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Lyman Ngiam Bench D 31/8/16** [1]
Classification
Higher order taxa
The order taxa for Veillonella Parvula is listed as below:
Kingdom – Domain – Phylum – Class – Order – Family – Genus
[Bacteria]-[Terrabacteria group]-[Firmicutes]-[Negativicutes]-[Veillonellales]-[Veillonellacea]-[Veillonella]
Species
There are a total of 14 species under the genus Veillonella. Veillonella parvula is one of the species name. There are many different description in terms of the strain, as listed below:
Type strain: strain ATCC10790 = CCUG 5123 = DSM 2008 = JCM 12972 = NCTC 11810
(consult LPSN http://www.bacterio.net/index.html for this information)
Description and significance
Veillonella parvula is a gram negative, anaerobic, coccus bacteria that is part of the normal flora of the mouth, gastrointestinal tract and vagina in humans. The microorganism is first discovered by Veillon and Zuber in 1898.
Generally, Veillonella parvula has been treated as normal commensal, however in rare cases, it can also cause infection as a pathogenic bacteria. Over the past years, reports has identified Veillonella species as a cause of endocarditis, obstructive pneumonitis, lung abscess, chronic sinusitis, chronic tonsillitis, liver abscess, and even meningitis. However,the most common reported infection caused by Veillonella parvula is osteomyelitis.
One of the significant feature of this microoganism is the ability to confer multi antimicrobial resistance properties to Streptococcus mutans, a primary pathogen in dental caries and thrives in dental plague. The resistance is obtained via formation of a dual species biofilm between Veillonella parvula and Streptococcus mutans.
Give a general description of the species (e.g. where/when was it first discovered, where is it commonly found, has it been cultured, functional role, type of bacterium [Gram+/-], morphology, etc.) and explain why it is important to study this microorganism. Examples of citations [1], [2]
Genome structure
The genome of Veillonella parvula type strain DSM 2008 consist of a single circular chromosome that is 2,132,142 bp longs with 38.6% of GC contents.
In terms of the gene identified, there are a total of 1920 genes that have been reported, however only 1859 of the genes are protein coding genes and 15 genes being identified as pseudogenes.
- insert table and figure**
Select a strain for which genome information (e.g. size, plasmids, distinct genes, etc.) is available.
Cell structure and metabolism
- Cell wall structure
Veillonella parvula has a morphology of a coccus bacteria, and since it is a gram negative bacteria, the cell wall structure consist of an outer membrane, peptidoglycan layer and cytoplasmic membrane. The peptidoglycan layer consist of A1γ-type with glutamic acid in D configuration, diaminopimelic acid in meso configuration and covalently bound cadaverine or putrescine attached in α-linkage to glutamic acid.
- Metabolic functions
Since the bacteria is an anaerobic bacteria, the main energy are produced via fermentative pathway, however it has been reported that Veillonellae are unable to use glucose or other carbohydrates for fermentation, instead it uses other organic acids such as pyruvate, malate or fumarate for fermentation. These molecules are usually end product of other carbohydrate-fermenting bacteria, therefore, Veillonella Parvula co-exist with carbohydrate-fermenting bacteria as a way to obtain required precursor molecules for its survival.
Besides that, another unique metabolic characteristic of the bacteria is the utilisation of methyl-CoA decarboxylase for the conversion of free energy derived from decarboxylation reactions into an electrochemical gradient of sodium ions. Oxaloacetate decarboxylase plays important role in citrate fermentation pathway and has additional function to conserve free energy from decarboxylation via generation of sodium ion gradient. Sodium ion bioenergetics play important roles in link between exergonic and endogenic reactions in the membrane.
- Cell characterisitc
Another structural characteristic trait of veillonellae is their ability to form intergeneric coaggregates with other bacteria in the same niche. Besides that, the bacteria are unable to adhere itself to the surfac, instead it relies on specific attachment to certain surface structure on other bacterium via lectin-carbohydrate interactions.
Apart from that, in the presence of plasmalogens such as plasmenylethanolamine and plasmenylserine, these ether lipids are able to replace the phospholipids found in Veillonella parvula membrane and aid in regulation of membrane fluidity.
Cell wall, biofilm formation, motility, metabolic functions.
Ecology
Veillonella parvula is a stric anaerobe bacteria. Currently, there are 11 species that are known to inhabit the oral cavity and gastrointestinal tract of homeothermic vertebrates. However, Veillonella parvula have been isolated from human.
In terms of its habitat, the natural habitat of this bacteria is human dental plague and majority of it resides in the subgingival sites. The bacteria can also be found commonly in gastrointestinal tracts. Although there are many other Veillonellae species that occupy the oral cavity, Veillonella parvula is the only species within the genus that are involved in oral diseases, such as gingivitis. Other opportunistic infections such as endocaritis, meningitis,
Aerobe/anaerobe, habitat (location in the oral cavity, potential other environments) and microbe/host interactions.
Pathology
Do these microorganisms cause disease in the oral cavity or elsewhere?
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
- ↑ MICR3004
This page is written by Lyman Ngiam Tze Kin for the MICR3004 course, Semester 2, 2016
