title: Redirecting carbon flux through pgi-deficient and heterologous transhydrogenase toward efficient succinate production in Corynebacterium glutamicum.
abstract: Corynebacterium glutamicum is particularly known for its potentiality in succinate production. We engineered C. glutamicum for the production of succinate. To enhance C3-C4carboxylation efficiency, chromosomal integration of the pyruvate carboxylase gene pyc resulted in strain NC-4. To increase intracellular NADH pools, the pntAB gene from Escherichia coli, encoding for transhydrogenase, was chromosomally integrated into NC-4, leading to strain NC-5. Furthermore, we deleted pgi gene in strain NC-5 to redirect carbon flux to the pentose phosphate pathway (PPP). To solve the drastic reduction of PTS-mediated glucose uptake, the ptsG gene from C. glutamicum, encoding for the glucose-specific transporter, was chromosomally integrated into pgi-deficient strain resulted in strain NC-6. In anaerobic batch fermentation, the production of succinate in pntAB-overexpressing strain NC-5 increased by 14% and a product yield of 1.22 mol/mol was obtained. In anaerobic fed-batch process, succinic acid concentration reached 856 mM by NC-6. The yields of succinate from glucose were 1.37 mol/mol accompanied by a very low level of by-products. Activating PPP and transhydrogenase in combination led to a succinate yield of 1.37 mol/mol, suggesting that they exhibited a synergistic effect for improving succinate yield.
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China.
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China. cheng@njtech.edu.cn.
authors.forename: Heng
authors.initials: H
authors.lastname: Cai
authors.affiliation: College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China.
authors.forename: Zhongjun
authors.initials: Z
authors.lastname: Chen
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211816, China.|College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Xu
mesh_terms: D061249:Batch Cell Culture Techniques; D002876:Chromosomes, Bacterial / Q000235:genetics*; D048230:Corynebacterium glutamicum / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005285:Fermentation; D017353:Gene Deletion; D005956:Glucose-6-Phosphate Isomerase / Q000235:genetics* / Q000378:metabolism; D060847:Metabolic Engineering; D000074041:Microorganisms, Genetically-Modified; D009250:NADP Transhydrogenases / Q000235:genetics* / Q000378:metabolism; D010427:Pentose Phosphate Pathway; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism; D019802:Succinic Acid / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D019802:Succinic Acid; D009250:NADP Transhydrogenases; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C031629:phosphoenolpyruvate-glucose phosphotransferase; D005956:Glucose-6-Phosphate Isomerase
keywords: Corynebacterium glutamicum; NADH; Phosphoglucose isomerase; Succinic acid; Transhydrogenase