Sialylated O-Glycans from Hen Egg White Ovomucin are Decomposed by Mucin-degrading Gut Microbes

Ovomucin, a hen egg white protein, is characterized by its hydrogel-forming properties, high molecular weight, and extensive O-glycosylation with a high degree of sialylation. As a commonly used food ingredient, we explored whether ovomucin has an effect on the gut microbiota. O-Glycan analysis revealed that ovomucin contained core-1 and 2 structures with heavy modification by N-acetylneuraminic acid and/or sulfate groups. Of the two mucin-degrading gut microbes we tested, Akkermansia muciniphila grew in medium containing ovomucin as a sole carbon source during a 24 h culture period, whereas Bifidobacterium bifidum did not. Both gut microbes, however, degraded ovomucin O-glycans and released monosaccharides into the culture supernatants in a species-dependent manner, as revealed by semi-quantified mass spectrometric analysis and anion exchange chromatography analysis. Our data suggest that ovomucin potentially affects the gut microbiota through O-glycan decomposition by gut microbes and degradant sugar sharing within the community.