scholarly journals Influence of calcium on microbial reduction of solid phase uranium(VI)

2007 ◽  
Vol 97 (6) ◽  
pp. 1415-1422 ◽  
Author(s):  
Chongxuan Liu ◽  
Byong-Hun Jeon ◽  
John M. Zachara ◽  
Zheming Wang
Keyword(s):  
Solid Phase ◽  
Microbial Reduction

Extracellular electron transfer through microbial reduction of solid-phase humic substances

2010 ◽  
Vol 3 (6) ◽  
pp. 417-421 ◽  
Author(s):  
Eric E. Roden ◽  
Andreas Kappler ◽  
Iris Bauer ◽  
Jie Jiang ◽  
Andrea Paul ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Humic Substances ◽  
Solid Phase ◽  
Microbial Reduction ◽  
Extracellular Electron Transfer

scholarly journals Influence of Aqueous and Solid-Phase Fe(II) Complexants on Microbial Reduction of Crystalline Iron(III) Oxides†

1999 ◽  
Vol 33 (22) ◽  
pp. 4022-4028 ◽  
Author(s):  
Matilde M. Urrutia ◽  
Eric E. Roden ◽  
John M. Zachara
Keyword(s):  
Solid Phase ◽  
Microbial Reduction

scholarly journals Copper availability governs nitrous oxide accumulation in wetland soils and stream sediments

2021 ◽  
Author(s):  
Neha Sharma ◽  
Elaine Flynn ◽  
Jeffrey Catalano ◽  
Daniel Giammar
Keyword(s):  
Nitrous Oxide ◽  
Kinetic Model ◽  
Solid Phase ◽  
Stream Sediments ◽  
Microbial Reduction ◽  
Aquatic Systems ◽  
Wetland Soils ◽  
Nitrogen Species ◽  
Riparian Wetland ◽  
Abiotic Reduction

Denitrification is microbially-mediated through enzymes containing metal cofactors. Laboratory studies of pure cultures have highlighted that the availability of Cu, required for the multicopper enzyme nitrous oxide reductase, can limit N2O reduction. However, in natural aquatic systems, such as wetlands and hyporheic zones in stream beds, the role of Cu in controlling denitrification remains incompletely understood. In this study, we collected soils and sediments from three natural environments -- riparian wetlands, marsh wetlands, and a stream -- to investigate their nitrogen species transformation activity at background Cu levels and different supplemented Cu loadings. All of the systems displayed low solid-phase associated Cu (40 - 280 nmol g-1), which made them appropriate sites for evaluating the effect of limited Cu availability on denitrification. In laboratory incubation experiments, high concentrations of N2O accumulated in all microcosms lacking Cu amendment except for one stream sediment sample. With Cu added to provide dissolved concentrations at trace levels (10-300 nM), reduction of N2O to N2 in the wetland soils and stream sediments was enhanced. A kinetic model could account for the trends in nitrogen species by combining the reactions for microbial reduction of NO3- to NO2-/N2O/N2 and abiotic reduction of NO2- to N2. The model revealed that the rate of N2O to N2 conversion increased significantly in the presence of Cu. For riparian wetland soils and stream sediments, the kinetic model also suggested that overall denitrification is driven by abiotic reduction of NO2- in the presence of inorganic electron donors. This study demonstrated that natural aquatic systems containing Cu at concentrations less than or equal to crustal abundances may display incomplete reduction of N2O to N2 that would cause N2O accumulation and release to the atmosphere.

scholarly journals Metal Concentrations in Soil Paste Extracts as Affected by Extraction Ratio

2002 ◽  
Vol 2 ◽  
pp. 966-971 ◽  
Author(s):  
Filip M.G. Tack ◽  
Nic Dezillie ◽  
Marc G. Verloo
Keyword(s):  
Moisture Content ◽  
Soil Solution ◽  
Solid Phase ◽  
Microbial Reduction ◽  
Extraction Ratio ◽  
Metal Concentrations ◽  
Metal Levels ◽  
Observed Behaviour ◽  
Small Pool ◽  
Iron And Manganese

Saturated paste extracts are sometimes used to estimate metal levels in the soil solution. To assess the significance of heavy-metal concentrations measured in saturation extracts, soil paste extracts were prepared with distilled water in amounts ranging from 60–200% of the moisture content at saturation. Trace metals behaved as if a small pool consistently was dissolved independent of the extraction ratio applied. Metal concentrations in the solution hence were not buffered by the solid phase, but the observed behaviour would allow the estimation of metal concentrations in the soil solution as a function of moisture content. The behaviour of iron and manganese suggested that some microbial reduction occurred. The intensity increased with increasing extraction ratio but not to the extent of affecting dissolution of trace elements.

scholarly journals Kinetics of Microbial Reduction of Solid Phase U(VI)

2006 ◽  
Vol 40 (20) ◽  
pp. 6290-6296 ◽  
Author(s):  
Chongxuan Liu ◽  
Byong-Hun Jeon ◽  
John M. Zachara ◽  
Zheming Wang ◽  
Alice Dohnalkova ◽  
...  
Keyword(s):  
Solid Phase ◽  
Microbial Reduction ◽  
Kinetics Of

Microbial effects on mineral–radionuclide interactions and radionuclide solid-phase capture processes

2012 ◽  
Vol 76 (3) ◽  
pp. 777-806 ◽  
Author(s):  
D. R. Brookshaw ◽  
R. A. D. Pattrick ◽  
J. R. Lloyd ◽  
D. J. Vaughan
Keyword(s):  
Solid Phase ◽  
Microbial Reduction ◽  
Mineral Dissolution ◽  
Analysis Tool ◽  
Self Organizing Map ◽  
Mineral Surfaces ◽  
Recent Developments ◽  
Co Precipitation ◽  
Species Specific ◽  
Abiotic Interactions

