title: Arsenite as an Electron Donor for Anoxygenic Photosynthesis: Description of Three Strains of Ectothiorhodospira from Mono Lake, California and Big Soda Lake, Nevada.
abstract: Three novel strains of photosynthetic bacteria from the family Ectothiorhodospiraceae were isolated from soda lakes of the Great Basin Desert, USA by employing arsenite (As(III)) as the sole electron donor in the enrichment/isolation process. Strain PHS-1 was previously isolated from a hot spring in Mono Lake, while strain MLW-1 was obtained from Mono Lake sediment, and strain BSL-9 was isolated from Big Soda Lake. Strains PHS-1, MLW-1, and BSL-9 were all capable of As(III)-dependent growth via anoxygenic photosynthesis and contained homologs of arxA, but displayed different phenotypes. Comparisons were made with three related species:Ectothiorhodospira shaposhnikoviiDSM 2111,Ectothiorhodospira shaposhnikoviiDSM 243T, andHalorhodospira halophilaDSM 244. All three type cultures oxidized arsenite to arsenate but did not grow with As(III) as the sole electron donor. DNA-DNA hybridization indicated that strain PHS-1 belongs to the same species asEct. shaposhnikoviiDSM 2111 (81.1% sequence similarity), distinct fromEct. shaposhnikoviiDSM 243T(58.1% sequence similarity). These results suggest that the capacity for light-driven As(III) oxidation is a common phenomenon among purple photosynthetic bacteria in soda lakes. However, the use of As(III) as a sole electron donor to sustain growth via anoxygenic photosynthesis is confined to novel isolates that were screened for by this selective cultivation criterion.
authors.affiliation: U.S. Geological Survey, Menlo Park, CA 94025, USA. smccann@usgs.gov.
authors.forename: Shelley
authors.initials: S
authors.lastname: Hoeft McCann
authors.affiliation: Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA. alisonboren@gmail.com.
authors.forename: Alison
authors.initials: A
authors.lastname: Boren
authors.affiliation: Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA. jhernan4@ucsc.edu.
authors.forename: Jaime
authors.initials: J
authors.lastname: Hernandez-Maldonado
authors.affiliation: Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA. bstonebu@ucsc.edu.
authors.forename: Brendon
authors.initials: B
authors.lastname: Stoneburner
authors.affiliation: Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA. saltikov@ucsc.edu.
authors.forename: Chad W
authors.initials: CW
authors.lastname: Saltikov
authors.affiliation: Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA. stolz@duq.edu.
authors.forename: John F
authors.initials: JF
authors.lastname: Stolz
authors.affiliation: U.S. Geological Survey, Menlo Park, CA 94025, USA. roremlan@usgs.gov.
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Oremland
keywords: Ectothiorhodospira; anoxygenic photosynthesis; arsenite; arxA; soda lakes