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

Abstract

This study was conducted to investigate the prebiotic potential of <i>Chlorella pyrenoidosa</i> polysaccharides to provide useful information for developing <i>C. pyrenoidosa</i> as a green healthy food. <i>C. pyrenoidosa</i> polysaccharides were prepared and their physicochemical characteristics were determined. The digestibility and fermentation characteristics of <i>C. pyrenoidosa</i> polysaccharides were evaluated using in vitro models. The results revealed that <i>C. pyrenoidosa</i> polysaccharides were composed of five non-starch polysaccharide fractions with monosaccharide compositions of Man, Rib, Rha, GlcA, Glc, Gal, Xyl and Ara. <i>C. pyrenoidosa</i> polysaccharides could not be degraded under saliva and the gastrointestinal conditions. However, the molecular weight and contents of residual carbohydrates and reducing sugars of <i>C. pyrenoidosa</i> polysaccharides were significantly reduced after fecal fermentation at a moderate speed. Notably, <i>C. pyrenoidosa</i> polysaccharides 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, <i>C. pyrenoidosa</i> polysaccharides can promote growth of <i>Parabacteroides distasonis</i> and increase short-chain fatty acid contents, thereby probably contributing to the promotion of intestinal health and prevention of diseases. Thus, these results suggested that <i>C. pyrenoidosa</i> polysaccharides 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.