[Metabolic engineering of the substrate utilization pathway in increases L-lysine production].

L-lysine is an essential amino acid with broad applications in the animal feed, human food, and pharmaceutical industries. The fermentation production of L-lysine by has limitations such as poor substrate utilization efficiency and low saccharide conversion rates. We deleted the global regulatory factor gene and introduced heterologous genes, including the maltose phosphotransferase genes () from , to enhance the use efficiency of disaccharides and trisaccharides. The engineered strain . XC3 demonstrated improved L-lysine production, yield, and productivity, which reached 160.00 g/L, 63.78%, and 4.44 g/(L‧h), respectively. Furthermore, we overexpressed the glutamate dehydrogenase gene () and assimilated nitrate reductase genes () from . , along with nitrite reductase genes () from . , in strain . XC3. This allowed the construction of . XC4 with a nitrate assimilation pathway. The L-lysine production, yield, and productivity of . XC4 were elevated to 188.00 g/L, 69.44%, and 5.22 g/(L‧h), respectively. After optimization of the residual sugar concentration and carbon to nitrogen ratio, the L-lysine production, yield, and productivity were increased to 204.00 g/L, 72.32%, and 5.67 g/(L‧h), respectively, in a 5 L fermenter. These values represented the increases of 40.69%, 20.03%, and 40.69%, respectively, compared with those of the starting strain XC1. By engineering the substrate utilization pathway, we successfully constructed a high-yield L-lysine producing strain, laying a solid foundation for the industrial production of L-lysine.