High-Level Biosynthesis of 2'-Fucosyllactose by Metabolically Engineered .

2'-Fucosyllactose (2'-FL) is the most abundant oligosaccharide in human milk. In this study, a highly efficient biosynthetic route for 2'-FL production was designed the pathway of GDP-l-fucose using engineered BL21(DE3). Specifically, plasmid-based strains with previously deleted and were further reconstructed by introducing pathway genes and α1,2-fucosyltransferase-encoding to realize 2'-FL synthesis. The 2'-FL titer was enhanced to 3.92 g/L by further introducing and . Subsequently, the additional expression cassette was chromosomally integrated into locus to strengthen fucosylation reaction and a strong constitutive promoter (P) was used to replace the original promoters of and to improve 2'-FL synthesis. The maximal 2'-FL titer reached 9.06 and 79.23 g/L in shake-flask and fed-batch cultivation, respectively. The 2'-FL productivity reached 1.45 g/L/h, showing remarkable production potential in large-scale industrial application.