Understanding and Modulation of Interfacial Properties within Plant Cell Wall Pores to Facilitate Enzymatic Deconstruction and Conversion to Biofuels

PI: Hodge， david提案号：1336622机构：密歇根州立大学头衔：了解和调节植物细胞壁孔内的界面特性以促进酶解和转化为生物燃料本项目将研究植物细胞壁聚合物在纳米级细胞壁孔内施加的非共价力对影响生物燃料生产的植物细胞壁解构的许多重要现象的多方面作用。这些力如何受到植物细胞壁特性的影响，以及这些特性在预处理和水解过程中如何演变，从而导致改善多糖转化的结果。具体来说，这涉及到表面特性在以下方面的作用：(1)水渗入细胞壁和细胞壁膨胀；(2)纤维素水解酶对细胞壁内结合位点的可及性；(3)酶与细胞壁内化学和物理修饰表面的结合。为此，pi将研究一种理解植物细胞壁抗逆性的新范式，特别是细胞壁孔隙度和酶无法进入的表面积的限制，将植物细胞壁基质理解为一种可水膨胀的水凝胶，并理解水凝胶膨胀的孔隙度，这是由于水膨胀的相反力量与植物细胞壁基质对木质素化带来的膨胀的阻力。此外，pi建议使用比过去探索的更广泛的植物细胞壁来源（禾本科单子叶植物和木本双子叶植物），并探索更广泛的预处理/脱木质素条件，从而产生不同范围的细胞壁特性(木质素含量，羧酸盐含量)，他们将能够显著提高对细胞壁基质特性如何影响水膨胀和孔隙度的理解，并能够将这些差异与改进的酶转化联系起来。通过比较不同的细胞壁和不同的性质，本项目将解决纤维素水解中几个重要的突出问题：(1)解开细胞壁刚性、木质素含量、细胞壁膨胀和孔隙度之间的复杂关系，以及它们对细胞壁酶消化率的影响；(2)了解控制带电和不带电聚合物探针、酶和非催化性聚糖结合蛋白模块渗透细胞壁孔的限制因素；(3)进一步了解影响禾本科植物和木本植物抗逆性的基本特性差异。该项目的工作将有助于开发生物能源技术，以取代进口石油，并提供农村收入和就业。通过实践经验和这些生物能源技术的例子来教育工程本科学生是工程教育演变的一个合乎逻辑的发展。pi将进一步发展国际生物能源教育计划，目标是通过学生在国际环境中获得的不同经验和观点，加强学生的知识获取，增加自我指导和终身学习。

PI: Hodge, DavidProposal Number: 1336622Institution: Michigan State UniversityTitle: Understanding and Modulation of Interfacial Properties within Plant Cell Wall Pores to Facilitate Enzymatic Deconstruction and Conversion to BiofuelsThis project will investigate the multifaceted role that the non-covalent forces exerted by plant cell wall polymers within nanoscale cell wall pores have on a number of important phenomena influencing plant cell wall deconstruction for biofuel production, how these forces are impacted by plant cell wall properties and how these properties evolve during pretreatment and hydrolysis that lead to outcomes of improved polysaccharide conversion. Specifically this involves the role of surface properties in influencing: (1) water infiltration into the cell wall and cell wall swelling, (2) cellulolytic enzyme accessibility to binding sites within the cell wall, and (3) enzyme binding to chemically and physically modified surfaces within the cell wall. For this, the PIs will investigate a new paradigm for understanding plant cell wall recalcitrance, specifically that the limitations of cell wall porosity and inaccessible surface area to enzymes, can be best investigated in the context of understanding the plant cell wall matrix as a water-swellable hydrogel and understanding the porosity in the context of hydrogel swelling due to the opposing forces of water swelling versus the resistance of the plant cell wall matrix to swelling imparted by lignification. Additionally, the PIs propose that using a wider range of plant cell wall sources than have been explored in the past (graminaceous monocots and a woody dicot) and exploring a wider range of pretreatment/delignification conditions that result in a diverse range of cell wall properties (lignin contents, carboxylate contents) they will be able to significantly improve the understanding of how cell wall matrix properties impact water swelling and porosity and be able to link these differences to improved enzymatic conversion.By comparing the diverse cell walls with the diverse properties, this project will address several important outstanding problems in cellulose hydrolysis: (1) untangle the complex relationship between cell wall rigidity, lignin content, cell wall swelling, and porosity in its impact on cell wall enzymatic digestibility, (2) understand the limiting factors controlling the penetration of charged and uncharged sets of polymer probes, enzymes, and non-catalytic glycan-binding protein modules into cell wall pores, and (3) develop an improved understanding of the fundamental differences in properties influencing recalcitrance in grasses versus woody dicots.The project work will help enable the development of bioenergy technologies for displacing imported petroleum, and providing rural income and employment. The education of undergraduate engineering students by engaging them with hands-on experiences and examples of these bioenergy technologies is a logical development in the evolution of engineering education. The PIs will further develop an international bioenergy education program with the goal of enhancing student knowledge acquisition and increasing self-directed and life-long learning through the diverse experiences and perspectives that students gain in this international environment.