Acetobacterium

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Acetobacterium
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Acetobacterium

Balch et al. [1]
Species

Acetobacterium bakii
Acetobacterium carbinolicum
Acetobacterium fimetarium
Acetobacterium malicum
Acetobacterium paludosum
Acetobacterium tundrae
Acetobacterium wieringae
Acetobacterium woodii

Acetobacterium is a genus of anaerobic, Gram-positive bacteria that belong to the Eubacteriaceae family. The type species of this genus is Acetobacterium woodii. [1] The name, Acetobacterium, has originated because they are acetogens, predominantly making acetic acid as a byproduct of anaerobic metabolism. Most of the species reported in this genus are homoacetogens, i.e. solely producing acetic acid as their metabolic byproduct. They should not be confused with acetic acid bacteria which are aerobic, Gram-negative Alphaproteobacteria.

Other acetogens use the Wood–Ljungdahl pathway to reduce CO or CO2 and produce acetate, but what distinguishes A.woodii and other Acetobacterium from other acetogens is that it conserves energy by using an Rnf complex to create a sodium gradient rather than a proton gradient. This means that A.woodii would need sodium in its environment in order to make ATP. [2]

When reducing CO2 to acetate the Acetobacterium uses the Wood–Ljungdahl pathway with CO2 as the electron acceptor. However, the Acetobacterium can use other electron acceptors like caffeate. [3] To use caffeate as an electron acceptor the bacterium couples hydrogen dependent caffeate reduction with electrons from hydrogen and uses sodium ions as coupling ions. The step in the electron transport chain that creates the sodium gradient is the ferredoxin-dependent reduction of NAD+. [4]

One application of Acetobacterium, is that A. woodii could be used in the transformation of tetrachloromethane to dichloromethane and carbon dioxide by reductive dechlorinations, but the reactions taken to get to the final product are unknown. [5] This reaction is useful because the products, CO2 and dichloromethane are less toxic than tetrachloromethane. Another application of A.woodii is that it can reduce the effects of greenhouse gases since A.woodii can be used to convert CO2 and CO into acetyl-CoA which could then be used to make other chemicals like ethanol and acetate. [6] The production of ethanol by Acetobacterium using chemolithotrophic methods is important because ethanol can be used as a biofuel. [2] By using the ethanol that is produced by the bacterium researchers aim to create a sustainable way to create energy. [6]

Related Research Articles

Acetate Chemical compound

An acetate is a salt formed by the combination of acetic acid with a base. "Acetate" also describes the conjugate base or ion typically found in aqueous solution and written with the chemical formula C
2
H
3
O
2
. The neutral molecules formed by the combination of the acetate ion and a positive ion are also commonly called "acetates". The simplest of these is hydrogen acetate with corresponding salts, esters, and the polyatomic anion CH
3
CO
2
, or CH
3
COO
.

Anaerobic respiration is respiration using electron acceptors other than molecular oxygen (O2). Although oxygen is not the final electron acceptor, the process still uses a respiratory electron transport chain.

Carbon fixation Conversion of carbon from CO2 to organic compounds

Carbon fixation or сarbon assimilation is the process by which inorganic carbon is converted to organic compounds by living organisms. The compounds are then used to store energy and as structure for other biomolecules. Carbon is primarily fixed through photosynthesis, but some organisms use a process called chemosynthesis in the absence of sunlight.

Sodium acetate Chemical compound

Sodium acetate, NaCH3COO, also abbreviated NaOAc, is the sodium salt of acetic acid. This colorless deliquescent salt has a wide range of uses.

In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can be applied to any desymmetrizing reaction of the following type: 2 A → A' + A", regardless of whether it is a redox or some other type of process.

An acetogen is a microorganism that generates acetate (CH3COO) as an end product of anaerobic respiration or fermentation. However, this term is usually employed in a narrower sense only to those bacteria and archaea that perform anaerobic respiration and carbon fixation simultaneously through the reductive acetyl coenzyme A (acetyl-CoA) pathway (also known as the Wood-Ljungdahl pathway). These genuine acetogens are also known as "homoacetogens" and they can produce acetyl-CoA (and from that, in most cases, acetate as the end product) from two molecules of carbon dioxide (CO2) and four molecules of molecular hydrogen (H2). This process is known as acetogenesis, and is different from acetate fermentation, although both occur in the absence of molecular oxygen (O2) and produce acetate. Although previously thought that only bacteria are acetogens, some archaea can be considered to be acetogens.

Acidogenesis is the second stage in the four stages of anaerobic digestion:

Acetogenesis is a process through which acetate is produced either by the reduction of CO2 or by the reduction of organic acids.

Mixed acid fermentation

Mixed acid fermentation is the biological process by which a six-carbon sugar e.g. glucose is converted into a complex and variable mixture of acids. It is an anaerobic fermentation reaction that is common in bacteria. It is characteristic for members of the Enterobacteriaceae, a large family of Gram-negative bacteria that includes E. coli.

Microbial metabolism is the means by which a microbe obtains the energy and nutrients it needs to live and reproduce. Microbes use many different types of metabolic strategies and species can often be differentiated from each other based on metabolic characteristics. The specific metabolic properties of a microbe are the major factors in determining that microbe's ecological niche, and often allow for that microbe to be useful in industrial processes or responsible for biogeochemical cycles.

