Reduction of selenate and selenite to elemental selenium by Wolinella succinogenes

1992 ◽  
Vol 38 (12) ◽  
pp. 1328-1333 ◽  
Author(s):  
Francisco A. Tomei ◽  
Larry L. Barton ◽  
Cheryl L. Lemanski ◽  
Thomas G. Zocco
Keyword(s):  
Stationary Growth Phase ◽  
Elemental Selenium ◽  
Bacterial Cells ◽  
Wolinella Succinogenes ◽  
Stationary Growth ◽  
X Ray ◽  
Dense Granules ◽  
Transmission Electron ◽  
Final Electron ◽  
Final Electron Acceptor

Cultures of Wolinella succinogenes were adapted to grow in the presence of 1 mM [Formula: see text] or 10 mM [Formula: see text]. Both selenium salts were reduced to red, amorphous, elemental selenium but only after the culture reached the stationary growth phase. Bacterial cells taken from a culture actively reducing selenium were examined by transmission electron microscopy and were found to have large, electron-dense granules in the cytoplasm. These granules were verified by energy-dispersive X-ray spectroscopy to consist of selenium. Wolinella succinogenes was unable to grow with [Formula: see text] or [Formula: see text] as the final electron acceptor. Key words: Wolinella, selenium, cytology, selenate.

Solvothermal route to Bi3Se4 nanorods at low temperature

2001 ◽  
Vol 16 (12) ◽  
pp. 3361-3365 ◽  
Author(s):  
Yuan-fang Liu ◽  
Jing-hui Zeng ◽  
Wei-xin Zhang ◽  
Wei-chao Yu ◽  
Yi-tai Qian ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Reaction Mechanism ◽  
Low Temperature ◽  
Hydrazine Hydrate ◽  
Photoelectron Spectra ◽  
Elemental Selenium ◽  
X Ray ◽  
Transmission Electron ◽  
Microscope Images ◽  
Diffraction Patterns

Nanorods Bi3Se4 were synthesized directly through the reaction between BiCl3 and elemental selenium in an autoclave with hydrazine hydrate as solvent at 165 °C for 10 h. X-ray powder diffraction patterns, x-ray photoelectron spectra, and transmission electron microscope images show that the products are well-crystallized hexagonal Bi3Se4 nanorods. The solvent hydrazine hydrate played an important role in formation and growth of Bi3Se4 nanorods. The possible reaction mechanism was proposed.

Molecular and atomic analysis of uranium complexes formed by three eco-types of Acidithiobacillus ferrooxidans

2002 ◽  
Vol 30 (4) ◽  
pp. 669-672 ◽  
Author(s):  
M. Merroun ◽  
C. Hennig ◽  
A. Rossberg ◽  
G. Geipel ◽  
T. Reich ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Acidithiobacillus Ferrooxidans ◽  
Energy Dispersive ◽  
Bacterial Cells ◽  
X Ray ◽  
Uranium Complexes ◽  
Transmission Electron ◽  
Polyphosphate Bodies ◽  
Atomic Analysis

A combination of EXAFS, transmission electron microscopy and energy-dispersive X-ray was used to conduct a molecular and atomic analysis of the uranium complexes formed by Acidithiobacillus ferrooxidans. The results demonstrate that this bacterium accumulates uranium as phosphate compounds. We suggest that at toxic levels when the uranium enters the bacterial cells, A. ferrooxidans can detoxify and efflux this metal by a process in which its polyphosphate bodies are involved.

scholarly journals Preparation of red and grey elemental selenium for food fortification

2021 ◽  
Author(s):  
B. Khandsuren ◽  
J. Prokisch
Keyword(s):  
Electron Microscope ◽  
Sodium Selenite ◽  
Food Science ◽  
Elemental Selenium ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Form ◽  
Transmission Electron ◽  
Particle Size Analyzer ◽  
Wide Range

AbstractIn recent years, the importance of nanomaterials in food science, medicine, etc. has been increasing quickly. Herein, organic and inorganic red selenium nanoparticles synthesised by the reduction of sodium selenite with chemical and biological reducing agents. Grey hexagonal form in aqueous and powder was assembled at a high temperature of 85 °C for 10 min. Also, selenium enriched yogurt powder was made that contained about 2,000 mg kg−1 selenium, 93.8% of which is in nano form with a size of 50–500 nm. The synthesised nanoparticles were characterised by Dynamic Light Scattering Particle Size Analyzer (DLS), X-ray Diffraction Analysis (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The prepared SeNPs could be promising additive for a wide range of applications.

