Navigating the Gut Buffet: Control of Polysaccharide Utilization in Bacteroides spp.

Bacteroides spp. are members of the human gut microbiota that confer myriad benefits on their hosts. Among them is the provision of energy from otherwise indigestible polysaccharides comprising part of the host diet, lining the intestinal mucosal layer, and decorating the surface of other microbes. Bacteroides spp. devote ∼20% of their genomes to the transport and breakdown of a wide variety of polysaccharides, and to the regulation of these processes. Bacteroides spp. rely on different families of transcriptional regulators to ensure that carbohydrate utilization genes are expressed under specific conditions. The regulators and mechanisms controlling carbohydrate utilization are often unique to these gut-dwelling bacteria, and do not conform to those of model organisms.