In vitro saliva-gastrointestinal digestion and fecal fermentation of Oudemansiella radicata polysaccharides reveal its digestion profile and effect on the modulation of the gut microbiota

Oudemansiella radicata is a commercialized and nutrient-rich mushroom farmed in China. Polysaccharides (ORP) found in this mushroom possess strong biological properties. In this study, the digestibility and fermentation of ORP and its effects on gut microbiota composition were examined in a simulated digestion and fermentation system in vitro. Results showed that the molecular weight of ORP decreased after simulated digestion. However, no free monosaccharide was detected, indicating that ORP was indigestible. Besides, the overall structure of ORP was not damaged after digestion. When ORP was degraded and utilized by gut microbiota during the fermentation process, several short-chain fatty acids were formed, acetic acid, propionic acid and n-butyric acid were the main products. Notably, ORP could significantly modulate the composition, via increasing the relative abundances of Bacteroides and Parabacteroides. These results suggest that ORP can be used as a functional food to improve health and prevent diseases by promoting gut health.