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Artigos de revistas sobre o assunto "Bacterial surface"
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Absolom, Darryl R. "The role of bacterial hydrophobicity in infection: bacterial adhesion and phagocytic ingestion". Canadian Journal of Microbiology 34, n.º 3 (1 de março de 1988): 287–98. http://dx.doi.org/10.1139/m88-054.
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The role that bacterial surface hydrophobicity (surface tension) plays in determining the extent of adhesion of polymer substrates and phagocytic ingestion is reviewed. The early attachment phase in bacterial adhesion is shown to depend critically on the relative surface tensions of the three interacting phases; i.e., bacteria, substrate, and suspending liquid surface tension. When suspended in a liquid with a high surface tension such as Hanks balanced salt solution, the most hydrophobic bacteria adhere to all surfaces to the greatest extent. When the liquid surface tension (γLV) is larger than the bacterial surface tension (γBV), then for any single bacterial species the extent of adhesion decreases with increasing substrate surface tension (γSV). When γLV < γBV then adhesion increases with increasing γSV. Bacterial surface tension also determines in part the extent of phagocytic ingestion and the degree to which antibodies aspecifically adsorb onto the bacterium resulting in opsonization. The nonspecific adsorption of antibodies results in a considerable modification in the surface properties of the bacteria. Bacterial surface hydrophobicity can be altered significantly through exposure to subinhibitory concentrations of antibiotics, surfactants, lectins, etc. The effect of these changes on subsequent phagocytic ingestion is discussed.
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Evans, Adele, Anthony J. Slate, Millie Tobin, Stephen Lynch, Joels Wilson Nieuwenhuis, Joanna Verran, Peter Kelly e Kathryn A. Whitehead. "Multifractal Analysis to Determine the Effect of Surface Topography on the Distribution, Density, Dispersion and Clustering of Differently Organised Coccal-Shaped Bacteria". Antibiotics 11, n.º 5 (21 de abril de 2022): 551. http://dx.doi.org/10.3390/antibiotics11050551.
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The topographic features of surfaces are known to affect bacterial retention on a surface, but the precise mechanisms of this phenomenon are little understood. Four coccal-shaped bacteria, Staphylococcus sciuri, Streptococcus pyogenes, Micrococcus luteus, and Staphylococcus aureus, that organise in different cellular groupings (grape-like clusters, tetrad-arranging clusters, short chains, and diploid arrangement, respectively) were used. These differently grouped cells were used to determine how surface topography affected their distribution, density, dispersion, and clustering when retained on titanium surfaces with defined topographies. Titanium-coated surfaces that were smooth and had grooved features of 1.02 µm-wide, 0.21 µm-deep grooves, and 0.59 µm-wide, 0.17 µm-deep grooves were used. The average contact angle of the surfaces was 91°. All bacterial species were overall of a hydrophobic nature, although M. luteus was the least hydrophobic. It was demonstrated that the 1.02 µm-wide featured surface most affected Strep. pyogenes and S. sciuri, and hence the surfaces with the larger surface features most affected the cells with smaller dimensions. The 0.59 µm featured surface only affected the density of the bacteria, and it may be suggested that the surfaces with the smaller features reduced bacterial retention. These results demonstrate that the size of the topographical surface features affect the distribution, density, dispersion, and clustering of bacteria across surfaces, and this is related to the cellular organisation of the bacterial species. The results from this work inform how surface topographical and bacterial properties affect the distribution, density, dispersion, and clustering of bacterial retention.
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Vadillo-Rodríguez, Virginia, Henk J. Busscher, Willem Norde, Joop de Vries, René J. B. Dijkstra, Ietse Stokroos e Henny C. van der Mei. "Comparison of Atomic Force Microscopy Interaction Forces between Bacteria and Silicon Nitride Substrata for Three Commonly Used Immobilization Methods". Applied and Environmental Microbiology 70, n.º 9 (setembro de 2004): 5441–46. http://dx.doi.org/10.1128/aem.70.9.5441-5446.2004.
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ABSTRACT Atomic force microscopy (AFM) has emerged as a powerful technique for mapping the surface morphology of biological specimens, including bacterial cells. Besides creating topographic images, AFM enables us to probe both physicochemical and mechanical properties of bacterial cell surfaces on a nanometer scale. For AFM, bacterial cells need to be firmly anchored to a substratum surface in order to withstand the friction forces from the silicon nitride tip. Different strategies for the immobilization of bacteria have been described in the literature. This paper compares AFM interaction forces obtained between Klebsiella terrigena and silicon nitride for three commonly used immobilization methods, i.e., mechanical trapping of bacteria in membrane filters, physical adsorption of negatively charged bacteria to a positively charged surface, and glutaraldehyde fixation of bacteria to the tip of the microscope. We have shown that different sample preparation techniques give rise to dissimilar interaction forces. Indeed, the physical adsorption of bacterial cells on modified substrata may promote structural rearrangements in bacterial cell surface structures, while glutaraldehyde treatment was shown to induce physicochemical and mechanical changes on bacterial cell surface properties. In general, mechanical trapping of single bacterial cells in filters appears to be the most reliable method for immobilization.
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Hogan, Kayla, Sai Paul, Guanyou Lin, Jay Fuerte-Stone, Evgeni V. Sokurenko e Wendy E. Thomas. "Effect of Gravity on Bacterial Adhesion to Heterogeneous Surfaces". Pathogens 12, n.º 7 (15 de julho de 2023): 941. http://dx.doi.org/10.3390/pathogens12070941.
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Bacterial adhesion is the first step in the formation of surface biofilms. The number of bacteria that bind to a surface from the solution depends on how many bacteria can reach the surface (bacterial transport) and the strength of interactions between bacterial adhesins and surface receptors (adhesivity). By using microfluidic channels and video microscopy as well as computational simulations, we investigated how the interplay between bacterial transport and adhesivity affects the number of the common human pathogen Escherichia coli that bind to heterogeneous surfaces with different receptor densities. We determined that gravitational sedimentation causes bacteria to concentrate at the lower surface over time as fluid moves over a non-adhesive region, so bacteria preferentially adhere to adhesive regions on the lower, inflow-proximal areas that are downstream of non-adhesive regions within the entered compartments. Also, initial bacterial attachment to an adhesive region of a heterogeneous lower surface may be inhibited by shear due to mass transport effects alone rather than shear forces per se, because higher shear washes out the sedimented bacteria. We also provide a conceptual framework and theory that predict the impact of sedimentation on adhesion between and within adhesive regions in flow, where bacteria would likely bind both in vitro and in vivo, and how to normalize the bacterial binding level under experimental set-ups based on the flow compartment configuration.
