In the present study, the changes of polysaccharides from Gracilaria rubra (GRPS) under simulated oral, gastric and small intestine digestion conditions were firstly investigated. The results indicated that GRPS was not digested under such conditions. Then, the prebiotic property of GRPS was investigated via in vitro fermentation by human gut microbiota in mixed cultures. The results showed that GRPS was gradually degraded and utilized by gut microbiota. With the proceeding of fermentation, pH kept a downward trend and the concentration of short-chain fatty acids increased, especially acetic, propionic and isobutyric acids. Furthermore, GRPS exhibited a modulatory effect on microbial structure by lowering the ratio of Firmicutes/Bacteroidetes and increasing the relative abundances of bacteria that could degrade GRPS to satisfy the growth of gut microbiota. The results suggested that GRPS had the potential to be developed as prebiotics.

在本研究中，从多糖的变化龙须杨梅模拟口腔，胃和小肠中消化的条件下（GRPS）为首次研究。结果表明，在这种条件下GRPS没有被消化。然后，通过体外研究了GRPS的益生元特性在混合培养中由人类肠道菌群发酵。结果表明，肠道菌群逐渐降解并利用了GRPS。随着发酵的进行，pH值保持下降趋势，短链脂肪酸的浓度增加，尤其是乙酸，丙酸和异丁酸。此外，GRPS通过降低菌毛/拟杆菌的比例和增加可降解GRPS以满足肠道菌群生长的细菌的相对丰度，对微生物结构表现出调节作用。结果表明，GRPS具有开发成益生元的潜力。