The genetic basis of anoxygenic photosynthetic arsenite oxidation |
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| Authors: | Jaime Hernandez‐Maldonado Benjamin Sanchez‐Sedillo Brendon Stoneburner Alison Boren Laurence Miller Shelley McCann Michael Rosen Ronald S. Oremland Chad W. Saltikov |
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| Affiliation: | 1. Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, CA, USA;2. US Geological Survey, CA, USA;3. US Geological Survey, Carson City, NV, USA |
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| Abstract: | ‘Photoarsenotrophy’, the use of arsenite as an electron donor for anoxygenic photosynthesis, is thought to be an ancient form of phototrophy along with the photosynthetic oxidation of Fe(II), H2S, H2 and  . Photoarsenotrophy was recently identified from Paoha Island's (Mono Lake, CA) arsenic‐rich hot springs. The genomes of several photoarsenotrophs revealed a gene cluster, arxB2AB1CD, where arxA is predicted to encode for the sole arsenite oxidase. The role of arxA in photosynthetic arsenite oxidation was confirmed by disrupting the gene in a representative photoarsenotrophic bacterium, resulting in the loss of light‐dependent arsenite oxidation. In situ evidence of active photoarsenotrophic microbes was supported by arxA mRNA detection for the first time, in red‐pigmented microbial mats within the hot springs of Paoha Island. This work expands on the genetics for photosynthesis coupled to new electron donors and elaborates on known mechanisms for arsenic metabolism, thereby highlighting the complexities of arsenic biogeochemical cycling. |
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. Photoarsenotrophy was recently identified from Paoha Island's (Mono Lake, CA) arsenic‐rich hot springs. The genomes of several photoarsenotrophs revealed a gene cluster, arxB2AB1CD, where arxA is predicted to encode for the sole arsenite oxidase. The role of arxA in photosynthetic arsenite oxidation was confirmed by disrupting the gene in a representative photoarsenotrophic bacterium, resulting in the loss of light‐dependent arsenite oxidation. In situ evidence of active photoarsenotrophic microbes was supported by arxA mRNA detection for the first time, in red‐pigmented microbial mats within the hot springs of Paoha Island. This work expands on the genetics for photosynthesis coupled to new electron donors and elaborates on known mechanisms for arsenic metabolism, thereby highlighting the complexities of arsenic biogeochemical cycling.