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Patel, Nirav, Ryan Guillemette, Ratnesh Lal e Farooq Azam. "Bacterial surface interactions with organic colloidal particles: Nanoscale hotspots of organic matter in the ocean". PLOS ONE 17, n.º 8 (25 de agosto de 2022): e0272329. http://dx.doi.org/10.1371/journal.pone.0272329.
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Colloidal particles constitute a substantial fraction of organic matter in the global ocean and an abundant component of the organic matter interacting with bacterial surfaces. Using E. coli ribosomes as model colloidal particles, we applied high-resolution atomic force microscopy to probe bacterial surface interactions with organic colloids to investigate particle attachment and relevant surface features. We observed the formation of ribosome films associating with marine bacteria isolates and natural seawater assemblages, and that bacteria readily utilized the added ribosomes as growth substrate. In exposure experiments ribosomes directly attached onto bacterial surfaces as 40–200 nm clusters and patches of individual particles. We found that certain bacterial cells expressed surface corrugations that range from 50–100 nm in size, and 20 nm deep. Furthermore, our AFM studies revealed surface pits in select bacteria that range between 50–300 nm in width, and 10–50 nm in depth. Our findings suggest novel adaptive strategies of pelagic marine bacteria for colloid capture and utilization as nutrients, as well as storage as nanoscale hotspots of DOM.
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Sejati, Bramasto Purbo, Tetiana Haniastuti, Ahmad Kusumaatmaja e Maria Goreti Widyastuti. "The Influence of Surface Damage on Miniplates: A Study of Bacterial Attachment Across Various Strains". F1000Research 14 (4 de fevereiro de 2025): 158. https://doi.org/10.12688/f1000research.159954.1.
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Background Miniplates are frequently used in oral and maxillofacial surgery to address malocclusion issues. However, surface damage to miniplates is a significant concern that can affect surgical outcomes and patient quality of life. This study aims to evaluate the influence of miniplate surface damage on bacterial attachment, which may lead to postoperative infections. Methods Miniplates with varying degrees of surface damage were used in this study. The damaged surfaces were subjected to special treatments to simulate postoperative conditions. Various bacterial strains, including Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus mutans, were tested. Each type of bacteria was cultured on different miniplates for specific durations, and bacterial attachment was subsequently measured and analyzed. Results Surface damage to miniplates significantly influenced bacterial attachment. Miniplates with more severe surface damage exhibited higher levels of bacterial attachment compared to undamaged miniplates. Furthermore, the type of bacteria impacted attachment levels, with certain strains demonstrating higher adhesion than others. Conclusion Surface damage to miniplates increases the risk of postoperative infections due to enhanced bacterial attachment. Therefore, maintaining the integrity of miniplates during and after orthognathic surgery is crucial. Further research is necessary to develop prevention and management strategies for postoperative infections related to miniplate surface damage.
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Dang, Hongyue, Tiegang Li, Mingna Chen e Guiqiao Huang. "Cross-Ocean Distribution of Rhodobacterales Bacteria as Primary Surface Colonizers in Temperate Coastal Marine Waters". Applied and Environmental Microbiology 74, n.º 1 (26 de outubro de 2007): 52–60. http://dx.doi.org/10.1128/aem.01400-07.
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ABSTRACT Bacterial surface colonization is a universal adaptation strategy in aquatic environments. However, neither the identities of early colonizers nor the temporal changes in surface assemblages are well understood. To determine the identities of the most common bacterial primary colonizers and to assess the succession process, if any, of the bacterial assemblages during early stages of surface colonization in coastal water of the West Pacific Ocean, nonnutritive inert materials (glass, Plexiglas, and polyvinyl chloride) were employed as test surfaces and incubated in seawater off the Qingdao coast in the spring of 2005 for 24 and 72 h. Phylogenetic analysis of the 16S rRNA gene sequences amplified from the recovered surface-colonizing microbiota indicated that diverse bacteria colonized the submerged surfaces. Multivariate statistical cluster analyses indicated that the succession of early surface-colonizing bacterial assemblages followed sequential steps on all types of test surfaces. The Rhodobacterales, especially the marine Roseobacter clade members, formed the most common and dominant primary surface-colonizing bacterial group. Our current data, along with previous studies of the Atlantic coast, indicate that the Rhodobacterales bacteria are the dominant and ubiquitous primary surface colonizers in temperate coastal waters of the world and that microbial surface colonization follows a succession sequence. A conceptual model is proposed based on these findings, which may have important implications for understanding the structure, dynamics, and function of marine biofilms and for developing strategies to harness or control surface-associated microbial communities.
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Du, Cezhi, Chengyong Wang, Tao Zhang, Xin Yi, Jianyi Liang e Hongjian Wang. "Reduced bacterial adhesion on zirconium-based bulk metallic glasses by femtosecond laser nanostructuring". Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 234, n.º 4 (30 de dezembro de 2019): 387–97. http://dx.doi.org/10.1177/0954411919898011.
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As high-performing materials, bulk metallic glasses have attracted widespread attention for biomedical applications. Herein, the bacterial adhesion properties of femtosecond laser-nanostructured surfaces of four types of zirconium-based bulk metallic glasses are assessed. Laser-induced periodical surface structures and nanoparticle structures were fabricated by femtosecond laser irradiation under different energy intensities (0.23 and 2.3 J/mm2). Surface topography, roughness, wettability, and surface energy were investigated after femtosecond laser irradiation and the surface bacterial adhesion properties were explored using Escherichia coli and Staphylococcus aureus as respective representatives of Gram-negative and Gram-positive bacteria. 4′,6-Diamidino-2-phenylindole fluorescence staining was used to characterize and assess the bacterial surface coverage rate. The in vitro cytotoxicity of polished and laser-nanostructured surfaces was investigated using MC3T3-E cells. The obtained results demonstrate that femtosecond laser surface nanostructuring retained the amorphous structure of zirconium-based bulk metallic glasses and led to an obvious decrease in bacterial adhesion compared with polished surfaces. The inhibition of bacterial adhesion on laser-induced periodical surface structures was greater than on nanostructured surfaces after 24 h of bacterial incubation. In addition, femtosecond laser nanostructuring did not have an apparent effect on the cytotoxicity of zirconium-based bulk metallic glasses.
