Coupled ARTP and ALE strategy to improve anaerobic cell growth and succinic acid production by Escherichia coli

BACKGROUND: Escherichia coli AFP111, a facultative anaerobic strain, shows a very low cell growth and succinic acid production rate in minimal medium during exclusively anaerobic fermentation. Therefore, atmospheric and room temperature plasma (ARTP) and adaptive laboratory evolution (ALE) strategies were adopted to improve cell growth and succinic acid production under anaerobic conditions. RESULTS: A mutant, BER208, was obtained by ARTP and ALE used successively. When cultured in a 3L stirred bioreactor, the specific growth rate of BER208 was increased 3.12-fold compared with AFP111. Also, it consumed 40gL^-1 glucose and produced 27.9gL^-1 succinic acid with a glucose utilization rate of 0.54gL^-1h^-1 and succinic acid productivity of 0.38gL^-1h^-1, which were 3.7-fold and 2.5-fold higher than those of the original strain. Further investigation showed that the activities of glucokinase and phosphoenolpyruvate carboxykinase (PCK) were increased 3.3-fold and 16-fold in the mutant compared with the original strain. CONCLUSION: The combined strategy of ARTP and ALE was an effective approach to obtain mutants with improved performance.