User:S4441208

Name Christoffer Vinther Soerensen Bench ID E Date 31/8 ^[1]

Organism: Veillonella parvula

Classification

Higher order taxa

Bacteria; Firmicutes; Clostridia; Clostridiales; Veillonellaceae; Veillonella

Species

Veillonella parvula

Description and significance

The genus Veillonella was first described back in 1898 by Veillon and Zuber, and the name Veillonella was proposed in 1933 by Prevot. ^[1] V. parvula are small, nonfermentative non-sporeforming, strictly anaerobic, gram-negative cocci. They are a natural part of the flora found in the oral, genitourinary, respiratory, and intestinal tracts of humans and animals. In the oral region it has been isolated from most surfaces of the oral cavity, but are found in highest numbers in dental plaque. The genus cannot metabolize carbohydrates because they lack glucokinase and fructokinase. Instead it is able to utilize short-chain organic acids, especially lactate as energy sources.^[2]

V. parvula is of interest because it is sometimes involved in causing opportunistic infections.

Genome structure

Strain: V. parvula strain Te3T

The genome is one main circular chromosome containing 2,132,142 bp with a GC content of 38.6%. It has 1,920 predicted genes, of which 1,859 are protein coding genes and 61 RNA's.^[4]

Cell structure and metabolism

V.parvula are small (approximately 0.3 to 0.5 µm in diameter), nonfermentative non-sporeforming, strictly anaerobic, gram-negative cocci that grows in pairs or short chains. The cell wall of V. parvula have an outer membrane which clearly shows presence of lipopolysaccharides. Putresine and cadaverine are a major part of the layer of peptidoglycan. ^[4] V. parvula has an unusual metabolism, where it uses the enzyme methylmalonyl-CoA decarboxylase to convert the free energy from decarboxylation reactions into an electrochemical gradient of sodium ions. Hereby they can use the end products of other bacteria that ferments on carbohydrate and produce i.e. lactic acid, such as S.mutans ^[4]

V. parvula is often found in dual-species dental biofilm (dental plaque), the other species often being S. mutans. These have a mutualistic relationship. V. parvula is by itself not able to adhere to surfaces, but it is able to attach to other bacterias, such as S. mutans. S. mutans is growing on sugars it produces lactate, which V. parvula can then utilize to obtain the electrochemical gradient. ^[3] ^[4] V. Parvula can actually be involved in reducing the amount of caries you get from having S. Mutans in dental plaque. This is because V. Parvula can reduce the lactic acid produced by S. Mutans to weaker acids, and thereby reduce the damage made to the enamel by lactic acid. ^[2]

Lactate metabolism by V. parvula has the following stoichiometry:

8 lactate ⇋ 5 propionate+ 3 acetate + 3 CO2 + H2. ^[6]

Ecology

V. parvula have quite important functions regarding the ecology of dental plaque since they are able to reduce lactic acid to weaker acids. Lactic acid is involved in breaking down the enamel, and is the strongest acid produced in quantity by oral bacteria. ^[2]

Pathology

Of the genus Veillonella, V. Parvula is the only species involved in oral diseases such as gingivitis. This species has also been isolated from cases with endocarditis, meningitis, discitis, but this is very rare cases though. Most often it is involved in multispecies infections.^[4]

Application to biotechnology

V. parvula has no immediate application to biotechnology, but the thing that would probably be most interesting for biotechnologists is the enzyme methylmalonyl-CoA decarboxylase and in general the metabolism of V. parvula.

Current research

Recently a team of scientists reviewed case reports related to the Veillonella species from 1976 to October 2015 with pubmed, they found 53 articles, of which only 30 was available in English language, so the following data is only regarded to these 30 and the case they worked on, giving a total of 31 cases. They found that the median age of patients was 55 years, with a range from 3-88 years old. 19 out of the 31 patients were men. V. parvula was the most detected species and was seen in 48.4% of the cases. The most common underlying diseases before infection from Veillonella was immunodefiency, malignancy and collagen diseases. They also found that a fifth of the patients actually was previously healthy. ^[5]