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Müller, Rainer, Gerhard Gröger, Karl-Anton Hiller, Gottfried Schmalz e Stefan Ruhl. "Fluorescence-Based Bacterial Overlay Method for Simultaneous In Situ Quantification of Surface-Attached Bacteria". Applied and Environmental Microbiology 73, n.º 8 (16 de fevereiro de 2007): 2653–60. http://dx.doi.org/10.1128/aem.02884-06.
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ABSTRACT For quantification of bacterial adherence to biomaterial surfaces or to other surfaces prone to biofouling, there is a need for methods that allow a comparative analysis of small material specimens. A new method for quantification of surface-attached biotinylated bacteria was established by in situ detection with fluorescence-labeled avidin-D. This method was evaluated utilizing a silicon wafer model system to monitor the influences of surface wettability and roughness on bacterial adhesion. Furthermore, the effects of protein preadsorption from serum, saliva, human serum albumin, and fibronectin were investigated. Streptococcus gordonii, Streptococcus mitis, and Staphylococcus aureus were chosen as model organisms because of their differing adhesion properties and their clinical relevance. To verify the results obtained by this new technique, scanning electron microscopy and agar replica plating were employed. Oxidized and poly(ethylene glycol)-modified silicon wafers were found to be more resistant to bacterial adhesion than wafers coated with hydrocarbon and fluorocarbon moieties. Roughening of the chemically modified surfaces resulted in an overall increase in bacterial attachment. Preadsorption of proteins affected bacterial adherence but did not fully abolish the influence of the original surface chemistry. However, in certain instances, mostly with saliva or serum, masking of the underlying surface chemistry became evident. The new bacterial overlay method allowed a reliable quantification of surface-attached bacteria and could hence be employed for measuring bacterial adherence on material specimens in a variety of applications.
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Corcionivoschi, Nicolae, Igori Balta, Eugenia Butucel, David McCleery, Ioan Pet, Maria Iamandei, Lavinia Stef e Sorin Morariu. "Natural Antimicrobial Mixtures Disrupt Attachment and Survival of E. coli and C. jejuni to Non-Organic and Organic Surfaces". Foods 12, n.º 20 (21 de outubro de 2023): 3863. http://dx.doi.org/10.3390/foods12203863.
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The contact and adherence of bacteria to various surfaces has significant consequences on biofilm formation through changes in bacterial surface structures or gene expression with potential ramifications on plant and animal health. Therefore, this study aimed to investigate the effect of organic acid-based mixtures (Ac) on the ability Campylobacter jejuni and Escherichia coli to attach and form biofilm on various surfaces, including plastic, chicken carcass skins, straw bedding, and eggshells. Moreover, we aimed to explore the effect of Ac on the expression of E. coli (luxS, fimC, csgD) and C. jejuni (luxS, flaA, flaB) bacterial genes involved in the attachment and biofilm formation via changes in bacterial surface polysaccharidic structures. Our results show that Ac had a significant effect on the expression of these genes in bacteria either attached to these surfaces or in planktonic cells. Moreover, the significant decrease in bacterial adhesion was coupled with structural changes in bacterial surface polysaccharide profiles, impacting their adhesion and biofilm-forming ability. Essentially, our findings accentuate the potential of natural antimicrobials, such as Ac, in reducing bacterial attachment and biofilm formation across various environments, suggesting promising potential applications in sectors like poultry production and healthcare.
Teses / dissertações sobre o assunto "Bacterial surface"
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Château, Maarten de. "Functional, structural and evolutionary studies on a family of bacterial surface proteins". Lund : Dept. of Cell and Molecular Biology, Lund University, 1996. http://catalog.hathitrust.org/api/volumes/oclc/38947242.html.
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Lloyd, Diarmuid Padraig. "Microscopic studies of surface growing bacterial populations". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10509.
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In this thesis, I present three microscopy studies of surface growing Escherichia coli (E. coli ) microcolonies. All experiments were carried out by growing microcolonies on agarose pads, and imaging their growth using phase contrast, fluorescence and confocal microscopy. In the first project, the importance of spatial structure and growth strategies between competing populations of E. coli was studied. An agarose pad was seeded with bacterial cells and their colonisation success tracked. Cell lag-times and local cell density were found to play important roles in determining the eventual success of a colony. Arrangements of neighbouring cells were found to be partially responsible at high cell densities. These results were reproduced using a simple simulation, which also highlighted the importance of exponential expansion in determining colonisation success. The second project investigates the effect of confinement on growing microcolonies restricted to one plane (2d growth). Colonies were grown in agarose microchannels with different aspect ratios, and in unconfined environments. In particular internal physical colony structure and genealogical structure was studied by using single-cell tracking. Results showed that relatedness between cells was directionally biased (cells tended to be more closely related to cells at their poles, than to their side) regardless of the amount of spatial restriction. Furthermore, confinement caused cells to align with each other more, and induced high cell velocities at the colony edges driven by cell expansion. In the final project, growth of secondary layers in growing colonies of E. coli was studied. Cells initially grew as a monolayer, before invading the agarose bulk, producing a secondary layer. By analysing time-lapse movies, this layer was found to initially expand rapidly well in excess of cell growth rates and initial colony expansion rates, before slowing down. The initial secondary growth rate likely depends on the colony area at agarose invasion. Furthermore, the colony area when colonies invaded the agarose depended on their rate of growth, suggesting a complex interplay between forces exerted by the agarose, and by the colony.
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Petkova, Petya Stoyanova. "Surface nano-structured materials to control bacterial contamination". Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/398122.
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The spread of bacteria and infections, initially associated with an increased number of hospital-acquired infections, has now extended into the community causing severe and difficult to treat diseases. Additionally, many of those diseases are evoked by bacteria that have become resistant to antibiotics. Overcoming the ability of bacteria to develop resistance will potentially reduce the burden of these infections on the healthcare systems worldwide and prevent thousands of deaths each year.
