title: Enhancement of succinate production by metabolically engineered Escherichia coli with co-expression of nicotinic acid phosphoribosyltransferase and pyruvate carboxylase.
abstract: Escherichia coli BA002, in which the ldhA and pflB genes are deleted, cannot utilize glucose anaerobically due to the inability to regenerate NAD(+). To restore glucose utilization, overexpression of nicotinic acid phosphoribosyltransferase (NAPRTase) encoded by the pncB gene, a rate-limiting enzyme of NAD(H) synthesis pathway, resulted in a significant increase in cell mass and succinate production under anaerobic conditions. However, a high concentration of pyruvate accumulated. Thus, co-expression of NAPRTase and the heterologous pyruvate carboxylase (PYC) of Lactococcus lactis subsp. cremoris NZ9000 in recombinant E. coli BA016 was investigated. The total concentration of NAD(H) was 9.8-fold higher in BA016 than in BA002, and the NADH/NAD(+) ratio decreased from 0.60 to 0.04. Under anaerobic conditions, BA016 consumed 17.50 g l(-1) glucose and produced 14.08 g l(-1) succinate with a small quantity of pyruvate. Furthermore, when the reducing agent dithiothreitol or reduced carbon source sorbitol was added, the cell growth and carbon source consumption rate of BA016 was reasonably enhanced and succinate productivity increased.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing, 211816, Jiangsu, China.
authors.forename: Jiangfeng
authors.initials: J
authors.lastname: Ma
authors.forename: Dongmei
authors.initials: D
authors.lastname: Gou
authors.forename: Liya
authors.initials: L
authors.lastname: Liang
authors.forename: Rongming
authors.initials: R
authors.lastname: Liu
authors.forename: Xu
authors.initials: X
authors.lastname: Chen
authors.forename: Changqing
authors.initials: C
authors.lastname: Zhang
authors.forename: Jiuhua
authors.initials: J
authors.lastname: Zhang
authors.forename: Kequan
authors.initials: K
authors.lastname: Chen
authors.forename: Min
authors.initials: M
authors.lastname: Jiang
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D005798:Genes, Bacterial; D005818:Genetic Engineering; D010430:Pentosyltransferases / Q000235:genetics*; D011766:Pyruvate Carboxylase / Q000235:genetics*; D019802:Succinic Acid / Q000378:metabolism*
chemical_list: D019802:Succinic Acid; D010430:Pentosyltransferases; C021864:nicotinate phosphoribosyltransferase; D011766:Pyruvate Carboxylase