User:S4403863
Teo Jia Ling Tricia; Bench E; 31/08/2016
[1]
Classification
Higher order taxa
Bacteria – Bacteria – Firmicutes – Negativicutes – Selenomonadales – Veillonellaceae – Veillonella
Species
Veillonella parvula
Strain ATCC 10790
http://www.eol.org/data_objects/3602510
Description and significance
It is a non-motile, non-spore forming, anaerobic gram-negative coccus. It can grow in pairs or in chains and grow to about 0.3 to 0.5m in size (1).
It was first described by Veillon and Zuber in 1898 as “Staphylococcus parvulus” (2) before being renamed as Veillonella parvula by Prévot in 1933 (3) and early experiments were conducted on V. parvula oral isolates (4). It is commonly found in the human oral cavity, especially in subgingival dental plaque, gastrointestinal tract and vagina, as part of the microflora (1, 4, 5). It is involved in establishing early microbial colonies in dental plaque formation, along with Streptococcus and other species (6, 7) and can make up 10% of the early colonizing bacteria on the enamel (8). However, it can also be associated with dental and other infections (1)(9).
It plays an important role in microbial food chain by metabolizing end products of carbohydrate-fermenting bacteria, such as lactic acid bacteria, allowing it to symbiotically establish itself in anaerobic environments (10, 11). Despite its prevalence in the human body, studies on this bacterium has been extremely limited due to its difficulty in manipulation. Thus, it is still not well understood (12).
12 species have been described under the same genus (12), of which 6 species have been suggested to facilitate the development of oral biofilms (13). V. parvula is the most abundant in the human oral cavity and gastrointestinal tract (12).
Examples of citations [1], [2]
Genome structure
V. parvula is the only fully assembled genome in the Veillonella genus and comprises of 2,132,142 bp genome size circular chromosome, with 38.6% GC content. It encodes 1, 920 genes, of which 73.6% are functional, 61 RNAs and 1,859 proteins (1).
Cell structure and metabolism
V. parvula has a distinctive lipopolysaccharide (LPS) on its outer membrane. Its cell wall also consists of cadaverine and putrescine, which are essential for growth (14) and it is non-motile (1).
Biofilms develop when initial colonizers, streptococci and actinomyces bind to host-derived receptors in the saliva film-coated tooth enamel. This allows subsequent binding of Veillonella and other bacteria via coadhesion. Coaggregation, involving binding and cell-to-cell recognition between genetically distinct microbial species, subsequently follows, resulting in plaque formation. Saliva is a complex nutrient source. Development of plaque is thought to involve spatial organization of different bacteria and interactions between species, which in combination, is able to metabolize latent nutrients into usable ones to be further processed by other species (11).
V. parvula is involved in plaque development as it is able to interact metabolically with streptococci. Consumption of sucrose is then converted to glucose or fructose by streptococci. Most glucose is converted to lactate which is utilized by Veillonella, converting it into propionate, acetate and carbon dioxide for energy. This sets up a metabolic food chain in the dental plaque. It is also able to utilize other fermented organic acids such as pyruvate, malate and fumarate. V. parvula is unable to utilize carbohydrates and amino acids for energy (10, 11).
Some sucrose is converted by streptococcal extracellular glucosyltransferase into dextran, which allows Veillonella to adhere and establish itself on tooth surfaces. Fructose, a product of dextran synthesis, can then be incorporated into Veillonella lipopolysaccharide (LPS), contributing to the production of endotoxic LPS (10).
Ecology
Aerobe/anaerobe, habitat (location in the oral cavity, potential other environments) and microbe/host interactions.
V. parvula is an anaerobe, found in subgingival plaque (15). Development of thick plaque provides favourable anaerobic conditions, thus V. parvula is mostly distributed in deeper plaque layers. It is found to increase in numbers in presence of gingival infection (10).
In the development of biofilm and plaque, V. parvula associates with other oral microbes to establish itself in the oral microbial ecosystem via coadhesion and coaggregation. Coaggregation is mediated by binding of lectin-like adhesins to receptor polysaccharide on streptococci (5, 11).
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 Tricia Teo for the MICR3004 course, Semester 2, 2016
