Bacteria Genomes - PORPHYROMONAS GINGIVALIS

Porphyromonas gingivalis is a Gram-negative , anaerobic pathogenic oral bacterium and is a major etiological agent in the initiation and progression of severe forms of periodontal disease.

An opportunistic pathogen, P. gingivalis can exist harmoniously with the host, with disease episodes ensuing from a shift in the ecological balance within the periodontal microenvironment.

Colonisation of the subgingival region is facilitated by the ability of P. gingivalis to adhere to available substrates such as adsorbed salivary molecules, matrix proteins, epithelial cells, and bacteria that are already established as a biofilm on tooth and epithelial surfaces.

Whole-genome comparative analysis with other available complete genome sequences confirms the close relationship between the Cytophaga-Flavobacteria-Bacteroides (CFB) phylum and the green-sulfur bacteria. Within the CFB phyla, the genomes most similar to that of P. gingivalis are those of Bacteroides thetaiotaomicron and B. fragilis. Outside of the CFB phyla the most similar genome to P. gingivalis is that of Chlorobium tepidum, supporting the previous phylogenetic studies that indicated that the Chlorobia and CFB phyla are related, albeit distantly.

Genome analysis also reveals that P. gingivalis can metabolize a range of amino acids and generate a number of metabolic end products that are toxic to the human host or human gingival tissue and contribute to the development of periodontal disease

Although periodontal disease is localised to the tissues surrounding the tooth, evidence is accumulating that infection with P. gingivalis may predispose to more serious systemic conditions such as cardiovascular disease and to delivery of preterm infants.

References: J. Bacteriol. 185 (18):5591-601 (2003)
http://www.pgingivalis.org/pathogen.htm
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=98945