玉米秸秆分批补料获得高还原糖浓度酶解液的条件优化

Optimization of corn stover hydrolysis by fed-batch process

摘要:

木质纤维素高浓度还原糖水解液的获得是纤维乙醇产业化发展的方向。在发酵工业领域，分批补料法是实现这一目标的重要研究途径。本研究采用分批补料法对获得高浓度玉米秸秆酶解还原糖的条件进行了优化。以稀硫酸预处理的玉米秸秆为原料，考察了液固比、补加量与补加时间对分批补料糖化的影响。结果表明，秸秆高浓度酶解液条件的初始物料为20％ (重量/体积)，木聚糖酶220 U/g (底物)，纤维素酶6 FPU/g (底物)，果胶酶50 U/g (底物)，在24 h、48 h后分批补加8％预处理后的物料，同时添加与补料量相应的木聚糖酶20 U/g (底物)，纤维素酶2 FPU/g (底物)，72 h后，最终糖化结果与非补料法相比，还原糖浓度从48.5 g/L提高到138.5 g/L，原料的酶解率最终达到理论值的62.5％。试验结果表明补料法可以显著提高秸秆水解液还原糖浓度。

Abstract:

High-concentration sugars production from stover is an important perspective technology for the cellulosic ethanol industrialization. Fed-batch process is an effective way to achieve this goal in the fermentation industry. In this study, based on fed-batch process, high-concentration sugars were produced from pretreated corn stover by enzymatic hydrolysis. After being pretreated by the dilute sulphuric acid, the impacts of the ratio of solid raw material to liquid culture, the content of supplementary materials and the refilling time on the saccharification rate were investigated. Results showed that the initial ratio of solid raw material to liquid culture was 20% (W/V) and the initial concentrations of enzymes for xylanase, cellulose and pectinase were 220 U, 6 FPU, and 50 U per gram of substrates, respectively. After 24 hours and 48 hours, 8% pretreated corn stovers were added respectively together with the additions of xylanase (20 U) and cellulose (2 FPU) per gram of substrates. After 72 hours, the final concentration of reducing sugar was increased to 138.5 g/L from 48.5 g/L of the non fed-batch process. The rate of enzyme hydrolysis of the raw material was 62.5% of the thoretical value in the fed-batch process. This study demonstrated that the fed-batch process could significantly improve the concentration of reducing sugar.