Collaborative Research: EAGER:Studying lignocellulosic fine structure and its dynamics in enzymatic hydrolysis of biomass using molecule-recognizing AFM and computational modeling

木质纤维素生物质是一种以结晶纤维素、水合半纤维素和木质素为主要成分的复合结构。长期以来，它一直被认为是一种潜在的低成本和可持续的混合糖来源，可用于生产生物燃料和其他增值化学品。植物已经进化出高超的机制来抵抗来自微生物和动物王国对其细胞壁结构糖的攻击，统称为生物量抵抗。这些机制是由一些因素组成的，这些因素被认为是导致生物质酶水解效率低下的原因。因此，木质纤维素的精细结构，即纤维素、半纤维素和木质素相互结合的方式，以及生物质和酶之间的分子相互作用如何使木质纤维素的精细结构在水解过程中演变，对于克服上述减缓水解反应的因素的酶和工艺的逻辑和特定设计至关重要。然而，由于目前还无法直接检测到木质纤维素组分的构象和分布，这些迫切需要的信息几乎缺失。在这个EAGER项目中，来自佐治亚大学的徐炳倩研究员和来自密歇根理工大学的周文研究员将采用一种独特的方法，将新开发的CBM功能化AFM（原子力显微镜）技术与计算建模相结合，直接检测木质纤维素组分的构象和分布。从而克服了实现酶解过程中木质纤维素组分（构象和分布）动力学的长期技术困难。EAGER拨款将支持这项合作研究，通过获取急需的数据来探索这一高风险、高回报的项目。目的是为选择和设计更好的酶和过程来有效地克服生物质抗性提供工具和方法。本研究的意义在于：(1)具有分子识别的纳米尺度的木质纤维素精细结构研究，(2)构建生物质颗粒的三维结构图像，(3)监测木质纤维素在水解过程中的精细结构动力学。实验和计算建模方法的结合将有可能为解决未解决的木质纤维素组分构象和分布提供新的方法和证据，提供对木质纤维素水解过程的分子尺度理解，这可能是克服生物质顽固性的关键。此外，该技术的发展还将为其他生物系统中的单分子研究增加独特的能力，以探测生物分子及其相互作用。

ABSTRACT Lignocellulosic biomass is a composite structure with crystalline cellulose, hydrated hemicellulose, and lignin as major components. It has long been recognized as a potential lowcost and sustainable source of mixed sugars for production of biofuels and other value-added chemicals. Plants have evolved superb mechanisms for resisting assault on their cell wall structural sugars from the microbial and animal kingdoms, collectively known as biomass recalcitrance. These mechanisms are comprised of factors that are believed to contribute to the inefficiency of enzymatic hydrolysis of biomass. The lignocellulosic fine structure, i.e. the way cellulose, hemicelluloses, and lignin are bonding with each other, and how the lignocellulosic fine structure evolves during hydrolysis due to the molecular interactions between biomass and enzymes, is thus crucial for logistic and specific design of enzymes and processes to overcome the above factors that slow down the hydrolytic reactions. However, such urgently needed information is pretty much missing because direct detection of lignocellulose component conformation and distribution is NOT possible so far. In this EAGER project, Investigators Bingqian Xu from University of Georgia and Wen Zhou from Michigan Technological University will employ a unique approach which is to combine the newly developed CBM functionalized AFM (atomic force microscope) technology with computational modeling to directly detect lignocellulose component conformation and distribution, thereby overcoming the long-standing technical difficulties in realizing the dynamics of lignocellulosic components (conformation and distribution) during the enzymatic hydrolysis. An EAGER grant would support this collaborated research to explore this proposed high-risk, high-reward project by getting the much needed data. The aim is a tool and methodology for selection and design of better enzymes and processes to overcome the biomass recalcitrance efficiently. The significance of the proposed research lies in the ability (1) to study the lignocellulosic fine structure in nanometer scale with molecular recognition, (2) to construct the 3D structural image of biomass particle, and (3) to monitor the lignocellulosic fine structure dynamics in hydrolysis. The combination of experimental and computational modeling methods will potentially provide a new approach and evidence to tackle the unsolved lignocelluloses component conformation and distribution, offering molecular scale understanding of the lignocellulose hydrolysis process which could be critical in overcoming biomass recalcitrance. In addition, development of the technology will also add unique capabilities for single molecule studies in other biosystems to probe the biomolecules and their interactions.