New Arsenite-Oxidizing Bacteria Isolated from Australian Gold Mining Environments--Phylogenetic Relationships

Santini, Joanne M.; Sly, Lindsay I.; Wen, Anbang; Comrie, Dean; Wulf-Durand, Pascal De; Macy, Joan M.

doi:10.1080/014904502317246174

Cited by 101 publications

(79 citation statements)

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“…The arsenite-oxidizing bacteria so far isolated either can gain energy from arsenite oxidation (25,32,33) or have been proposed to do so as part of a detoxification process (14,15,27,30,36). Chemolithoautotrophic arsenite oxidation, for which oxygen is used as the terminal electron acceptor, arsenite is the electron donor, and carbon dioxide is the carbon source, has to date only been reported for organisms isolated from gold mines (32, 33).…”

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confidence: 99%

Molybdenum-Containing Arsenite Oxidase of the Chemolithoautotrophic Arsenite Oxidizer NT-26

2004

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The chemolithoautotroph NT-26 oxidizes arsenite to arsenate by using a periplasmic arsenite oxidase. Purification and preliminary characterization of the enzyme revealed that it (i) contains two heterologous subunits, AroA (98 kDa) and AroB (14 kDa); (ii) has a native molecular mass of 219 kDa, suggesting an ␣ 2 ␤ 2 configuration; and (iii) contains two molybdenum and 9 or 10 iron atoms per ␣ 2 ␤ 2 unit. The genes that encode the enzyme have been cloned and sequenced. Sequence analyses revealed similarities to the arsenite oxidase of Alcaligenes faecalis, the putative arsenite oxidase of the beta-proteobacterium ULPAs1, and putative proteins of Aeropyrum pernix, Sulfolobus tokodaii, and Chloroflexus aurantiacus. Interestingly, the AroA subunit was found to be similar to the molybdenum-containing subunits of enzymes in the dimethyl sulfoxide reductase family, whereas the AroB subunit was found to be similar to the Rieske iron-sulfur proteins of cytochrome bc 1 and b 6 f complexes. The NT-26 arsenite oxidase is probably exported to the periplasm via the Tat secretory pathway, with the AroB leader sequence used for export. Confirmation that NT-26 obtains energy from the oxidation of arsenite was obtained, as an aroA mutant was unable to grow chemolithoautotrophically with arsenite. This mutant could grow heterotrophically in the presence of arsenite; however, the arsenite was not oxidized to arsenate.Arsenic is ubiquitous in the environment and is most commonly found in an insoluble form associated with rocks and minerals (11). In soluble forms, arsenic occurs as trivalent arsenite [As(III)] and pentavalent arsenate [As(V)]. Arsenate, a phosphate analogue, can enter cells via the phosphate transport system and is toxic because it can interfere with normal phosphorylation processes by replacing phosphate. It was recently demonstrated that arsenite enters cells at a neutral pH by aqua-glyceroporins (glycerol transport proteins) in bacteria, yeasts, and mammals (23, 39), and its toxicity lies in its ability to bind sulfhydryl groups of cysteine residues in proteins, thereby inactivating them.Arsenite is considered to be more toxic than arsenate and can be oxidized to arsenate chemically or microbially (12, 16). The arsenite-oxidizing bacteria so far isolated either can gain energy from arsenite oxidation (25,32,33) or have been proposed to do so as part of a detoxification process (14,15,27,30,36). Chemolithoautotrophic arsenite oxidation, for which oxygen is used as the terminal electron acceptor, arsenite is the electron donor, and carbon dioxide is the carbon source, has to date only been reported for organisms isolated from gold mines (32, 33). Aerobic growth with arsenite as the electron donor is exergonic, generating a substantial amount of free energy (32).Arsenite oxidation by the chemolithoautotrophic arsenite oxidizer NT-26, a member of the ␣-Proteobacteria, has been studied in detail (32). Preliminary biochemical studies showed the NT-26 arsenite oxidase (Aro) to be periplasmic and its synthesis to be induc...

