Acid-and-ethanol tolerance plays an important role in the cell viability of Oenococcus oeni and affects the enological characteristics of malolactic fermentation in wine. To reveal the mechanism of the response to acid-and-ethanol in O. oeni, we analyzed the changes to its gene expression profile after acid-and-ethanol shock for the first time using RNA-Seq. Some physiological indicators related to this stress response were also characterized. Bioinformatic and physiological analyses showed that the O. oeni strengthened the biosynthesis of peptidoglycan as a response to ethanol toxicity, and the cell membranes altered their fatty acid compositions for keeping the acidic H⁺ outside when the cells were shocked with acid-and-ethanol. When H⁺ entered the cytoplasm, the F₀F₁-ATPase system began discharging H⁺ (producing ATP), and the cells increased their expression of recN and mutT genes for minimizing the DNA damage. The cells also used two-component systems to communicate between same-species cells for improving the overall population survival rate. Genes encoding spermidine and putrescine transport were also upregulated to increase resistance to the acid-and-ethanol environment. This study fills important gaps in the current understanding of the bacterial acid-and-ethanol stress response mechanism, and it may be beneficial to screen more robust O. oeni strains in future works.

中文翻译：

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应用RNA-Seq分析酸和乙醇联合作用对Oenococcus oeni的冲击

耐酸和乙醇在Oenococcus oeni的细胞活力中起着重要作用，并影响葡萄酒中苹果酸乳酸发酵的酶学特性。为了揭示O. oeni对酸和乙醇的响应机制，我们首次使用RNA-Seq分析了酸和乙醇休克后其基因表达谱的变化。与这种压力反应有关的一些生理指标也进行了表征。生物信息学和生理学分析表明，O。oeni增强了肽聚糖的生物合成，以响应乙醇毒性，并且细胞膜改变了其脂肪酸组成以保持酸性H ⁺当细胞被酸和乙醇冲击时，细胞外。当H ⁺进入细胞质时，F ₀ F ₁ -ATPase系统开始释放H ⁺（产生ATP），并且细胞增加了rec N和mut T基因的表达，从而最大程度地减少了DNA损伤。这些细胞还使用两组分系统在同种细胞之间进行通讯，以提高总体种群存活率。编码亚精胺和腐胺转运的基因也被上调，以增加对酸和乙醇环境的抵抗力。这项研究填补了目前对细菌酸和乙醇应激反应机制的了解中的重要空白，并且可能对筛选更健壮的生物有益O. oeni菌株在未来的工作中。