Prevotella Fusca

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Higher order taxa

Domain: Bacteria, Phylum: Bacteroidetes, Class: Bacteroides, Order:Bacteroidales, Family: Prevotellaceae, Genus: Provotella (1)


Genus species: Prevotella Fusca



Description and significance


“The human oral Microbiome is the most studied human microflora, due to the fact that it is easily sampled and is strongly associated with important oral infectious diseases such as tooth decay and gum disease” (2). Within the oral microbiome the microbes are characterized from the 16S rRNA gene sequence as they are used during a cloning process in hope of a clear understanding of the roles that microbiomes provide (3). There are many different species of bacteria that are living in the oral cavity, Prevotella Fusca are among one of the species. Prevotella Fusca originates from the subgingival plaque that is located within the oral cavity (4). “The DNA G+C content of the type strain is 43 mol%” (4).


Prevotella Fusca is a gram-negative, bacilli-shaped bacterium that appears to have a genome size of 0.8 µm wide by 1.2–6.0 µm long, after incubation the diameter had increased to 1.8–2.2 mm (4). The gram-negative bacteria are bacilli or circular shaped that consist of a high convex to pyramidal, with an off-white rough surface appearance (4). If the cells are incubated longer there is a color change to a deep orange-brown within the center of the colonies (4). Characteristics of Prevotella generally consist of gram-negative bacteria.


The oral cavity consists of many different habitats at which microbes are able to grow. Studies have shown 280 bacterial species that have been found on cultures with samples from the oral cavity (3). “It has been estimated that less than half of the bacterial species present in the oral cavity can be cultivated using anaerobic microbiological methods and that there are likely 500 to 700 common oral species” (3). The oral cavity can have an increased amount of microbes due to the food that enters the mouth along with the saliva and the process of digestion, resulting in all the areas that the microbe passes through (3). Prevotella Fusca is an anaerobic organism, meaning that it does not require oxygen for growth. The optimal temperature for growth was at 35 degrees Celsius, with good growth at 25 degrees Celsius, and no growth at 20 degrees Celsius (4). The optimum pH for growth of Prevotella Fusca was pH 7, with good growth at pH 6, and no growth at pH 8 (4). When using the antibiotic disk sensitivity test the results had shown to be resistant towards Kanamycin and Vanocomysin, however was sensitive towards colistin (4).

Cell Metabolism

Presence of Acetic Acid, Succinic acid and Lactic Acid will allow metabolism to become present in Peptone Yeast Broth with Glucose (4). Isovaleric Acid and Isobutyric Acid will produce metabolism to be present in Peptone Yeast Broth with sugars (4). “Strain W1435 gave positive reactions in the Rapid ID 32A panel for a- galactosidase, b-galactosidase, b-galactosidase 6-phosphate, a-glucosidase, b-glucosidase, b-Nacetylglucosaminidase, a-fucosidase, mannose fermentation, raffinose fermentation, alkaline phosphatase, leucyl glycine arylamidase, alanine arylamidase and glutamyl glutamic acid arylamidase" (4). Reactions to arginine arylamidase were weak, however depending on the kit that was being used on these tests would depend on the results that were seen (4). The cellular Fatty Acid Methyl Ester results in Prevotella Fusca along with Prevotella Scopos (4).


Within the genus of Prevotella there are two strains that are related. Both strains of Prevotella Fusca and Prevotella Scopos are anaerobic, non-motile, and gram-negative bacilli (4). The phylogenetic analysis of the 16Sr RNA gene sequence showed that strain W1435 and strain W2025 was related to the genus Prevotella resulting in the naming of Prevotella Fusca and Prevotella Scopos (4). “Strains W1435 and W2052 had sequence similarities of 95.9 and 98.1%” (4). Analyzing the results had shown that the two strains were closely related to the strain of Prevotella Melaninogenica (4).

Current Research

A variety of tests were performed to distinguish the difference between Prevotella Fusca and Prevotella Scopos. These strains are easily identified by 16S rRNA gene sequence analysis with a variety of tests to be done. An incubation test was done to study the growth and the number of colonies along with different characteristics that were seen such as a color or pigment changes. Fermentation tests were done to distinguish and ferment carbohydrates. Test with different acids were done to see the amounts that were produced as metabolic by-products in PY broth (4). Other tests had shown that “Gelatin, arginine, aesculin and urea are not hydrolysed, as well as Indole and catalase are not produced and nitrate is not reduced” (4).


[1] [ "HOMD :: Human Oral Microbiome Database." HOMD :: Human Oral Microbiome Database. N.p., n.d. Web. 12 Mar. 2014. ]

[2] [ Chen, T., Yu, W-Han, Izard, J., Baranova, O.V., Lakshmanan, A., Dewhirst, F.E. (2010) The Human Oral Microbiome Database: a web accessible resource for investigating oral microbe taxonomic and genomic information. Database, Vol. 2010, Article ID baq013, doi: 10.1093/database/baq013]

[3] [ Dewhirst, F.E., Chen, T., Izard, J, Paster, B.J., Tanner, A.C.R., Yu, W.-H., Lakshmanan, A., Wade, W.G. (2010) The Human Oral Microbiome. J. Bacteriol. 192: 5002-5017.]

[4][ Downes, Julia, and William Wade. "Prevotella fusca sp. nov. and Prevotella scopos sp. nov., isolated from the human oral cavity." International Journal of Systematic and Evolutionary Microbiology”. 2011. Volume 61 (2011): 854-858.]

Edited by Samantha Sanborn, student of Rachel Larsen at the University of Southern Maine