The nano-scale particles are promising candidates to fight bacteria, since developing of resistance to their action is less likely to occur. Nanoparticles (NPs) can be incorporated into polymeric matrices to design a wide variety of nanocomposites. Such nano-structures consisting of inorganic and inorganic/organic NPs represent a novel class of materials with a broad range of applications.
This thesis is about the development of antibacterial nano-structured materials aimed at preventing the spread of bacteria. To achieve this, two versatile physicochemical and biotechnological tools, namely sonochemistry and biocatalysis were innovatively combined. Ultrasound irradiation used for the generation of various nano-structures and its combination with biocatalysts (enzymes) opens new perspectives in materials processing, here illustrated by the production of NPs coated medical textiles, water treatment membranes and chronic wound dressings.
The first part of the thesis aims at the development of antibacterial medical textiles to prevent the bacteria transmission and proliferation using two single step approaches for antibacterial NPs coating of textiles. In the first approach antibacterial zinc oxide NPs (ZnO NPs) and chitosan (CS) were deposited simultaneously on cotton fabric by ultrasound irradiation. The obtained hybrid NPs coatings demonstrated durable antibacterial properties after multiple washing cycles. Moreover, the presence of biopolymer in the NP hybrids improved the biocompatibility of the material in comparison with ZnO NPs coating alone.
In the second approach, a simultaneous sonochemical/enzymatic process for durable antibacterial coating of cotton with ZnO NPs was carried out. The enzymatic treatment provides better adhesion of the ZnO NPs and, as a consequence, enhanced coating stability during exploitation. Likewise to the antibacterial coatings obtained in the first approach, the antibacterial efficiency of these textiles was maintained after multiple intensive laundry regimes used in hospitals. The NPs-coated cotton fabrics inhibited the growth of the most medically relevant bacteria species.
In the second part of the thesis, hybrid antibacterial biopolymer/silver NPs and cork matrices, were enzymatically assembled into an antimicrobial material with potential for water remediation. Intrinsically antibacterial amino-functional biopolymers, namely CS and aminocellulose were used as doping agents to stabilize colloidal dispersions of silver NPs (AgNPs), additionally providing the particles with functionalities for covalent immobilization on cork to impart durable antibacterial effect. The biopolymers promoted the antibacterial efficacy of the obtained nanocomposites in conditions simulating a real situation in constructed wetlands.
In the last, third part of the thesis, a bioactive nanocomposite hydrogel for wound treatment was developed. Sonochemically synthesized epigallocatechin gallate nanospheres (EGCG NSs) were incorporated and simultaneously crosslinked enzymatically into a thiolated chitosan hydrogel. The potential of the generated material for chronic wound treatment was evaluated by assessing its antibacterial properties and inhibitory effect on myeloperoxidase and collagenase biomarkers of chronic wound infection. Sustained release of the EGCG NSs from the biopolymer matrix was achieved. The latter, coupled with the good biocompatibility of the hydrogel, suggested its potential for chronic wound management.La propagación de bacterias e infecciones, inicialmente limitada a infecciones adquiridas en el hospital, se ha extendido al resto de la sociedad causando enfermedades muy graves y más difíciles de tratar. Además, muchas de estas enfermedades son provocadas por bacterias que se han hecho resistentes a los antibióticos convencionales. Por lo tanto, limitar la capacidad de estas bacterias para desarrollar resistencia puede potencialmente reducir la alta incidencia de estas infecciones y evitar miles de muertes cada año. Las partículas de escala nanométrica son unas candidatas prometedoras para combatir las bacterias, ya que su mecanismo de acción las hace disminuir las probabilidades en el desarrollo de resistencia. Las nanopartículas (NPs) se pueden incorporar en matrices poliméricas para diseñar una amplia variedad de materiales nanocompuestos. Estas nanoestructuras consisten en NPs orgánicas/inorgánicas e inorgánicas representando una nueva clase de materiales con una amplia gama de aplicaciones. Esta tesis trata sobre el desarrollo de materiales antibacterianos con estructura nanométrica dirigidos a prevenir la propagación de bacterias. Para lograr esto, dos herramientas fisicoquímicas y biotecnológicas versátiles tales como sonoquímica y biocatálisis, se combinaron de manera innovadora. La irradiación por ultrasonido se ha utilizado para la generación de nanoestructuras diversas y su combinación con biocatalizadores (enzimas) abre nuevas perspectivas en el tratamiento de materiales, aquí ilustrados por la producción de textiles médicos recubiertos con NPs, membranas de tratamiento de agua y apósitos para heridas crónicas. La primera parte de la tesis tiene como objetivo el desarrollo de textiles médicos antibacterianos para prevenir la transmisión y proliferación de bacterias utilizando dos estrategias "de un solo paso" para el recubrimiento antibacteriano de estos textiles con NPs. En el primer enfoque NPs antibacterianas de óxido de zinc (ZnO NPs) y quitosano (CS) fueron depositadas simultáneamente sobre tejido de algodón por irradiación de ultrasonido. Los recubrimientos híbridos de NPs obtenidos demostraron propiedades antibacterianas duraderas después de varios lavados exhaustivos. Por otra parte, la presencia de biopolímeros en las NPs híbridas mejoraba la biocompatibilidad del material en comparación con el recubrimiento de solamente de ZnO NPs. En la segunda parte de la tesis, híbridos antibacterianos hechos de biopolímeros y NPs de plata y matrices de corcho, fueron ensamblados enzimáticamente en un material antimicrobiano para su utilización en la remediación de aguas. Biopolímeros antibacterianos aminofuncionalizados (CS y aminocelulosa) se utilizaron como agentes dopantes para estabilizar las dispersiones coloidales de plata (Ag NPs). Además, estas partículas presentan todas las funciones necesarias para su inmovilización covalente en el corcho proporcionando un efecto antibacteriano duradero. Estos biopolímeros aumentaron la eficacia antibacteriana de estos nanocompuestos en condiciones que simulan una situación real en humedales construidos. En la tercera parte de la tesis, se desarrolló un hidrogel nanocompuesto bioactivo para el tratamiento de heridas crónicas. Nanoesferas de galato de epigalocatequina (EGCG NSs) fueron sintetizadas a través de sonoquimica y se incorporaron y simultáneamente reticularon enzimáticamente en un hidrogel de quitosano tiolado. El potencial del material generado para el tratamiento de heridas crónicas fue evaluado por sus propiedades antibacterianas y su efecto inhibidor sobre biomarcadores producidos en heridas crónicas infectadas (mieloperoxidasa y colagenasa). También se consiguió la liberación sostenida de EGCG NSs por parte de la matriz generada, que junto con su buena biocompatibilidad, demostraba su potencial para el tratamiento de heridas crónicas.
