Ecophysiology and taxonomy of Bacteroides and related taxa

Recent taxonomic changes among Bacteroides and related species has led to a clearer insight into the site specificity of these taxa. Two recently described centers of variation within the genus Bacteroides sensu stricto and Prevotella intermedia are reported. However, considerable taxonomic problems still remain unresolved within this large and complex group of microorganisms. These bacteria are metabolically diverse, and this is reflected in their colonization sites. In the rumen, gastrointestinal tract, or the oral cavity, specific members of this group contribute significantly to the initial attack on both simple and complex carbohydrates, and by doing so, obtain carbon and energy for their survival. Depletion of carbohydrates from the milieu results in a gradual change in microbial activity to proteolysis. In some sites, such as the periodontal pocket, potent proteinases produced by species such as Porphyromonas gingivalis may facilitate degradation of available proteins to their constituent peptides and amino acids. These products are not only likely to affect the growth of these species, but must profoundly affect the nutrient network of this ecosystem.