How do commensal bacteria protect against gut infection? (SCHULLER_F17DTP1)

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The human body is populated by trillions of commensal bacteria (microbiota), the majority of which reside in the colon. Most bacteria are strictly anaerobic and do not tolerate oxygen. While the human host provides the bacteria with a nutrient-rich environment, the microbiota enhances the metabolism of polysaccharides and produces essential vitamins. In addition, the microbiota protects the host against enteric infections and has a beneficial role in tissue homeostasis and modulation of the immune system. While it is well established how foodborne pathogens interfere with intestinal function, the underlying molecular mechanisms of how the microbiota counteracts these influences remain largely unknown. This is mainly due to a lack of experimental intestinal model systems supporting the survival of anaerobic bacteria.Here we will assess the impact of pathogen-commensal-host interactions using a Vertical Diffusion Chamber (VDC) system which we have recently developed to allow us to perform co-incubations of human intestinal epithelial cells with bacteria in an anaerobic environment. The aim of this project is to optimise the VDC culture model to support optimal growth and adhesion of gut symbionts, determine the interactions of commensals with the epithelial surface, and investigate the effect of gut commensals on enteropathogenic E. coli-induced epithelial permeability, loss of ion absorption and inflammation.