Effects of fructooligosaccharides and Saccharomyces boulardii on the compositional structure and metabolism of gut microbiota in students

Fructooligosaccharides (FOS) are a common prebiotic widely used in functional foods. Meanwhile, Saccharomyces boulardii is a fungal probiotic frequenly used in the clinical treatment of diarrhea. Compared with single use, the combination of prebiotics and probiotics as symbiotics may be more effective in regulating gut microbiota as recently reported in the literature. The present study aimed to investigate the effects of FOS, S. boulardii and their combination on the structure and metabolism of the gut microbiota in healthy primary and secondary school students using an in vitro fermentation model. The results indicated that S. boulardii alone could not effectively regulate the community structure and metabolism of the microbiota. However, both FOS and the combination of FOS and S. boulardii could effectively regulate the microbiota, significantly inhibiting the growth of Escherichia-Shigella and Bacteroides, and controlling the production of the gases including H2S and NH3. In addition, both FOS and the combination could significantly promote the growth of Bifidobacteria and Lactobacillus, lower environmental pH, and enhance several physiological functions related to synthesis and metabolism. Nevertheless, the combination had more unique benefits as it promoted the growth of Lactobacillus, significantly increased CO2 production and enhanced the functional pathways of carbon metabolism and pyruvic acid metabolism. These findings provide guidance for clinical application and a theoretical basis for the development of synbiotic preparations.