甘蔗渣在添加剂和辅助酶作用下的浓醪酶解糖化

Thick-mash enzymatic hydrolysis of sugarcane bagasse with additives and accessory enzymes

纤维质水解产糖的成本高昂是目前纤维素乙醇生产工业化的瓶颈性问题,所以底物在低酶用量条件下浓醪水解糖化的研究值得探讨。该文尝试采用添加剂和辅助酶强化酶解过程,开展分批补料式浓醪底物水解糖化的研究。以碱催化常压甘油有机溶剂预处理甘蔗渣为底物,实验通过单因素和正交实验确定添加剂浓度为:10mg/g干基的BSA、25mg/g干基的吐温20及10mg/g干基茶皂素,确定木聚糖酶添加量0.6mg/g干基。为达到总基质浓度350g/L,实验确立初始基质浓度190g/L,分别于7h、10h及13h分别补料60、50及50g/L。该酶解体系在6FPU/g干基质条件下酶解48h的可发酵性糖接近220g/L,葡萄糖和木糖质量浓度分别高达160.7g/L和58.7g/L。分批补料策略依然是实现基质浓醪水解的理想方式,使用添加剂及辅助酶能显著促进纤维基质的浓醪酶解,这为后续纤维素乙醇浓醪发酵提供可能。

The high cost of cellulose hydrolysis is the bottleneck problem of industrialization of cellulosic ethanol production. Therefore, it is worthwhile to study the hydrolysis and saccharification of substrate under low enzyme usage. This study focused on obtaining high-titer fermentable sugars from fed-batch thick-mash enzymatic hydrolysis by using additives and accessory enzymes. Sugarcane bagasse treated by alkali-catalyzed atmospheric glycerol organosolv (al-AGO) was used as substrate. The optimized amounts of additives were as below: 10 mg/g dry substrate tea saponin, 25 mg/g dry substrate Tween 20, 10 mg/g dry substrate bull serum albumin (BSA), and 0.6 mg/g dry substrate endo-xylanase. In order to reach 350 g/L total solid content during thick-mash enzymatic hydrolysis of al-AGO pretreated lignocellulosic substrate, 190 g/L initial solid content was applied, followed by feeding 60, 50 and 50 g/L substrate at 7, 10 and 13 h, respectively. After 48 h enzymatic hydrolysis with 6 FPU/g dry substrate, the hydrolysis process achieved 220 g/L fermentable sugars, in which, the titers of glucose and xylose were as high as 160.7 g/L and 58.7 g/L, respectively. Therefore, fed-batch strategy is still desirable for thick-mash enzymatic hydrolysis of lignocellulosic substrate, and using reasonable additives and accessory enzymes is evidently conducive for improving the process.