scholarly journals Actinide Biocolloid Formation in Brine by Halophilic Bacteria

1999 ◽  
Vol 556 ◽  
Author(s):  
J. B. Gillow ◽  
A. J. Francis ◽  
C. J. Dodge ◽  
R. Harris ◽  
T. J. Beveridge ◽  
...  
Keyword(s):  
Cell Surface ◽  
Halophilic Bacteria ◽  
Halophilic Bacterium ◽  
Bulk Sample ◽  
Bacterial Cells ◽  
Waste Isolation Pilot Plant ◽  
X Ray ◽  
Uranyl Carbonate ◽  
Transmission Electron ◽  
X Ray Absorption

AbstractWe examined the ability of a halophilic bacterium (WIPP 1A) isolated from the Waste Isolation Pilot Plant (WIPP) site to accumulate uranium in order to determine the potential for biocolloid facilitated actinide transport. The bacterial cell surface functional groups involved in the complexation of the actinide were determined by titration. Uranium, added as uranyl nitrate, was removed from solution at pH 5 by cells but at pH 7 and 9 very little uranium was removed due to its limited solubility. Although present as soluble species, uranyl citrate at pH 5, 7, and 9, and uranyl carbonate at pH 9 were not removed by the bacterium because they were not bioavailable due to their neutral or negative charge. Addition of uranyl EDTA to brine at pH 5, 7, and 9 resulted in the immediate precipitation of U. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) analysis revealed that uranium was not only associated with the cell surface but also accumulated intracellularly as uranium-enriched granules. Extended X-ray absorption fine structure (EXAFS) analysis of the bacterial cells indicated the bulk sample contained more than one uranium phase. Nevertheless these results show the potential for the formation of actinide bearing bacterial biocolloids that are strictly regulated by the speciation and bioavailability of the actinide.

scholarly journals Concentration-Dependent Multi-Potentiality of L-Arginine: Antimicrobial Effect, Hydroxyapatite Stability, and MMPs Inhibition

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6605
Author(s):  
Mohammed Nadeem Bijle ◽  
Mallikarjuna Rao Pichika ◽  
Kit-Kay Mak ◽  
Abhishek Parolia ◽  
Muneer Gohar Babar ◽  
...  
Keyword(s):  
Day Treatment ◽  
Antimicrobial Effect ◽  
Bacterial Cells ◽  
Bacterial Survival ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
X Ray ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Computational Molecular Docking

This study’s objective was to examine L-arginine (L-arg) supplementation’s effect on mono-species biofilm (Streptococcus mutans/Streptococcus sanguinis) growth and underlying enamel substrates. The experimental groups were 1%, 2%, and 4% arg, and 0.9% NaCl was used as the vehicle control. Sterilised enamel blocks were subjected to 7-day treatment with test solutions and S. mutans/S. sanguinis inoculum in BHI. Post-treatment, the treated biofilms stained for live/dead bacterial cells were analysed using confocal microscopy. The enamel specimens were analysed using X-ray diffraction crystallography (XRD), Raman spectroscopy (RS), and transmission electron microscopy (TEM). The molecular interactions between arg and MMP-2/MMP-9 were determined by computational molecular docking and MMP assays. With increasing arg concentrations, bacterial survival significantly decreased (p < 0.05). The XRD peak intensity with 1%/2% arg was significantly higher than with 4% arg and the control (p < 0.05). The bands associated with the mineral phase by RS were significantly accentuated in the 1%/2% arg specimens compared to in other groups (p < 0.05). The TEM analysis revealed that 4% arg exhibited an ill-defined shape of enamel crystals. Docking of arg molecules to MMPs appears feasible, with arg inhibiting MMP-2/MMP-9 (p < 0.05). L-arginine supplementation has an antimicrobial effect on mono-species biofilm. L-arginine treatment at lower (1%/2%) concentrations exhibits enamel hydroxyapatite stability, while the molecule has the potential to inhibit MMP-2/MMP-9.

