Improved production of 2'-fucosyllactose in engineered Saccharomyces cerevisiae expressing a putative α-1, 2-fucosyltransferase from Bacillus cereus

2'-fucosyllactose (2'-FL) is one of the most abundant oligosaccharides in human milk. It constitutes an authorized functional additive to improve infant nutrition and health in manufactured infant formulations. As a result, a cost-effective method for mass production of 2'-FL is highly desirable. A microbial cell factory for 2'-FL production was constructed in Saccharomyces cerevisiae by expressing a putative α-1, 2-fucosyltransferase from Bacillus cereus (FutBc) and enhancing the de novo GDP-L-fucose biosynthesis. When enabled lactose uptake, this system produced 2.54 g/L of 2'-FL with a batch flask cultivation using galactose as inducer and carbon source, representing a 1.8-fold increase compared with the commonly used α-1, 2-fucosyltransferase from Helicobacter pylori (FutC). The production of 2'-FL was further increased to 3.45 g/L by fortifying GDP-mannose synthesis. Further deleting gal80 enabled the engineered strain to produce 26.63 g/L of 2'-FL with a yield of 0.85 mol/mol from lactose with sucrose as a carbon source in a fed-batch fermentation. FutBc combined with the other reported engineering strategies holds great potential for developing commercial scale processes for economic 2'-FL production using a food-grade microbial cell factory.