木质素磺酸盐及其酶法改性对木质纤维素高固发酵的影响研究

Biochemical conversion is the most common method of producing ethanol from lignocelluloses. High solid enzymatic saccharification and fermentation, and applications of lignin co-products are the keys to reduce cost and improve ethanol yield. Lignosulfonates could improve the enzymatic saccharification of cellulose and lignocelluloses. However, the effect of lignosulfonates on the subsequent fermentation is unknown. In this project, the lignin from enzymatic saccharification and fermentation residue will be used as raw material to prepare lignosulfonates with different sulfonic group content and different molecular weight. The effect of lignosulfonates and its enzymatic modification on the fermentation of glucose, cellulose and lignocellulose hydrolysate will be studied, and also the simultaneous saccharification and fermentation. The role of lignosulfonates on the fluidity and dispersibility of substrate slurry will be investigated to reveal the mechanism of lignosulfonates on high solid fermentation. The relationship between molecular structure of lignosulfonates and saccharification fermentation efficiency will be established, which will be helpful to develop a new method to enhance high solid enzymatic saccharification and fermentation simultaneously. The results of this project will not only provide a new approach of efficient utilization of lignin co-products, but also establish the theoretical foundation of anionic surfactant, such as lignosulfonates, for enhancing high solid fermentation of lignocelluloses.

生物转化法是木质纤维素制备燃料乙醇的主要方法，高固酶解发酵以及木质素副产物的有效利用是降低生产成本提高乙醇得率的关键。木质素磺酸盐能够促进纯纤维素和木质纤维素的酶解，然而，其对后续发酵过程的影响不得而知。本项目以酶解发酵残渣为原料合成不同磺化度和不同分子量级分的木质素磺酸盐，研究木质素磺酸盐及其酶法改性对葡萄糖溶液、纯纤维素及木质纤维素酶解液高固发酵以及木质纤维素同步糖化发酵的影响；探索木质素磺酸盐对底物浆体流变性和分散性的作用，阐明木质素磺酸盐对高固发酵的影响机制，构建木质素磺酸盐的分子结构与糖化发酵效率之间的构效关系，建立一种木质素磺酸盐同时促进木质纤维素酶解和发酵的新方法。本项目的研究成果将为木质素副产物的高效利用提供新思路，并为木质素磺酸盐等阴离子型表面活性剂强化木质纤维素的高固发酵奠定理论基础。

推广车用乙醇汽油、大力发展纤维素燃料乙醇是国家战略性举措，我国力争2025年实现纤维素乙醇规模化生产。降低木质纤维素酶解发酵成本和实现酶解发酵残渣资源化高效利用是降低纤维素乙醇成本的重要途径。. 本项目以酶解发酵残渣为原料合成了不同磺化度和不同分子量级分的木质素磺酸盐，研究了木质素磺酸盐及其酶法改性对木质纤维素酶解液以及木质纤维素糖化发酵的影响；阐明了表面活性剂对木质纤维素高固发酵的影响机制，建立了能够同时促进木质纤维素酶解和发酵的新方法。重要研究结果包括：. （1）木质素磺酸盐的分子量和磺化度是影响其能否促进木质纤维素酶解发酵的重要指标，分子量适中且磺化度较高的木质素磺酸盐更有利于木质纤维素的同步糖化发酵。木质素磺酸盐不仅能够促进纯纤维素和木质纤维素的酶解糖化，还能促进乙醇的生产。. （2）木质素磺酸盐的酶法改性有利于增加其反应活性，降低酚羟基含量。选取合适的生物酶，如辣根过氧化物酶，可以制备分子量和亲水性可控的木质素磺酸盐。经酶法改性后，木质素磺酸盐对悬浮浆体的流变性和分散稳定性能提高。. 本项目的研究成果为木质素副产物的高效利用提供了新思路，并为木质素磺酸盐等阴离子型表面活性剂强化木质纤维素的高固发酵奠定了理论基础。