Biosynthetic Routes for Producing Various Fucosyl-Oligosaccharides.

Fucosyl-oligosaccharides (FOSs) play physiologically important roles as prebiotics， neuronal growth factors， and inhibitors of enteropathogens. However，?challenges in designed synthesis and mass production of FOSs hamper their industrial applications. Here， we report flexible biosynthetic routes to produce various FOSs， including unnatural ones， through in vitro enzymatic reactions of various sugar acceptors， such as glucose， cellobiose， and agarobiose， and GDP-l-fucose as the fucose donor by using α1，2-fucosyltransferase (FucT2). Also， the whole-cell conversion for fucosylation of various sugar acceptors by overexpressing the genes associated with GDP-l-fucose production and fucT2 gene in Escherichia coli was demonstrated by producing 17.74 g/L of 2'-fucosylgalactose (2'-FG). Prebiotic effects of 2'-FG were verified on the basis of selective fermentability of 2'-FG by probiotic bifidobacteria. These biosynthetic routes can be used to engineer industrial microorganisms for more economical， more flexible， and safer production of FOSs than chemical synthesis of FOSs.