Synthesis of 2′-fucosyllactose from apple pomace–derived xyloglucan oligosaccharides by an α-L-fucosidase from Pedobacter sp. CAU209.

2′-Fucosyllactose (2′-FL) is known for its ability to provide various health benefits to infants, such as gut maturation, pathogen resistance, improved immunity, and nervous system development. However, the production of 2′-FL using α-L-fucosidases is hindered by the lack of low-cost natural fucosyl donors and high-efficiency α-L-fucosidases. In this work, a recombinant xyloglucanase from Rhizomucor miehei (RmXEG12A) was applied to produce xyloglucan-oligosaccharide (XyG-oligos) from apple pomace. Then, an α-L-fucosidase gene (PbFucB) was screened from the genomic DNA of Pedobacter sp. CAU209 and expressed in Escherichia coli. The capability of purified PbFucB to catalyze XyG-oligos and lactose to synthesize 2′-FL was further evaluated. The deduced amino acid sequence of PbFucB shared the highest identity (38.4%) with that of other reported α-L-fucosidases. PbFucB showed the highest activity at pH 5.5 and 35 °C. It catalyzed the hydrolysis of 4-nitrophenyl-α-L-fucopyranoside (pNP-Fuc, 20.3 U mg−1), 2′-FL (8.06 U mg−1), and XyG-oligos (0.43 U mg−1). Furthermore, PbFucB demonstrated a high enzymatic conversion rate in 2′-FL synthesis with pNP-Fuc or apple pomace–derived XyG-oligos as donors and lactose as acceptor. Under the optimized conditions, PbFucB converted 50% of pNP-Fuc or 31% of the L-fucosyl residue in XyG-oligos into 2′-FL. This work elucidated an α-L-fucosidase that mediates the fucosylation of lactose and provided an efficient enzymatic strategy to synthesize 2′-FL either from artificial pNP-Fuc or natural apple pomace–derived XyG-oligos. Key points: • Xyloglucan-oligosaccharide (XyG-oligos) was produced from apple pomace by a xyloglucanase from Rhizomucor miehei. • An α-L-fucosidase (PbFucB) from Pedobacter sp. CAU209 shared the highest identity (38.4%) with reported α-L-fucosidases. •PbFucB synthesized 2′-FL using apple pomace–derived XyG-oligos and lactose with a conversion ratio of 31%. [ABSTRACT FROM AUTHOR]