Enzymatic synthesis of fucose-containing galacto-oligosaccharides using β-galactosidase and identification of novel disaccharide structures

Fucosylated oligosaccharides have an important role in maintaining a healthy immune system and homeostatic gut microflora. This study employed a commercial β-galactosidase in the production of fucose-containing galacto-oligosaccharides (fGOS) from lactose and fucose. The production was optimized using experiment design and optimal conditions for a batch production in 3-liter scale. The reaction product was analyzed and the produced galactose-fucose disaccharides were purified. The structures of these disaccharides were determined using NMR and it was verified that one major product with the structure Galβ1–3Fuc and two minor products with the structures Galβ1–4Fuc and Galβ1–2Fuc were formed. Additionally, the product composition was defined in more detail using several different analytical methods. It was concluded that the final product contained 42% total monosaccharides, 40% disaccharides and 18% of larger oligosaccharides. 290 μmol of fGOS was produced per gram of reaction mixture and 37% of the added fucose was bound to fGOS. The fraction of fGOS from total oligosaccharides was determined as 44%. This fGOS product could be used as a new putative route to deliver fucose to the intestine.