The Experts below are selected from a list of 10290 Experts worldwide ranked by ideXlab platform
Stefanie Mangold - One of the best experts on this subject based on the ideXlab platform.
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visualization of acidithiobacillus ferrooxidans biofilms on pyrite by atomic force and Epifluorescence Microscopy under various experimental conditions
Hydrometallurgy, 2008Co-Authors: Stefanie Mangold, Kerstin Harneit, Thore Rohwerder, Gunter Claus, Michaela Laxander, Wolfgang SandAbstract:Abstract For studying why cells of At. ferrooxidans A2 attach to given locations on pyrite surfaces, a newly developed combination of atomic force and Epifluorescence Microscopy (AFM and EFM, respectively) was used. Attached bacterial cells were visualized under various conditions and stained concomitantly with 4′,6-diamidino-2-phenylindol (DAPI) and the isothiocyanate-labeled lectin concanavalin A (FITC-ConA). By comparing AFM images generated by contact mode in air or intermittent contact mode in mineral salt solution, significant differences were observed. Most strikingly, images acquired in fluid showed smoother surfaces with little surface detail. Although bacterial cell width and length did not vary either by using contact mode in air or intermittent contact mode in mineral salt solution scans, cell height imaged in air were 30 ± 10% below those imaged in fluid, indicating dehydration under this condition. Extracellular polysaccharides of attached cells were successfully stained with FITC-ConA. Evaluation of the corresponding AFM images confirmed that the cell integrity was not affected by the DAPI and lectin staining. In the future, the novel microscopic technique could also be used for testing other lectins and staining methods. Hence, the high spatial resolution of AFM imaging in combination with specific staining and possibly also quantification of EPS and other cell components under in situ conditions could be achieved.
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novel combination of atomic force Microscopy and Epifluorescence Microscopy for visualization of leaching bacteria on pyrite
Applied and Environmental Microbiology, 2008Co-Authors: Stefanie Mangold, Kerstin Harneit, Thore Rohwerder, Gunter Claus, Wolfgang SandAbstract:Bioleaching of metal sulfides is an interfacial process comprising the interactions of attached bacterial cells and bacterial extracellular polymeric substances with the surface of a mineral sulfide. Such processes and the associated biofilms can be investigated at high spatial resolution using atomic force Microscopy (AFM). Therefore, we visualized biofilms of the meso-acidophilic leaching bacterium Acidithiobacillus ferrooxidans strain A2 on the metal sulfide pyrite with a newly developed combination of AFM with Epifluorescence Microscopy (EFM). This novel system allowed the imaging of the same sample location with both instruments. The pyrite sample, as fixed on a shuttle stage, was transferred between AFM and EFM devices. By staining the bacterial DNA with a specific fluorescence dye, bacterial cells were labeled and could easily be distinguished from other topographic features occurring in the AFM image. AFM scanning in liquid caused deformation and detachment of cells, but scanning in air had no effect on cell integrity. In summary, we successfully demonstrate that the new microscopic system was applicable for visualizing bioleaching samples. Moreover, the combination of AFM and EFM in general seems to be a powerful tool for investigations of biofilms on opaque materials and will help to advance our knowledge of biological interfacial processes. In principle, the shuttle stage can be transferred to additional instruments, and combinations of AFM and EFM with other surface-analyzing devices can be proposed.
Wolfgang Sand - One of the best experts on this subject based on the ideXlab platform.