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Haynie, Teron D. "Synthesis of Bacterial Surface Glycans for Conjugate Vaccines". BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8669.
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Bacteria are coated with repeating units of oligosaccharides that exhibit remarkable diversity. Often, glycan units of three or even two sugars are sufficient to identify a species of bacteria. Such specificity makes bacterial surface glycans attractive vaccine targets. However, efforts to create effective vaccines against carbohydrates have been hampered by poor vaccine design as well as the human immune tendency to respond to glycan antigens with non-specific, T-cell independent mechanisms. As a result, carbohydrate vaccines have historically produced only adequate memory responses in healthy individuals and poor responses in the elderly or immunocompromised. To circumvent these issues, a novel conjugate vaccine was developed that utilizes theQβ virus-like particle carrier that displays both a carbohydrate antigen as well as a Natural Killer T cell adjuvant. This unique vaccine has been reported to stimulate the production of high affinity (nanomolar) antibodies against carbohydrate antigens. To further conjugate vaccine research, the present work synthesizes two bacterial surface antigens: a trisaccharide from Streptococcus pneumoniae serotype 23F (Sp23F), and a pentasaccharide from Ruminococcus gnavus (Rg). Sp23F has been characterized as one of the more virulent and disease-causing strains of S. pneumoniae. Rg secretes highly immunostimulatory proteins and is associated with irritable bowel syndrome. The Sp23F antigen is synthesized with an alkyne at the reducing end of the sugar to facilitate coupling to Qβ. A selection reagent for Sp23F is also synthesized to enable the extraction of antibodies and B cells that bind the antigen. In conjunction with providing a conjugate vaccine antigen, the Rg pentasaccharide will be examined as a TLR4 ligand and was therefore synthesized without an alkyne. The Rg conjugate vaccine shows promise in treating irritable bowel syndrome as well as facilitating research into the role Rg plays in the human microbiome.
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Ramos, Isabel Cristina Santos Silva de Faria. "Culturable bacterial community of the estuarine surface microlayer". Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/849.
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Mestrado em MicrobiologiaA camada superficial aquática (1-1000 μm) é um ecossistema único, definido como a interface entre a hidrosfera e a atmosfera. É uma camada exposta a altas intensidades de radiação solar Ultra-Violeta, sendo enriquecida com compostos orgânicos e poluentes antropogénicos. Além disso, está sujeita a condições instáveis de temperatura e salinidade. Assim sendo, é razoável colocar-se a hipótese de que esta camada é habitada por comunidades bacterianas distintas e especializadas. Apenas alguns estudos sobre este tema foram publicados e os resultados foram frequentemente divergentes. Apesar do já reconhecido enviesamento introduzido pelas metodologias dependentes do cultivo, tais técnicas permanecem essenciais para a compreensão da fisiologia e ecologia da comunidade bacteriana. Os estuários são ambientes confinados e frequentemente muito poluídos, o que provavelmente favorece a formação de camadas superficiais claramente distintas das águas subjacentes. Portanto, o objectivo deste trabalho foi comparar as comunidades bacterianas cultiváveis da camada superficial aquática e da coluna de água. Foram escolhidos três locais ao longo do estuário Ria de Aveiro atendendo a diferentes parâmetros ambientais e exposição a poluentes. A amostragem foi realizada utilizando o método 'Glass- Plate'. As amostras foram obtidas em maré baixa, durante o dia e noite, em cinco campanhas, tendo em vista a quantificação das unidades formadoras de colónias e subsequente isolamento para caracterização filogenética. Para estes fins, usámos dois meios de cultura: GSP (Pseudomonas Aeromonas Selective Agar Base) e EA (Estuarine Agar). A quantificação das UFC indica que o número de bactérias provenientes da camada superficial (bacterioneuston) é cerca de três vezes mais abundante do que o proveniente da coluna de água (bacterioplâncton). Verifica-se uma diminuição da abundância de bacterioneuston de dia para noite, ao contrário do bacterioplâncton, que tende a aumentar durante o mesmo período. Dos isolados obtidos, o rDNA 16S foi e digerido com a enzima HaeIII. A partir de 402 isolados, foram identificados 72 perfis diferentes. Desses, 21 perfis foram exclusivos da camada superficial e 28 foram exclusivos da coluna de água. Representantes dos diferentes perfis foram analisados por sequenciação e bactérias pertencentes a 5 Filos: Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes e Deinococci-Thermus; e 9 Classes: Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Epsilonproteobacteria, Actinobacteria, Flavobacteria, Sphingobacteria, Deinococci e Bacilli foram identificadas. Os isolados afiliaram com sequências provenientes de ambientes aquáticos bem como de áreas altamente contaminadas. Os resultados apontam para uma comunidade cultivável distinta/particular na microcamada superficial estuarina. ABSTRACT: The sea surface microlayer (SML) is an unique ecosystem, defined as the interfacial film (uppermost 1–1000 μm) between the atmosphere and the ocean. Thereby, it is exposed to high intensities of solar radiation, and is enriched with organic compounds and pollutants from anthropogenic inputs. Also it is subjected to unstable temperature and salinity conditions. Thus, it is proper to hypothesize that the SML is inhabited by distinct and specialized microbial communities. Only a few studies on this topic were published and results wee frequently divergent. Despite the previously recognized biases introduced by culture-dependent methodologies, such techniques remain essential to understand bacterial population’s physiology and ecology. Estuaries are confined and frequently highly polluted environments, which probably favor the formation of distinct surface layers clearly distinct from underlying waters. Therefore, our goal was to compare the culturable bacterial communities occurring in SML and underlying waters (UW). Our work concerned three sampling sites in the estuary Ria de Aveiro, corresponding to different environmental parameters and exposure to pollutants. Sampling was conducted using the so-called ‘Glass-Plate’ method. The UW samples were collected directly into a sterilized glass bottle from a depth of approximately 0.4 m. Samples were obtained at low-tide, during day and night, in five campaigns, regarding the CFU (Colony Forming Units) quantification and subsequent recovery of bacterial isolates. For these purposes we used two culture media: GSP (Pseudomonas Aeromonas Selective Agar Base) and EA (Estuarine Agar). CFU quantification indicates that bacterioneuston is about three times more abundant than bacterioplankton. Generally bacterioneuston abundance decreases from day to night while bacterioplankton usually increases during the same period. From all the obtained isolates the 16S rDNA was amplified using universal primers and digested with the enzyme HaeIII. The profiles were analyzed using the software GelCompar and representatives of each pattern were selected for sequencing. From 402 isolates, 72 different profiles were identified. From those 21 profiles were exclusive from SML samples and 28 were exclusive from UW samples. Sequencing results allowed identifying bacteria belonging to 5 different Phyla: Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes and Deinococci-Thermus; and 9 Classes: Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Epsilonproteobacteria, Actinobacteria, Flavobacteria, Sphingobacteria, Deinococci e Bacilli. Isolates affiliated with sequences from aquatic environments as well as highly contaminated areas. The results point to a distinct/particular culturable community within the SML of this estuarine environment.
