Benjamin Sanchez-Sedillo Brendon Stoneburner Alison Boren Laurence G. Miller Shelley McCann Michael R. Rosen Ronald S. Oremland Chad W. Saltikov Jamie Hernandez-Maldonado 2017 <p><span>“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), H</span>₂<span>S, H</span>₂<span>, and NO</span>₂^-<span>. Photoarsenotrophy was recently identified from Paoha Island's (Mono Lake, CA) arsenic-rich hot springs. The genomes of several photoarsenotrophs revealed a gene cluster,&nbsp;</span><i>arxB2AB1CD,</i><span> where </span><i>arxA</i><span> is predicted to encode for the sole arsenite oxidase. The role of </span><i>arxA</i><span> in photosynthetic arsenite oxidation was confirmed by disrupting the gene in a representative photoarsenotrophic bacterium, resulting in the loss of light-dependent arsenite oxidation. </span><i>In situ&nbsp;</i><span>evidence of active photoarsenotrophic microbes was supported by </span><i>arxA</i><span> 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.</span></p> application/pdf 10.1111/1462-2920.13509 en Society for Applied Microbiology The genetic basis of anoxygenic photosynthetic arsenite oxidation article