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Name Bench ID Date MICR3004

Classification

Higher order taxa

Bacteria – Bacteroidetes – Bacteroidia – Bacteroidales – Porphyromonadaceae - Porphyromonas - P. gingivalis

Species

Species: Porphyromonas gingivalis

Strain: 2561 = ATCC 33277 = CCUG 25893 = CCUG 25928 = CIP 103683 = DSM 20709 = JCM 12257 = NCTC 11834

Description and significance

Puzzle globe
Black-pigmented colonies of periodontopathogen P. gingivalis on horse blood agar

Porphyromonas gingivalis is an obligately aerobic, gram-negative bacterium belonging to the phylum Bacteroidetes [2]. Characterised by its rod shaped morphology, it is a non-spore bearing and non-motile bacterium most commonly inhabiting the oral cavity [2]. Recognised as an opportunistic pathogen, P. gingivalis is capable of living in commensal harmony with the host [3]. Termed as a pathobiont, the bacterium can cause episodes of diseases when a change in the ecological balance of the periodontal microenvironment transpires [4] [5]. Although the bacterium is capable of existing as a commensal organism, certain strains are known to be more virulent and pathogenic than others [3]. Virulent strains have found to include, W83, W50, ATCC 49417 and A7A1 [6] [7]. Avirulent strains include ATCC 381, 33277 and 23A4 [6] [7]. In vitro studies of the bacterium have found cells cultured in broth with a size range from 0.5 by 1 to 2 μm [2]. Cells grown on a solid media showed coccobacilli or very short rod structures (2). On blood agar plates, the bacterium forms black-pigmented colonies, predominately smooth, shiny and convex with a diameter between 1 to 2 mm [2] [8],.

Typically found in the oral cavity of individuals, P. gingivalis has been implicated with periodontal diseases, most commonly associated with chronic periodontitis [3]. A report from the Centres for Disease Control and Prevention (CDC) recorded 47. 2 % of adults in the United Stated aged 30 years or older have experienced some form of periodontal disease [9]. In light of this information, recent studies have also reported that P. gingivalis is associated with systematic diseases, including cardiovascular diseases, rheumatoid arthritis and decreased kidney function [10]. Studies underlying the molecular mechanisms behind the bacterial pathogenesis are key to design effective treatments. Consequently reducing the potential development of inflammatory diseases that arise as a secondary consequence of periodontitis.

Genome structure

The genome of strain W88 is comprised of a circular chromosome made up of 2 343 479 bp’s [11]. On average the guanine and cytosine content make up approximately 48.3 % of the genome [11].. The circular chromosome encodes 1909 protein genes 65 RNA genes [11]. 4 ribosomal operons (rrn, 5S rRNA-23S rRNA-tRNAAla-tRNAIle-16S rRNA) including 53 tRNA genes showing specificity for all 20 amino acids have been documented [11]. Interestingly the number of rrn operons and tRNA genes in strain W83 were identical to those of an avirulent strain counterpart ATCC 33277 [7] [11]. Nonetheless the extensive rearrangement between the two strains through the introduction of mobile elements inevitably altered the virulence of the bacterium [11].

The genome of W83 is composed predominately (85%) of ORF [11]. Encoding a total of 1,990 ORF, 1075 presented detectable biological roles [11]. Of the remaining ORF, 184 were categorised as a conserved hypothetical protein or conserved domain protein, 208 had to known function, and 523 encoded hypothetical proteins [11].

Cell structure and metabolism

EDIT

Cell Wall: P. gingivalis is an obligately aerobic, non-motile gram-negative bacterium [2]. The cell wall is characterised by three distinct layers, including two membranous structures known as the inner membrane (IM) and the outer membrane (OM) [12]. Connecting the two layers is a gel like structure known as the periplasm and a thin layer of peptidoglycan [12]. The IM and OM possess a trilamellar structure composed of phospholipids [12]. Distributed along the outer membrane are lipoproteins and lipopolysaccharides (LPS), which serve as an anchor for lipids [12]. Chemically LPS is composed of three subunits, the O specific polysaccharide chain, the core and lipid A [12].

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Gram negative cell wall structure

Fimbriae: Protruding the outer membrane of the cell wall, thin proteinaceous surface appendages aid and mediate bacterial attachment to the host [8]. Approximately 25 μm long these structures have a robust ability to interact with salivary proteins, epithelial cells, extracellular matrix proteins and the fibroblasts of the host [8]. Two distinct fimbriae types are displayed on the cell surfaces of the bacteria, known as FimA and Mfa protein [8]. These surface structures are proposed to have a role in the progression of periodontal inflammatory reactions. Six genotypes of FimA structures exist (type I-V and Ib), ranging from 40.5 to 49kDa in size [8]. Strain W83 is classed under type IV and are poorly fimbriated whereas strain ATCC 33277 are an abundantly fimbriated type I strain [8]. The progression of chronic periodontitis is most closely associated with type II strains followed by type IV [8].

Biofilm formation: The bacterium colonises the oral cavity by forming a complex biofilm known as plaque [13]. They are recognised as secondary or late colonisers and require antecedent organisms to form the necessary environmental conditions for growth [8]. Upon contact the bacterium must resist the plethora of host responses working against bacterial colonisation [13]. Host factors are known to include mechanical shearing produced from the force of the tongue, saliva and gingival crevicular fluid flow [13]. Successful colonisers must therefore possess a diverse repertoire of virulence factors to overcome host defences [13].

