title: Minimal Escherichia coli cell for the most efficient production of ethanol from hexoses and pentoses.
abstract: To obtain an efficient ethanologenic Escherichia coli strain, we reduced the functional space of the central metabolic network, with eight gene knockout mutations, from over 15,000 pathway possibilities to 6 pathway options that support cell function. The remaining pathways, identified by elementary mode analysis, consist of four pathways with non-growth-associated conversion of pentoses and hexoses into ethanol at theoretical yields and two pathways with tight coupling of anaerobic cell growth with ethanol formation at high yields. Elimination of three additional genes resulted in a strain that selectively grows only on pentoses, even in the presence of glucose, with a high ethanol yield. We showed that the ethanol yields of strains with minimized metabolic functionality closely matched the theoretical predictions. Remarkably, catabolite repression was completely absent during anaerobic growth, resulting in the simultaneous utilization of pentoses and hexoses for ethanol production.
authors.affiliation: BioTechnology Institute, University of Minnesota, 240 Gortner Laboratory, 1479 Gortner Avenue, St. Paul, MN 55108, USA.
authors.forename: Cong T
authors.initials: CT
authors.lastname: Trinh
authors.forename: Pornkamol
authors.initials: P
authors.lastname: Unrean
authors.forename: Friedrich
authors.initials: F
authors.lastname: Srienc
mesh_terms: D000693:Anaerobiosis; D018533:Biomass; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics; D000431:Ethanol / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006601:Hexoses / Q000378:metabolism*; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008954:Models, Biological; D010429:Pentoses / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D006601:Hexoses; D010429:Pentoses; D000431:Ethanol