One numerically predominant genera of colonic anaerobes is Bacteroides , which are also opportunistic pathogens that can cause serious infections in humans if they escape from the colon due to abdominal surgery or other trauma. We are also interested in how activities of Bacteroides and other colonic bacteria affect the host.
Polysaccharides are probably the main source of carbohydrate in the colon.
Most polysaccharides that enter the colon come from the host's diet, but some are produced by the host. Bacteroides species are notable for their ability to ferment a variety of dietary and host-derived polysaccharides which may contribute to their success in colonizing the colon. This ability could also be a virulence factor. We have cloned some genes involved in breakdown of host mucopolysaccharide such as chondroitin sulfate and heparin, and we are using genetic and biochemical approaches to study the significance of mucopoly-saccharide utilization genes for colonization and virulence. Bacteroides have evolved a novel system for polysaccharide utilization.