Motility: Non-motile [3]

Metabolic Functions: P. gingivalis is dependent on nitrogenous substrates for energy production ([13]. Despite the nitrogenous compounds present in the oral cavity, the bacterium has a limited ability to ferment free amino acids [13]. Aspartic acid and Asparagine are among the few, which can be metabolised to yield succinate.

Ecology

Pathology

Application to biotechnology

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

Current research

Summarise some of the most recent discoveries regarding this species.

References

1. Boone D, R and Castenholtz R, W. Bergey's Manual of Systematic Bacteriology. 2nd Ed. Vol. 1. Springer-Verlag: New York; 2002.

2. Shah N, H., Collins D, M. (1988) Proposal for Reclassification of Bacteroides asaccharolyticus, Bacteroides gingivalis, and Bacteroides endodontalis in a New Genus, Porphyromonas. Int J Syst Evol Microbiol 38 :128-131.

3. Naito, M., Hirakawa, H., Yamashita, A., Ohara, N., Shoji, M., Yukitake, H., Nakayama, K., Toh, H., Yoshimura, F., Kuhara, S., Hattori, M., Hayashi, T., Nakayama, K. (2008) Determination of the genome sequence of Porphyromonas gingivalis strain ATCC 33277 and genomic comparison with strain W83 revealed extensive genome rearrangements in P. gingivalis. DNA Res 15 :215-225.

4. Ohara-Nemoto, Y., Rouf, S. M., Naito, M., Yanase, A., Tetsuo, F., Ono, T., Kobayakawa, T., Shimoyama, Y., Kimura, S., Nakayama, K., Saiki, K., Konishi, K. & Nemoto, T. K. (2014) Identification and characterization of prokaryotic dipeptidyl-peptidase 5 from Porphyromonas gingivalis. J Biol Chem, 289: 5436-48.

5. Lamont, R. J. & Jenkinson, H. F. (1998) Life below the gum line: pathogenic mechanisms of Porphyromonas gingivalis. Microbiol Mol Biol Rev, 62: 1244-63.

6. Igboin, C. O., Griffen, A. L. and Leys, E. J. (2009) Porphyromonas gingivalis strain diversity. J Clin Microbiol, 47,: 3073-81.

7. Grenier, D. and Mayrand, D. 1987. Selected characteristics of pathogenic and nonpathogenic strains of Bacteroides gingivalis. J Clin Microbiol, 25: 738-40.

8. [1]

9. [2]

11. Chatterjee. S and Chaudhuri K. (2012) Outer membrane vesicles of bacteria. SpringerBriefs in Microbiology

  • Chapter Book

12. How, K. Y., Song, K. P. and Chan, K. G. (2016) Porphyromonas gingivalis: An Overview of Periodontopathic Pathogen below the Gum Line. Front Microbiol, 7: 53.

13. Bao, K., Belibasakis, G. N., Thurnheer, T., Aduse-Opoku, J., Curtis, M. A. and Bostanci, N. (2014) Role of Porphyromonas gingivalis gingipains in multi-species biofilm formation. BMC Microbiol, 14: 258.

14. Cugini, C., Klepac-Ceraj, V., Rackaityte, E., Riggs, J. E. and Davey, M. E. (2013. Porphyromonas Gingivalis: Keeping The Pathos Out Of The Biont. J Oral Microbiol, 5.

15. Goulbourne, P. A. and Ellen, R. P. (1991) Evidence that Porphyromonas (Bacteroides) gingivalis fimbriae function in adhesion to Actinomyces viscosus. J Bacteriol, 173: 5266-74.

16. Jenkinson, H. F. and Demuth, D. R. (1997) Structure, function and immunogenicity of streptococcal antigen I/II polypeptides. Mol Microbiol, 23: 183-90.

17. Lamont, R. J., Gil, S., Demuth, D. R., Malamud, D. and Rosan, B. (1994) Molecules of Streptococcus gordonii that bind to Porphyromonas gingivalis. Microbiology, 140: 867-72.

18. Nagata, H., Murakami, Y., Inoshita, E., Shizukuishi, S. and Tsunemitsu, A. (1990) Inhibitory effect of human plasma and saliva on co-aggregation between Bacteroides gingivalis and Streptococcus mitis. J Dent Res, 69: 1476-9.

19. Lewis, J. P., Iyer, D. and Anaya-Bergman, C. (2009) Adaptation of Porphyromonas gingivalis to microaerophilic conditions involves increased consumption of formate and reduced utilization of lactate. Microbiology, 155: 3758-74.

20. K. E., Fleischmann, R. D., Deboy, R. T., Paulsen, I. T., Fouts, D. E., Eisen, J. A., Daugherty, S. C., Dodson, R. J., Durkin, A. S., Gwinn, M., Haft, D. H., Kolonay, J. F., Nelson, W. C., Mason, T., Tallon, L., Gray, J., Granger, D., Tettelin, H., Dong, H., Galvin, J. L., Duncan, M. J., Dewhirst, F. E. and Fraser, C. M. (2003) Complete genome sequence of the oral pathogenic Bacterium porphyromonas gingivalis strain W83. J Bacteriol, 185: 5591-601.

21. Mysak, J., Podzimek, S., Sommerova, P., Lyuya-Mi, Y., Bartova, J., Janatova, T., Prochazkova, J. and Duskova, J. (2014) Porphyromonas gingivalis: major periodontopathic pathogen overview. J Immunol Res, 2014: 476068.








This page is written by Amy Pham for the MICR3004 course, Semester 2, 2016