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Auditto, Sanjana. "Synthesis of organic conductive polymers to struggle bacterial infections". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0179.
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Les biofilms sont à l'origine de nombreux problèmes industriels, sanitaires et domestiques conduisant à d’intenses activités de recherche pour concevoir des solutions pour lutter contre leur formation et développement. Deux voies sont classiquement utilisées pour résoudre ces problèmes, soit l’utilisation de polymères anti-salissures soit des surfaces antibactériennes agissant par effet de contact ou par libération continue de biocides. Par ailleurs, des surfaces sensibles à divers stimuli (microenvironnement, lumière, ondes acoustiques etc.) ont été développées pour libérer de manière contrôlée les agents biocides. De plus, l’action d’un potentiel électrique (effet bioélectrique) a suscité un intérêt pour perturber les biofilms, mais reste sous-exploité. C’est dans ce contexte que s’inscrit ce travail avec le développement de surfaces électrostimulables biocompatibles à partir soit de (i) monocouches auto-assemblées (SAMs) déposées sur électrodes de titane ou d’or, (ii) polymères conducteurs (PCs) fonctionnalisés, pour empêcher l'adhésion/tuer les bactéries. Les SAMs à base de phosphoniums ont démontrées d’intéressantes propriétés antibactériennes, sans libération d’agent biocide, contre des souches Gram positive et négative (S. aureus, K. pneumoniae). D’autres part des films minces d’homo- et copolymères de PCs, à base de pyrrole fonctionnalisés par des phosphoniums, ont été obtenus par électropolymérisation et analysés en modifiant et en appliquant un ensemble de paramètres et testés comme antibactérien. Enfin, des phosphoniums hydrophiles ont été synthétisés et des études préliminaires ont mis en évidence leur intérêt potentiel comme vecteurs de médicamentsBacterial biofilms are in the background of many industrial, health and domestic adverse effects with economic losses leading to intensive research to design solutions to combat their formation and development. Two routes are commonly used to solve these issues, one aiming at preventing the adhesion of bacteria and the other at inhibiting and killing adhered microorganisms. Recent work has been done in that direction with the use of polymer-based antifouling or antibacterial surfaces acting either by contact effect or continuous release of bacterial substances. Besides, responsive surfaces to various stimuli (microenvironment, light, acoustic waves, etc.) have been developed to release biocides in a controlled way. In addition, the use of an electrical potential (bioelectric effect) has aroused interest to disrupt biofilms but remains underexploited. The present work focuses on the development of biocompatible electrostimulable surfaces based on either (i) self-assembled monolayers (SAMs) deposited on titanium or gold electrodes, or (ii) functionalized conductive polymers (CPs), to prevent adhesion and/or kill bacteria. Phosphonium-based SAMs have demonstrated interesting antibacterial properties, without release of biocidal agent, against Gram positive and negative strains (S. aureus, K. pneumoniae). In addition, thin films of homo- and copolymers of phosphonium-based pyrrole CPs were obtained by electropolymerization, and analyzed by modifying and applying a set of parameters and tested as antibacterial coatings. Lastly, hydrophilic phosphoniums have been synthesized and preliminary studies have highlighted their potential use as nanocarriers for drug delivery
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Mitik-Dineva, Natasa. "Bacterial attachment to micro- and nano- structured surfaces". Swinburne Research Bank, 2009. http://hdl.handle.net/1959.3/48547.
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The ongoing interest in bacterial interactions with various surfaces, followed by attachment and subsequent biofilm formation, has been driven by the importance of bacterial activities in number of medical, industrial and technological applications. However, bacterial adhesion to surfaces has not been completely understood due to the complexity of parameters involved. The study presented herein investigates the attachment pattern of nine medically and environmentally significant bacteria belonging to different taxonomic lineages: Firmicutes - Bacillus, Gammaproteobacteria, Alphaproteobacteria and Bacteriodetes. Physicochemical assessment techniques such as contact angle and surface charge measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), confocal microscopy (CLSM), as well as X-ray photoelectron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) analysis were all employed in order to attain better insight into the factors that influence bacterial interactions with surfaces. Bacterial surface characteristics such as surface wettability and charge in addition to substratum surface wettability, tension, charge and chemistry were also considered. However due to the recent interest in designing micro-textured surfaces with antibacterial and/or antifouling effects the prime was given to the influence of micro- and nano-meter scale surface textures on bacterial adhesion. The interactions between selected bacteria and glass, polymer and optical fibre surfaces were studied. Carefully designed methods for surface modification allowed alteration of the topography of glass, polymer and optical fibre surfaces while maintaining other surface parameters near constant. This allowed isolated assessment of only the effects of surface roughness on bacterial adhesion. Obtained results indicated consistent cellular inclination towards the smoother surfaces for all of the tested species. Enhanced bacterial presence on the smoother surfaces was also accompanied by changes in the bacterial metabolic activity as indicated by the elevated levels of secreted extracellular polymeric materials (EPS) and modifications in the cells morphology. The results indicate that nano-scale surface roughness exert greater influence on bacterial adhesion than previously believed and should therefore be considered as a parameter of primary interest alongside other wellrecognized factors that control initial bacterial attachment.
