Abstract:The differences in fermentation characteristics of six polysaccharides with unique structures，including gum arabic（GA），hawthorn pectin（HP），arabinoxylan（AX），guar gum（GG），Dendrobium officinale polysaccharide（DOP），and oat β-glucan（OG），exposed to the same initial gut microbiota were studied.Using the digesta of porcine colon as inoculum，the changes to short-chain fatty acids （SCFAs）as well as the gut microbiota were determined after 0，12，24 h and 48 h of fermentation under anaerobic conditions. Resultingly，acetic acid，propionic acid，and butyric acid were the main SCFAs produced through fermentation of the six polysaccharides.Specifically，gum arabic had a strong ability to promote propionic acid production，while D.officinale polysaccharide and oat β-glucan promoted high acetic acid and butyric acid production. Additionally，D. officinale polysaccharide and oat β-glucan produced highest total SCFAs，while hawthorn pectin produced the lowest. Analysis of the gut microbiota showed that Firmicutes，Bacteroidetes，and Proteobacteria were the dominant bacteria involved in the process of fermentation.At the genus level，the six polysaccharides had various promoting effects on different genera.Gum arabic promoted the proliferation of Blautia，while the other five polysaccharides promoted the proliferation of Lactobacillus. Notably，the abundance of Lactobacillus was the highest after fermentation of oat β-glucan，followed by that of arabinoxylan and D.officinale polysaccharide.In general，D.officinale polysaccharide and oat β-glucan showed the best fermentation characteristics.