基于微流控技术的木质纤维素固相酶解过程强化研究

High-solids enzymatic hydrolysis of lignocellulose has a lot of advantages, such as high sugar concentration, less waste water discharge and low separation cost etc., which is the trend of biomass energy industry. In the case of low conversion efficiency of lignocellulose high-solids enzymatic hydrolysis, exploring the law of transfer-reaction as well as to guide the establishment of directional process strengthening technology is an important scientific problem to break through the industrial technological and economic barrier. Studies have shown that the process of cellulase passing through the porous structure of lignocellulose to the fiber surface is the rate-limiting step to the enzymatic hydrolysis. However, based on the traditional black box or simplified methods, the critical pore size and effective mass transfer carrier (water) are not clear so far, and the kinetic theories are difficult to guide the enzymatic hydrolysis of natural lignocellulose. Therefore, in this project, 1) the porous structure characteristics of lignocellulose are analyzed, and the effective pore size and water for mass transfer during enzymatic hydrolysis were revealed. 2) A novel microfluidics -fluorescence microscopy dynamic tracking technology was developed, to study the kinetic behavior of high-solids enzymatic hydrolysis of lignocellulose. Then the basic law of transfer-reaction for high-solids enzymatic hydrolysis was established, and the rate-limiting step, the key factors and strengthening characteristics (effective pore and water and effective strengthening force field for mass transfer) can be obtained. Then efficient strengthening technical schemes and process can be established, which could lay a theoretical and technical foundation for the efficient transformation of lignocellulosic resources.

木质纤维素固相酶解具有糖浓高、废水少、分离成本低等优势，是木质纤维素能源工业发展的方向。当前固相酶解转化效率低，探索酶解过程传递-反应规律并指导定向强化技术的建立，是突破其工业技术经济瓶颈的重要基础问题。研究表明酶分子穿过木质纤维素多孔结构传递到纤维表面的过程是影响酶解效率的关键，然而基于传统黑箱式和简化式的研究方法，当前并不清楚该传递过程中临界传质孔径和有效传质载体（水），所建立的动力学理论难以指导天然木质纤维素的酶解。因此，本项目1）从木质纤维素原料多孔特性认知切入，解析其多孔结构特性，揭示酶解过程的有效传递媒介（孔径及水分）；2）开发微流控芯片-荧光显微镜动态跟踪技术，研究木质纤维素固相酶解过程动力学行为，建立固相酶解传递-反应基本规律，解析过程限速步骤、影响因素及强化特性（有效传质媒介及强化力场），指导高效强化技术方案和工艺的建立，为实现木质纤维素资源高效转化奠定理论和技术基础。

木质纤维素水解成糖，对于进一步将其转化为能源或其他化学品至关重要。然而，低酶解转化效率限制了木质纤维素工业的发展。两个步骤被视为影响转化效率的瓶颈。首先，多孔结构限制了酶向纤维素表面的传递。第二，即使能到达纤维素表面，纤维素表面酶的交通堵塞仍然会降低催化效率。本项目使用微流控耦合原子力显微成像技术揭示，周期法向力（PNF）强化毛细管水传递可以同时克服以上两个瓶颈---通过全局强化多孔介质中酶快速到达纤维素表面，同时局部缓解酶在纤维素表面上的交通堵塞，从而显著提高水解速率和产率。PNF已成功应用于半工业规模的反应器上用于木质纤维素的酶水解。