In vitro faecal fermentation of novel oligosaccharides enzymatically synthesized using microbial transglycosidases acting on sucrose

Fermentation profiles of five enzymatically synthesized purified oligosaccharides (kojibiose, 4-galactosyl-kojibiose, lactulosucrose, and sets of lactosyl- (DP 4-6) and raffinosyl-oligofructosides (DP 4-7)) were studied using an in vitro batch-culture fermentation system inoculated with human faecal slurries, simulating the events in the distal colon. Selectivity index for bifidobacteria and lactobacilli was calculated for each oligosaccharide to obtain a comparative relationship between the growth of these beneficial bacteria with respect to the other bacterial groups studied. Results showed a strong bifidogenic effect for all oligosaccharides, with similar Bifidobacterium levels compared to those produced by well-established prebiotics such as lactulose and fructo-oligosaccharides. Accordingly, acetic acid was the most prevalent SCFA produced. Oligosaccharides sharing structural features such as monomer composition and type of glycosidic linkage were grouped by dendrogram analysis, thus, underlining the potential correlation between the structural features of prebiotic candidates and their impact on the composition and metabolism of the human faecal microbiota.