Electron donor-dependent radionuclide reduction and nanoparticle formation by Anaeromyxobacter dehalogenans strain 2CP-C

Authors

Matthew J. Marshall, Pacific Northwest National Laboratory
Alice C. Dohnalkova, Pacific Northwest National Laboratory
David Kennedy, Pacific Northwest National LaboratoryFollow
Andrew Plymale, Pacific Northwest National LaboratoryFollow
Sara Thomas, Georgia Institute of Technology
Frank Löffler, Georgia Institute of Technology
Robert Sanford, University of Illinois
John M. Zachara, Pacific Northwest National LaboratoryFollow
James K. Fredrickson, Pacific Northwest National LaboratoryFollow
Alexander Beliaev, Pacific Northwest National LaboratoryFollow

Date of this Version

2009

Citation

Environmental Microbiology (2009) 11(2), 534–543; doi:10.1111/j.1462-2920.2008.01795.x

Abstract

Anaeromyxobacter dehalogenans strain 2CP-C reduces U(VI) and Tc(VII) to U(IV)O_2(s) (uraninite) and Tc(IV)O2(S) respectively. Kinetic studies with resting cells revealed that U(VI) or Tc(VII) reduction rates using H₂ as electron donor exceeded those observed in acetate-amended incubations. The reduction of U(VI) by A. dehalogenans 2CP-C resulted in extracellular accumulation of ~5 nm uraninite nanoparticles in association with a lectin-binding extracellular polymeric substance (EPS). The electron donor did not affect UO_2(S) nanoparticle size or association with EPS, but the utilization of acetate as the source of reducing equivalents resulted in distinct UO_2(S) nanoparticle aggregates that were ~50 nm in diameter. In contrast, reduction of Tc(VII) by A. dehalogenans 2CP-C cell suspensions produced dense clusters of TcO₂ particles, which were localized within the cell periplasm and on the outside of the outer membrane. In addition to direct reduction, A. dehalogenans 2CP-C cell suspensions reduced Tc(VII) indirectly via an Fe(II)-mediated mechanism. Fe(II) produced by strain 2CP-C from either ferrihydrite or Hanford Site sediment rapidly removed ⁹⁹Tc(VII)O₄^– from solution.