A number of studies have shown that the polysaccharides from microalgae exhibit diverse biological activities, however, little is known about their digestibility and impact on human gut microbiota. In this study, a simulating digestion and fermentation system were established to investigate the digestibility and fermentation of intracellular polysaccharides from Chlorella zofingiensis (CZIP-S3). The results indicated that CZIP-S3 is a macromolecular polysaccharide composed of mannose, glucose, galactose and rhamnose, consisting of a main chain and two branched repeating units. CZIP-S3 could not be digested in the upper gastrointestinal tract. However, CZIP-S3 could be metabolized into smaller molecules by the gut microbiota. The pH values continuously decrease during fermentation, whereas, the amount of short-chain fatty acids steadily increase. Furthermore, CZIP-S3 could modulate the composition of gut microbiota, via lowering the ratio of Firmicutes/Bacteroidetes and increasing the relative abundance of Bacteroides, Bifidobacterium and Akkermansia. The data suggested that CZIP-S3 could potentially be used as an ingredient for functional foods or prebiotics to improve human health by promoting the relative abundances of beneficial bacteria.
Keywords: Chlorella zofingiensis; Digestion; Gut microbiota; Intracellular polysaccharide; Physicochemical characterization; Short-chain fatty acids.
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