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In biochemistry, chemosynthesis is the biological conversion of one or more carbon-containing molecules and nutrients into organic matter using the oxidation of inorganic compounds or ferrous ions as a source of energy, rather than sunlight, as in photosynthesis. Chemoautotrophs, organisms that obtain carbon from carbon dioxide through chemosynthesis, are phylogenetically diverse. Groups that include conspicuous or biogeochemically-important taxa include the sulfur-oxidizing gamma and epsilon proteobacteria, the Aquificae, the methanogenic archaea and the neutrophilic iron-oxidizing bacteria.
Sulfur-reducing bacteria are microorganisms able to reduce elemental sulfur (S0) to hydrogen sulfide (H2S). These microbes use inorganic sulfur compounds as electron acceptors to sustain several activities such as respiration, conserving energy and growth, in absence of oxygen. The final product or these processes, sulfide, has a considerable influence on the chemistry of the environment and, in addition, is used as electron donor for a large variety of microbial metabolisms. Several types of bacteria and many non-methanogenic archaea can reduce sulfur. Microbial sulfur reduction was already shown in early studies, which highlighted the first proof of S0 reduction in a vibrioid bacterium from mud, with sulfur as electron acceptor and H2 as electron donor. The first pure cultured species of sulfur-reducing bacteria, Desulfuromonas acetoxidans, was discovered in 1976 and described by Pfennig Norbert and Biebel Hanno as an anaerobic sulfur-reducing and acetate-oxidizing bacterium, not able to reduce sulfate. Only few taxa are true sulfur-reducing bacteria, using sulfur reduction as the only or main catabolic reaction. Normally, they couple this reaction with the oxidation of acetate, succinate or other organic compounds. In general, sulfate-reducing bacteria are able to use both sulfate and elemental sulfur as electron acceptors. Thanks to its abundancy and thermodynamic stability, sulfate is the most studied electron acceptor for anaerobic respiration that involves sulfur compounds. Elemental sulfur, however, is very abundant and important, especially in deep-sea hydrothermal vents, hot springs and other extreme environments, making its isolation more difficult. Some bacteria – such as Proteus, Campylobacter, Pseudomonas and Salmonella – have the ability to reduce sulfur, but can also use oxygen and other terminal electron acceptors.
Geoglobus is a hyperthermophilic member of the Archaeoglobaceae within the Euryarchaeota. It consists of two species, the first, G. ahangari, isolated from the Guaymas Basin hydrothermal system located deep within the Gulf of California. As a hyperthermophile, it grows best at a temperature of 88 °C and cannot grow at temperatures below 65 °C or above 90 °C. It possess an S-layer cell wall and a single flagellum. G. ahangari is an anaerobe, using poorly soluble ferric iron (Fe3+) as a terminal electron acceptor. It can grow either autotrophically using hydrogen gas (H2) or heterotrophically using a large number of organic compounds, including several types of fatty acids, as energy sources. G. ahangari was the first archaeon isolated capable of using hydrogen gas coupled to iron reduction as an energy source and the first anaerobe isolated capable of using long-chain fatty acids as an energy source.
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.
In taxonomy, Thermococcus is a genus of thermophilic Archaea in the family the Thermococcaceae.
Sulfurimonas is a bacterial genus within the class of Campylobacterota, known for reducing nitrate, oxidizing both sulfur and hydrogen, and containing Group IV hydrogenases. This genus consists of four species: Sulfurimonas autorophica, Sulfurimonas denitrificans, Sulfurimonas gotlandica, and Sulfurimonas paralvinellae. The genus' name is derived from "sulfur" in Latin and "monas" from Greek, together meaning a “sulfur-oxidizing rod”. The size of the bacteria varies between about 1.5-2.5 μm in length and 0.5-1.0 μm in width. Members of the genus Sulfurimonas are found in a variety of different environments which include deep sea-vents, marine sediments, and terrestrial habitats. Their ability to survive in extreme conditions is attributed to multiple copies of one enzyme. Phylogenetic analysis suggests that members of the genus Sulfurimonas have limited dispersal ability and its speciation was affected by geographical isolation rather than hydrothermal composition. Deep ocean currents affect the dispersal of Sulfurimonas spp., influencing its speciation. As shown in the MLSA report of deep-sea hydrothermal vents Campylobacterota, Sulfurimonas has a higher dispersal capability compared with deep sea hydrothermal vent thermophiles, indicating allopatric speciation.
