Field evidence of selenium bioreduction in a uranium-contaminated aquifer

Environ Microbiol Rep. 2013 Jun;5(3):444-52. doi: 10.1111/1758-2229.12032.

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acetates / metabolism
  • Betaproteobacteria / classification
  • Betaproteobacteria / genetics
  • Betaproteobacteria / metabolism*
  • Biodegradation, Environmental
  • Biofilms / growth & development
  • Colorado
  • Groundwater / chemistry
  • Groundwater / microbiology
  • Humans
  • Microbial Consortia / physiology
  • Oxidation-Reduction
  • Oxygen / metabolism
  • Phylogeny
  • RNA, Ribosomal, 16S / classification
  • RNA, Ribosomal, 16S / genetics*
  • Selenic Acid
  • Selenium / metabolism*
  • Selenium Compounds / metabolism
  • Thauera / classification
  • Thauera / genetics
  • Thauera / metabolism*
  • Uranium / metabolism*
  • Water Pollutants, Chemical / metabolism*

Substances

  • Acetates
  • RNA, Ribosomal, 16S
  • Selenium Compounds
  • Water Pollutants, Chemical
  • Uranium
  • Selenium
  • Selenic Acid
  • Oxygen