Cong T. Trinh and Friedrich Srienc. Chemical Engineering and Materials Science, and BioTechnology Institute, University of Minnesota, 1479 Gortner Ave, St. Paul, MN 55108
For the economic production of biofuels it is important that the available feedstock is converted into the product in the most efficient way. An efficient E. coli strain with minimal metabolic functionality for best ethanol production was rationally designed using elementary mode analysis. The entire solution space of more than 15,000 genetically independent pathways of the E. coli central metabolism identified by elementary mode analysis was reduced to less than ten most efficient ethanol producing pathways by elimination of inefficient pathways with gene knockout mutations. In the remaining efficient pathways a tight coupling of cell growth and ethanol production is enforced. The constructed mutant strain is able to efficiently convert hexoses and pentoses into ethanol at high yields. Moreover, the mutant does not exhibit catabolite repression by glucose and is able to simultaneously utilize hexoses and pentoses at similar rates resulting in favorable production kinetics. In addition, the constructed mutant is also able to efficiently convert at high yield glycerol, an abundant and inexpensive biodiesel side product, into ethanol.
