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Methanogens are microorganisms that produce methane as a metabolic byproduct in hypoxic conditions. They belong to the domain Archaea and are members of the phylum Euryarchaeota. Methanogens are common in wetlands, where they are responsible for marsh gas, and can occur in the digestive tracts of animals including ruminants and humans, where they are responsible for the methane content of belching and flatulence. In marine sediments, the biological production of methane, termed methanogenesis, is generally confined to where sulfates are depleted below the top layers and methanogens play an indispensable role in anaerobic wastewater treatments. Other methanogens are extremophiles, found in environments such as hot springs and submarine hydrothermal vents as well as in the "solid" rock of Earth's crust, kilometers below the surface.
In biology, syntrophy, synthrophy, or cross-feeding is the phenomenon of one species feeding on the metabolic products of another species to cope up with the energy limitations by electron transfer. In this type of biological interaction, metabolite transfer happens between two or more metabolically diverse microbial species that live in close proximity to each other. The growth of one partner depends on the nutrients, growth factors, or substrates provided by the other partner. Thus, syntrophism can be considered as an obligatory interdependency and a mutualistic metabolism between two different bacterial species.
Campylobacterota are a phylum of bacteria. All species of this phylum are Gram-negative.
Hydrogen-oxidizing bacteria are a group of facultative autotrophs that can use hydrogen as an electron donor. They can be divided into aerobes and anaerobes. The former use hydrogen as an electron donor and oxygen as an acceptor while the latter use sulphate or nitrogen dioxide as electron acceptors. Species of both types have been isolated from a variety of environments, including fresh waters, sediments, soils, activated sludge, hot springs, hydrothermal vents and percolating water.
Aggregatibacter actinomycetemcomitans is a Gram-negative, facultative anaerobe, nonmotile bacterium that is often found in association with localized aggressive periodontitis, a severe infection of the periodontium. It is also suspected to be involved in chronic periodontitis. Less frequently, A. actinomycetemcomitans is associated with nonoral infections such as endocarditis. Its role in aggressive periodontitis was first discovered by Danish-born periodontist Jørgen Slots, a professor of dentistry and microbiology at the University of Southern California School of Dentistry.
Methanobacterium is a genus of the Methanobacteriaceae family of Archaea. Despite the name, this genus belongs not to the bacterial domain but the archaeal domain. Methanobacterium are nonmotile and live without oxygen. Some members of this genus can use formate to reduce methane; others live exclusively through the reduction of carbon dioxide with hydrogen. They are ubiquitous in some hot, low-oxygen environments, such as anaerobic digestors, their wastewater, and hot springs.
Methanosphaera is a genus of microbes within the family Methanobacteriaceae. It was distinguished from other genera within Methanobacteriaceae in 1985 on the basis of the oligonucleotide sequence of its 16S RNA. Like other archaea within Methanobacteriaceae, those of Methanosphaera are methanogens, but while most use formate to reduce carbon dioxide, those of Methanosphaera use hydrogen to reduce methanol to methane.
Methanothermobacter is a genus of archaeans in the family Methanobacteriaceae. The species within this genus are thermophilic and grow best at temperatures between 55 °C and 65 °C. They are methanogens; they use carbon dioxide and hydrogen as substrates to produce methane for energy.
The 5,10-methenyltetrahydromethanopterin hydrogenase, the so-called iron-sulfur cluster-free hydrogenase, is an enzyme found in methanogenic archea such as Methanothermobacter marburgensis. It was discovered and first characterized by the Thauer group at the Max Planck Institute in Marburg. Hydrogenases are enzymes that either reduce protons or oxidize molecular dihydrogen.
Methanocaldococcus jannaschii is a thermophilic methanogenic archaean in the class Methanococci. It was the first archaeon, and third organism, to have its complete genome sequenced. The sequencing identified many genes unique to the archaea. Many of the synthesis pathways for methanogenic cofactors were worked out biochemically in this organism, as were several other archaeal-specific metabolic pathways.
Methanosphaera stadtmanae is a methanogen archaeon. It is a non-motile, Gram-positive, spherical-shaped organism that obtains energy by using hydrogen to reduce methanol to methane. It does not possess cytochromes and is part of the large intestine's biota.
