Direct and Fe(II)-Mediated Reduction of Technetium by Fe(III)-Reducing Bacteria

• DOI: 10.1128/aem.66.9.3743-3749.2000
• Publication Date: 2002-07-27T09:55:30Z
• Authors: J. R. Lloyd; V. A. Sole; C. V. G. Van Praagh; D. R. Lovley
• Keywords: Geobacter sulfurreducens; Electron acceptor; Geobacter; Electron donor

ABSTRACT The dissimilatory Fe(III)-reducing bacterium Geobacter sulfurreducens reduced and precipitated Tc(VII) by two mechanisms. Washed cell suspensions coupled the oxidation of hydrogen to enzymatic reduction Tc(IV), leading precipitation TcO 2 at periphery cell. An indirect, Fe(II)-mediated mechanism was also identified. Acetate, although not utilized efficiently as an electron donor for direct cell-mediated technetium, supported Fe(III), Fe(II) formed able transfer electrons abiotically Tc(VII). comparatively inefficient via this indirect when soluble Fe(III) citrate supplied cultures but enhanced in presence solid oxide. rate optimal, however, oxide stimulated addition humic analog shuttle anthaquinone-2,6-disulfonate, rapid formation Fe(II)-bearing mineral magnetite. Under these conditions, on nanocrystals biogenic magnetite removed from solution concentrations below limit detection scintillation counting. Cultures bacteria enriched radionuclide-contaminated sediment using acceptor 25 μM contained a single sp. detected 16S ribosomal DNA analysis were reduce precipitate radionuclide aquifer material, resulting Fe(II)-containing minerals that These results suggest may play important role immobilizing technetium sediments