Template:MICR3004: Difference between revisions
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Rachel Mackie | |||
43541005 | |||
23/09/2016 | |||
<ref>MICR3004</ref> | <ref>MICR3004</ref> | ||
==Classification== | ==Classification== | ||
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===Species=== | ===Species=== | ||
Parvula | Parvula | ||
==Description and significance== | ==Description and significance== | ||
Veillonella parvula is a gram negative, strictly anaerobic, cocci found in the oral cavity, gastrointestinal tract and urinary tract of humans and other animals7. Although this species usually grows in pairs, it has also been found in single cells, groups or chains8. Colonies are 1-3mm in diameter, entire, smooth and greyish in colour when grown on lactate agar media3. | |||
This species was first isolated by Veillon and Zuber in 1898 as Staphylococcus parvula and renamed as Veillonella parvula by Prévot in 19332. Although V. parvula is generally considered as a commensal organism, it has been found to participate in multispecies infections at various sites in the body as well as rare pure culture infections2. Oral V. parvula is of particular interest due to its role in the early development of human dental plaque and associated oral diseases, such as periodontitis7. | |||
==Genome structure== | ==Genome structure== | ||
V. Parvula strain Te3T, isolated from human gastrointestinal tract, was the first complete genome sequence of the family Veillonellaceae2. The strain Te3T genome is a single replicon, circular chromosome, which is 2,132,142 bp in length with 38.6% GC content2. It is consists of 1920 genes with 1859 genes coding for proteins, 61 genes coding RNA molcules and 15 pseudogenes2. | |||
*Figure - scanning electron micrograph of V.p type strain Te3T 2. | |||
==Cell structure and metabolism== | ==Cell structure and metabolism== | ||
V. parvula is characterised by an unusual metabolism surrounding the activity of methylmalonyl-CoA decarboxylase, an enzyme which catalyses the decarboxylase reaction of organic acids to form an electrical gradient of sodium ions2. This species is unable to metabolise carbohydrates and instead gain their energy by fermenting short-chain organic acids, principally lactate and pyruvate8. Often these organic acids are metabolic end products from carbohydrate fermenting bacteria2. As lactic acid is metabolised, weaker acid products of propionic and acetic acids are formed. This metabolic process may provide a lactic acid sink, providing protection for acid producing bacteria, which is an important factor in caries process1. | |||
Another characteristic the V. parvula is the ability for form coaggregates with other bacteria. Although cannot adhere to surfaces itself, it can attach to structures on the surface of other cells, which is an important trait in biofilm and dental plaque formation2. | |||
Similar to other gram-negative bacteria the cell has an outer membrane and harbours lipopolysaccharide. However, it is more closely related to gram-positive cells due to the presence of cadaverine or putrescine in the peptidoglycan layer. Another feature of the cell wall is the presence of plasmalogens, ester lipids instead of phospholipids, in the cytoplasmic membrane providing finer regulation of membrane fluidity2. | |||
==Ecology== | ==Ecology== | ||
The genus Veillonella is one of the most prevalent and most abundant microorganism in the human oral cavity4. The main habitats of V. parvula in this niche are the tongue, buccal mucosa, dental plaque and saliva8. Although V. parvula has no ability to form plaque on its own, its role as early coloniser in biofilm formation has been found to facilitate the maturation of plaque through symbiotic associations with other organisms5. For example, a primary plaque forming bacteria, Eubacterium saburreum, forms filaments from protein and sucrose material, which aid in adherence of V. parvula6. During glucose metabolism the conversion of sucrose into dextrose by streptococci species has also been found to provide adherence to teeth5. Fructose, another by-product of this glucose conversion, can also be used by V. parvula in lipopolysaccharide formation5. In addition, the lactic acid and other organic acids produced by these and other organisms promote colonisation by providing a carbon and energy source for V. parvula. Removal of these acids also allows other organisms, which would normally be unable to withstand low pH, to inhabit the environment6. | |||
==Pathology== | ==Pathology== | ||
V. parvula is an important pathogen in oral diseases and has been linked to other local and systemic infections7. It plays a major role in dental caries and gum disease, and interradicular infections including abscesses and root canals5. | |||
Reports of non-oral diseases include tonsillitis8, meningitis, osteomyelitis, discitis, sinusitis, endocarditis and prosthetic joint infection7. | |||
Comparable to other gram-negative strict anaerobes, the pathogenicity is related to the lipopolysaccharides. However, the biological activity of lipopolysaccharides and the molecular mechanisms of the innate immune response leading to inflammatory infections are still largely unknown7. V. parvula is also know to produce hydrogen sulphide in response to proteins found in human blood plasma, which results in toxic effects8. | |||