AbstractUnderstanding the environmental and biogeochemical behaviour of radionuclides is essential for managing our nuclear legacy safely. Remediation efforts and the concept of geological disposal of nuclear waste focus on immobilizing radionuclides within the subsurface. Here we review recent developments in the understanding of solid-phase capture processes of Cs, Sr, Tc, U, Pu and Np. Abiotic interactions between minerals and these radionuclides (including sorption, reductive precipitation and co-precipitation) have been studied in various conditions. Microbially driven processes are much less well characterized, for example the effects of microbial reduction on the structure and reactivity of existing minerals, or their role in the formation of new minerals. Metabolites released by bacteria can play a role in both mineral dissolution and formation, and better understanding their release and role in mineralization has great potential in the development of solid-phase capture processes for radionuclides.With the aid of a map of the research landscape covered by this review (created using a cluster-analysis tool, a self-organizing map), we highlight the most promising sequestration processes for specific radionuclides. However, radionuclides exhibit highly species-specific behaviour in their interactions with minerals and microorganisms. More research is required to characterize the role mineral surfaces play in bioreductive immobilization of Pu and Np, the reduction products formed, and their relative stability. Further studies should concentrate on more environmentally relevant experiments that include bacteria, minerals and radionuclides.

scholarly journals Resistance of Solid-Phase U(VI) to Microbial Reduction during In Situ Bioremediation of Uranium-Contaminated Groundwater

2004 ◽  
Vol 70 (12) ◽  
pp. 7558-7560 ◽  
Author(s):  
Irene Ortiz-Bernad ◽  
Robert T. Anderson ◽  
Helen A. Vrionis ◽  
Derek R. Lovley
Keyword(s):  
Solid Phase ◽  
Microbial Reduction ◽  
Contaminated Groundwater ◽  
Substantial Portion ◽  
In Situ Bioremediation ◽  
Subsurface Sediments

ABSTRACT Speciation of solid-phase uranium in uranium-contaminated subsurface sediments undergoing uranium bioremediation demonstrated that although microbial reduction of soluble U(VI) readily immobilized uranium as U(IV), a substantial portion of the U(VI) in the aquifer was strongly associated with the sediments and was not microbially reducible. These results have important implications for in situ uranium bioremediation strategies.

scholarly journals Chemical and Biological Interactions during Nitrate and Goethite Reduction by Shewanella putrefaciens 200

2003 ◽  
Vol 69 (6) ◽  
pp. 3517-3525 ◽  
Author(s):  
D. Craig Cooper ◽  
Flynn W. Picardal ◽  
Arndt Schimmelmann ◽  
Aaron J. Coby
Keyword(s):  
Solid Phase ◽  
High Surface ◽  
High Surface Area ◽  
Fold Increase ◽  
Shewanella Putrefaciens ◽  
Microbial Reduction ◽  
Biological Interactions ◽  
Biological Reduction ◽  
Low Ionic Strength ◽  
Twofold Decrease

ABSTRACT Although previous research has demonstrated that NO3 − inhibits microbial Fe(III) reduction in laboratory cultures and natural sediments, the mechanisms of this inhibition have not been fully studied in an environmentally relevant medium that utilizes solid-phase, iron oxide minerals as a Fe(III) source. To study the dynamics of Fe and NO3 − biogeochemistry when ferric (hydr)oxides are used as the Fe(III) source, Shewanella putrefaciens 200 was incubated under anoxic conditions in a low-ionic-strength, artificial groundwater medium with various amounts of NO3 − and synthetic, high-surface-area goethite. Results showed that the presence of NO3 − inhibited microbial goethite reduction more severely than it inhibited microbial reduction of the aqueous or microcrystalline sources of Fe(III) used in other studies. More interestingly, the presence of goethite also resulted in a twofold decrease in the rate of NO3 − reduction, a 10-fold decrease in the rate of NO2 − reduction, and a 20-fold increase in the amounts of N2O produced. Nitrogen stable isotope experiments that utilized δ15N values of N2O to distinguish between chemical and biological reduction of NO2 − revealed that the N2O produced during NO2 − or NO3 − reduction in the presence of goethite was primarily of abiotic origin. These results indicate that concomitant microbial Fe(III) and NO3 − reduction produces NO2 − and Fe(II), which then abiotically react to reduce NO2 − to N2O with the subsequent oxidation of Fe(II) to Fe(III).

Solid-phase immunoelectron microscopy for rapid diagnosis of enteroviruses

1984 ◽  
Vol 42 ◽  
pp. 226-227 ◽  
Author(s):  
K. Pegg-Feige ◽  
F. W. Doane
Keyword(s):  
Electron Microscopy ◽  
Cell Culture ◽  
Immunoelectron Microscopy ◽  
Detection Method ◽  
Solid Phase ◽  
Protein A ◽  
Plant Viruses ◽  
Rapid Diagnosis ◽  
Virus Diagnosis ◽  
Antiviral Antibody

Immunoelectron microscopy (IEM) applied to rapid virus diagnosis offers a more sensitive detection method than direct electron microscopy (DEM), and can also be used to serotype viruses. One of several IEM techniques is that introduced by Derrick in 1972, in which antiviral antibody is attached to the support film of an EM specimen grid. Originally developed for plant viruses, it has recently been applied to several animal viruses, especially rotaviruses. We have investigated the use of this solid phase IEM technique (SPIEM) in detecting and identifying enteroviruses (in the form of crude cell culture isolates), and have compared it with a modified “SPIEM-SPA” method in which grids are coated with protein A from Staphylococcus aureus prior to exposure to antiserum.

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