[Metabolic engineering of Corynebacterium glutamicum for L-valine production].

L-valine is an important essential branched-chain amino acid widely used in industries such as feed, pharmaceuticals, and food. In order to further enhance the production performance of L-valine, this study systematically engineered the metabolism of a Corynebacterium glutamicum strain, preserved in the laboratory, which is capable of producing L-valine. First, strain VH-9 was obtained by enhancing the precursor supply, synthesis pathway, and transport system of L-valine. In a 5 L fermenter, the titer, yield, and productivity of L-valine were 76.6 g/L, 0.45 g/g, and 2.39 g/(L·h), respectively. Furthermore, strain VH-18 was obtained by enhancing the uptake of substrate glucose and balancing energy supply to reduce succinate accumulation, with the titer, yield, and productivity of L-valine increased to 82.7 g/L, 0.52 g/g, and 2.58 g/(L·h), respectively. After optimization of fermentation conditions, the titer, yield, and productivity of L-valine in strain VH-18 were further improved to 88.7 g/L, 0.54 g/g, and 2.77 g/(L·h), respectively. This study has achieved the high-efficiency production of L-valine through a systems metabolic engineering strategy.