Chlorella pyrenoidosa Polysaccharides as a Prebiotic to Modulate Gut Microbiota: Physicochemical Properties and Fermentation Characteristics In Vitro

This study was conducted to investigate the prebiotic potential ofChlorella pyrenoidosapolysaccharides to provide useful information for developingC. pyrenoidosaas a green healthy food.C. pyrenoidosapolysaccharides were prepared and their physicochemical characteristics were determined. The digestibility and fermentation characteristics ofC. pyrenoidosapolysaccharides were evaluated using in vitro models. The results revealed thatC. pyrenoidosapolysaccharides were composed of five non-starch polysaccharide fractions with monosaccharide compositions of Man, Rib, Rha, GlcA, Glc, Gal, Xyl and Ara.C. pyrenoidosapolysaccharides could not be degraded under saliva and the gastrointestinal conditions. However, the molecular weight and contents of residual carbohydrates and reducing sugars ofC. pyrenoidosapolysaccharides were significantly reduced after fecal fermentation at a moderate speed. Notably,C. pyrenoidosapolysaccharides could remarkably modulate gut microbiota, including the promotion of beneficial bacteria, inhibition of growth of harmful bacteria, and reduction of the ratio of Firmicutes to Bacteroidetes. Intriguingly,C. pyrenoidosapolysaccharides can promote growth ofParabacteroides distasonisand increase short-chain fatty acid contents, thereby probably contributing to the promotion of intestinal health and prevention of diseases. Thus, these results suggested thatC. pyrenoidosapolysaccharides had prebiotic functions with different fermentation characteristics compared with conventional prebiotics such as fructooligosaccharide, and they may be a new prebiotic for improving human health.Keywords:Chlorella pyrenoidosa;polysaccharides;fermentation;gut microbiota;prebiotic