title: High glycolytic flux improves pyruvate production by a metabolically engineered Escherichia coli strain.
abstract: We report pyruvate formation in Escherichia coli strain ALS929 containing mutations in the aceEF, pfl, poxB, pps, and ldhA genes which encode, respectively, the pyruvate dehydrogenase complex, pyruvate formate lyase, pyruvate oxidase, phosphoenolpyruvate synthase, and lactate dehydrogenase. The glycolytic rate and pyruvate productivity were compared using glucose-, acetate-, nitrogen-, or phosphorus-limited chemostats at a growth rate of 0.15 h(-1). Of these four nutrient limitation conditions, growth under acetate limitation resulted in the highest glycolytic flux (1.60 g/g . h), pyruvate formation rate (1.11 g/g h), and pyruvate yield (0.70 g/g). Additional mutations in atpFH and arcA (strain ALS1059) further elevated the steady-state glycolytic flux to 2.38 g/g h in an acetate-limited chemostat, with heterologous NADH oxidase expression causing only modest additional improvement. A fed-batch process with strain ALS1059 using defined medium with 5 mM betaine as osmoprotectant and an exponential feeding rate of 0.15 h(-1) achieved 90 g/liter pyruvate, with an overall productivity of 2.1 g/liter h and yield of 0.68 g/g.
authors.affiliation: Center for Molecular BioEngineering, Department of Biological and Agricultural Engineering, University of Georgia, Athens, GA 30602, USA.
authors.forename: Yihui
authors.initials: Y
authors.lastname: Zhu
authors.forename: Mark A
authors.initials: MA
authors.lastname: Eiteman
authors.forename: Ronni
authors.initials: R
authors.lastname: Altman
authors.forename: Elliot
authors.initials: E
authors.lastname: Altman
mesh_terms: D019342:Acetic Acid / Q000378:metabolism; D004798:Enzymes / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis / Q000235:genetics*; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008954:Models, Biological; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism*
chemical_list: D004798:Enzymes; D029968:Escherichia coli Proteins; D010758:Phosphorus; D019289:Pyruvic Acid; D005947:Glucose; D009584:Nitrogen; D019342:Acetic Acid