Thioalkalivibrio thiocyanoxidans sp. nov. and Thioalkalivibrio paradoxus sp. nov., novel alkaliphilic, obligately autotrophic, sulfur-oxidizing bacteria capable of growth on thiocyanate, from soda lakes.

Sorokin, D. Yu.; Tourova, T. P.; Lysenko, Anatoly M.; Mityushina, L. L.; Kuenen, J.G.

doi:10.1099/00207713-52-2-657

Cited by 95 publications

(66 citation statements)

References 12 publications

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“…The first two groups of bacteria showed high levels of cyanase activity contrary to the third group of bacteria. Recently described new genera and species of the third type of thiocyanate degrading bacteria included Thioalkalivibrio paradoxus and Thioalkalivibrio thiocyanoxidans [Sorokin et al, 2002]; Thialkalivibrio thiocyanodenitrificans , able to grow with thiocyanate as electron donor, either aerobically or anaerobically, and with nitrate or nitrite as electron acceptor [Sorokin et al, 2004] and Thiohalophilus thiocyanoxidans capable of anaerobic growth with nitrite as electron acceptor and thiocyanate as electron donor under hypersaline conditions (2-4 M NaCl) [Sorokin et al, 2007b].…”

Section: Sulfur Compoundsmentioning

confidence: 99%

Biodegradation of Organic Pollutants by Halophilic Bacteria and Archaea

Borgne¹,

2008

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Hypersaline environments are important for both surface extension and ecological significance. As all other ecosystems, they are impacted by pollution. However, little information is available on the biodegradation of organic pollutants by halophilic microorganisms in such environments. In addition, it is estimated that 5% of industrial effluents are saline and hypersaline. Conventional nonextremophilic microorganisms are unable to efficiently perform the removal of organic pollutants at high salt concentrations. Halophilic microorganisms are metabolically different and are adapted to extreme salinity; these microorganisms are good candidates for the bioremediation of hypersaline environments and treatment of saline effluents. This literature survey indicates that both the moderately halophilic bacteria and the extremely halophilic archaea have a broader catabolic versatility and capability than previously thought. A diversity of contaminating compounds is susceptible to be degraded by halotolerant and halophile bacteria. Nevertheless, significant research efforts are still necessary in order to estimate the true potential of these microorganisms to be applied in environmental processes and in the remediation of contaminated hypersaline ecosystems. This effort should be also focused on basic research to understand the overall degradation mechanism, to identify the enzymes involved in the degradation process and the metabolism regulation.

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Section: Sulfur Compoundsmentioning

confidence: 99%

Biodegradation of Organic Pollutants by Halophilic Bacteria and Archaea

Borgne¹,

2008

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“…Several Thioalkalivibrio strains are adapted to concentrated soda brines with Na ϩ concentrations up 4.5 M, but not T. paradoxus. Like most Thioalkalivibrio strains, T. paradoxus grows optimally at moderate sodium concentrations (0.5 to 1 M) (21,29). Glycine betaine and small amounts of sucrose are the only compatible solutes identified so far, and ectoine was not present (29)(30)(31).…”

Section: Discussionmentioning

confidence: 99%

“…Genes for the Sox complex are incomplete: the soxCD genes for sulfane dehydrogenase are missing, suggesting that the remaining SoxAX, SoxYZ, and SoxB proteins (see Table S2 in the supplemental material) oxidize thiosulfate to sulfur, which is then stored in the sulfur globules previously observed in T. paradoxus cells (Fig. 7) (21). Both SOR and PDO might then oxidize the transiently formed sulfur from the globules upon depletion of the primary substrate.…”

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“…paradoxus grows best by aerobic dissimilatory oxidation of thiosulfate and thiocyanate; however, sulfide, polysulfide and CS 2 are also used (21). A survey for proteins predicted to play a role in sulfur metabolism showed that the genome (23) encodes-in addition to the SOR-a glutathione persulfide (di)oxygenase (PDO) homologous to the human ETHE1 protein (see Table S2 in the supplemental material).…”

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“…paradoxus does not grow anaerobically on nitrate or on other electron acceptors, but it might use nitrate in addition to oxygen during microaerobic growth on thiosulfate (21). A cytochrome c nitrite reductase was purified and crystallized from T. paradoxus cells grown aerobically in the presence of nitrate (28), and nitrate reductase genes are found in the genome as well.…”

