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Kiranjot Kaur Bench C 43535675 Porphyromonas gingivalis

Classification

Higher order taxa

Bacteria (Kindom) – Bacteria (Domain) – Bacteroidetes (Phylum) – Bacteroidia (Class) – Bacteroidales (Order) – Prophyeomonadaceae (Family) – Prophyromonas (Genus)

Species

P. gingivalis Type Strain ATCC 33277 (http://www.bacterio.net/index.html)

Description and significance

Porphyromonas gingivalis, previously named Bacteriodes gongivalis, is a gram negative bacterium which occurs as coccobacilli or as long rods (0.5 by 1.0 to 2.0 microm). This organism is a major pathogen in chronic periodontitis. Although it is a natural member of the human oral microbiome it can become highly destructive and proliferate to high cell numbers. However P. gingivalis is detected rarely or in low numbers in healthy individuals. It is a secondary coloniser of dental plaque and is able to destroy periodontal tissues. It was first isolated by Slots from a human gingival sulcus. It is a non-motile bacterium and has an absolute requirement for iron for it to grow and is able to be cultured on blood agar hemin and menadione. It forms small 1 to 2mm convex colonies with brown to black pigment. P. gingivalis is a fermentative organism.

Genome structure

Using the type strain P. gingivalis has a circular genome with no plasmids found. It contains 2,354,866 nucleotides with 2154 genes and of those 2089 are protein encoding genes and 65 RNA encoding genes. This strain contains no pseudogenes and the DNA base composition is 46.5 to 48.4 mol% of G+C. The 16S rRNA sequence for this strain is X73964.

Cell structure and metabolism

P. gingivalis is a non-motile organism which requires anaerobic conditions to grow and is able to be cultured in the resence of heme and vitamin K. It gains it metabolic energy by fermenting amino acids. These organisms are late colonisers and contain multiple virulence factors allowing for their survival.

Ecology

P. gingivalis is an obligate anaerobic bacterium that resides in the oral cavity. It is a natural member of the oral microbiome and is a late coloniser. It is found in close proximity to and interacts with juxtaposing gingical tissue. This organism is able to avoid immune surveillance and is able to invade cells and tissue to allow for its replication and growth. P. gingivalis actively invades gingival epithelial cells and allowing it to maintaining viability and replicate. It is established in the periodontal pocket.

Pathology

P. gingivalis is a major pathogen in periodontitis and is part of sublingual plaque. It invades macrophages to limit exposure to the extracellular environment and is also able to evade the immune system. The strain differences in P. gingivalis can influence virulence. This pathogen has also been linked in with systemic diseases such as cardiovascular diseases. It is able to invade epithelial, endothelial and smooth muscular cells. It can be aided in entering in to the circulation of the body via eating. P. gingivalis is able to invade cardiovascular cells invasion of cells allows access to host proteins and iron, which are essential for its survival. It has been found to be present in artheromas of the circulatory system. Invasion allows persistence of the pathogen in infected tissue allowing to avoid humoral and cellular responses. Intracellular survival also provides protection against antibiotics.

Application to biotechnology

Bioengineering, biotechnologically relevant enzyme/compound production, drug targets,…

Current research

Summarise some of the most recent discoveries regarding this species.

References

References examples

1. Sahm, K., MacGregor, B.J., Jørgensen, B.B., and Stahl, D.A. (1999) Sulphate reduction and vertical distribution of sulphate-reducing bacteria quantified by rRNA slotblot hybridization in a coastal marine sediment. Environ Microbiol 1: 65-74.

2. Human Oral Microbiome

This page is written by Kiranjot Kaur for the MICR3004 course, Semester 2, 2016