Utilization of fucosylated oligosaccharides by Bifidobacterium bifidum BGN4 and expression of cloned BGN4 α-L-fucosidase genes in E. coli

Abstract

Bifidobacterium is the most predominant in the intestine of breast-fed infants and beneficial for the maintenance of the balanced microflora in the gut. Human milk oligosaccharides (HMO) is the third most common solid component (15 g/L) in human milk and contains abundant fucosylated oligosaccharides (FO). Therefore, Bifidobacterium which can use fucosylated HMO is expected to be selectively enriched in the intestine of breast-fed infants. The utilization of human milk saccharides (HMS) and artificial fucosylated oligosaccharides (2-fucosyllactose, 3-fucosyllactose) by various Bifidobacterium strains were assessed. B. bifidum BGN4 showed specific growth in the presence of 2FL or 3FL. Using the annotated sequences of two theoretical α-L-fucosidase genes (BBB_0176 and BBB_1341) in the genome of B. bifidum BGN4, those genes have been cloned in E. coli for the expression and characterization of the corresponding enzymes. AFL03772, product of BBB_0176, hydrolyzed α-(1→2) and α-(1→3) linkages of 2- and 3-fucosyllactoses

whereas AFL04933, product of BBB_1341, hydrolyzed α-(1→3) linkage of 3-fucosyllactose. Based on the results obtained in this study, B. bifidum BGN4 has been concluded to have two α-L-fucosidase enzymes to hydrolyze FO. Therefore, B. bifidum BGN4 may be used as beneficial bacteria which can preferentially grow in the intestine of the breast-fed infants.