Forest Products Laboratory and Center for Bioenergy and Bioproducts, Auburn University , 520 Devall Drive, Auburn, Alabama 36849, United States.
J Agric Food Chem. 2014 Jan 29;62(4):918-26. doi: 10.1021/jf405711f. Epub 2014 Jan 15.
Aldehydes and acids play important roles in the fermentation inhibition of biomass hydrolysates. A series of carbonyl compounds (vanillin, syringaldehyde, 4-hydroxybenzaldehyde, pyrogallol aldehyde, and o-phthalaldehyde) were used to examine the quantitative structure-inhibitory activity relationship of carbonyl compounds on alcoholic fermentation, based on the glucose consumption rate and the final ethanol yield. It was observed that pyrogallol aldehyde and o-phthalaldehyde (5.0 mM) reduced the initial glucose consumption rate by 60 and 89%, respectively, and also decreased the final ethanol yield by 60 and 99%, respectively. Correlating the molecular descriptors to inhibition efficiency in yeast fermentation revealed a strong relationship between the energy of the lowest unoccupied molecular orbital (ELUMO) of aldehydes and their inhibitory efficiency in fermentation. On the other hand, vanillin, syringaldehyde, and 4-hydroxybenzaldehyde (5.0 mM) increased the final ethanol yields by 11, 4, and 1%, respectively. Addition of vanillin appeared to favor ethanol formation over glycerol formation and decreased the glycerol yield in yeast fermentation. Furthermore, alcohol dehydrogenase (ADH) activity dropped significantly from 3.85 to 2.72, 1.83, 0.46, and 0.11 U/mg at 6 h of fermentation at vanillin concentrations of 0, 2.5, 5.0, 10.0, and 25.0 mM correspondingly. In addition, fermentation inhibition by acetic acid and benzoic acid was pH-dependent. Addition of acetate, benzoate, and potassium chloride increased the glucose consumption rate, likely because the salts enhanced membrane permeability, thus increasing glucose consumption.
醛类和酸类在生物质水解物的发酵抑制中起着重要作用。研究了一系列羰基化合物（香草醛、丁香醛、4-羟基苯甲醛、焦儿醛和邻苯二甲醛）对醇发酵的定量构效关系抑制活性，基于葡萄糖消耗率和最终乙醇产量。结果表明，焦儿醛和邻苯二甲醛（5.0 mM）分别降低了初始葡萄糖消耗率 60%和 89%，最终乙醇产量分别降低了 60%和 99%。将分子描述符与酵母发酵中的抑制效率相关联，揭示了醛类的最低未占据分子轨道能量（ELUMO）与其在发酵中的抑制效率之间存在很强的关系。另一方面，香草醛、丁香醛和 4-羟基苯甲醛（5.0 mM）分别将最终乙醇产量提高了 11%、4%和 1%。香草醛的添加似乎有利于乙醇的形成而不利于甘油的形成，并降低了酵母发酵中的甘油产量。此外，在 6 h 的发酵过程中，ADH 活性从 3.85 显著下降至 2.72、1.83、0.46 和 0.11 U/mg，分别对应于香草醛浓度为 0、2.5、5.0、10.0 和 25.0 mM。此外，乙酸和苯甲酸的发酵抑制作用与 pH 有关。添加醋酸盐、苯甲酸盐和氯化钾会增加葡萄糖的消耗率，这可能是因为盐增强了膜的通透性，从而增加了葡萄糖的消耗。
