Revealing dynamics of individual mucin glycan utilisation by gut bacteria: the interaction between dietary- and mucin glycans and the intestinal bacteria

Degradation and utilisation of dietary- and mucin glycans by gut bacteria is essential for human intestinal health. A method was set up to release and purify glycans followed by characterisation and semi-quantification of N-glycans by MALDI-TOF MS and O-glycans by PGC-LC-MS/MS. Pasteurised bacteria influence glycosylation during in vitro mucus production. Akkermansia muciniphila, Ruminococcus torques, and Bacteroides thetaiotaomicron, in monoculture, co-culture, and as part of a synthetic community, degraded and utilised porcine gastric mucin glycans in different patterns in vitro. Enzymatic processes were explored by incubating bacterial extracts with various glycans and enzyme activities found were compared with proteomics characterised enzymes. Different mucin glycans influenced the bacterial composition of the synthetic community in vitro. The presence of both galacto-oligosaccharides and porcine gastric mucins influenced glycan degradation and utilisation by Akkermansia muciniphila, Ruminococcus torques, and Bacteroides thetaiotaomicron in monocultures and co-cultures. This thesis has advanced diet-glycan-bacteria research and future studies regarding these interactions can be applied for the improvement of host health.