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visualization of acidithiobacillus ferrooxidans biofilms on pyrite by atomic force and Epifluorescence Microscopy under various experimental conditions
Hydrometallurgy, 2008Co-Authors: Stefanie Mangold, Kerstin Harneit, Thore Rohwerder, Gunter Claus, Michaela Laxander, Wolfgang SandAbstract:Abstract For studying why cells of At. ferrooxidans A2 attach to given locations on pyrite surfaces, a newly developed combination of atomic force and Epifluorescence Microscopy (AFM and EFM, respectively) was used. Attached bacterial cells were visualized under various conditions and stained concomitantly with 4′,6-diamidino-2-phenylindol (DAPI) and the isothiocyanate-labeled lectin concanavalin A (FITC-ConA). By comparing AFM images generated by contact mode in air or intermittent contact mode in mineral salt solution, significant differences were observed. Most strikingly, images acquired in fluid showed smoother surfaces with little surface detail. Although bacterial cell width and length did not vary either by using contact mode in air or intermittent contact mode in mineral salt solution scans, cell height imaged in air were 30 ± 10% below those imaged in fluid, indicating dehydration under this condition. Extracellular polysaccharides of attached cells were successfully stained with FITC-ConA. Evaluation of the corresponding AFM images confirmed that the cell integrity was not affected by the DAPI and lectin staining. In the future, the novel microscopic technique could also be used for testing other lectins and staining methods. Hence, the high spatial resolution of AFM imaging in combination with specific staining and possibly also quantification of EPS and other cell components under in situ conditions could be achieved.
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novel combination of atomic force Microscopy and Epifluorescence Microscopy for visualization of leaching bacteria on pyrite
Applied and Environmental Microbiology, 2008Co-Authors: Stefanie Mangold, Kerstin Harneit, Thore Rohwerder, Gunter Claus, Wolfgang SandAbstract:Bioleaching of metal sulfides is an interfacial process comprising the interactions of attached bacterial cells and bacterial extracellular polymeric substances with the surface of a mineral sulfide. Such processes and the associated biofilms can be investigated at high spatial resolution using atomic force Microscopy (AFM). Therefore, we visualized biofilms of the meso-acidophilic leaching bacterium Acidithiobacillus ferrooxidans strain A2 on the metal sulfide pyrite with a newly developed combination of AFM with Epifluorescence Microscopy (EFM). This novel system allowed the imaging of the same sample location with both instruments. The pyrite sample, as fixed on a shuttle stage, was transferred between AFM and EFM devices. By staining the bacterial DNA with a specific fluorescence dye, bacterial cells were labeled and could easily be distinguished from other topographic features occurring in the AFM image. AFM scanning in liquid caused deformation and detachment of cells, but scanning in air had no effect on cell integrity. In summary, we successfully demonstrate that the new microscopic system was applicable for visualizing bioleaching samples. Moreover, the combination of AFM and EFM in general seems to be a powerful tool for investigations of biofilms on opaque materials and will help to advance our knowledge of biological interfacial processes. In principle, the shuttle stage can be transferred to additional instruments, and combinations of AFM and EFM with other surface-analyzing devices can be proposed.
R Undaangeles - One of the best experts on this subject based on the ideXlab platform.
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morphology and orientated growth of second phase precipitates in a eu2 doped equimolar kcl kbr solid solution an Epifluorescence Microscopy study by using the doping ion as a fluorochrome
Journal of Electron Microscopy, 2020Co-Authors: A E Corderoborboa, R UndaangelesAbstract:The shape and orientation of second-phase precipitates in a Eu2+-doped equimolar KCl:KBr solid solution are reported in this paper as they were unveiled by Epifluorescence Microscopy. To make this, Microscopy images of different optical cross sections of some precipitate fields and, also, of some representative precipitates in these fields, were recorded by using the Eu2+ ion itself as a fluorochrome. From these images, the corresponding precipitate fields and individual precipitates were electronically reconstructed into the host lattice space. Previously, the KCl:KBr:Eu2+ system was characterized by absorption and fluorescence optical spectrophotometry, to tailor properly the fluorescence mirror unit, as well as by powder and single-plate X-ray diffraction, to correlate the host lattice orientation with those of the observed precipitates. These are shaped as plates, with broad faces parallel to host lattice {100}, {110} or {120}planes (the {100}, {110} and {120} precipitates, respectively), and as rods, aligned with a host lattice ˂100> direction (the ˂100> precipitates). The {100}, {110}, {120}-precipitate broad faces are in the shapes of 72.6° rhomboids, rectangles and 59.5° rhomboids, with a side lying along host lattice , and directions, respectively, and with another side lying along a direction. A typical precipitate field and the spatial reconstructions of typical {100}, {110}, {120} and ˂100> precipitates, as well as their corresponding electronic 3D-geometrical models, are described in detail. It is discussed that four different europium precipitation states are responsible for the precipitation and that the precipitate lattices are spatially coherent with the host lattice.
