In vitro fermentation of polysaccharide from the seeds of Plantago asiatica L. by human fecal microbiota

In vitro fermentation of the polysaccharide (PLCP, Mw = 1.90 × 106 Da) from seeds of Plantago asiatica L. and the contribution of its carbohydrates to the fermentation was investigated in this study. The polysaccharide was characterized by high contents of xylose, arabinose and glucuronic acid, and it was subjected to human fecal cultures to be fermented in vitro for 24 h. During fermentation, pH in fecal cultures decreased from 6.1 to 5.1 and the levels of total short-chain fatty acid (SCFA), acetic, propionic and n-butyric acids all significantly increased. Xylanase, arabinofuranosidase, xylosidase and glucuronidase activities were also improved. After 24 h incubation, 47.2 ± 1.6% of total carbohydrate in polysaccharide, including 42.9 ± 1.5% of arabinose, 53.2 ± 1.6% of xylose and 76.4 ± 1.2% of glucuronic acid, were consumed. In addition, relationship between carbohydrate consumption of the polysaccharide and SCFA production was also evaluated. It was found that the increase of acetic and n-butyric acid productions mainly resulted from the fermentation of glucuronic acid and xylose in polysaccharide, while the increase of propionic acid production was primarily due to the fermentation of arabinose and xylose. These results showed that the polysaccharide was physiologically active for human large bowel, and its carbohydrate composition determined its SCFA production.