Ruminococcus torques is a keystone degrader of intestinal mucin glycoprotein, releasing oligosaccharides used by Bacteroides thetaiotaomicron .

. Our findings underscore the importance of understanding the mucin degradation mechanisms of different gut bacteria and their consequences on interspecies interactions, which may identify keystone bacteria that disproportionately contribute to defects in mucus protection and could therefore be targets to prevent or treat IBD.