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A Sulfur Oxygenase from the Haloalkaliphilic Bacterium Thioalkalivibrio paradoxus with Atypically Low Reductase Activity

et al. 2017

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Sequence comparisons showed that the sulfur oxygenase reductase (SOR) of the haloalkaliphilic bacterium Thioalkalivibrio paradoxus Arh 1 (TpSOR) is branching deeply within dendrograms of these proteins (29 to 34% identity). A synthetic gene encoding TpSOR expressed in Escherichia coli resulted in a protein 14.7 Ϯ 0.9 nm in diameter and an apparent molecular mass of 556 kDa. Sulfite and thiosulfate were formed from elemental sulfur in a temperature range of 10 to 98°C (optimum temperature Ϸ 80°C) and a pH range of 6 to 11.5 (optimum pH Ϸ 9; 308 Ϯ 78 U/mg of protein). Sulfide formation had a maximum specific activity of 0.03 U/mg, or Ͻ1% of the corresponding activity of other SORs. Hence, reductase activity seems not to be an integral part of the reaction mechanism. TpSOR was most active at NaCl or glycine betaine concentrations of 0 to 1 M, although 0.2% of the maximal activity was detected even at 5 M NaCl and 4 M betaine. The melting point of TpSOR was close to 80°C, when monitored by circular dichroism spectroscopy or differential scanning fluorimetry; however, the denaturation kinetics were slow: 55% of the residual activity remained after 25 min of incubation at 80°C. Sitedirected mutagenesis showed that the active-site residue Cys 44 is essential for activity, whereas alanine mutants of the two other conserved cysteines retained about 0.5% residual activity. A model of the sulfur metabolism in T. paradoxus is discussed.IMPORTANCE Sulfur oxygenase reductases (SORs) are the only enzymes catalyzing an oxygen-dependent disproportionation of elemental sulfur and/or polysulfides to sulfite, thiosulfate, and hydrogen sulfide. SORs are known from mesophilic and extremophilic archaea and bacteria. All SORs seem to form highly thermostable 24-subunit hollow spheres. They carry a low-potential mononuclear nonheme iron in the active site and an indispensable cysteine; however, their exact reaction mechanisms are unknown. Typically, the reductase activity of SORs is in the range of 5 to 50% of the oxygenase activity, but mutagenesis studies had so far failed to identify residues crucial for the reductase reaction. We describe here the first SOR, which is almost devoid of the reductase reaction and which comes from a haloalkaliphilic bacterium.KEYWORDS Thioalkalivibrio, alkaliphile, extremophiles, sulfur disproportionation, sulfur oxygenase reductase, thermostability, Allochromatium vinosum, Acidianus ambivalens S ulfur oxygenase reductases (SORs) catalyze a dioxygen-dependent disproportionation reaction of elemental sulfur (S 0 , consisting mostly of cyclo-octasulfur) with sulfite, thiosulfate, and sulfide as detectable products (1-3). It is not yet known whether thiosulfate is a primary reaction product of the enzyme reaction or whether it is formed

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Octaheme CytochromecNitrite Reductase

Tikhonova¹,

Polyakov²,

Boyko³

et al. 2004

Handbook of Metalloproteins

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Octaheme cytochrome c nitrite reductase (TvNiR) from bacterium Thioalkalivibrio nitratireducens catalyzes the six‐electron reduction of nitrite and two‐electron reduction of hydroxylamine to ammonium without release of any intermediates. TvNiR also catalyzes the six‐electron reduction of sulfite to sulfide. High‐resolution structures of the TvNiR apo‐form and its complexes with the substrates (nitrite and sulfite) and inhibitors (azide and phosphate) were obtained. The subunit of TvNiR consists of two domains. The N‐terminal domain has a unique fold and contains three hemes. The remaining five hemes are located in the catalytic C‐terminal domain, with the heme arrangement, including the catalytic heme, being identical to that found in pentaheme cytochrome c nitrite reductases (ccNiRs). The catalytic machinery of TvNiR resembles that of ccNiRs. It comprises the lysine residue in the proximal position of the catalytic heme, the catalytic triad of tyrosine, histidine, and arginine on the distal side, channels for the substrate and product transport, and two conserved Ca 2+ ‐binding sites. The complete set of eight hemes forms a spatial pattern characteristic of other structurally characterized octaheme cytochromes. In the crystalline state and in solution, TvNiR exists as a stable hexamer containing 48 hemes, which are clustered into three isolated groups, each group comprising 16 interacting hemes.

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Thioalkalivibrio thiocyanoxidans sp. nov. and Thioalkalivibrio paradoxus sp. nov., novel alkaliphilic, obligately autotrophic, sulfur-oxidizing bacteria capable of growth on thiocyanate, from soda lakes.

Cited by 95 publications

References 12 publications

Biodegradation of Organic Pollutants by Halophilic Bacteria and Archaea

Biodegradation of Organic Pollutants by Halophilic Bacteria and Archaea

A Sulfur Oxygenase from the Haloalkaliphilic Bacterium Thioalkalivibrio paradoxus with Atypically Low Reductase Activity

Octaheme CytochromecNitrite Reductase

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