High-level L-valine production by systematically engineered Escherichia coli W

Abstract

A less frequently employed Escherichia coli strain W, yet possessing useful metabolic characteristics such as less acetic acid production and high L-valine tolerance, was metabolically engineered for the production of L-valine. The engineered E. coli W (ΔlacI ΔilvA) strain overexpressing the ilvBNmut, ilvCED, ygaZH and lrp genes was able to produce an impressively high concentration of 60.7 g/L L-valine by fed-batch culture in 29.5 h, resulting in a high volumetric productivity of 2.06 g/L/h. The results obtained in this study suggest that E. coli W can be a good alternative to Corynebacterium glutamicum and E. coli K-12, which have so far been the most efficient L-valine producer. Furthermore, it is expected that various bioproducts including other amino acids might be more efficiently produced by this revisited platform strain of E. coli.