In Vitro Digestion and Fecal Fermentation of Polysaccharides from Physalis alkekengi and its Impacts on Human Gut Microbiota

This study aimed to investigate the effects of in vitro digestion and fermentation of Physalis alkekengi polysaccharides(PAP) and short-chain fatty acids(SCFAs) on the gut microbiome. Human saliva-gastrointestinal digestion and fecal fermentation were simulated in vitro. The results show that the molecular weight of Physalis alkekengi polysaccharides decreased from 8.07×104 to 5.60×104 during saliva-gastroenterization and from 8.07×104 to 1.18×104 after fermentation of feces for 48 hours. During gastric digestion, the level of reducing sugars increased from 0.887 to 1.153 mg/mL. Additionally, a considerable production of free monosaccharides was found during saliva-gastrointestinal digestion. Our data showed that the level of reducing sugars produced by PAPs increased during gastrointestinal digestion. Glucose release decreased with molecular weight, suggesting partial degradation of PAPs during gastrointestinal digestion. Further studies are warranted on the identification of the metabolites generated by polysaccharides from Physalis alkekengi during large intestine fermentation. Some beneficial bacteria, such as genera Bacteroides, Phascolarctobacterium, and Bifidobacterium, significantly increased after digestion and can ameliorate the level of harmful bacteria such as Escherichia-Shigella. These findings suggest that PAPs can alter the composition of gut microbiota and promote the production of beneficial short-chain fatty acids, such as acetic acid, propionic acid, and isovaleric acid.