A solvothermal route to wurtzite ZnSe nanoparticles

2000 ◽  
Vol 15 (3) ◽  
pp. 629-632 ◽  
Author(s):  
J. H. Zhan ◽  
X. G. Yang ◽  
W. X. Zhang ◽  
D. W. Wang ◽  
Y. Xie ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Zinc Powder ◽  
Transmission Electron Microscopy Observation ◽  
Elemental Selenium ◽  
X Ray Diffraction ◽  
Microscopy Observation ◽  
Znse Nanoparticles ◽  
X Ray ◽  
Transmission Electron

Zinc powder reacts with equivalent elemental selenium in solvent ethylenediamine at 120 °C for 6 h to form a complex, which is converted to ZnSe nanoparticles by pyrolysis or protonization. X-ray diffraction results suggest that the as-formed products have wurtzite structure. Transmission electron microscopy observation show that particles with spherical and laminar morphology were produced by pyrolysis and protonization, respectively. The formation of ZnSe nanoparticles is also investigated by infrared and thermal analysis.

Montmorillonite mitigates the toxic effect of heavy oil on hydrocarbon-degrading bacterial growth: implications for marine oil spill bioremediation

Clay Minerals ◽  
2013 ◽  
Vol 48 (4) ◽  
pp. 639-654 ◽  
Author(s):  
S. K. Chaerun ◽  
K. Tazaki ◽  
M. Okuno
Keyword(s):  
Toxic Effect ◽  
Oil Spill ◽  
Bacterial Growth ◽  
Heavy Oil ◽  
Control Treatment ◽  
Bacterial Cells ◽  
Marine Oil ◽  
X Ray ◽  
Transmission Electron ◽  
Degrading Bacteria

AbstractThe ability of montmorillonite to mitigate the toxic effect of heavy oil from theNakhodkaoil spill, by growth of hydrocarbon-degrading bacteria and enable bioremediation was studied. Montmorillonite enhanced the bacterial growth significantly (P< 0.05) in the main treatment containing heavy oil+bacteria+montmorillonite (OBM), because the specific growth rate (μ) was greater than that in the biotic control treatment containing heavy oil+bacteria (OB). Significant amounts of Si and Al (major constituents of montmorillonite) were not released in the aqueous phase over the ∽24-day experiment (P> 0.05). Transmission electron microscopic observation showed that the hydrocarbon-degrading bacterial cells were covered and encrusted with montmorillonite particles. Scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (STEM-EDS) also showed that the surrounding of the bacterial cells was frequently rich in Si but not in Al. Fourier transform infrared (FTIR) spectroscopy indicated that the heavy oil-bacterial cell-montmorillonite particle complex retained the composition of both water and heavy oil. X-ray powder diffractrometery (XRD) analysis revealed that heavy oil and heavy oil-bacteria did not change the basal spacing of montmorillonite over a period of 24 days. The enhancement of hydrocarbon-degrading bacterial growth is attributed to montmorillonite likely serving as both bacterial growth-supporting carrier and protective outer layer against high concentrations of heavy oil that inhibit growth. These results shed light on the interactions in oil-bacteria-clay complexes and could potentially be used in marine oil spill bioremediation.

scholarly journals Potent antibacterial action of phycosynthesized selenium nanoparticles using Spirulina platensis extract

2021 ◽  
Vol 10 (1) ◽  
pp. 49-60
Author(s):  
Basant E.F. ElSaied ◽  
Amany M. Diab ◽  
Ahmed A. Tayel ◽  
Mousa A. Alghuthaymi ◽  
Shaaban H. Moussa
Keyword(s):  
Spirulina Platensis ◽  
Bacterial Species ◽  
Antibacterial Properties ◽  
Selenium Nanoparticles ◽  
Bacterial Cells ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Bioactive Agents ◽  
Size Diminution

