Effects of Carbon Sources on Succinate Production by Dual-phase Fermentations of Recombinant Escherichia coli / 中国生物工程杂志

ABSTRACT

The effects of different carbon sources added to aerobic medium on cell growth,enzyme activity and metabolite distribution was investigated in dual-phase fermentations.The results showed that both cell density and enzyme activity were enhanced by adding 4mmol/L glucose or 12,54,80mmol/L sodium acetate to aerobic medium,respectively.Then centrifugated cells that had grown aerobically in different conditions were transferred to anaerobic fermentation,the enzyme activity and metabolite distribution changed.To analyze the anaerobic enzyme activity and metabolite distribution,it was concluded that during the anaerobic fermentation of Escherichia coli NZN111 overexpressed malic enzyme,PEP carboxykinase(PCK)was the key enzyme of succinate production,pyruvate kinase(PYK)was associated to the accumulation of by-product pyruvate,and isocitrate lyase(ICL)have some influence on the concentration of succinate.The yield of succinate in anaerobic stage could reach 89.0%,which was 16.6% higher than that of the control by adding 80mmol/L sodium acetate as carbon source in aerobic medium.