Improvement of the Efficiency of Pyruvate Production by Escherichia coli Whole-Cell Biocatalyst through Expression of Cytochrome b562

Abstract:

Pyruvate is widely used in pharmaceutical, agrochemical and chemical industries. Two strategies were used to improve the efficiency of bioconversion to pyruvate. First, the efficiency of adenine dinucleotide(FAD) synthesis was improved by expressing cytochrome b562, reducing the reaction time from 27 h to 21 h and increasing the productivity by 28.5%. Secondly, the directional evolution of L-amino acid deaminase(pm1) was achieved by site-saturation mutagenesis to improve its catalytic ability, and the yield of pyruvate in the triple mutant E418A/V438I/L278I was 25.58 g/L, which was 44.60% higher than that of the control strain. All the results showed that the efficiency of pyruvate produced by E. coli whole-cell biocatalyst could be effectively increased by the improvement of pm1 catalytic ability and FAD synthesis efficiency using site-saturation mutagenesis and expressing pm1 chaperone (cytochrome b562).