The ethanol fermentation efficiency was affected by multiple stress tolerance of yeast during brewing and bioethanol industry. The effect of KCl on the multiple stress tolerance of yeast cells was examined. Results showed that KCl addition significantly enhanced the tolerance of yeast cells to osmotic and ethanol stress, which correlated with the decreased membrane permeability, the increased intracellular ergosterol and ATP content, and the improved activity of complex II and complex III in yeast cells. Biomass and viability of yeast cells under osmotic and ethanol stress were increased significantly by KCl addition. Supplementation of 4 and 10 g L⁻¹ KCl exhibited the best promotion activity for yeast cells present in medium with 500 g L⁻¹ sucrose and 10% (v v⁻¹) ethanol, respectively. These results suggested that exogenous potassium addition might be an effective strategy to improve yeast tolerance and fermentation efficiency during industrial very‐high‐gravity (VHG) fermentation.

中文翻译：

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补充钾离子改善啤酒酵母多重耐受性的细胞机制

在酿造和生物乙醇工业中，酵母的多重胁迫耐受性影响了乙醇的发酵效率。检查了氯化钾对酵母细胞多重胁迫耐受性的影响。结果表明，添加KCl可以显着提高酵母细胞对渗透压和乙醇胁迫的耐受性，这与降低的膜通透性，增加的细胞内麦角固醇和ATP含量以及提高复合物II和复合物III在酵母细胞中的活性有关。添加氯化钾可明显提高酵母细胞在渗透压和乙醇胁迫下的生物量和活力。补充4和10 g L ^-1 KCl对存在于500 g L ^-1蔗糖和10％（v v ^-1）的培养基中的酵母细胞表现出最佳的促进活性）乙醇。这些结果表明，外源钾的添加可能是提高工业超高重力（VHG）发酵过程中酵母耐受性和发酵效率的有效策略。