III型纤维素高固含量酶解的独特性及其机理研究

高效的高固含量酶解是木质纤维素生物炼制大规模工业化的前提。然而，木质纤维素酶解转化率随着固含量的增加而直线下降，从而导致高固含量酶解成为生物炼制的一大难题。高固含量酶解转化率的下降主要是由酶解产物和预处理降解物浓度增大导致的抑制作用加大而引起。III型纤维素酶解的独特性：低酶吸附量却展现出2-5倍于I型纤维素的酶解效率、高固酶解转化率降低及受抑制程度远小于I型纤维素，使得其成为破解高固含量酶解难题的契机。本课题拟以III型纤维素高固酶解为研究对象，以I型纤维素高固酶解为参照，通过研究高固酶解过程中纯化的核心纤维素酶在纤维素上的动态吸附、活性变化及受各因素抑制特征，并通过机理模型辅助，解析III型纤维素高固酶解的机理，进而研发基于III型纤维素的木质纤维素原料的高固酶解技术，从而为解决木质纤维素高固酶解转化率低下这一难题提供新思路。

Efficient enzymatic hydrolysis of lignocellulosic biomass at high solid loading is a prerequisite for industrialization of lignocellulosic biorefinery. However, the conversion of enzymatic hydrolysis linearly decreases with increasing solid loading. Therefore, enzymatic hydrolysis at high solid loading becomes a bottleneck for a biorefinery. The main causes for decreased conversion of enzymatic hydrolysis at high solid loading are increased inhibitions from hydrolysis products and degradation products generated during pretreatment. The uniqueness of cellulose III enzymatic hydrolysis, which include low enzyme absorption but 2-5 times higher hydrolysis efficiency compared to cellulose I and much smaller conversion reduction at high solid loading and much lower inhibition rate by inhibitors, renders it a good opportunity to resolve the bottleneck of enzymatic hydrolysis at high solid loading. This project will study the enzymatic hydrolysis of cellulose III at high solid loading with using cellulose I as the control. The dynamic absorption behavior of core cellulases on cellulose during high solid loading hydrolysis, the changes of cellulase activities, and the inhibition from various factors will be studied. A mechanistic kinetic model will be developed and used together with experimental results to interpret the mechanism of enzymatic hydrolysis of cellulose III at high solid loading. Technology for high solid loading enzymatic hydrolysis of lignocellulosic biomass will then be developed based on cellulose III to resolve the issue of low conversion.