Selective fermentation of potential prebiotic lactose-derived oligosaccharides by probiotic bacteria

The growth of potential probiotic strains from the genera Lactobacillus, Bifidobacterium and Streptococcus was evaluated with the novel lactose-derived trisaccharides 4′-galactosyl-kojibiose and lactulosucrose and the potential prebiotics lactosucrose and kojibiose. The novel oligosaccharides were synthesised from equimolar sucrose:lactose and sucrose:lactulose mixtures, respectively, using a Leuconostoc mesenteroides dextransucrase and purified by liquid chromatography. The growth of the strains using the purified carbohydrates as the sole carbon source was evaluated by recording the culture optical density and calculating maximum growth rates and lag phase parameters. The results revealed an apparent bifidogenic effect of lactulosucrose, being a moderate substrate for streptococci and not utilised by lactobacilli. In addition, 4′-galactosyl-kojibiose was selectively fermented by Bifidobacterium breve, which was the only tested bifidobacterial species able to ferment kojibiose. The described fermentation properties of the specific probiotic strains on the lactose-derived oligosaccharides would enable the design of prebiotics with a high degree of selectivity.