Abstract: The anaerobic fermentation of yeast mannoprotein (MP) by the gut microbiota in vitro was carried out to evaluate the probiotic activity of MP in this study. The results showed that MP could modulate the structure of the gut microbiota, increasing the relative abundance of Bacteroidetes and decreasing the relative abundances of Firmicutes and Proteobacteria and the ratio of Firmicutes to Bacteroidetes. The concentration of short-chain fatty acids, especially acetic acid and propionic acid, in the fermentation broth were significantly increased by MP. MP showed similar prebiotic activity to inulin. Inulin could stimulate the proliferation of Bifidobacterium, whereas MP could selectively promote the growth of Bacteroides, Veillonella, Clostridium_sensu_srticto, Blautia, Faecalibacterium, Fusicatenibacter and Butyricicoccus. MP had no significant inhibitory effect on lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophages (P > 0.05), whereas the fermentation broth showed anti-inflammatory activity similar to that of inulin, which was superior to that of the blank group. Thus, MP is expected to serve as a functional food ingredient that can offer health benefits by modulating the gut microbiota.

Key words: yeast; mannoprotein; gut microbiota; short-chain fatty acids; anti-inflammatory activity