Improved production of 2′-fucosyllactose in engineered Escherichia coli by expressing putative α-1,2-fucosyltransferase, WcfB from Bacteroides fragilis

- 2′-Fucosyllactose (2-FL) is a value-added human milk oligosaccharide in terms of nutraceutical and pharmaceutical purpose.
- The wcfB gene coding for α-1,2-fucosyltransferase from Bacteroides fragilis was screened from eleven candidates.
- The replacement of FucT2 from Helicobacter pylori with WcfB from B. fragilis leads to improvement of 2-FL titer by 10 fold in batch fermentation.
- 2-FL concentration, yield and productivity were enhanced further by 50%, 62% and 100% through the complete deletion of lacZ.
- Engineered E. coli deleting lacZ and expressing GDP-L-fucose biosynthetic enzymes and WcfB produced 15.4 g/L of 2-FL in fed-batch fermentation.

2′-Fucosyllactose (2-FL) is one of most abundant oligosaccharides in human milk, which is involved in many biological functions for infant health. Since 2-FL has a great potential in application to functional food materials and pharmaceuticals, several microbial systems for mass production of 2-FL have been developed in recent years. Microbial production of 2-FL was suggested to be influenced by a number of factors including fucosylation activity of α-1,2-fucosyltransferase. In the present study, the wcfB gene coding for α-1,2-fucosyltransferase from Bacteroides fragilis was screened from eleven candidates of putative α-1,2-fucosyltransferase. Introduction of the wcfB gene allows the lacZ-deleted strain of E. coli expressing the genes for guanosine 5′-diphosphate (GDP)-l-fucose biosynthetic enzymes to produce 2-FL. As a result of fed-batch fermentation, 15.4 g/L extracellular concentration of 2-FL with 2-FL yield of 0.858 g/g lactose and productivity of 0.530 g/L/h were obtained. In addition, the feasibility of industrial production of 2-FL using this microbial system was demonstrated by performing fed-batch fermentation in a 75 L bioreactor.