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Field evidence of selenium bioreduction in a uranium‐contaminated aquifer
Author(s) -
Williams Kenneth H.,
Wilkins Michael J.,
N'Guessan A. Lucie,
Arey Bruce,
Dodova Elena,
Dohnalkova Alice,
Holmes Dawn,
Lovley Derek R.,
Long Philip E.
Publication year - 2013
Publication title -
environmental microbiology reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.229
H-Index - 69
ISSN - 1758-2229
DOI - 10.1111/1758-2229.12032
Subject(s) - selenate , selenium , environmental chemistry , aquifer , chemistry , groundwater , biofilm , uranium , microorganism , bioremediation , contamination , bacteria , geology , ecology , biology , metallurgy , organic chemistry , materials science , geotechnical engineering , paleontology
Summary Removal of selenium from groundwater was documented during injection of acetate into a uranium‐contaminated aquifer near R ifle, C olorado ( USA ). Bioreduction of aqueous selenium to its elemental form ( Se 0 ) concentrated it within mineralized biofilms affixed to tubing used to circulate acetate‐amended groundwater. Scanning and transmission electron microscopy revealed close association between Se 0 precipitates and cell surfaces, with Se 0 aggregates having a diameter of 50–60 nm. Accumulation of Se 0 within biofilms occurred over a three‐week interval at a rate of c . 9 mg Se 0 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 D echloromonas sp. and T hauera sp., with isolates exhibiting genetic similarity to the latter known to reduce selenate to Se 0 . Enrichment cultures of selenate‐respiring microorganisms were readily established using R ifle site groundwater and acetate, with cultures dominated by strains closely related to D . aromatica (96–99% similarity). Predominance of D echloromonas 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.