Computational and Experimental Studies of Cellulose Degradation for the Production of Biofuels

来源于生物质如植物材料的KhareCellulose为生产生物燃料乙醇提供了有吸引力的可再生原料。 天然存在的纤维素是主要呈半结晶形式的长链聚合物分子。 在纤维素酶解生产乙醇的过程中，聚合纤维素分子在第一阶段被分解成较短的片段。 这些片段通过酶的作用进一步分解成更短的片段，导致二糖纤维二糖，最后导致单糖葡萄糖;这些糖分子的发酵产生乙醇。 在初始阶段形成的纤维素的短片段已经被认为附着在结晶纤维素的表面上，并且假设这种现象减缓了酶水解过程的总体速率。 该建议的目的是确定从纤维素晶体表面分离这种纤维素片段的过程的能量学。 在这项研究中获得的基本理解将是有用的，在长期的增加纤维素的酶水解的速率，从而增加乙醇生产率从纤维素。 拟议的工作将包括一种方法，将联合收割机分子模拟研究与使用原子力显微镜（AFM）进行的实验。 分子模拟解释了详细的化学相互作用以及系统的特定分子结构。 这些模拟将用于表征从纤维素晶体表面分离纤维低聚物片段的过程的分子途径以及该过程所需的能量。 模拟结果将被验证对AFM测量的分离纤维素碎片从纤维素表面所需的力。 在这项工作中，将开发一个详细的纤维素低聚物从纤维素晶体表面分离的过程的机械理解。 如果成功的话，在拟议的工作中获得的基础知识将导致新的策略，用于增加纤维素生物质的酶水解速率，从而提高从纤维素经济生产乙醇的能力。 这将对消除目前对化石燃料日益严重的依赖产生重大影响。 拟议的工作将涉及界面热力学、有机化学和替代能源领域的多学科研究。 从事该项目的研究生将接受分子模拟，AFM测量和化学合成技术的跨学科培训。

CBET-0854463KhareCellulose that is derived from biomass such as plant material provides an attractive renewable feedstock for the production of the biofuel ethanol. The naturally occurring cellulose is a long chain polymeric molecule that is predominantly in semi-crystalline form. In the process of enzymatic hydrolysis of cellulose for the production of ethanol, the polymeric cellulose molecule is broken down into shorter fragments in the first stage. These fragments are further broken down by the action of enzymes to even shorter fragments leading to the disaccharide cellobiose and finally to the monosaccharide glucose; fermentation of these sugar molecules yields ethanol. The short fragments of cellulose that are formed in the initial stage have been suggested to be attached to the surface of the crystalline cellulose and it is hypothesized that this phenomenon slows down the overall rate of enzymatic hydrolysis process. The objective of this proposal is to determine the energetics of the process of separation of such cellulose fragments from the cellulose crystal surface. The fundamental understanding gained in this study will be useful in the long term for increasing the rate of enzymatic hydrolysis of cellulose and thus increasing the rate of ethanol production from cellulose. The proposed work will consist of an approach that will combine molecular simulation studies with experiments performed using atomic force microscopy (AFM). Molecular simulations account for the detailed chemical interactions as well as the specific molecular structure of the system. These simulations will be used to characterize the molecular pathway of the process of separating the cello-oligomer fragments from the surface of a cellulose crystal and the energy required for this process. The simulation results will be validated against AFM measurements of the force required for separating cellulose fragments from the cellulose surface. A detailed mechanistic understanding of the process of cello-oligomer separation from a cellulose crystal surface will be developed in this work. If successful, the fundamental knowledge gained in the proposed work will lead to new strategies for increasing the rate of enzyme hydrolysis of cellulosic biomass and hence the ability for economical production of ethanol from cellulose. This will have significant implications on removing the current, ever increasing dependence on fossil fuels. The proposed work will involve multidisciplinary research in the areas of interfacial thermodynamics, organic chemistry and alternate energy sources. The graduate students working on the project will receive interdisciplinary training in the techniques of molecular simulations, AFM measurements and chemical synthesis.