Acidithiobacillus caldus formerly belonged to the genus Thiobacillus prior to 2000, when it was reclassified along with a number of other bacterial species into one of three new genera that better categorize sulfur-oxidizing acidophiles. As a member of the Gammaproteobacteria class of Pseudomonadota, A. caldus may be identified as a Gram-negative bacterium that is frequently found in pairs. Considered to be one of the most common microbes involved in biomining, it is capable of oxidizing reduced inorganic sulfur compounds (RISCs) that form during the breakdown of sulfide minerals. The meaning of the prefix acidi- in the name Acidithiobacillus comes from the Latin word acidus, signifying that members of this genus love a sour, acidic environment. Thio is derived from the Greek word thios and describes the use of sulfur as an energy source, and bacillus describes the shape of these microorganisms, which are small rods. The species name, caldus, is derived from the Latin word for warm or hot, denoting this species' love of a warm environment.
Methanococcus maripaludis is a species of methanogenic archaea found in marine environments, predominantly salt marshes. Methanococcus maripaludis is a weakly motile, non-spore-forming, Gram-negative, strict anaerobic mesophile with a pleomorphic coccoid-rod shape, averaging 1.2 by 1.6 μm is size. The genome of M. maripaludis has been sequenced. It has been described as an electric bacteria. Methanococcus maripaludis grows quickly and doubles in two hours.
Pelotomaculum thermopropionicum is an anaerobic, thermophilic, syntrophic propionate-oxidizing bacterium, the type species of its genus. The type strain is strain SI(T).
Fervidobacterium islandicum is a species of extremely thermophilic anaerobic bacteria, first isolated from an Icelandic hot spring.
Finegoldia is a genus of Gram-positive bacteria. They are anaerobic cocci of the class Clostridia, with Finegoldia magna being the type species. F. magna was formerly known, along with several other Gram-positive anaerobic cocci (GPACs), as Peptostreptococcus magnus, but was moved into its own genus in 1999. The name is in honor of Sydney M. Finegold, an American microbiologist, while magna is Latin for large. It is an opportunistic human pathogen that normally colonizes skin and mucous membranes. It is often seen in biofilms on chronic ulcers such as in diabetic foot or decubitus ulcers. Most surveys have found it to be susceptible to penicillins, carbapenems and metronidazole, though resistant strains have been identified. Resistance to clindamycin is common and has been seen in over 10% of isolates in the US. One review stated that "the combination of diminished antimicrobial susceptibility, its prevalence, and the described virulence factors gives F. magna a special position among the GPAC."
Interspecies hydrogen transfer (IHT) is a form of interspecies electron transfer. It is a syntrophic process by which H2 is transferred from one organism to another, particularly in the rumen and other anaerobic environments.
Sulfobacillus thermosulfidooxidans is a species of bacteria of the genus Sulfobacillus. It is an acidophilic, mixotrophic, moderately thermophilic, Gram-positive, sporulating facultative anaerobe. As its name suggests, it is capable of oxidizing sulfur.
References
- ↑ Wasserfallen, A.; Nolling, J.; Pfister, P.; Reeve, J.; Conway de Macario, E. (2000). "Phylogenetic analysis of 18 thermophilic Methanobacterium isolates supports the proposals to create a new genus, Methanothermobacter gen. nov., and to reclassify several isolates in three species, Methanothermobacter thermautotrophicus comb. nov., Methanothermobacter wolfeii comb. nov., and Methanothermobacter marburgensis sp. nov". International Journal of Systematic and Evolutionary Microbiology. 50 (1): 43–53. doi: 10.1099/00207713-50-1-43 . ISSN 1466-5026. PMID 10826786.
- ↑ Liesegang, H.; Kaster, A.-K.; Wiezer, A.; Goenrich, M.; Wollherr, A.; Seedorf, H.; Gottschalk, G.; Thauer, R. K. (2010). "Complete Genome Sequence of Methanothermobacter marburgensis, a Methanoarchaeon Model Organism". Journal of Bacteriology. 192 (21): 5850–5851. doi:10.1128/JB.00844-10. ISSN 0021-9193. PMC 2953689 . PMID 20802048.
- ↑ Stanley Falkow; Eugene Rosenberg; Karl-Heinz Schleifer; Erko Stackebrandt, eds. (2006-10-10). The Prokaryotes. Vol. 3. Springer Science & Business Media. p. 240. ISBN 0387254935 . Retrieved 2016-09-01.
- ↑ Casini, Isabella; McCubbin, Tim; Esquivel-Elizondo, Sofia; Luque, Guillermo G.; Evseeva, Daria; Fink, Christian; Beblawy, Sebastian; Youngblut, Nicholas D.; Aristilde, Ludmilla; Huson, Daniel H.; Dräger, Andreas; Ley, Ruth E.; Marcellin, Esteban; Angenent, Largus T.; Molitor, Bastian (2023). "An integrated systems-biology approach reveals differences in formate metabolism in the genus Methanothermobacter". iScience. doi: 10.1016/j.isci.2023.108016 .
