Regulation of NADH Oxidase Expression via a Thermo-regulated Genetic Switch for Pyruvate Production in Escherichia coli

Abstract

As a chemical, pyruvate can be used as a raw material for drug, agrochemical, chemical, and food industries. In the microbial production of pyruvate, although continuous expression of exogenous NADH oxidase (noxE) can improve glucose consumption, it can lead to a decrease of pyruvate yield. For efficient pyruvate production, a thermo-regulated genetic switch was designed to dynamically control the expression of noxE from Lactococcus lactis on the Escherichia coli MP-XB010CN chromosome. At the initial stage of fermentation, switching on the genetic switch for efficient noxE expression can promote growth rate and biomass accumulation, then switching off noxE expression can weaken the TCA pathway and improve the pyruvate yield. High pyruvate concentration of 93.0 g/L and yield of 0.71 g/g glucose were achieved with the thermo-regulated two-phase fermentation. Efficient cell growth and pyruvate production were reached separately by switching cultivation temperature. The results indicated that the genetic switch for controlling the noxE gene accurate expression was an effective strategy for improving pyruvate production.