U(VI) sequestration in hydroxyapatite produced by microbial glycerol 3-phosphate metabolism

Appl Environ Microbiol. 2009 Sep;75(18):5773-8. doi: 10.1128/AEM.00628-09. Epub 2009 Jul 24.

Abstract

Previous studies have demonstrated the potential for removal of U(VI) from solution via precipitation of U(VI)-bearing calcium-phosphate (Ca-P) minerals coupled to microbial hydrolysis of glycerol phosphate compounds. We evaluated this process in circumneutral-pH groundwater from Area 2 of the U.S. Department of Energy Field Research Center at Oak Ridge National Laboratory. Area 2 groundwater contains high concentrations of dissolved calcium (ca. 4 mM), and thus, release of phosphate during glycerol phosphate metabolism has the potential to create conditions favorable for U(VI) sequestration in Ca-P minerals. Microbial enumeration and isolation studies verified the presence of aerobic and nitrate-reducing glycerol 3-phosphate (G3P)-metabolizing microorganisms in Area 2 sediments. Coprecipitation of U(VI) with Ca-P minerals coupled to microbial G3P hydrolysis was demonstrated in artificial groundwater under aerobic and nitrate-reducing conditions. Transmission electron microscopy analysis and mineral-washing experiments demonstrated that U(VI) was incorporated into the structure of the insoluble Ca-P mineral hydroxyapatite [Ca5(PO4)3OH]. Our results support the idea that U(VI) can be effectively removed from solution in contaminated aquifers through stimulation of microbial organophosphate metabolism.

Publication types

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

MeSH terms

  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • DNA, Ribosomal / chemistry
  • DNA, Ribosomal / genetics
  • Durapatite / metabolism*
  • Gammaproteobacteria / classification
  • Gammaproteobacteria / genetics
  • Gammaproteobacteria / isolation & purification
  • Gammaproteobacteria / metabolism*
  • Glycerophosphates / metabolism*
  • Phylogeny
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Uranium / metabolism*
  • Water Microbiology*
  • Water Pollutants, Chemical / metabolism*
  • Water Pollutants, Radioactive / metabolism*

Substances

  • DNA, Bacterial
  • DNA, Ribosomal
  • Glycerophosphates
  • RNA, Ribosomal, 16S
  • Water Pollutants, Chemical
  • Water Pollutants, Radioactive
  • Uranium
  • Durapatite
  • alpha-glycerophosphoric acid