液氨解构甜菜渣细胞壁及促进纤维素高效酶解的机制研究

甜菜渣是制备纤维素燃料乙醇的理想原料，但是纤维素酶解效率低制约着其产业化发展。从本征的理化结构出发，剖析甜菜渣的抗降解屏障，选择性破坏关键顽抗因子，解构细胞壁，是实现甜菜渣纤维素高效酶解的关键。实验室已证实液氨能够选择性去除果胶、引起木质素再分布，提高酶解效率，但是液氨预处理过程中甜菜渣细胞壁组分的溶出及迁移的规律，化学组分的变化和细胞壁结构变化间的联系，及二者变化对甜菜渣纤维素酶解效率的影响仍不明确。本项目拟采用多种先进分析技术从甜菜渣宏观形态、显微结构、超微结构、分子、基团、元素、化学键等水平展开研究。首先，研究液氨预处理对甜菜渣化学组成及分布、物理结构及形态的影响；通过分析细胞壁理化性质变化与纤维素酶解效率的关系揭示甜菜渣的抗降解屏障及其特殊性；通过探讨抗降解屏障的变化阐明液氨预处理促进甜菜渣纤维素高效酶解的机制。项目的实施将揭示甜菜渣的抗降解屏障，阐明液氨预处理过程中甜菜渣的不同组分溶出、再分布规律，及其对细胞壁物理形态的解构机制。研究材料具有代表性和主体地域特色，研究策略独特。预期研究成果将丰富纤维素酶催化反应理论内涵，为甜菜渣高值化利用提供重要的理论基础与技术储备。

Sugar beet pulp has been deemed as an ideal cellulosic material for fuel ethanol production. However, the low efficiency in enzymatic hydrolysis hinders the development of fuel ethanol production. Cognition of the critical recalcitrant barriers, selective removal of the recalcitrant barriers and destruction of cell wall become the vital subject in the enzymatic hydrolysis. Our previous results showed that the aqueous ammonia pretreatment degraded the pectin of sugar beet pulp, led to cell wall dislocation and lignin redistribution, destroyed rigid structure and enhanced enzymatic hydrolysis. However, the interactive effects of chemical compositions and physical structures, and their mechanism on enzymatic hydrolysis are still ambiguous and should be studied further more. In this project, various advanced analytical methods will be used to verify the recalcitrant factors in enzymatic hydrolysis and elucidate the mechanism of aqueous ammonia pretreatment in the aspects of macrostructure, microstructure, ultrastructure, molecule, chemical group, chemical element, and chemical bonds level. Firstly, the influence of aqueous ammonia pretreatment on the chemical composition content, migration and distribution in the cell wall, and the morphology and structure of the cell wall will be analyzed. Furthermore, the relationship between the various physicochemical factors and the enzymatic hydrolysis efficiency will be discussed to uncover the recalcitrant barriers and their particularity. Finally, the mechanism of aqueous ammonia pretreatment will be clarified based on the variation of recalcitrant barriers. This project will uncover the recalcitrant barriers of sugar beet pulp, and clarify the dissolution and redistribution of various compositions in sugar beet pulp during the aqueous ammonia pretreatment. Additionally, the effect of chemical variation on the physical destruction of cell wall structure will also be analyzed. Not only is the related material representative and region characteristic, but also the research strategy is unique. The results of this project will enrich the theory of enzymatic hydrolysis of cellulose, and lay the theoretical and technical basis for the utilization of sugar beet pulp.