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geometry and spatial orientation of a quadruple node of triple junctions in a europium doped ki crystal as determined by Epifluorescence Microscopy
Journal of Microscopy, 2016Co-Authors: A E Corderoborboa, R UndaangelesAbstract:The geometry and spatial orientation of a typical arrangement of four triple junctions and six grain boundaries sharing a common quadruple node in a Eu2+ -doped KI crystal are investigated by Epifluorescence Microscopy using the proper doping ion as a fluorochrome. To achieve this, an electronic three-dimensional reconstruction of the studied arrangement of crystal defects was built from Microscopy images of different optical cross-sections of this arrangement. Previously, the doping ions were induced, by subjecting the crystal to a long annealing treatment, to form europium precipitates into the crystal grain boundaries. The optical properties of these precipitates were characterized by fluorescence spectrophotometry and used to tailor properly the microscope fluorescence mirror unit, whereas the single-crystal character of the microscope samples was tested by X-ray diffraction. By inspecting the reconstruction under handling, the dihedral angles between the grain boundaries that meet at a common triple junction as well as the angles between the triple junctions sharing the quadruple node were successfully measured at the quadruple node site. The measuring procedures are carefully described. The resulting values (132o, 109o, 119o, 125o, 111o, 124o, 124o, 111o, 125o, 129o, 109o and 122o ± 2o) for the dihedral angles depart for some few degrees from the characteristic angle (120o) of a 3-fold symmetry rotation, whereas the resulting values (104o, 111o, 117o, 103o, 100o and 121o ± 2o) for the triple junction angles are not far from the characteristic angle (109.47o) between the legs of a tetrahedron. These results, indicating that in the close neighbourhood of the quadruple node the studied arrangement of crystal defects deviates from a state of full structural stability, allow this arrangement to be fairly modelled in such a neighbourhood by a distorted tetrahedron. The angles between the studied triple junctions and the host lattice directions [11¯1], [111¯], [1¯11] and [1¯1¯1¯] were also measured at the quadruple node site, and the resulting values (8o, 7o, 6o and 8o ± 2o, respectively) indicate that a symmetry mismatching exists between the tetrahedral model of the studied Eu2+ -decorated arrangement of crystal defects and the KI matrix cubic crystal lattice. This symmetry mismatching is discussed to be responsible for the observed deviation from structural stability.
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Epifluorescence Microscopy a sensitive tool for studying the morphology and oriented growth of europium precipitates in ki single crystal hosts
Journal of Microscopy, 2015Co-Authors: A E Corderoborboa, R UndaangelesAbstract:The morphology and oriented growth of europium precipitates in well-annealed Eu²⁺-doped KI single crystals are investigated by Epifluorescence Microscopy using the proper doping ions as fluorochromes. To make this, electronic spatial reconstructions of some fields of precipitates and of some individual precipitates were built from Epifluorescence microscope images of different optical cross-sections of these objects. The building procedures are carefully explained. Previously, the KI:Eu²⁺ system was characterized by fluorescence spectrophotometry and the KI-host long-range translational order was tested by single-plate X-ray diffraction. Precipitates are shaped as plates, with their broad faces being parallel to host lattice planes of either {100}- or {110}-forms (the {100}- or {110}-plates, respectively) and as rods lying along host lattice -directions. The {100}-plates have rhomboidal broad faces with a side lying along a -direction, an internal angle of about 45°, as measured on the corresponding {100}-plane, and, consequently, another side (the {100} -side) lying along a direction on this plane. The {110}-plates have rectangular broad faces with a side lying along a -direction and with another side (the {110} -side) lying along a -direction on the corresponding {110}-plane. Spatial reconstructions of a typical precipitate field, a typical {100}-plate, a typical {110}-plate and a typical rod are described in detail. Precipitates were measured in their different dimensions and the measuring procedures are explained. The plate thicknesses and rod diameters are into a common narrow range of values (0.5-0.2 μm) which contains also the inferior limits of the obtained length ranges for the {100} - and {110} -sides (5.1-0.3 and 4.9-0.3 μm, respectively). It is discussed that that three different europium precipitation states are responsible for the studied precipitation and that plates grew from rods during annealing.
