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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 of 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 H
2 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.
Geothrix fermentans is a rod-shaped, anaerobic bacterium. It is about 0.1 µm in diameter and ranges from 2-3 µm in length. Cell arrangement occurs singly and in chains. Geothrix fermentans can normally be found in aquatic sediments such as in aquifers. As an anaerobic chemoorganotroph, this organism is best known for its ability to use electron acceptors Fe(III), as well as other high potential metals. It also uses a wide range of substrates as electron donors. Research on metal reduction by G. fermentans has contributed to understanding more about the geochemical cycling of metals in the environment.
Shewanella frigidimarina is a species of bacteria, notable for being an Antarctic species with the ability to produce eicosapentaenoic acid. It grows anaerobically by dissimilatory Fe (III) reduction. Its cells are motile and rod shaped. ACAM 591 is its type strain.
Desulfofrigus oceanense is a bacterium. It is a psychrophilic Gram-negative and sulfate-reducing bacteria with type strain Asv26T.
Desulfofrigus fragile is a bacterium. It is a psychrophilic Gram-negative and sulfate-reducing bacteria with type strain Lsv21T.
Desulfuromusa ferrireducens is a species of psychrophilic, Fe(III)-reducing bacteria. It is Gram-negative, rod-shaped and motile. Its type strain is 102T.
Psychroserpens burtonensis is a species of psychrophilic, yellow-pigmented bacteria. It is non-motile and nutritionally fastidious. Its type strain is ACAM 188.
Gelidibacter algens is a species of psychrophilic, yellow-pigmented bacteria. It is saccharolytic, exhibits rapid gliding motility, and its cells are rod-like to filamentous. Its type strain is ACAM 536.
Rhodoferax is a genus of Betaproteobacteria belonging to the purple nonsulfur bacteria. Originally, Rhodoferax species were included in the genus Rhodocyclus as the Rhodocyclus gelatinous-like group. The genus Rhodoferax was first proposed in 1991 to accommodate the taxonomic and phylogenetic discrepancies arising from its inclusion in the genus Rhodocyclus. Rhodoferax currently comprises four described species: R. fermentans, R. antarcticus, R. ferrireducens, and R. saidenbachensis. R. ferrireducens, lacks the typical phototrophic character common to two other Rhodoferax species. This difference has led researchers to propose the creation of a new genus, Albidoferax, to accommodate this divergent species. The genus name was later corrected to Albidiferax. Based on geno- and phenotypical characteristics, A. ferrireducens was reclassified in the genus Rhodoferax in 2014. R. saidenbachensis, a second non-phototrophic species of the genus Rhodoferax was described by Kaden et al. in 2014.
Glaciecola punicea is a psychrophilic bacteria found in Antarctic sea-ice habitats, being the type species of its genus. It is pigmented, psychrophilic, and a strictly aerobic chemoheterotroph. Its type strain is. Its genome has been sequenced.
Glaciecola pallidula is a psychrophilic bacteria found in Antarctic sea-ice habitats, being the type species of its genus. It is pigmented, psychrophilic, and a strictly aerobic chemoheterotroph. Its type strain is.
Geobacter bemidjiensis is a Fe(III)-reducing bacteria. It is Gram-negative, slightly curved rod-shaped and is motile via means of monotrichous flagella. Its type strain is BemT.
Geobacter psychrophilus is a Fe(III)-reducing bacterium. It is Gram-negative, slightly curved, rod-shaped and motile via means of monotrichous flagella. Its type strain is P35T.
Sphingomonas alpina is a Gram-negative, aerobic, psychrophilic and motile bacteria from the genus of Sphingomonas which has been isolated from alpine soil from the High Tauern in Austria.
Sphingomonas glacialis is a Gram-positive, rod-shaped, psychrophilic and non-motile bacteria from the genus of Sphingomonas which has been isolated from cryoconite from the Stubai Glacier in Tyrol in Austria.
Desulfuromonas is a Gram negative bacterial genus from the family of Desulfuromonadaceae. Desulfuromonas can reduce elemental sulfur to H2S. Desulfuromonas occur in anoxic sediments and saline lakes.
Desulfovibrio ferrireducens is a psychrotolerant bacterium from the genus of Desulfovibrio which has been isolated from permanently cold sediments from Fjord in Svalbard.
Violacein is a naturally-occurring bis-indole pigment with antibiotic properties. Violacein is produced by several species of bacteria, including Chromobacterium violaceum, and gives these organisms their striking purple hues. Violacein shows increasing commercially interesting uses, especially for industrial applications in cosmetics, medicines and fabrics.
Desulfofaba gelida is a Gram-negative, sulfate-reducing and psychrophilic bacterium from the genus of Desulfofaba which has been isolated from marine mud from Hornsund in Norway.
Geopsychrobacter is a genus of bacteria from the order Desulfuromonadales.
References
- ↑ Vandieken, V. (2006). "Desulfuromonas svalbardensis sp. nov. and Desulfuromusa ferrireducens sp. nov., psychrophilic, Fe(III)-reducing bacteria isolated from Arctic sediments, Svalbard". International Journal of Systematic and Evolutionary Microbiology. 56 (5): 1133–1139. doi: 10.1099/ijs.0.63639-0 . hdl: 21.11116/0000-0001-CF69-1 . ISSN 1466-5026. PMID 16627667.
