Microbial reduction of U(VI) at the solid-water interface.
Microbial (Geobacter sulfurreducens) reduction of 0.1 mM U(VI) in the presence of synthetic Fe(III) oxides and natural Fe(III) oxide-containing solids was investigated in pH 6.8 artificial groundwater containing 10 mM NaHCO3. In most experiments, more than 95% of added U(VI) was sorbed to solids, so that U(VI) reduction was governed by reactions at the solid-water interface. The rate and extent of reduction of U(VI) associated with surfaces of synthetic Fe(III) oxides (hydrous ferric oxide, goethite, and hematite) was comparable to that observed during reduction of aqueous U(VI). In contrast, microbial reduction of U(VI) sorbed to several different natural Fe(III) oxide-containing solids was slower and less extensive compared to synthetic Fe(III) oxide systems. Addition of the electron shuttling agent anthraquinone-2,6-disulfonate (AQDS; 0.1 mM) enhanced the rate and extent of both Fe(III) and U(VI) reduction. These findings suggest that AQDS facilitated electron transfer from G. sulfurreducens to U(VI) associated with surface sites atwhich direct enzymatic reduction was kinetically limited. Our results demonstrate that association of U(VI) with diverse surface sites in natural soils and sediments has the potential to limit the rate and extent of microbial U(VI) reduction and thereby modulate the effectiveness of in situ U(VI) bioremediation.
Jeon
Ong-Hun
OH
Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama 35487-0206, USA.
Kelly
Shelly D
SD
Kemner
Kenneth M
KM
Barnett
Mark O
MO
Burgos
William D
WD
Dempsey
Brian A
BA
Roden
Eric E
EE
D000880:Anthraquinones / Q000494:pharmacology; D004798:Enzymes / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism*; D045302:Geobacter / Q000378:metabolism*; D019015:Geologic Sediments / Q000737:chemistry; D007700:Kinetics; D010084:Oxidation-Reduction; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D017693:Sodium Bicarbonate / Q000737:chemistry; D013499:Surface Properties; D014501:Uranium / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism
D000880:Anthraquinones; D004798:Enzymes; D005290:Ferric Compounds; D012722:Sewage; D014874:Water Pollutants, Chemical; C408124:anthraquinone-2,6-disulfonate; C000499:ferric oxide; D014501:Uranium; D017693:Sodium Bicarbonate