Metabolic Engineering of <i>Escherichia coli</i> for Production of Ectoine

Abstract

Ectoine, a cyclic amino acid derivative is produced by some moderately halophilic microorganisms. It is widely used in the field of medicine and cosmetics; however its high cost, low yield and complicated production process restrict its use in an industry. The present study was carried out to construct an engineered Escherichia coli for the heterologous ectoine production. Firstly, the ectoine synthesis cluster (ectABC genes) from Halomonas elongata were introduced into E. coli for the ectoine production in heterologous system. Secondly, the effect of deletion for lysA and thrA on producing ectoine was investigated. Thirdly, the bioconversion conditions for synthesizing ectoine were optimized. In this study, nine strains of E.coli BW25113 were constructed, and an engineering strain ABC (∆lysA)/BW25113 with ectoine synthesis ability was screened out. An improved yield of ectoine was obtained with optimized conditions like 100 mmol/L sodium aspartate, 100 mmol/L glycerol, 80 mmol/L glucose and 120 mmol/L KCl at temperature 30°C, and the pH 7.0. A yield 2.08 g/L of ectoine was obtained. After preliminary optimization, the ABC (∆lysA)/BW25113 catalytic synthesis of ectoine increased by 2 times, indicating that optimized reaction conditions can increase the yield of ectoine. Here, we successfully constructed an engineered Escherichia coli for the heterologous production of ectoine. Our study herein provides a feasible and valuable biosynthesis pathway of ectoine with a potential for large-scale industrial production using simple and cheap feedstocks.