Fed‐batch culture of a metabolically engineered Escherichia coli strain designed for high‐level succinate production and yield under aerobic conditions

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Abstract
An aerobic succinate production system developed by Lin et al. (Metab Eng, in press) is capable of achieving the maximum theoretical succinate yield of 1.0 mol/mol glucose for aerobic conditions. It also exhibits high succinate productivity. This succinate production system is a mutant E. coli strain with five pathways inactivated: ΔsdhAB, Δ(ackA‐pta), ΔpoxB, ΔiclR, and ΔptsG. The mutant strain also overexpresses Sorghum vulgare pepc. This mutant strain is designated HL27659k(pKK313). Fed‐batch reactor experiments were performed for the strain HL27659k(pKK313) under aerobic conditions to determine and demonstrate its capacity for high‐level succinate production. Results showed that it could produce 58.3 g/l of succinate in 59 h under complete aerobic conditions. Throughout the entire fermentation the average succinate yield was 0.94 ± 0.07 mol/mol glucose, the average productivity was 1.08 ± 0.06 g/l‐h, and the average specific productivity was 89.77 ± 3.40 mg/g‐h. Strain HL27659k (pKK313) is, thus, capable of large‐scale succinate production under aerobic conditions. The results also showed that the aerobic succinate production system using the designed strain HL27659k(pKK313) is more practical than conventional anaerobic succinate production systems. It has remarkable potential for industrial‐scale succinate production and process optimization.