Caminibacter hydrogeniphilus is a species of thermophilic, hydrogen-oxidizing bacterium. It is anaerobic, rod-shaped, motile and has polar flagella. The type strain is AM1116T.
Persephonella marina is a Gram-negative, rod shaped bacteria that is a member of the Aquificota phylum. Stemming from Greek, the name Persephonella is based upon the mythological goddess Persephone. Marina stems from a Latin origin, meaning "belonging to the sea". It is a thermophile with an obligate chemolithoautotrophic metabolism. Growth of P. marina can occur in pairs or individually, but is rarely seen aggregating in large groups. The organism resides on sulfidic chimneys in the deep ocean and has never been documented as a pathogen.
Nautilia lithotrophica is a thermophilic sulfur-reducing epsilon-proteobacterium isolated from a deep-sea hydrothermal vent. It is strictly anaerobic, with type strain 525T.
Caminibacter profundus is a species of moderately thermophilic, microaerobic to anaerobic, chemolithoautotrophic bacterium. It is a Gram-negative, non-motile rod, with type strain CRT.
Deferribacter desulfuricans is a species of sulfur-, nitrate- and arsenate-reducing thermophile first isolated from a deep-sea hydrothermal vent. It is an anaerobic, heterotrophic thermophile with type strain SSM1T.
Methanothermococcus okinawensis is a thermophilic, methane-producing archaeon first isolated from deep-sea hydrothermal vent on the western Pacific Ocean. Its cells are highly motile, irregular cocci, with a polar bundle of flagella. Its type strain is IH1T. It grows at an optimal temperature of 60–65 °C and pH of 6.7. It is strictly anaerobic and reduces carbon dioxide with hydrogen to produce methane, but it can also use formate. Research studies indicate that it might be able to survive extreme conditions in solar system's other bodies, such as Saturn's moon Enceladus.
Tepidibacter is a genus of Gram-positive bacteria in the family Clostridiaceae.
Caloranaerobacter is a Gram-negative, thermophilic, anaerobic and chemoorganotrophic bacterial genus from the family of Clostridiaceae.
Caloranaerobacter azorensis is a Gram-negative, thermophilic, anaerobic, chemoorganotrophic and motile bacterium from the genus of Caloranaerobacter which has been isolated from a deep-sea hydrothermal vent from the Lucky Strike hydrothermal vent site from the Mid-Atlantic Ridge.
Lebetimonas is a genus of bacteria from the family Nautiliaceae.
Lebetimonas acidiphila is a thermophilic, acidophilic, hydrogen-oxidizing and motile bacterium from the genus of Lebetimonas. To observe growth there temperature should be between 30 and 68 degrees Celsius.
The hydrothermal vent microbial community includes all unicellular organisms that live and reproduce in a chemically distinct area around hydrothermal vents. These include organisms in the microbial mat, free floating cells, or bacteria in an endosymbiotic relationship with animals. Chemolithoautotrophic bacteria derive nutrients and energy from the geological activity at Hydrothermal vents to fix carbon into organic forms. Viruses are also a part of the hydrothermal vent microbial community and their influence on the microbial ecology in these ecosystems is a burgeoning field of research.
Thermodesulfobacterium hveragerdense is a bacterial species belonging to genus Thermodesulfobacterium, which are thermophilic sulfate-reducing bacteria. This species is found in aquatic areas of high temperature, and lives in freshwater like most, but not all Thermodesulfobacterium species It was first isolated from hotsprings in Iceland.
References
- ↑ Gotz, D. (2002). "Persephonella marina gen. nov., sp. nov. and Persephonella guaymasensis sp. nov., two novel, thermophilic, hydrogen-oxidizing microaerophiles from deep-sea hydrothermal vents". International Journal of Systematic and Evolutionary Microbiology. 52 (4): 1349–1359. doi:10.1099/ijs.0.02126-0. ISSN 1466-5026.
