Prevotella Oris

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Duncan Keogh MICR3004 2017

Classification

Higher order taxa

Bacteria – Bacteroidetes – Bacteroidetes – Bacteroidales – Prevotellaceae – Prevotella

Species

Prevotella Oris (Previously Bacteroides Oris)

Description and significance

Prevotella Oris was originally a member of the genus Bacteroides however, it was reclassified in 1990 into the Prevotella genus. Prevotella species make up a large proportion of the bacterial community within the rumen of Bovine, representing up to 60% of the relative abundance of the microbial community when using rRNA analysis . Within humans, Prevotella regularly colonises the oral cavity, and is where the organism was originally isolated. They can also be pathogenic, particularly in invasive anaerobic infections with an origin of infection being linked to respiratory tract entry in many instances . They are also common in subgingival plaque, dental caries and malodour in the oral cavity. Therefore, it can be seen that bacteria of the Prevotella genus are important in both their metagenomic roles within the oral microbiome, metagenomics of the ruminal microbiome of bovine and also, from a biomedical perspective of bacterial infections.

Genome structure

Prevotella Oris C735 is available on Biocyc. The genome contains 2690 genes, within a genome of 3,346,228 bp. This includes 185 total pathways, 1094 enzymatic reactions and 50 tRNAs.

Cell structure and metabolism

Prevotella Oris is a gram-negative, non-motile, rod-shaped, anaerobic bacterium. Prevotella Oris has been found within plaque however, other species of Prevotella are found in higher abundance in comparison. There is evidence to suggest a synergestic relationship between Prevotella species and Fusobacterium nucleatum. This biofilm formation is important in plaque formation within the subgingival crevice. Prevotella Oris C375 lacks a complete TCA cycle on Biocyc but does contain Fermentative pathways for acetate formation via pyruvate, and also nitrate reduction pathways. Prevotella have also been shown to be able to inhibit human immunoglobulin A1. This achieved through a protease that cleaves the immunoglobulin at the hinge site which separates it into the Fab and Fc regions. However, IgG neutralising antibodies can be raised by humans in order to inhibit these proteases. Prevotella Oris is also one of few species of bacteria to produce hyaluronidase, which is able to degrade components of the host extracellular matrix components. Prevotella Oris has also been noted as containing bacterial resistance genes, in particular beta-lactamase. Prevotella Oris also requires Iron for it’s growth, typically of concentration between 0.05–0.5 μM with hemin being a particularly successful due to the production of haemolysin.

Ecology

Prevotella are found in anaerobic conditions due to their anaerobic classification. Although they are generally a non-pathogenic bacterium, they are regularly isolated from bacterial infection sites and oral disorders, including predominantly endodontic infections and also dentoalveolar abscesses. However, cases of Prevotella isolation from meningitis samples should also be noted. Prevotella are also able to modulate the pH of their surrounding environment, thus allowing them to grow at a range of pH including acidic conditions. This, combined with the ability to grow in nitrogen rich environments along with acid tolerance allows Prevotella to grow in the deep periodontal pockets whilst also allowing the formation and maintenance of plaque, especially in tandem with Fusobacterium nucleatum which is also able to alter environmental pH thus, allowing the maintenance of a solid biofilm in the form of plaque. Prevotella oris is also a regular inhabitant of the vaginal and cervical flora.

Pathology

As aforementioned, Prevotella Oris is regularly identified in oral infections such as endodontic infections and also dentoalveolar abscesses. Although this is one area which Prevotella can infect, it is important to note it’s ability to disseminate and establish infection in a wide range of locations. The aforementioned hyaluronidase is important in this ability to degrade extracellular matrix allows the entry through various endothelial linings and thus, a greater ease of dissemination. Clinically, Prevotella infections display general symptoms and characteristics of an anaerobic infection. These generally comprise foul-smelling discharge, mucosal location, necrosis and gas within discharges and tissue itself. More specifically, Prevotella oris is regularly identified within many respiratory infections including sinusitis, respiratory abscesses, pneumonia and pleural empyema. Investigations into the mucosal microbiota of individuals experiencing inflammatory bowel disease has also shown a possible link between Prevotella and disease state. Within patients with Ulcerative Colitis and also Crohn’s Disease, both groups were found to have significantly higher abundance of Prevotella species in comparison to the healthy control group.

