Structural characterization of oligosaccharide from Spirulina platensis and its effect on the faecal microbiota in vitro

[Display omitted] In the present study, an oligosaccharide SPO-1 from Spirulina platensis was prepared by glycosidase from a marine bacterium. The prebiotic activity of SPO-1 on the growth of Lactobacillus paracasei and Bifidobacterium animalis, and its effect on human gut microbiota were examined in vitro. The molecular weight of the tetrasaccharide SPO-1 was 650.2Da, and it was mainly composed of glucose with α-type glycosidic linkages. The prebiotic activity score of SPO-1 was the highest for the growth of probiotic strains L. paracasei and B. animalis. Furthermore, as fermentation proceeded, SPO-1 was gradually degraded and utilized by intestinal bacteria. The results showed that after treatment with SPO-1, carbohydrate consumption and short-chain fatty acids levels were increased, especially those of i-butyric and i-valeric acids. Moreover, SPO-1 significantly promoted the abundance, diversity and composition of gut microbiota, especially stimulating the growth of Bacteroides, Escherichia-Shigella and Megamonas. In addition, the change in intestinal microbiota function predicted by phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) after treatment with SPO-1 is mainly related to the terms “carbohydrate metabolism” and “amino acid metabolism”. These results suggest that SPO-1 is a potential oligosaccharide in regulation of intestinal microbiota.