ABSTRACT
This chapter evaluates how gut mucous glycoproteins are degraded by intestinal bacteria and how this may bear on host microbial associations in man. The mammalian alimentary canal harbors an abundant microbial flora, primarily at both ends. The oral and nasopharyngeal cavities provide ecologically different habitats, each with its distinctive varieties of autochthanous bacteria. Several lines of evidence indicate that the indigenous enteric microflora degrades gut mucin glycoproteins. There are: comparison of mucin excreted by germ-free and conventional animals; biochemical analysis of mucous constituents in the gut lumen in regions of high and regions of low bacterial population densities; and studies of mucin degradation in fecal cultures during growth of bacteria. Commercial hog gastric mucin (HGM) is structurally similar to human epithelial mucins and can be used as a substrate to measure mucin degradation in vitro experiments. Degradation of the oligosaccharide side chains of gut mucins required hydrolytic cleavage of the individual glycoside linkages.
