UNS: Microbial detoxification of cellulosic biomass hydrolysates by anaerobic removal and recovery of aromatic compounds

PI: Daniel R. noguera提案号：1506820从植物生物质中生产生物燃料面临的一个主要挑战是，在将生物质的纤维素部分转化为可发酵糖的过程中，会产生不需要的副产品。这些副产品主要来自生物质的水溶性木质素部分，对发酵过程有毒，并降低生物燃料的产量。该项目将研究利用细菌将这些副产品转化为一种单一的芳香化合物，这种化合物可以作为一种有价值的副产物在工程生物过程中回收，而不消耗有价值的糖。本研究的过程也将促进对相关厌氧微生物过程如何影响自然碳循环的基本理解。该项目的其他影响包括与指导高中生、本科生和研究生有关的研究主题的教育活动。这项拟议研究的总体目标是研究厌氧细菌将纤维素生物质水解物中发现的植物源芳香族化合物转化为单一酚类化合物的潜力，该化合物可以作为纤维素生物炼制中有价值的副产物回收。所提出的方法利用了芳香化合物厌氧微生物降解的优势，特别是Rhodopseudomonas属培养成员的代谢，这些成员有效地消耗了大量的芳香化合物，而不利用生物燃料生产所需的糖。据推测，水解物中的芳烃是通过苯甲酰辅酶a途径降解的。拟议的研究将对这种生物进行基因工程改造，根据突变的位置，将生物质水解物中通常存在的大量芳香化合物转化为苯甲酸或对羟基苯甲酸。现有红假单胞菌收集的代谢多样性将进行测试，以确定最佳菌株解毒纤维素水解物。实验将在光养和反硝化条件下使用红假单胞菌菌株的混合物进行，使用用工业相关生物质负荷制备的玉米秸秆水解物以及模拟水解物的合成介质的变体。利用RNA-Seq和基因组重测序技术，对表现最佳的红假单胞菌的厌氧芳香降解的遗传和调控网络进行重建。一旦该菌株被设计成促进芳香化合物作为苯甲酸的生物转化，从纤维素水解物中去除芳香化合物的速率过程和苯甲酸副产物的回收将在生物反应器系统中进行研究。研究成果将用于加强威斯康星大学麦迪逊分校环境工程专业三门课程的内容。

PI: Daniel R. NogueraProposal Number: 1506820A major challenge facing the production of biofuels from plant biomass is the presence of unwanted byproducts resulting from the conversion of the cellulosic portions of the biomass to fermentable sugars. These byproducts, primarily from the water soluble lignin fraction of the biomass, are toxic to the fermentation process, and reduce biofuel production yield. This project will investigate the use of bacteria to convert these byproducts into a single aromatic compound which can be recovered as a valued co-product in an engineered biological process without consuming the valuable sugars. The course of this research will also advance fundamental understanding on how related anaerobic microbial processes affect the natural carbon cycle. Other impacts of the project include educational activities related to mentoring high school, undergraduate, and graduate students on topics related to the research.The overall goal of this proposed research is to study the potential of anaerobic bacteria to convert plant-derived aromatic compounds found in cellulosic biomass hydrolysates into a single phenolic compound that can be recovered as a valued co-product in a cellulosic biorefinery. The proposed approach takes advantage of anaerobic microbial degradation of aromatic compounds, and in particular, the metabolism of cultured members of the Rhodopseudomonas genus that are effective at consuming a large variety of aromatic compounds without utilizing the sugars needed for biofuel production. It is hypothesized that the aromatics present in the hydrolysates are degraded R. palustris through the benzoyl-CoA pathway. The proposed research will genetically engineer this organism to transform the large diversity of aromatics typically present in biomass hydrolysates to either benzoic acid or p-hydroxybenzoic acid, depending on the location of the mutation. The metabolic diversity of an existing Rhodopseudomonas collection will be tested to identify the best strains for detoxification of cellulosic hydrolysates. Experiments will be carried out with a mixture of the Rhodopseudomonas strains under phototrophic and denitrifying conditions, using both corn stover hydrolysates prepared with industrially relevant biomass loadings as well as variations of a synthetic medium that simulates the hydrolysate. The genetic and regulatory networks of anaerobic aromatic degradation in the best performing Rhodopseudomonas strains will be reconstructed, using RNA-Seq and genome re-sequencing. Once the strain has been engineered to promote the biotransformation of aromatics as benzoic acid, the rate processes for removal of aromatic compounds from cellulosic hydrolysates and the recovery of the benzoic acid co-product will be studied in bioreactor systems. Research outcomes will be used to enhance content for three courses in the Environmental Engineering program at the University of Wisconsin, Madison.