==Application to biotechnology== | ==Application to biotechnology== | ||
Researchers have developed the first genetic transformation system of Veillonella isolated from saliva using Escherichia coli-Veillonella shuttle vector4. These findings provide valuable tools for the further genetic study of this species4. The use of genetic manipulation can provide important clinical information on the biology, pathogenesis and antibiotic resistance. | |||
==Current research== | ==Current research== | ||
Recent studies investigating the interactions between V. parvula and other bacteria in multispecies biofilm environments aim to determine the development and pathogenesis of human dental plaque. Since caries are highly associated with lactic acid producing bacteria, V. parvula levels may serve as a biological indicators and an early warning sign of acid production5. Understanding these interactions during biofilm formation may help in the development of methods for prevention of oral diseases. | |||
V. parvula has been reported to confer general resistance to streptomycin3, penicillin5, tetracycline, vancomycin, aminoglycosides, ciprofloxacin, and an intermediate resistance to erythromycin8, chloramphenicol and lincomycin2. It is however, susceptible to penicillin G, cephalotin and clindamycin2. | |||
==References== | ==References== | ||
1. Becker, M.R et al. (2002) Molecular Analysis of Bacterial Species Associated with Childhood Caries. J. Clin. 40(3) : 1001-1009 | |||
2. Gronow, S (2009) Complete genome sequence of Veillonella parvula type strain (Te3T ). Standards in Genomic Sciences 1 : 57-65 | |||
3. http://www.homd.org Human Oral Microbiome | |||
4. Lui, J et al. (2012) Establishment of a Tractable Genetic Transformation System in Veillonella spp. Appl. Environ. Microbiol. 78(9) : 3488-3491 | |||
5. Mashima, A & Nakazawa, F (2015) Interaction between Streptococcus spp. and Veillonella tobetsuensis in the Early Stages of Oral Biofilm Formation. J. Bacteriol. 197(13) : 2104-2111 | |||
6. Mashimo, P.A et al. (1981) Eubacterium saburreum and Veillonella párvula: A Symbiotic Association of Oral Strains*. J Periodontol. 52(7) : 374-9 | |||
7. Mater, G et al. (2009) Receptor Recognition of and Immune Intracellular Pathways for Veillonella parvula Lipopolysaccharide. Clin Vaccine Immunol. 16(12) : 1804-1809 | |||
8. Rocas, I.N & Siqueira, J.F (2005) Culture-Independent Detection of Eikenella corrodens and Veillonella parvula in Primary Endodontic Infections. J. Endodontics. 32(6) : 509–512 | |||
<references/> | <references/> | ||
This page is written by | This page is written by Rachel Mackie for the MICR3004 course, Semester 2, 2016 | ||
Revision as of 05:35, 23 September 2016
Rachel Mackie 43541005 23/09/2016 [1]
Classification
Higher order taxa
Bacteria; Firmicutes; Negativicutes; Selenomonadales; Veillonellaceae; Veillonella
Species
Parvula
Description and significance
Veillonella parvula is a gram negative, strictly anaerobic, cocci found in the oral cavity, gastrointestinal tract and urinary tract of humans and other animals7. Although this species usually grows in pairs, it has also been found in single cells, groups or chains8. Colonies are 1-3mm in diameter, entire, smooth and greyish in colour when grown on lactate agar media3.
This species was first isolated by Veillon and Zuber in 1898 as Staphylococcus parvula and renamed as Veillonella parvula by Prévot in 19332. Although V. parvula is generally considered as a commensal organism, it has been found to participate in multispecies infections at various sites in the body as well as rare pure culture infections2. Oral V. parvula is of particular interest due to its role in the early development of human dental plaque and associated oral diseases, such as periodontitis7.
Genome structure
V. Parvula strain Te3T, isolated from human gastrointestinal tract, was the first complete genome sequence of the family Veillonellaceae2. The strain Te3T genome is a single replicon, circular chromosome, which is 2,132,142 bp in length with 38.6% GC content2. It is consists of 1920 genes with 1859 genes coding for proteins, 61 genes coding RNA molcules and 15 pseudogenes2.
- Figure - scanning electron micrograph of V.p type strain Te3T 2.
Cell structure and metabolism
V. parvula is characterised by an unusual metabolism surrounding the activity of methylmalonyl-CoA decarboxylase, an enzyme which catalyses the decarboxylase reaction of organic acids to form an electrical gradient of sodium ions2. This species is unable to metabolise carbohydrates and instead gain their energy by fermenting short-chain organic acids, principally lactate and pyruvate8. Often these organic acids are metabolic end products from carbohydrate fermenting bacteria2. As lactic acid is metabolised, weaker acid products of propionic and acetic acids are formed. This metabolic process may provide a lactic acid sink, providing protection for acid producing bacteria, which is an important factor in caries process1.
