Highly efficient production of ectoine via an optimized combination of precursor metabolic modules in Escherichia coli BL21

Ectoine is an osmotic pressure protectant observed in various microorganisms and is widely used in cosmetics and pharmaceuticals. The market value of ectoine has increased considerably with social progress, resulting in high demand for ectoine production technology. Herein, a microbial cell factory in Escherichia coli that produces ectoine at high titers is described as developing efficient and environmentally friendly bio-based ectoine production technology. The ectoine biosynthetic pathway of Halomonas hydrothermalis was introduced into E. coli BL21 (DE3). Subsequent overexpression of precursor metabolic modules, including aspartate branching, pyruvate-oxoacetate, and glutamate biosynthesis pathways, resulted in the final strain, E. coli BCT08, which produced ectoine at a titer of 36.58 g/L during 30 h of fermentation. Sugar feeding speed optimization improved the ectoine titer to 131.8 g/L after 96 h of cultivation. This represents a remarkable achievement in ectoine production from glucose under low-salt conditions and has vast potential for industrial applications.