Biosynthesis of Pyruvate from Malic Acid by Whole-cell Biotransformation Using Recombinant Escherichia coli
It is proposed to establish a synthetic route of pyruvate obtained from malic acid by whole cell biotransforma-tion using Escherichia coli.With Escherichia coli BL21(DE3)as the host,endogenous malice enzyme(ME)and aldose reductase(AR)from Candida boidinii were co-overexpressed on pET28a,and catalytic key factors such as cell concen-tration,substrate concentration,temperature and pH were investigated.Activities of malic enzyme from Escherichia coli and aldose reductase from Candida boidinii were(2.8±0.21),(3.1±0.34)U/mL respectively.The suitable catalytic condi-tions were as follows,the cell concentration of bacterial OD600nm value was 30,the mass concentration of substrate malic acid was 30g/L,the molar ratio of xylose to malic acid was 1.0,temperature was 40 ℃,the pH value of the reaction system was 7.8,pyruvate yield was up to 23.16 g/L.This study provides a new method for the biological production of pyruvate.
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