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

PI：丹尼尔R. Noguera提案编号：由植物生物质生产生物燃料所面临的主要挑战是存在由生物质的纤维素部分转化为可发酵糖而产生的不需要的副产物。 这些副产物主要来自生物质的水溶性木质素级分，对发酵过程有毒，并降低生物燃料生产产率。 该项目将研究使用细菌将这些副产品转化为单一的芳香族化合物，该化合物可以在工程生物过程中作为有价值的副产品回收，而无需消耗有价值的糖。 这项研究的过程也将推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指导高中生、本科生和研究生开展与研究相关的主题的教育活动。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产物中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品回收。 所提出的方法利用了芳香族化合物的厌氧微生物降解，特别是红曲霉属的培养成员的代谢，所述红曲霉属的培养成员在不利用生物燃料生产所需的糖的情况下有效地消耗大量芳香族化合物。 据推测，存在于水解产物中的芳香族化合物是降解的R。palustris通过苯甲酰辅酶A途径。 拟议的研究将对这种生物进行基因工程改造，将生物质水解产物中通常存在的大量芳香族化合物转化为苯甲酸或对羟基苯甲酸，具体取决于突变的位置。 将测试现有的红曲霉菌群的代谢多样性，以确定用于纤维素水解产物解毒的最佳菌株。 实验将在光养和发酵条件下用红球藻菌株的混合物进行，使用用工业相关生物质负载制备的玉米秸秆水解产物以及模拟水解产物的合成培养基的变体。 将使用RNA-Seq和基因组重新测序，重建表现最好的红曲霉菌株中厌氧芳香族降解的遗传和调控网络。 一旦该菌株被工程化以促进芳族化合物作为苯甲酸的生物转化，将在生物反应器系统中研究从纤维素水解产物中去除芳族化合物和回收苯甲酸副产物的速率过程。 研究成果将用于增强麦迪逊的威斯康星州大学环境工程课程的三门课程的内容。

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.