Factors involved in colonization of the gut epithelial surface.

Some indigenous microbes form climax communities on gastrointestinal epithelial surfaces during succession in animals of many types. Most communities form in mucous layers on the surfaces, where some microbes in the communities may utilize the mucin as a source of carbon and energy. The mucous gel may also serve physically to stabilize the community. Some microbial types that colonize early during succession may serve, perhaps synergistically with dietary components, to lower the oxygen tension and oxidation-reduction potential so that oxygen-intolerant anaerobes can colonize the epithelial surfaces. Microbes in the communities may adhere to the epithelial surface; the mechanisms by which they adhere may depend upon a variety of factors, including the type of epithelium and the rate of flow of lumenal contents in the areas. Dietary fiber may influence the composition of these communities by providing nutrients for the microbes or altering their environmental conditions including peristaltic rate, mucous concentration and composition, and oxygen tension and oxidation-reduction potential.