This project will design novel 1-propanol and 2-butanol pathways based on a diol dehydratase, to engineer the pathways in Escherichia coli, and to develop biological processes to convert lignocellulosic biomass into liquid biofuels 1-propanol and 2-butanol. The research work consists of the efforts in releasing fermentable sugars from lignocellulosic materials microbially, designing and constructing metabolic pathways and microbial production platforms to convert the released sugars into the desired products, and developing integrated processes to deliver 1-propanol and 2-butanol from lignocellulosic resources. The key elements of this research work are the protein engineering of a diol dehydratase to enhance dehydration of 2,3-butanediol and metabolic engineering of E. coli to enable the efficient production of 1-propanol and 2-butanol from Caldicellulosiruptor bescii treated lignocellulosic biomass. Eventually, the long-term objective of the proposed project is to develop scalable and ustainable technologies to efficiently generate 1-propanol and 2-butanol from renewable sources, specifically 1) improving E. coli strain properties for efficient 1-propanol production; 2) improving the properties of the diol dehydratase to meet process metrics via protein engineering; 3) developing strains and integrated processes for the generation of 1-propanol and 2-butanol from lignocellulosic biomass.
Both 1-propanol and 2-butanol have the physicochemical properties of high energy density, low vapor pressure, and low water content, which make them better liquid biofuels than currently widely-used bioethanol. The outcome of this research will advance our understanding of microbial metabolism and lead to the development of practical technologies for the production of 1-propanol and 2-butanol from lignocellulosic biomass through microbial fermentation, representing the efforts of expanding natural metabolism for bioenergy applications and impacting the disciplines of chemistry, biological sciences, and engineering. The research and education efforts will be integrated as the following: 1) A Metabolic Engineering & Synthetic Biology Course and a Metabolic Engineering & Synthetic Biology Laboratory will be developed based on the proposed research to strengthen the BioChemical Engineering Program at the University of Georgia (UGA), which will provide undergraduate and graduate students with the interdisciplinary training of chemistry, biological sciences, and engineering. 2) The proposed research will be integrated with community education through the existing cooperative extensions at UGA including the Georgia 4-H organization and the educational programs at the State Botanical Garden of Georgia with the priority of encouraging the participation of minority and educationally or economically disadvantaged groups. 3) The proposed research will be integrated with the existing programs of Bioenergy Systems Research Institute at UGA to provide students with training, internships, exchanges, and scholarships.