Abstract Weak acids are known to have a negative impact on yeast performance, restraining production efficiency during the production of bioethanol and other fermentative yeast-derived products. These acids, which might be hydrophilic or lipophilic exert negative effects on yeasts when they diffuse into the cell in their unionized state as a result of their pH being lower than the pka of yeast growth medium. Consequently, the unionized acids dissociate into their respective cations and anions, as intracellular pH is typically neutral. Further, proton accumulation tends to reduce intracellular pH. As a result, the anions destabilize the internal cell machinery, thus affecting cellular metabolism on various levels. Overcoming this acid-mediated stress in budding yeast would in part, harness the potential of using lignocellulosic biomass hydrolysate – which is typically acetic acid-rich – as a cheaper feedstock for large-scale bioethanol production. Since organic acids are key intermediates in ethanol fermentation, this review focuses on the prospects of bioethanol production from lignocellulosic biomass using weak acid-tolerant strains of yeasts derived by metabolic engineering.

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酵母弱酸诱导胁迫耐受的机制：提高木质纤维素生物质生物乙醇生产的前景

摘要 众所周知，弱酸会对酵母性能产生负面影响，在生物乙醇和其他发酵酵母衍生产品的生产过程中会抑制生产效率。这些酸可能是亲水性或亲脂性的，当它们以未结合状态扩散到细胞中时，由于它们的 pH 值低于酵母生长培养基的 pka，它们会对酵母产生负面影响。因此，未电离的酸解离成它们各自的阳离子和阴离子，因为细胞内的 pH 值通常是中性的。此外，质子积累往往会降低细胞内的 pH 值。结果，阴离子破坏了内部细胞机制，从而在各个层面影响细胞代谢。在萌芽酵母中克服这种酸介导的压力将部分地，利用木质纤维素生物质水解物（通常富含乙酸）作为大规模生物乙醇生产的廉价原料的潜力。由于有机酸是乙醇发酵的关键中间体，本综述重点介绍了使用代谢工程衍生的弱耐酸酵母菌株从木质纤维素生物质生产生物乙醇的前景。