Hybrid Chemical and Biological Valorization of Residual Biorefinery Lignin

PI姓名：智友文提案编号：植物生物质如木材、稻草和农业残留物代表了用于生产液体运输燃料和化学品的丰富、廉价和可再生的原料。 生物质主要由碳水化合物聚合物纤维素和半纤维素以及复杂的酚聚合物木质素组成。 纤维素生物炼制是大规模生物燃料生产的新兴平台，将纤维素和半纤维素部分转化为糖，然后发酵生产生物乙醇。 该过程的副产物是植物生物质中的残留木质素。 在纤维素之后，木质素是地球上第二丰富的生物聚合物，占植物生物量的15-40%。 虽然木质素是一种富含能量的材料，但它很难转化为生物燃料，而且通常只是简单地燃烧以获得热量，这是这种资源的一种相对低价值的应用。 需要用于利用木质素的具有成本效益的方法来提高生物炼制的经济可行性和环境可持续性。 该项目旨在通过创新的两步法将木质素转化为生物燃料原料。 第一个过程通过在没有空气的情况下加热木质素副产物将其转化为重油，这一过程称为热解，第二个过程使用细菌将复杂的热解油分解为可制成燃料和化学品的芳香族化合物。 与该项目相关的教育活动包括为初中和高中学生提供与使用类似于生物质生物聚合物的乐高玩具的生物质利用相关主题的实践外展活动。该研究的总体目标是开发并获得对混合热解的基本了解-生物转化过程，从生物炼制残余木质素中制造生物燃料前体。所提出的方法能够在两步法中将木质素衍生的酚类单体生物转化为燃料和化学品。 第一步集中于木质素的热催化解聚成非均相酚类单体。在第二步中，木质素热解产生的各种单体然后被微生物转化为儿茶酚和原儿茶酸，它们进入中枢代谢，然后转化为乙酰辅酶A和丙酮酸，这是生产各种先进生物燃料和化学品的两种关键代谢前体。 该项目有三个研究目标。第一个目标是表征来自快速热解过程的木质素单体。 第二个目标是研究所选细菌菌株利用这些木质素单体的能力，然后探索定制热解过程的条件如何使热解油发生有益的变化，从而提高木质素单体的生物转化效率。 这将部分地通过在水相中乳化木质素单体和细菌的菌株工程化以改善性能来实现。 第三个目标是开发一个实验室规模的发酵过程，在一个可扩展的平台上实现目标2，然后使用这些信息进行初步的技术经济和生命周期分析。

PI name: Zhiyou WenProposal number: 1605034Plant biomass such as wood, grass straw, and agricultural residues represent an abundant, cheap, and renewable feedstock for the production of liquid transportation fuels and chemicals. Biomass consists mainly of the carbohydrate polymers cellulose and hemicellulose, and the complex phenolic polymer lignin. The cellulosic biorefinery is in emerging platform for large-scale biofuels production that converts the cellulosic and hemicellulosic fractions to sugars, which are then fermented to produce bioethanol. A byproduct of this process is the residual lignin in the plant biomass. After cellulose, lignin is the second-most abundant biopolymer on Earth and accounts for 15-40% of plant biomass. Although lignin is an energy-rich material, it is difficult to convert into biofuels and is often simply burned for heat, a relatively low-value application of this resource. A cost-effective method for utilizing lignin is needed to improve economic viability and environmental sustainability of the biorefinery. This project seeks to convert the lignin into a biofuel feedstock by an innovative two-step process. The first process converts the lignin byproduct into a dense oil by heating it up in the absence of air, a process called pyrolysis, and the second process uses bacteria to break down the complex pyrolysis oils to aromatic compounds which can be made into fuels and chemicals. The educational activities associated with this project include hands-on outreach activities for middle and high-school students on the topics related to biomass utilization using Lego toys which resemble biomass biopolymers.The overall goal of the research is to develop and gain fundamental understanding of a hybrid pyrolysis-bioconversion process to make biofuel precursors from biorefinery residual lignin. The proposed process enables the bioconversion of lignin-derived phenolic monomers to fuels and chemicals in a two-step process. The first step focuses on the thermocatalytic depolymerization of lignin into heterogeneous phenolic monomers. In the second step, the various monomers generated by lignin pyrolysis are then microbially converted into the catechol and protocatechute, which enter central metabolism and are then converted into acetyl-CoA and pyruvate, two key metabolic precursors for the production of various advanced biofuels and chemicals. The project has three research objectives. The first objective is to characterize of the lignin monomers derived from the fast pyrolysis process. The second objective is to study the capability of selected bacterial strains to utilize these lignin monomers, and then explore how tailoring the conditions of the pyrolysis process makes beneficial changes in the pyrolysis oil that improves the bioconversion efficiency of the lignin monomers. This will be accomplished in part by emulsifying the lignin monomers in an aqueous phase and strain engineering of bacteria for improved performance. The third objective is to develop a bench-scale fermentation process for accomplishing objective 2 in a scalable platform, and then use this information for preliminary techno-economic and life-cycle analyses.