarray analysis showed the induction of genes involved in inhibition of RNA and protein synthesis.
The results point out that low pH activates GSR, mainly heat shock response, that is important for long-term cell survival and suggest that a fine regulatory PKA-dependent mechanism that might affect cell cycle in order to acquire tolerance to acid environment.
These findings might guide the construction of a high-fermentative stress-tolerant industrial yeast strain that can be used in complex industrial fermentation processes.
本研究旨在确定使酵母细胞能够在低 pH 环境（如生物乙醇发酵环境）中存活的分子机制。
通过微阵列分析评估了在 pH 2 下生长的工业菌株 JP1 细胞，结果表明，大多数在低 pH 下诱导的基因是一般应激反应 (GSR) 的一部分。此外，通过适应性选择分离出了一种耐酸酵母突变体，该突变体易于在无机但弱有机酸中在低 pH 下生长。它在酸-温度协同处理下表现出更高的存活率。然而，它在一些与蛋白激酶 A (PKA) 途径缺陷相关的生理方面存在缺陷。微阵列分析显示，与抑制 RNA 和蛋白质合成相关的基因被诱导。
结果表明，低 pH 激活 GSR，主要是热休克反应，这对于长期细胞存活很重要，并表明存在一种精细的 PKA 依赖性调节机制，可能会影响细胞周期，以获得对酸性环境的耐受性。
这些发现可能为构建能够用于复杂工业发酵过程的高发酵性应激耐受工业酵母菌株提供指导。
