title: Growth of Desulfovibrio vulgaris when respiring U(VI) and characterization of biogenic uraninite.
abstract: The capacity of Desulfovibrio vulgaris to reduce U(VI) was studied previously with nongrowth conditions involving a high biomass concentration; thus, bacterial growth through respiration of U(VI) was not proven. In this study, we conducted a series of batch tests on U(VI) reduction by D. vulgaris at a low initial biomass (10 to 20 mg/L of protein) that could reveal biomass growth. D. vulgaris grew with U(VI) respiration alone, as well as with simultaneous sulfate reduction. Patterns of growth kinetics and solids production were affected by sulfate and Fe(2+). Biogenic sulfide nonenzymatically reduced 76% of the U(VI) and greatly enhanced the overall reduction rate in the absence of Fe(2+) but was rapidly scavenged by Fe(2+) to form FeS in the presence of Fe(2+). Biogenic U solids were uraninite (UO2) nanocrystallites associated with 20 mg/g biomass as protein. The crystallite thickness of UO2 was 4 to 5 nm without Fe(2+) but was <1.4 nm in the presence of Fe(2+), indicating poor crystallization inhibited by adsorbed Fe(2+) and other amorphous Fe solids, such as FeS or FeCO3. This work fills critical gaps in understanding the metabolic utilization of U by microorganisms and formation of UO2 solids in bioremediation sites.
authors.affiliation: Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University , Tempe, Arizona 85207-5701, United States.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhou
authors.forename: Raveender
authors.initials: R
authors.lastname: Vannela
authors.forename: Sung Pil
authors.initials: SP
authors.lastname: Hyun
authors.forename: Kim F
authors.initials: KF
authors.lastname: Hayes
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Rittmann
mesh_terms: D000327:Adsorption; D000332:Aerobiosis; D001426:Bacterial Proteins / Q000032:analysis; D001673:Biodegradation, Environmental; D018533:Biomass; D002254:Carbonates / Q000378:metabolism; D003460:Crystallization; D016969:Desulfovibrio vulgaris / Q000254:growth & development* / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism; D007700:Kinetics; D007773:Lactates / Q000032:analysis; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D010316:Particle Size; D056951:Photoelectron Spectroscopy; D013431:Sulfates / Q000378:metabolism; D013440:Sulfides / Q000378:metabolism; D014501:Uranium / Q000302:isolation & purification*; D017974:Uranium Compounds / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D002254:Carbonates; D005290:Ferric Compounds; D007773:Lactates; D013431:Sulfates; D013440:Sulfides; D017974:Uranium Compounds; D014501:Uranium; D007501:Iron; C012597:uranium dioxide; C486982:siderite