Synthesis of fucosylated lacto-N-tetraose using whole-cell biotransformation.

Fucosylated oligosaccharides present a predominant group of free oligosaccharides found in human milk. Here, a microbial conversion of lactose, d-glucose and l-fucose to fucosylated lacto-N-tetraose by growing Escherichia coli cultures is presented. The recombinant expression of genes encoding for the β1,3-N-acetylglucosaminyltransferase (LgtA) and the β1,3-galactosyltransferase (WbgO) enables the whole-cell biotransformation of lactose to lacto-N-tetraose. By the additional expression of a recombinant GDP-l-fucose salvage pathway together with a bacterial fucosyltransferase, lacto-N-tetraose is further converted into the respective fucosylated compounds. The expression of a gene encoding the α1,2-fucosyltransferase (FutC) in the lacto-N-tetraose producing E. coli strain led to the formation of lacto-N-fucopentaose I, whereas the expression of a gene encoding the α1,4-fucosyltransferase (FucT14) mainly led to the conversion of lacto-N-tetraose to lacto-N-difucohexaose II.