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Ye, Zhou. "Effect of Nanoscale Surface Structures on Microbe-Surface Interactions". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/85387.
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Bacteria in nature predominantly grow as biofilms on living and non-living surfaces. The development of biofilms on non-living surfaces is significantly affected by the surface micro/nano topography. The main goal of this dissertation is to study the interaction between microorganisms and nanopatterned surfaces. In order to engineer the surface with well-defined and repeatable nanoscale structures, a new, versatile and scalable nanofabrication method, termed Spun-Wrapped Aligned Nanofiber lithography (SWAN lithography) was developed. This technique enables high throughput fabrication of micro/nano-scale structures on planar and highly non-planar 3D objects with lateral feature size ranging from sub-50 nm to a few microns, which is difficult to achieve by any other method at present. This nanolithography technique was then utilized to fabricate nanostructured electrode surfaces to investigate the role of surface nanostructure size (i.e. 115 nm and 300 nm high) in current production of microbial fuel cells (MFCs). Through comparing the S. oneidensis attachment density and current density (normalized by surface area), we demonstrated the effect of the surface feature size which is independent of the effect on the surface area. In order to better understand the mechanism of microorganism adhesion on nanostructured surfaces, we developed a biophysical model that calculates the total energy of adhered cells as a function of nanostructure size and spacing. Using this model, we predict the attachment density trend for Candida albicans on nanofiber-textured surfaces. The model can be applied at the population level to design surface nanostructures that reduce cell attachment on medical catheters. The biophysical model was also utilized to study the motion of a single Candida albicans yeast cell and to identify the optimal attachment location on nanofiber coated surfaces, thus leading to a better understanding of the cell-substrate interaction upon attachment.Ph. D.
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Panhorst, Kimberly A. "Estimating Bacterial Loadings to Surface Waters from Agricultural Watersheds". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/36433.
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Fecal bacteria and pathogens are a major source of surface water impairment. In Virginia alone, approximately 73% of impaired waters are impaired due to fecal coliforms (FC). Because bacteria are a significant cause of water body impairment and existing bacterial models are predominantly based upon laboratory-derived information, bacterial models are needed that describe bacterial die-off and transport processes under field conditions. Before these bacterial models can be developed, more field-derived information is needed regarding bacterial survival and transport. The objectives of this research were to evaluate bacterial survival under field conditions and to develop a comprehensive, spatially variable (distributed) bacterial model that requires little or no calibration. Three field studies were conducted to determine die-off or diminution (settling plus die-off) rates of FC and Escherichia coli (EC) over time in: 1) dairy manure storage ponds and turkey litter storage sheds, 2) pasture and cropland soils to which dairy manure was applied, and 3) beef and dairy fecal deposits. The dairy manure storage ponds were sampled just under the pond surface. The FC and EC diminution (settling plus die-off) rates for dairy manure storage ponds were 0.00478 day-1 and 0.00781 day-1, respectively. The five samples collected for turkey litter in storage were inadequate to draw any conclusions. Bacterial die-off rates in cropland and pastureland soils were found to be statistically different from each other at the α = 0.05 level. The FC and EC die-off rates in cropland soils were 0.01351 day-1 and 0.01734 day-1, respectively, while the FC and EC die-off rates in pastureland soils were 0.02246 day-1 and 0.02796 day-1, respectively. Die-off rates for bacteria from dairy heifer, dairy milker, and beef cow fecal deposits were not statistically different from each other. The resulting die-off rate constants for fecal deposits were 0.01365 day-1 and 0.01985 day-1 for FC and EC, respectively. The EC/FC ratio was also evaluated for the fecal deposits and land-applied manure to determine if a quantifiable relationship was discernable. In general the EC/FC ratio declined over time, but no quantifiable relationship was discerned.
The bacterial model simulates die-off, bacterial partitioning between soil and water, and bacterial transport to surface waters in free (in solution) and sediment-adsorbed forms. Bacterial die-off was modeled using Chick's Law, bacterial partitioning was modeled with a linear isotherm equation, and bacterial transport was modeled using continuity and flow equations. The bacterial model was incorporated into the ANSWERS-2000 model, a continuous, distributed, nonpoint source pollution model. The model was tested using data from two plot studies. Calibration was required to improve runoff and sediment predictions. Bacterial model predictions underpredicted bacterial concentrations in runoff with a maximum underprediction error of 92.9%, but predictions were within an order of magnitude in all cases. Further model evaluation, on a larger watershed with predominantly overland flow, over a longer time period, is recommended, but such data were not available at the time of this assessment. The overall conclusions of this research were 1) FC and EC die-off or diminution under the examined field conditions followed Chick's Law, 2) measured die-off rate constants in the field were much less than those cited in literature for laboratory experiments, and 3) for the conditions simulated for two plot studies, the bacterial model predicted bacterial concentrations in runoff within an order of magnitude.
Master of Science
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Redford, Amanda J. "Interspecies and temporal variation in bacterial leaf surface communities". Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1456691.
Texto completo da fonteLivros sobre o assunto "Bacterial surface"
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Ian, Hancock, e Poxton Ian, eds. Bacterial cell surface techniques. Chichester [West Sussex]: Wiley, 1988.
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B, Sleytr Uwe, ed. Crystalline bacterial cell surface proteins. Austin, TX: R.G. Landes Co., 1996.
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Sleytr, Uwe B., Paul Messner, Dietmar Pum e Margit Sára, eds. Crystalline Bacterial Cell Surface Layers. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-73537-0.
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B, Sleytr U., ed. Crystalline bacterial cell surface layers. Berlin: Springer-Verlag, 1988.
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Saeid, Abdolkabir M. Bacterial surface modification of pyrite. Birmingham: University of Birmingham, 1994.
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Beveridge, Terry J., e Susan F. Koval, eds. Advances in Bacterial Paracrystalline Surface Layers. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4757-9032-0.