In biology, syntrophy, synthrophy, or cross-feeding is the phenomenon of one species living off the metabolic products of another species. In this type of biological interaction, the growth of one partner depends on the nutrients, growth factors, or substrates provided by the other partner. Jan Dolfing describes syntrophy as "the critical interdependency between producer and consumer". This term for nutritional interdependence is often used in microbiology to describe this symbiotic relationship between bacterial species. Morris et al. have described the process as "obligately mutualistic metabolism".

Fermentation Metabolic process

Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food production, it may more broadly refer to any process in which the activity of microorganisms brings about a desirable change to a foodstuff or beverage. The science of fermentation is known as zymology.

Wood–Ljungdahl pathway

The Wood–Ljungdahl pathway is a set of biochemical reactions used by some bacteria and archaea called acetogens and methanogens, respectively. It is also known as the reductive acetyl-coenzyme A (Acetyl-CoA) pathway. This pathway enables these organisms to use hydrogen as an electron donor, and carbon dioxide as an electron acceptor and as a building block for biosynthesis.

In enzymology, carbon monoxide dehydrogenase (CODH) (EC 1.2.7.4) is an enzyme that catalyzes the chemical reaction

Syngas fermentation, also known as synthesis gas fermentation, is a microbial process. In this process, a mixture of hydrogen, carbon monoxide, and carbon dioxide, known as syngas, is used as carbon and energy sources, and then converted into fuel and chemicals by microorganisms.

<i>Thermotoga maritima</i>

Thermotoga maritima is a hyperthermophilic, anaerobic organism that is a member of the order Thermotogales. It employs [FeFe]-hydrogenases to produce hydrogen gas (H2) by fermenting many different types of carbohydrates.

Desulfobulbus propionicus is a Gram-negative, anaerobic chemoorganotroph. Three separate strains have been identified: 1pr3T, 2pr4, and 3pr10. It is also the first pure culture example of successful disproportionation of elemental sulfur to sulfate and sulfide. Desulfobulbus propionicus has the potential to produce free energy and chemical products.

Syntrophococcus sucromutans is a Gram-negative strictly anaerobic chemoorganotrophic Firmicute. These bacteria can be found forming small chains in the habitat where it was first isolated, the rumen of cows. It is the type strain of genus Syntrophococcus and it has an uncommon one-carbon metabolic pathway, forming acetate from formate as a product of sugar oxidation.

CO-methylating acetyl-CoA synthase

Acetyl-CoA synthase (ACS), not to be confused with Acetyl-CoA synthetase or Acetate-CoA ligase, is a nickel-containing enzyme involved in the metabolic processes of cells. Together with Carbon monoxide dehydrogenase (CODH), it forms the bifunctional enzyme Acetyl-CoA Synthase/Carbon Monoxide Dehydrogenase (ACS/CODH) found in anaerobic organisms such as archaea and bacteria. The ACS/CODH enzyme works primarily through the Wood–Ljungdahl pathway which converts carbon dioxide to Acetyl-CoA. The recommended name for this enzyme is CO-methylating acetyl-CoA synthase.

Clostridium carboxidivorans is a Gram-positive anaerobic, spore-forming and motile bacterium from the genus Clostridium which has been isolated from an agricultural lagoon in Oklahoma in the United States.

References

  1. 1 2 Balch, W. E.; Schoberth, S.; Tanner, R. S.; Wolfe, R. S. (1977). "Acetobacterium, a New Genus of Hydrogen-Oxidizing, Carbon Dioxide-Reducing, Anaerobic Bacteria". International Journal of Systematic Bacteriology. 27 (4): 355. doi: 10.1099/00207713-27-4-355 .
  2. 1 2 Schiel-Bengelsdorf, Bettina; Dürre, Peter (2012-07-16). "Pathway engineering and synthetic biology using acetogens". FEBS Letters. 586 (15): 2191–2198. doi: 10.1016/j.febslet.2012.04.043 . ISSN   1873-3468. PMID   22710156.
  3. Müller, Volker; Imkamp, Frank; Biegel, Eva; Schmidt, Silke; Dilling, Sabrina (2008-03-01). "Discovery of a Ferredoxin:NAD+-Oxidoreductase (Rnf) in Acetobacterium woodii". Annals of the New York Academy of Sciences. 1125 (1): 137–146. doi:10.1196/annals.1419.011. ISSN   1749-6632.
  4. Imkamp, Frank; Biegel, Eva; Jayamani, Elamparithi; Buckel, Wolfgang; Müller, Volker (2007-11-15). "Dissection of the Caffeate Respiratory Chain in the Acetogen Acetobacterium woodii: Identification of an Rnf-Type NADH Dehydrogenase as a Potential Coupling Site". Journal of Bacteriology. 189 (22): 8145–8153. doi:10.1128/jb.01017-07. ISSN   0021-9193. PMC   2168664 . PMID   17873051.
  5. Egli, C; Tschan, T; Scholtz, R; Cook, A M; Leisinger, T (November 1988). "Transformation of tetrachloromethane to dichloromethane and carbon dioxide by Acetobacterium woodii". Applied and Environmental Microbiology. 54 (11): 2819–2824. ISSN   0099-2240. PMC   204379 . PMID   3145712.
  6. 1 2 Bertsch, Johannes; Müller, Volker (2015-09-01). "CO Metabolism in the Acetogen Acetobacterium woodii". Applied and Environmental Microbiology. 81 (17): 5949–5956. doi:10.1128/aem.01772-15. ISSN   0099-2240. PMC   4551271 . PMID   26092462.