Philippe Lebaron - One of the best experts on this subject based on the ideXlab platform.
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comparative assessment of Epifluorescence Microscopy flow cytometry and solid phase cytometry used in the enumeration of specific bacteria in water
Aquatic Microbial Ecology, 2001Co-Authors: Karine Lemarchand, Nathalie Parthuisot, Philippe Catala, Philippe LebaronAbstract:Rapid microbiology and the detection of rare events are important challenges in various fields of aquatic microbiology. Epifluorescence Microscopy, flow cytometry and solid-phase cyto- metry are techniques used for direct methods in microbiology but the range of application of these different instruments is not clearly defined. In this study, we examined the lower limit of bacterial concentration to which each technique can be reliably used. Techniques were compared for the enu- meration of (1) fluorescent beads, (2) labeled bacteria at different ratios of labeled/non-labeled cells, (3) Escherichia coli O157:H7 cells inoculated at different densities in tap water, and (4) E. coli O157:H7 cells in artificially contaminated natural seawater. The different methods gave results that correlated well despite the presence of a significant background of unlabeled cells. However, solid- phase cytometry was the only technique that allowed the accurate enumeration of rare events (down to 1 cell) providing the same sensitivity as traditional culture methods. The detection sensitivity was not affected by the presence of up to 10 7 unlabeled cells on the filter. In contrast, flow cytometry was a very rapid and accurate method but it could not be applied to the detection of rare events. E. coli O157:H7 cells could be detected rapidly and accurately in environmental water samples in the pres- ence of non-specific bacteria. Solid-phase cytometry combined with taxonomic probes allowed rapid and accurate detection of a large variety of species of ecological interest in a wide variety of aquatic environments.
Kathy L Rowlen - One of the best experts on this subject based on the ideXlab platform.
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quantitative intercomparison of transmission electron Microscopy flow cytometry and Epifluorescence Microscopy for nanometric particle analysis
Analytical Biochemistry, 2002Co-Authors: Matthew M Ferris, Carrie L Stoffel, Thain T Maurer, Kathy L RowlenAbstract:Nanometric biological particles such as viruses have received increased attention in a wide range of scientific fields. Evaluation of viral contributions to environmental processes and the use of viruses in medical applications such as gene therapy require viruses to be routinely and accurately enumerated. There are a variety of existing techniques for counting viruses, namely, plaque assays, transmission electron Microscopy (TEM), Epifluorescence Microscopy (EFM), and flow cytometry (FCM); each has advantages and disadvantages. While there have been attempts to intercompare some of these techniques to determine the most effective means to count viruses, no previous study used a technique-independent standard for quantitative comparison of collection efficiency, accuracy, and precision. In this work, polystyrene nanospheres were used as standards for the intercomparison of performance characteristics for TEM, EFM, FCM, as well as a custom-built flow cytometer (the Single Nanometric Particle Enumerator, SNaPE). EFM and SNaPE exhibited the highest degree of accuracy and precision, with particle concentrations deviating ≤5% from true and relative errors less than half that of TEM, EFM and SNaPE are also significantly more time and cost efficient than TEM.