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Molybdenum-Containing Arsenite Oxidase of the Chemolithoautotrophic Arsenite Oxidizer NT-26

2004

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“…1). Most of these strains are facultative chemolithoautotrophic arsenite oxidizers, and were isolated from arsenic-contaminated environments such as gold mine, 17,[31][32][33] hot creek, 34) and sediment. 35) In this study, we have newly isolated a facultative arsenite-oxidizing bacterium strain KGO-5 from arsenic-contaminated industrial soil, and it was phylogenetically closely related with Sinorhizobium meliloti with 16S rRNA gene sequence similarity of 99.3%.…”

Section: Discussionmentioning

confidence: 99%

Arsenite oxidation by a facultative chemolithoautotrophic Sinorhizobium sp. KGO-5 isolated from arsenic-contaminated soil

Dong

Ohtsuka

Dong

et al. 2014

Bioscience, Biotechnology, and Biochemistry

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A chemolithoautotrophic arsenite-oxidizing bacterium, designated strain KGO-5, was isolated from arsenic-contaminated industrial soil. Strain KGO-5 was phylogenetically closely related with Sinorhizobium meliloti with 16S rRNA gene similarity of more than 99%, and oxidized 5 mM arsenite under autotrophic condition within 60 h with a doubling time of 3.0 h. Additions of 0.01–0.1% yeast extract enhanced the growth significantly, and the strain still oxidized arsenite efficiently with much lower doubling times of approximately 1.0 h. Arsenite-oxidizing capacities (11.2–54.1 μmol h−1 mg dry cells−1) as well as arsenite oxidase (Aio) activities (1.76–10.0 mU mg protein−1) were found in the cells grown with arsenite, but neither could be detected in the cells grown without arsenite. Strain KGO-5 possessed putative aioA gene, which is closely related with AioA of Ensifer adhaerens. These results suggest that strain KGO-5 is a facultative chemolithoautotrophic arsenite oxidizer, and its Aio is induced by arsenic.

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“…Thus, some microorganisms can change the oxidation state of As as a mechanism of resistance to toxicity. Arsenic oxidation is mainly used by microorganisms as a detoxification strategy, although there have been isolated bacteria that use As in their metabolic processes linked to cellular respiration and energy conservation [84]. Biotic oxidation of As is mediated by enzymes known as arsenite oxidases, such as AroA/B, AsoA/B, and AoxA/B [85][86][87].…”

Section: Arsenic-bearing Ores Bioleachingmentioning

confidence: 99%

Bioleaching of Arsenic-Bearing Copper Ores

2018

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Abstract:World copper (Cu) production has been strongly affected by arsenic (As) content, because As-rich Cu concentrates are not desirable in the metal foundries. When As-rich Cu concentrates are processed by smelting they release As as volatile compounds into the atmosphere and inside furnaces, generating serious risks to human health. In recent years, exports of Cu concentrates are being penalized for the increasingly high As content of the ores, causing economies that depend on the Cu market to be seriously harmed by this impurity. In the last few decades, biohydrometallurgy has begun to replace the traditional Cu sulfide processing, however bioleaching processes for As-bearing Cu ores which contain enargite are still in the development stage. Researchers have not yet made successful progress in enargite bioleaching using typical mesophilic and thermophilic bacteria that oxidize sulfide. New approaches based on direct oxidative/reductive dissolution of As from enargite could result in significant contributions to Cu biohydrometallurgy. Thus, As-rich Cu concentrates could be pre-treated by bioleaching, replacing current technologies like roasting, pressure leaching and alkaline leaching by selective biological arsenite oxidation or arsenate reduction. In this article, we review the As problem in Cu mining, conventional technologies, the biohydrometallurgy approach, and As bioleaching as a treatment alternative.

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New Arsenite-Oxidizing Bacteria Isolated from Australian Gold Mining Environments--Phylogenetic Relationships

Cited by 101 publications

References 11 publications

Molybdenum-Containing Arsenite Oxidase of the Chemolithoautotrophic Arsenite Oxidizer NT-26

Molybdenum-Containing Arsenite Oxidase of the Chemolithoautotrophic Arsenite Oxidizer NT-26

Arsenite oxidation by a facultative chemolithoautotrophic Sinorhizobium sp. KGO-5 isolated from arsenic-contaminated soil

Bioleaching of Arsenic-Bearing Copper Ores

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