Effect of acetic acid and pH on the cofermentation of glucose and xylose to ethanol by a genetically engineered strain of Saccharomyces cerevisiae
Effect of acetic acid and pH on the cofermentation of glucose and xylose to ethanol by a genetically engineered strain of Saccharomyces cerevisiae
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DOI：
10.1111/j.1567-1364.2010.00623.x
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发表时间：
2010-06-01
影响因子：
3.2
通讯作者：
Mosier, Nathan S.
中科院分区：
文献类型：
--
作者：
Casey, Elizabeth;Sedlak, Miroslav;Mosier, Nathan S.
纤维素乙醇工业的当前挑战是存在于生物质水解产物中的抑制剂的影响。乙酸是在半纤维素的预处理期间释放的一种此类抑制剂的实例。研究了醋酸对酿酒酵母424 A（LNH-ST）发酵葡萄糖和木糖的影响。乙酸浓度为7.5和15 g L-1，代表在实际生物质水解产物中预期的浓度范围，在受控pH条件5、5.5和6下进行测试。发酵培养基中乙酸的存在导致观察到的最大细胞生物量浓度显著降低。葡萄糖和木糖的具体消费率下降，随着乙酸浓度的增加，与抑制作用更严重的木糖消费。乙酸存在时，乙醇产生速率也降低，但乙醇代谢产率在相同条件下增加。结果还表明，乙酸的抑制作用可以通过增加介质pH值来降低，从而证实乙酸的未解离形式是分子的抑制形式。
A current challenge of the cellulosic ethanol industry is the effect of inhibitors present in biomass hydrolysates. Acetic acid is an example of one such inhibitor that is released during the pretreatment of hemicellulose. This study examined the effect of acetic acid on the cofermentation of glucose and xylose under controlled pH conditions by Saccharomyces cerevisiae 424A(LNH-ST), a genetically engineered industrial yeast strain. Acetic acid concentrations of 7.5 and 15 g L-1, representing the range of concentrations expected in actual biomass hydrolysates, were tested under controlled pH conditions of 5, 5.5, and 6. The presence of acetic acid in the fermentation media led to a significant decrease in the observed maximum cell biomass concentration. Glucose- and xylose-specific consumption rates decreased as the acetic acid concentration increased, with the inhibitory effect being more severe for xylose consumption. The ethanol production rates also decreased when acetic acid was present, but ethanol metabolic yields increased under the same conditions. The results also revealed that the inhibitory effect of acetic acid could be reduced by increasing media pH, thus confirming that the undissociated form of acetic acid is the inhibitory form of the molecule.