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Published on: January 12, 2024
Anaerobic arsenite oxidation by novel denitrifying isolates
E Danielle Rhine1, Craig D Phelps, L Y Young
1Biotechnology Center for Agriculture and the Environment, Cook College, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA.
Environmental Microbiology
|April 21, 2006
Summary
Newly discovered microbes can oxidize arsenite to arsenate without oxygen, using nitrate. This anaerobic process is crucial for arsenic cycling in contaminated environments.
Area of Science:
- Microbiology
- Environmental Science
- Biogeochemistry
Background:
- Autotrophic microorganisms can oxidize arsenite [As(III)] to arsenate [As(V)] aerobically.
- Microbial oxidation of As(III) can occur anaerobically, coupled to other electron acceptors, and is relevant in specific environments.
Purpose of the Study:
- To isolate and characterize anaerobic, autotrophic arsenite-oxidizing microorganisms.
- To investigate the coupling of arsenite oxidation with nitrate reduction.
Main Methods:
- Enrichment cultures from contaminated soil using As(III), inorganic carbon, and nitrate.
- Isolation of two autotrophic As(III)-oxidizing strains (DAO1 and DAO10).
- 16S rRNA gene sequencing for phylogenetic identification and amplification of nosZ and cbbM genes.
Main Results:
- Two novel strains, DAO1 (related to Azoarcus) and DAO10 (related to Sinorhizobium), were isolated.
- Both strains stoichiometrically coupled As(III) oxidation to nitrate reduction under anaerobic conditions.
- Genes for denitrification (nosZ) and carbon fixation (cbbM) were identified in both isolates.
Conclusions:
- Anaerobic autotrophic oxidation of arsenite coupled to denitrification is a viable microbial process.
- These findings expand our understanding of arsenic biogeochemical cycling in anoxic environments.
- The isolated strains represent important players in the biological transformation of arsenic.
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