Abstract Selenium nanoparticles (SeNPs) are reinforced safe forms of the essential micronutrient selenium (Se) which take a lead in countless biotechnological and biomedical applications. The phycosynthesis of SeNPs was successfully investigated using cell-free extract of the microalgae, Spirulina platensis. The phycosynthesized S. platensis-SeNPs (SpSeNPs) were characterized using several characterization techniques such as UV-Visible, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and energy dispersive X-ray. They were effectually achieved using different concentration from sodium selenite (Na2SeO3) (1, 5, and 10 mM) to give size means of 12.64, 8.61, and 5.93 nm, respectively, with spherical shapes and highly negative zeta potentialities. The infrared analyses revealed the involvement of many phycochemials in SpSeNPs production. The antibacterial properties of SpSeNPs were confirmed, qualitatively and quantitatively, against foodborne microorganisms (Staphylococcus aureus and Salmonella typhimurium); the antibacterial activity was correlated and increased with SeNPs’ size diminution. The scanning micrographs of S. typhimurium cells treated with SpSeNPs indicated the severe action of nanoparticles to destroy bacterial cells in time-dependent manners. The innovative facile phycosynthesis of SeNPs using S. platensis is recommended to generate effectual bioactive agents to control hazardous bacterial species.

scholarly journals Model-based Characterization of the Parameters of Dissimilatory Sulfate Reduction Under the Effect of Different Initial Density of Desulfovibrio piger Vib-7 Bacterial Cells

2015 ◽  
Vol 9 (1) ◽  
pp. 55-69 ◽  
Author(s):  
Ivan Kushkevych ◽  
Marco Bolis ◽  
Milan Bartos
Keyword(s):  
Sulfate Reduction ◽  
Bacterial Growth ◽  
Growth Phase ◽  
Initial Density ◽  
Stationary Growth Phase ◽  
Exponential Growth Phase ◽  
Dissimilatory Sulfate Reduction ◽  
Bacterial Cells ◽  
Stationary Growth ◽  
Initial Concentration

The objective of this study was to design a model of dissimilatory sulfate reduction process using the Verhulst function, with a particular focus on the kinetics of bacterial growth, sulfate and lactate consumption, and accumulation of hydrogen sulfide and acetate. The effect of the initial density (0.12±0.011, 0.25±0.024, 0.5±0.048 and 1.0±0.096 mg cells/ml of medium) of the sulfate-reducing bacteriaDesulfovibrio pigerVib-7 on the growth and dissimilatory sulfate reduction was studied. The exponential growth phase of theD. pigerVib-7 was observed for 72 hours of cultivation at the (0.12 and 0.25 mg/ml) initial concentration of bacterial cells. Sulfate and lactate were consumed incompletely during this time. The increase in the initial concentration of cells to 0.5 and 1 mg/ml led to a shortening of the exponential bacterial growth phase and a shift to the stationary phase of the growth. In the case of 0.5 mg/ml seeding, the stationary growth phase was observed in the 36thhour of cultivation. The increase in the initial concentration of cells to 1 mg/ml led to the beginning of the stationary growth phase in 24th hours of cultivation. Under these conditions, sulfate and lactate were consumed completely in the 48th hour of cultivation. The kinetic analysis of the curves of bacterial growth and the process of dissimilatory sulfate reduction byD. pigerVib-7 was carried out.

Ultrastructure and X-ray analysis of phosphorus granules in a vesicular–arbuscular mycorrhizal fungus

1979 ◽  
Vol 57 (24) ◽  
pp. 2812-2818 ◽  
Author(s):  
J. A. White ◽  
M. F. Brown
Keyword(s):  
Arbuscular Mycorrhizal Fungus ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
X Ray ◽  
Dense Granules ◽  
Transmission Electron ◽  
Cellular Inclusions ◽  
Vesicular Arbuscular ◽  
Probable Site ◽  
High Concentrations

The vesicular–arbuscular mycorrhizal fungus Glomus mosseae was examined by transmission electron microscopy and energy dispersive X-ray analysis. Electron-dense granules, found within vacuoles, were analyzed by X-ray analysis and found to contain high concentrations of phosphorus and calcium. These granules were similar in appearance to the polyphosphate granules described in other organisms. Highly vacuolated intercellular hyphae and vesicles possessed the greatest number of phosphorus granules. The granules were present in vacuolated arbuscular hyphae but absent from completely collapsed arbuscules. It was determined that the active arbuscule was the most probable site of breakdown of phosphorus granules. There were two other types of cellular inclusions, one vacuolar and one cytoplasmic, that could not be identified by X-ray analysis but that could easily be mistaken for phosphorus granules. It was concluded that general morphological appearance and location were not adequate criteria for the identification of phosphorus granules.

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