In-vitro fermentation behaviors of alternansucrase-based glucooligosaccharides (GLOS) derived from melibiose, cellobiose and lactose

Glucooligosaccharides produced by glucansucrases via acceptor reactions are oligosaccharides that transit upper intestinal tract and evade digestion and may be considered to be a prebiotic. The prebiotic function of glucooligosaccharides can be dictated by the type of acceptor sugar used during its production. Therefore, the prebiotic effect on the gut microbiome and metabolite production can be used to inform the selection of acceptor sugars.In this study, alternansucrase-based glucooligosaccharides derived from different acceptor sugars (melibiose, cellobiose and lactose) and inulin (positive control) were investigated using in vitro colon model fermentation to examine their prebiotic effect and metabolite production. Microbiome composition was determined using shotgun metagenomics. Short chain fatty acids (SCFAs) and lactate formation was determined using 1H NMR spectroscopy.Hierarchical cluster analysis showed that Fusicatenibacter saccharivorans and Bacteroides uniformis increased in abundance after 24h fermentation in all three glucooligosaccharides. The highest abundance for Bifidobacterium longum was seen after supplementation with lactose derived glucooligosaccharides. Cellobiose derived glucooligosaccharides produced 2.6 times higher acetate than inulin followed by lactose and melibiose derived glucooligosaccharides (p<0.05). This study revealed that melibiose, cellobiose and lactose derived glucooligosaccharides can be considered as prebiotic alternatives to inulin since a Bifidogenic effect was observed as evidenced by presence of Bifodobacterium pseudocatenulatum, Bifodobacterium longum and Bifodobacterium adolescentis.