title: Metabolic flux analysis for succinic acid production by recombinant Escherichia coli with amplified malic enzyme activity.
abstract: A pfl ldhA double mutant Escherichia coli strain NZN111 was used to produce succinic acid by overexpressing the E. coli malic enzyme. Escherichia coli strain NZN111 harboring pTrcML produced 6 and 8 g/L of succinic acid from 20 g/L of glucose in flask culture at 37 degrees C and 30 degrees C, respectively. When NZN111(pTrcML) was cultured at 30 degrees C with intermittent glucose feeding the final succinic acid concentration obtained was 9.5 g/L and the ratio of succinic acid to acetic acid was 13:1. This system could not be analyzed by conventional metabolic flux analysis techniques, since some pyruvate and succinic acid were accumulated intracellularly. Therefore, a new flux analysis method was proposed by introducing intracellular pyruvate and succinic acid pools. By this new method the concentrations of intracellular metabolites were successfully predicted and the differences between the measured and calculated reaction rates could be considerably reduced.
authors.affiliation: Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical Engineering and BioProcess Engineering Research Center, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701, Korea.
authors.forename: S H
authors.initials: SH
authors.lastname: Hong
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
mesh_terms: D000123:Acetyltransferases / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D005818:Genetic Engineering / Q000379:methods; D005947:Glucose / Q000378:metabolism; D007218:Industrial Microbiology / Q000379:methods*; D007770:L-Lactate Dehydrogenase / Q000235:genetics; D008291:Malate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D008293:Malates / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism; D019802:Succinic Acid / Q000378:metabolism*
chemical_list: D008293:Malates; C030298:malic acid; D019289:Pyruvic Acid; D019802:Succinic Acid; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase; C046446:malate dehydrogenase-(oxaloacetate-decarboxylating) (NAD+); D000123:Acetyltransferases; C022560:formate C-acetyltransferase; D005947:Glucose