Another characteristic the V. parvula is the ability for form coaggregates with other bacteria. Although cannot adhere to surfaces itself, it can attach to structures on the surface of other cells, which is an important trait in biofilm and dental plaque formation2.
Similar to other gram-negative bacteria the cell has an outer membrane and harbours lipopolysaccharide. However, it is more closely related to gram-positive cells due to the presence of cadaverine or putrescine in the peptidoglycan layer. Another feature of the cell wall is the presence of plasmalogens, ester lipids instead of phospholipids, in the cytoplasmic membrane providing finer regulation of membrane fluidity2.
Ecology
The genus Veillonella is one of the most prevalent and most abundant microorganism in the human oral cavity4. The main habitats of V. parvula in this niche are the tongue, buccal mucosa, dental plaque and saliva8. Although V. parvula has no ability to form plaque on its own, its role as early coloniser in biofilm formation has been found to facilitate the maturation of plaque through symbiotic associations with other organisms5. For example, a primary plaque forming bacteria, Eubacterium saburreum, forms filaments from protein and sucrose material, which aid in adherence of V. parvula6. During glucose metabolism the conversion of sucrose into dextrose by streptococci species has also been found to provide adherence to teeth5. Fructose, another by-product of this glucose conversion, can also be used by V. parvula in lipopolysaccharide formation5. In addition, the lactic acid and other organic acids produced by these and other organisms promote colonisation by providing a carbon and energy source for V. parvula. Removal of these acids also allows other organisms, which would normally be unable to withstand low pH, to inhabit the environment6.
Pathology
V. parvula is an important pathogen in oral diseases and has been linked to other local and systemic infections7. It plays a major role in dental caries and gum disease, and interradicular infections including abscesses and root canals5. Reports of non-oral diseases include tonsillitis8, meningitis, osteomyelitis, discitis, sinusitis, endocarditis and prosthetic joint infection7.
Comparable to other gram-negative strict anaerobes, the pathogenicity is related to the lipopolysaccharides. However, the biological activity of lipopolysaccharides and the molecular mechanisms of the innate immune response leading to inflammatory infections are still largely unknown7. V. parvula is also know to produce hydrogen sulphide in response to proteins found in human blood plasma, which results in toxic effects8.
Application to biotechnology
Researchers have developed the first genetic transformation system of Veillonella isolated from saliva using Escherichia coli-Veillonella shuttle vector4. These findings provide valuable tools for the further genetic study of this species4. The use of genetic manipulation can provide important clinical information on the biology, pathogenesis and antibiotic resistance.
Current research
Recent studies investigating the interactions between V. parvula and other bacteria in multispecies biofilm environments aim to determine the development and pathogenesis of human dental plaque. Since caries are highly associated with lactic acid producing bacteria, V. parvula levels may serve as a biological indicators and an early warning sign of acid production5. Understanding these interactions during biofilm formation may help in the development of methods for prevention of oral diseases.
V. parvula has been reported to confer general resistance to streptomycin3, penicillin5, tetracycline, vancomycin, aminoglycosides, ciprofloxacin, and an intermediate resistance to erythromycin8, chloramphenicol and lincomycin2. It is however, susceptible to penicillin G, cephalotin and clindamycin2.
References
1. Becker, M.R et al. (2002) Molecular Analysis of Bacterial Species Associated with Childhood Caries. J. Clin. 40(3) : 1001-1009
2. Gronow, S (2009) Complete genome sequence of Veillonella parvula type strain (Te3T ). Standards in Genomic Sciences 1 : 57-65
3. http://www.homd.org Human Oral Microbiome
4. Lui, J et al. (2012) Establishment of a Tractable Genetic Transformation System in Veillonella spp. Appl. Environ. Microbiol. 78(9) : 3488-3491
5. Mashima, A & Nakazawa, F (2015) Interaction between Streptococcus spp. and Veillonella tobetsuensis in the Early Stages of Oral Biofilm Formation. J. Bacteriol. 197(13) : 2104-2111
6. Mashimo, P.A et al. (1981) Eubacterium saburreum and Veillonella párvula: A Symbiotic Association of Oral Strains*. J Periodontol. 52(7) : 374-9
7. Mater, G et al. (2009) Receptor Recognition of and Immune Intracellular Pathways for Veillonella parvula Lipopolysaccharide. Clin Vaccine Immunol. 16(12) : 1804-1809
8. Rocas, I.N & Siqueira, J.F (2005) Culture-Independent Detection of Eikenella corrodens and Veillonella parvula in Primary Endodontic Infections. J. Endodontics. 32(6) : 509–512
- ↑ MICR3004
This page is written by Rachel Mackie for the MICR3004 course, Semester 2, 2016