Application to biotechnology

Little to no research has been done on Prevotella oris as an organism with applications within biotechnology. However, there is a possibility for applications of Prevotella oris within the agriculture industry. Prevotella Bryantii 25A was investigated as a possible probiotic in managing Subacute Ruminal Acidosis within dairy cattle mainly due to the ability to regulate pH. Although Prevotella Bryantii 25A was unsuccessful, other species of Prevotella, such as Prevotella oris could be viable alternatives.

Current research

As previously mentioned, research into disorders within agricultural animals such as dairy cattle have investigated the possibility of Prevotella species as viable probiotics. Metabolically, Prevotella oris is largely unclassified and under investigated, so research into this aspect of the bacterium can provide insight into any advantageous effects of commensal colonisation, whilst also suggesting possible mechanisms for the virulent effect that the bacteria can present itself in. The most recent studies published on Prevotella oris all centre around the interactions of the bacteria with the host and also, interactions with other bacterial species within the host. These include classifying the expression levels of the haemolysin and hyaluronidase in different conditions to better understand the organisms influence in infections, and also understanding the role of the bacteria in Irritable Bowel Syndrome disease such as Ulcerative Colitis and Crohn’s Disease which Prevotella Oris has been noted as being in higher levels within hosts whom are affected by these diseases. Furthermore, we can also gain further insights into the role of Prevotella Oris within the oral cavity and plaque formation.

References

1. Shah HN, Collins DM. 1990. Prevotella, a new genus to include Bacteroides melaninogenicus and related species formerly classified in the genus Bacteroides. Int J Syst Bacteriol 40:205-8.

2. Stevenson DM, Weimer PJ. 2007. Dominance of Prevotella and low abundance of classical ruminal bacterial species in the bovine rumen revealed by relative quantification real-time PCR. Applied Microbiology and Biotechnology 75,1:165-74.

3. Yoon JY, Choo EJ, Choi SH, Kim MN, Kim NJ, Kim YS, Woo JH, Ryu JS, Chang MS. Clinical characteristics and outcome of invasive Prevotella infection. Korean Journal of Medicine. 2003 Mar 1;64(3):254-9.

4. Tanaka S, Yoshida M, Murakami Y, Ogiwara T, Shoji M, Kobayashi S, Watanabe S, Machino M, Fujisawa S. 2008. The relationship of Prevotella intermedia, Prevotella nigrescens and Prevotella melaninogenica in the supragingival plaque of children, caries and oral malodor. J Clin Pediatr Dent 32:195-200.

5. Biocyc Prevotella Oris C375

6. Okuda T, Kokubu E, Kawana T, Saito A, Okuda K, Ishihara K. 2012. Synergy in biofilm formation between Fusobacterium nucleatum and Prevotella species. Anaerobe 18:110-6.

7. Martinez JL, Delgado-Iribarren A, Baquero F. 1990. Mechanisms of iron acquisition and bacterial virulence. FEMS Microbiol Rev 6:45-56.

8. Boyanova L, Kolarov R, Gergova G, Dimitrova L, Mitov I. 2010. Trends in antibiotic resistance in Prevotella species from patients of the University Hospital of Maxillofacial Surgery, Sofia, Bulgaria, in 2003-2009. Anaerobe 16:489-92.

9. Dymock D, Weightman AJ, Scully C, Wade WG. 1996. Molecular analysis of microflora associated with dentoalveolar abscesses. J Clin Microbiol 34:537-42.

10. Takahashi N, Saito K, Schachtele CF, Yamada T. 1997. Acid tolerance and acid-neutralizing activity of Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum. Oral Microbiol Immunol 12:323-8.

11. Kabeerdoss J, Jayakanthan P, Pugazhendhi S, Ramakrishna BS. 2015. Alterations of mucosal microbiota in the colon of patients with inflammatory bowel disease revealed by real time polymerase chain reaction amplification of 16S ribosomal ribonucleic acid. Indian J Med Res 142:23-32.

12. Chiquette, J., M. J. Allison, and M. Rasmussen. 2012. Use of Prevotella Bryantii 25A and a Commercial Probiotic during Subacute Acidosis Challenge in Midlactation Dairy Cows. Journal of Dairy Science National Institute for Biotechnology.


This page is written by Duncan Keogh for the MICR3004 course, Semester 2, 2017