State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
School of Chemistry and Chemical Engineering, Shihezi University, Beisi Road, Shihezi, Xinjiang 800032, China.
J Biotechnol. 2022 Jul 20;353:36-43. doi: 10.1016/j.jbiotec.2022.05.006. Epub 2022 May 18.
Dilute acid hydrolysis of lignocellulose biomass had been used for production of cellulosic ethanol since 1940 s. The major technical barrier is the acid catalyzed dehydration of monosaccharides to furan aldehydes (furfural and 5-hydroxymethylfurfural), resulting in the high loss of fermentable sugars and significant inhibition on the fermentability of ethanologenic strains. This study re-examined the dilute acid hydrolysis of corn stover and cellulosic ethanol fermentation after a novel biodetoxification approach was introduced to de-bottleneck the inhibitor barrier. The cocktail of sulfuric acid, phosphoric acid and oxalic acid hydrolyzed corn stover to the 51.1 g/L of glucose (0.50 g/g cellulose) and 18.1 g/L of xylose (0.22 g/g xylan). The furfural, 5-hydroxymethylfurfural and acetic acid in the corn stover hydrolysate were completely removed by Paecilomyces variotii FN89, leading to the successful ethanol fermentation of 24.2 g/L, corresponding to 72.6 kg per metric ton of dry corn stover. No wastewater streams, solid wastes and toxic compounds were generated in hydrolysis, biodetoxification and fermentation. The techno-economic evaluations suggest that the cost reduction of replacing cellulase enzyme with cheap acid catalysts compensated the partial ethanol loss of sugar conversion to inhibitors (21.5-89.1%). The re-examination of acid hydrolysis process reveals that a substantial breakthrough in highly active and selective acid catalyst is required for acid hydrolysis to compete with enzymic hydrolysis for cellulosic ethanol fermentation.
自 20 世纪 40 年代以来，稀酸水解木质纤维素生物质已用于生产纤维素乙醇。主要的技术障碍是糖的酸催化脱水生成呋喃醛（糠醛和 5-羟甲基糠醛），导致可发酵糖的大量损失和对产乙醇菌株发酵能力的显著抑制。本研究在引入一种新的生物解毒方法以消除抑制剂障碍后，重新考察了玉米秸秆的稀酸水解和纤维素乙醇发酵。硫酸、磷酸和草酸的混合物将玉米秸秆水解为 51.1g/L 的葡萄糖（0.50g/g 纤维素）和 18.1g/L 的木糖（0.22g/g 木聚糖）。玉米秸秆水解液中的糠醛、5-羟甲基糠醛和乙酸被多形拟青霉 FN89 完全去除，从而成功发酵出 24.2g/L 的乙醇，相当于每公吨干玉米秸秆 72.6kg。在水解、生物解毒和发酵过程中没有废水、固体废物和有毒化合物产生。技术经济评估表明，用廉价的酸催化剂替代纤维素酶的成本降低，部分弥补了糖转化为抑制剂的乙醇损失（21.5-89.1%）。对酸水解工艺的重新考察表明，需要开发高活性和选择性的酸催化剂，才能使酸水解与酶解竞争用于纤维素乙醇发酵。
