Collaborative Research: Engineering yeast consortia for surface-display of complex cellulosome structures: A consolidated bioprocessing approach from cellulosic biomass to ethanol

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0903894ChenIntellectual MeritThe engineering strategy proposed emphasizes the efficiency of hydrolysis and synergy among cellulases, rather than focusing on the amount of enzymes produced or used. To emulate the success of a natural mechanism for efficient cellulose hydrolysis, complex cellulosomes (self-assembled multi-enzyme complexes) will be assembled on the yeast cell surface, enabling the ethanol-producing strain to utilize cellulose and concomitantly ferment it to ethanol. More importantly, by organizing these cellulases in an ordered structure, the enhanced synergy will increase the efficiency in hydrolysis, and thereby enhance ethanol production. The use of a single yeast strain for surface anchoring and cellulase secretion is unlikely to be successful again based on bioenergetic limitations. To solve this problem, a synthetic yeast consortium will be developed for the functional presentation of the complex cellulosome structures.Broader ImpactsEngineering microbes to utilize cellulose eliminates the need for cellulose treatment. If successful, this will allow vastly abundant low-cost agriculture residues to be used as raw materials for ethanol production. The enhanced value of crops leads to additional incomes to farmers, more efficient land use, and contributes to long-term agriculture sustainability. The increased production of ethanol reduces pollution to the environment and the need for imported petroleum. The integration of metabolic engineering strategies with the implementation of process technology represents a unique effort that expands the fundamental development of metabolic engineering into a practical remediation technology. The proposed research involves intersection of principles and methods of molecular genetics, synthetic biology, and fermentation. Graduate students participating in this research will gain an integrated perspective of the important interfaces and synergies connecting biochemistry, modern genetics, and process engineering. As the integration of research and education is one of the key programs of NSF, the proposed research will involve the participation of K-12 school students, undergraduates and graduate students, particularly from underrepresented groups.