Microbiology of inorganic arsenic: From metabolism to bioremediation

Ohtsuka

Bioscience, Biotechnology, and Biochemistry

et al. 2014

Self Cite

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.

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Arsenite oxidation by a facultative chemolithoautotrophicSinorhizobiumsp. KGO-5 isolated from arsenic-contaminated soil

Ohtsuka

Bioscience, Biotechnology, and Biochemistry

et al. 2014

Self Cite

“…Bosea thiooxidans is a reported heterotrophic, strict aerobe, and inorganic sulfur oxidizer [118]. After isolating, mineral studies with arsenopyrite and pyrite-bound As confirmed that Bosea WAO oxidizes sulfide and arsenite [119]. Arsenic mobilization from the mineral phase should have been enhanced by oxidation of sulfide in the pyrite lattice, and also by aqueous arsenite oxidation through the removal of it from the surface layer or by decreasing arsenite concentration from the solution [117].…”

Section: Enargite Bioleaching With Neutrophilic Microorganismsmentioning

confidence: 99%

“…It is known that bacteria are capable of naturally mobilizing As by redox reactions, thus reducing or oxidizing it [119][120][121][122][123]. The proposed idea of As-recovery by bio-oxidation from enargite or As-rich Cu concentrates comes from studies on arsenopyrite dissolution.…”

Section: Bioleaching Pre-treatment Releasing Arsenicmentioning

confidence: 99%

Bioleaching of Arsenic-Bearing Copper Ores

2018

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.

“…ANA-3 compared to that of other bacteria. 5,16 This observation raises the question of why for some enzymes a dedicated chaperone is required and why some others can insert their cofactor without the support of accessory proteins. The fact that a minimal amount of TorA can be matured in the absence of the chaperone TorD indicates that the maturation process can be done even without specific chaperone, although this appears not to be the rule.…”

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confidence: 99%

Chaperones in maturation of molybdoenzymes: Why specific is better than general?

et al. 2016

Molybdoenzymes play essential functions in living organisms and, as a result, in various geochemical cycles. It is thus crucial to understand how these complex proteins become highly efficient enzymes able to perform a wide range of catalytic activities. It has been established that specific chaperones are involved during their maturation process. Here, we raise the question of the involvement of general chaperones acting in concert with dedicated chaperones or not.