Cofactor Metabolic Engineering of IEscherichia coli/I for Aerobic L-Malate Production with Lower CO[sub.2] Emissions

• Published in: Bioengineering (Basel) Vol. 10; no. 8
• Main Authors: Jiang, Zhiming, Jiang, Youming, Wu, Hao, Zhang, Wenming, Xin, Fengxue, Ma, Jiangfeng, Jiang, Min
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.07.2023
• Subjects: Escherichia coli; Health aspects; Japan
• ISSN: 2306-5354; 2306-5354
• DOI: 10.3390/bioengineering10080881

Escherichia coli has been engineered for L-malate production via aerobic cultivation. However, the maximum yield obtained through this mode is inferior to that of anaerobic fermentation due to massive amounts of CO[sub.2] emissions. Here, we aim to address this issue by reducing CO[sub.2] emissions of recombinant E. coli during aerobic L-malate production. Our findings indicated that NADH oxidation and ATP-synthesis-related genes were down-regulated with 2 g/L of YE during aerobic cultivations of E. coli E23, as compared to 5 g/L of YE. Then, E23 was engineered via the knockout of nuoA and the introduction of the nonoxidative glycolysis (NOG) pathway, resulting in a reduction of NAD[sup.+] and ATP supplies. The results demonstrate that E23 (ΔnuoA, NOG) exhibited decreased CO[sub.2] emissions, and it produced 21.3 g/L of L-malate from glucose aerobically with the improved yield of 0.43 g/g. This study suggests that a restricted NAD[sup.+] and ATP supply can prompt E. coli to engage in incomplete oxidization of glucose, leading to the accumulation of metabolites instead of utilizing them in cellular respiration.