Chrysiogenes arsenatis is a species of bacterium in the family Chrysiogenaceae. It has a unique biochemistry. Instead of respiring with oxygen, it respires using the most oxidized form of arsenic, arsenate. It uses arsenate as its terminal electron acceptor. Arsenic is usually toxic to life. Bacteria like Chrysiogenes arsenatis are found in anoxic arsenic-contaminated environments.
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.
Marinobacter is a genus of bacteria found in sea water. They are also found in a variety of salt lakes. A number of strains and species can degrade hydrocarbons. The species involved in hydrocarbon degradation include M. alkaliphilus, M. arcticus, M. hydrocarbonoclasticus, M. maritimus, and M. squalenivorans.
Pyrobaculum is a genus of the Thermoproteaceae.
Venenivibrio stagnispumantis strain CP.B2 is the first microorganisms isolated from the terrestrial hot spring Champagne Pool in Waiotapu, New Zealand.
GFAJ-1 is a strain of rod-shaped bacteria in the family Halomonadaceae. It is an extremophile that was isolated from the hypersaline and alkaline Mono Lake in eastern California by geobiologist Felisa Wolfe-Simon, a NASA research fellow in residence at the US Geological Survey. In a 2010 Science journal publication, the authors claimed that the microbe, when starved of phosphorus, is capable of substituting arsenic for a small percentage of its phosphorus to sustain its growth. Immediately after publication, other microbiologists and biochemists expressed doubt about this claim, which was robustly criticized in the scientific community. Subsequent independent studies published in 2012 found no detectable arsenate in the DNA of GFAJ-1, refuted the claim, and demonstrated that GFAJ-1 is simply an arsenate-resistant, phosphate-dependent organism.
Desulfosporosinus is a genus of strictly anaerobic, sulfate-reducing bacteria, often found in soil.
Arsenate reductase (cytochrome c) (EC 1.20.2.1, arsenite oxidase) is an enzyme with systematic name arsenite:cytochrome c oxidoreductase. This enzyme catalyses the following chemical reaction
Bacillus selenitireducens is a bacterium first isolated from Mono Lake, California. It is notable for respiring oxyanions of selenium and arsenic. It is spore-forming, rod-shaped and alkaliphile, its type strain being MLS10.
Desulfitobacterium hafniense is a species of gram positive bacteria, its type strain is DCB-2T..
Arsenate-reducing bacteria are bacteria which reduce arsenates. Arsenate-reducing bacteria are ubiquitous in arsenic-contaminated groundwater (aqueous environment). Arsenates are salts or esters of arsenic acid (H3AsO4), consisting of the ion AsO43−. They are moderate oxidizers that can be reduced to arsenites and to arsine. Arsenate can serve as a respiratory electron acceptor for oxidation of organic substrates and H2S or H2. Arsenates occur naturally in minerals such as adamite, alarsite, legrandite, and erythrite, and as hydrated or anhydrous arsenates. Arsenates are similar to phosphates since arsenic (As) and phosphorus (P) occur in group 15 (or VA) of the periodic table. Unlike phosphates, arsenates are not readily lost from minerals due to weathering. They are the predominant form of inorganic arsenic in aqueous aerobic environments. On the other hand, arsenite is more common in anaerobic environments, more mobile, and more toxic than arsenate. Arsenite is 25–60 times more toxic and more mobile than arsenate under most environmental conditions. Arsenate can lead to poisoning, since it can replace inorganic phosphate in the glyceraldehyde-3-phosphate --> 1,3-biphosphoglycerate step of glycolysis, producing 1-arseno-3-phosphoglycerate instead. Although glycolysis continues, 1 ATP molecule is lost. Thus, arsenate is toxic due to its ability to uncouple glycolysis. Arsenate can also inhibit pyruvate conversion into acetyl-CoA, thereby blocking the TCA cycle, resulting in additional loss of ATP.
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.
Marinobacter antarcticus is a Gram-negative, aerobic, halotolerant, rod-shaped and motile bacterium from the genus of Marinobacter which has been isolated from Antarctic sediments.
Marinobacter aromaticivorans is a Gram-negative, rod-shaped and slightly halotolerant bacterium from the genus of Marinobacter which has been isolated from sediments from the South China Sea. Marinobacter aromaticivorans has the ability to degrade polycyclic aromatic hydrocarbons.
Marinobacter daqiaonensis is a Gram-negative and moderately halophilic bacterium from the genus of Marinobacter which has been isolated from sediments of the Daqiao saltern in Qingdao.
Marinobacter excellens is a Gram-negative and halophilic bacterium from the genus of Marinobacter which has been isolated from sediments from the Chazhma Bay from the Sea of Japan.
Marinobacter lacisalsi is a Gram-negative, non-spore-forming, aerobic and moderately halophilic bacterium from the genus of Marinobacter which has been isolated from the lake from Fuente de Piedra in Spain.
Marinobacter mobilis is a Gram-negative, halophilic, aerobic and motile bacterium from the genus of Marinobacter which has been isolated from sediments from the East China Sea.
Marinobacter segnicrescens is a Gram-negative, non-spore-forming, ellipsoid-shaped, moderately halophilic and motile bacterium from the genus of Marinobacter which has been isolated from sediments from the South China Sea.
Geobacter uraniireducens is a gram-negative, rod-shaped, anaerobic, chemolithotrophic, mesophilic, and motile bacterium from the genus of Geobacter. G. uraniireducens has been found to reduce iron and uranium in sediment and soil. It is being studied for use in bioremediation projects due to its ability to reduce uranium and arsenic.
