1. Field evidence of selenium bioreduction in a uranium-contaminated aquifer.
- Author
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Williams KH, Wilkins MJ, N'Guessan AL, Arey B, Dodova E, Dohnalkova A, Holmes D, Lovley DR, and Long PE
- Subjects
- Acetates metabolism, Betaproteobacteria classification, Betaproteobacteria genetics, Biodegradation, Environmental, Biofilms growth & development, Colorado, Groundwater chemistry, Groundwater microbiology, Humans, Microbial Consortia physiology, Oxidation-Reduction, Oxygen metabolism, Phylogeny, RNA, Ribosomal, 16S classification, Selenic Acid, Selenium Compounds metabolism, Thauera classification, Thauera genetics, Betaproteobacteria metabolism, RNA, Ribosomal, 16S genetics, Selenium metabolism, Thauera metabolism, Uranium metabolism, Water Pollutants, Chemical metabolism
- Abstract
Removal of selenium from groundwater was documented during injection of acetate into a uranium-contaminated aquifer near Rifle, Colorado (USA). Bioreduction of aqueous selenium to its elemental form (Se0) concentrated it within mineralized biofilms affixed to tubing used to circulate acetate-amended groundwater. Scanning and transmission electron microscopy revealed close association between Se0 precipitates and cell surfaces, with Se0 aggregates having a diameter of 50-60 nm. Accumulation of Se0 within biofilms occurred over a three-week interval at a rate of c. 9 mg Se0 m(-2) tubing day(-1). Removal was inferred to result from the activity of a mixed microbial community within the biofilms capable of coupling acetate oxidation to the reduction of oxygen, nitrate and selenate. Phylogenetic analysis of the biofilm revealed a community dominated by strains of Dechloromonas sp. and Thauera sp., with isolates exhibiting genetic similarity to the latter known to reduce selenate to Se0. Enrichment cultures of selenate-respiring microorganisms were readily established using Rifle site groundwater and acetate, with cultures dominated by strains closely related to D. aromatica (96-99% similarity). Predominance of Dechloromonas sp. in recovered biofilms and enrichments suggests this microorganism may play a role in the removal of selenium oxyanions present in Se-impacted groundwaters and sediments.
- Published
- 2013
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