2′-Fucosyllactose as a prebiotic modulates the probiotic responses of Bifidobacterium bifidum

2 '-Fucosyllactose (2 '-FL), one of the most representative oligosaccharides in human milk, is intimately linked to the enrichment of specific Bifidobacterium species. However, the efficacy of 2 '-FL in modulating the probiotic responses of bifidobacterium has been rarely researched. Thereinto, three key issues have yet to be reported: the effects of 2 '-FL hydrolysis on bifidobacterial growth, the protective effects of 2 '-FL on bifidobacterium under gastrointestinal stress and the inhibitory activity of 2 '-FL metabolites against Cronobacter spp. This work intended to address these concerns. 2 '-FL dramatically accelerated the growth and proliferation of Bifidobacterium bifidum YH17 and Bifidobacterium bifidum BBI01. The glucose in lactose core on 2 '-FL was preferable for B. bifidum to achieve substantial increases in biomass while the galactose was not readily available. Additionally, 2 '-FL showed unique advantages in ameliorating the resistance of B. bifidum to gastrointestinal challenges. 2 '-FL considerably improved the adhesive property of B. bifidum, thus facilitating the competitive elimination of Cronobacter sakazakii ATCC 29544 and Cronobacter muytjensii ATCC 51329 by B. bifidum. The growth inhibition of 2 '-FL on the Cronobacter strains was mediated by promoting the secretion of antibacterial substances from B. bifidum. The inhibitory activity hinged on the B. bifidum strains. 2 '-FL specifically induced B. bifidum BBI01 to produce some antibacterial substances that were proteinaceous, thermostable and relatively stable even at pH 8.0. These antibacterial substances played a key role in the inhibitory activity and had a synergistic effect with acidification. These observations provide a useful guideline for developing synbiotic supplements to intervene the infant gut microbiota.