Anaerobic arsenite oxidation by novel denitrifying isolates

E. Danielle Rhine, Craig D. Phelps, L. Y. Young

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165 Scopus citations


Autotrophic microorganisms have been isolated that are able to derive energy from the oxidation of arsenite [As(III)] to arsenate [As(V)]under aerobic conditions. Based on chemical energetics, microbial oxidation of As(III) can occur in the absence of oxygen, and may be relevant in some environments. Enrichment cultures were established from an arsenic contaminated industrial soil amended with As(III) as the electron donor, inorganic C as the carbon source and nitrate as the electron acceptor. In the active enrichment cultures, oxidation of As(III) was stoichiometrically coupled to the reduction of NO 3-. Two autotrophic As(III)-oxidizing strains were isolated that completely oxidized 5 mM As(III) within 7 days under denitrifying conditions. Based on 16S rRNA gene sequencing results, strain DAO1 was 99% related to Azoarcus and strain DAO10 was most closely related to a Sinorhizobium. The nitrous oxide reductase (nosZ) and the RuBisCO Type II (cbbM) genes were successfully amplified from both isolates underscoring their ability to denitrify and fix CO2 while coupled to As(III) oxidation. Although limited work has been done to examine the diversity of anaerobic autotrophic oxidizers of As(III), this process may be an important component in the biological cycling of arsenic within the environment.

Original languageEnglish (US)
Pages (from-to)899-908
Number of pages10
JournalEnvironmental microbiology
Issue number5
StatePublished - May 2006

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics


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