Arsenite oxidation by a facultative chemolithoautotrophic Sinorhizobium sp. KGO-5 isolated from arsenic-contaminated soil |
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Authors: | Dan Dong Toshihiko Ohtsuka Dian Tao Dong |
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Institution: | Graduate School of Horticulture, Chiba University, Matsudo, Japan |
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Abstract: | 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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Keywords: | arsenic arsenite oxidation Sinorhizobium bioremediation |
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