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J, Beveridge Terrance, Koval Susan F e NATO Advanced Research Workshop on Advances in Bacterial Paracrystalline Surface Layers (1992 : London, Ont.), eds. Advances in bacterial paracrystalline surface layers. New York: Plenum Press, 1993.
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K, Korhonen Timo, Dawes Edwin A, Mäkelä P. Helena, Federation of European Microbiological Societies. e Societas Biochemica, Biophysica, et Microbiologica Fenniae., eds. Enterobacterial surface antigens: Methods for molecular characterisation. Amsterdam: Elsevier, 1985.
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Paul, Actor, e American Society for Microbiology, eds. Antibiotic inhibition of bacterial cell surface assembly and function. Washington, D.C: American Society for Microbiology, 1988.
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Nava, Mozes, ed. Microbial cell surface analysis: Structural and physicochemical methods. New York: VCH, 1991.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Bacterial surface"
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Ofek, Itzhak, Halina Lis e Nathan Sharon. "Animal Cell Surface Membranes". In Bacterial Adhesion, 71–88. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4615-6514-7_3.
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Isticato, Rachele, e Ezio Ricca. "Spore Surface Display". In The Bacterial Spore, 349–66. Washington, DC, USA: ASM Press, 2016. http://dx.doi.org/10.1128/9781555819323.ch17.
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Cerone, Antonio, e Enrico Marsili. "A Formal Model for the Simulation and Analysis of Early Biofilm Formation". In From Data to Models and Back, 134–51. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70650-0_9.
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AbstractBiofilms are structured communities of bacterial cells adherent to a surface. This bacterial state is called sessile.This paper focuses on the modelling of the transition between planktonic and sessile state using Real-time Maude as the modelling language. With more and more bacteria joining the sessile community, the likelihood of producing a biofilm increases. Once the percentage of bacterial cells that adheres to the surface reaches a threshold, which is specific for the considered bacterium species, a permanent biofilm is formed. An important challenge is to predict the time needed for the formation of a biofilm on a specific surface, in order to plan when the material infrastructure that comprises such a surface needs to be cleaned or replaced. We exploit the model-checking features of Real-time Maude to formally prove that a regular cleaning or replacement of the infrastructure prevents the biofilm formation.
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Rozgonyi, Ferenc, Åsa Ljungh, Wubshet Mamo, Stellan Hjertén e Torkel Wadström. "Bacterial Cell-Surface Hydrophobicity". In Pathogenesis of Wound and Biomaterial-Associated Infections, 233–44. London: Springer London, 1990. http://dx.doi.org/10.1007/978-1-4471-3454-1_28.
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Reps, A. "Bacterial Surface-Ripened Cheeses". In Cheese: Chemistry, Physics and Microbiology, 137–72. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-2648-3_5.
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Reps, A. "Bacterial Surface-Ripened Cheeses". In Cheese: Chemistry, Physics and Microbiology, 137–72. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-2800-5_5.
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Parwin, Shabnam, Sashi Kalan e Preeti Srivastava. "Bacterial Cell Surface Display". In ACS Symposium Series, 81–108. Washington, DC: American Chemical Society, 2019. http://dx.doi.org/10.1021/bk-2019-1329.ch005.
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Ding, Aihao, e Carl Nathan. "Regulation of Cell Surface Receptor Expression by LPS". In Bacterial Endotoxic Lipopolysaccharides, 373–86. Boca Raton: CRC Press, 2024. https://doi.org/10.1201/9781003574859-18.
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Koch, Arthur L. "Stresses on the Surface Stress Theory". In Bacterial Growth and Lysis, 427–42. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4757-9359-8_50.
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Ardö, Ylva, Françoise Berthier, Katja Hartmann, Elisabeth Eugster-Meier, Marie-Therese Fröhlich-Wyder, Ernst Jakob e Daniel Wechsler. "Bacterial Surface-Ripened (Smear) Cheeses". In Global Cheesemaking Technology, 397–414. Chichester, UK: John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781119046165.ch10.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Bacterial surface"
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Madugula, Sita Sirisha, Blythe Dumerer, Ruben Millan-Solsona, Checa Nualart Marti, Liam Collins, Rama K. Vasudevan, Retterer Scott, Lance Zhang, Spencer Cox e Jennifer L. Morrell-Falvey. "Image Segmentation of Bacterial Biofilms to Study Pathogen-Surface Interactions". In 2024 IEEE International Conference on Big Data (BigData), 4939–40. IEEE, 2024. https://doi.org/10.1109/bigdata62323.2024.10826045.
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Durand, Hippolyte, Loïc Laplatine, Ali Kheir-Aldine, Caroline Fontelaye, Doriane Eyvrard, Anne-Gaëlle Bourdat, Malika Amdaoud, Guillaume Nonglaton e Thomas Alava. "Surface Biofunctionalization of Silicon Photonic Mach-Zehnder Interferometers for Bacterial Biosensor Development". In 2024 IEEE BioSensors Conference (BioSensors), 1–4. IEEE, 2024. http://dx.doi.org/10.1109/biosensors61405.2024.10712725.
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Ibrahim, Mohd Danial, Alyssa Asong Ananthan, Dayang Salyani Abang Mahmod, Awang Ahmad Sallehin Awang Husaini, Ngieng Ngui Sing, Shunsuke Nakano, Yuta Sunami e Pierre Barroy. "Antibacterial Properties of Snakeskin Inspired PDMS Surfaces Layered With Poly-DL-lactic Acid Nanosheet". In ASME 2023 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/smasis2023-111176.
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Abstract The increment of sterilization resistant bacteria minimizes the effectiveness of disinfectants which leads researchers into studying other means in minimizing bacterial contamination on surfaces. Hence, this study plans to investigate surfaces with the ability to discourage bacterial adhesion and reduces the need for frequent sterilization. This study tested the feasibility of applying snakeskin inspired microstructures onto a polydimethylsiloxane (PDMS) surface to reduce bacterial adhesion and increase its antibacterial properties. In theory, the microstructure of snakeskin is smaller or about the same size as a bacterium making it unfeasible for bacterial adhesion. The embeddedelastomeric stamping method was used for the biomimicry of snakeskin onto PDMS surfaces. The replicated snakeskin and controlled (no microstructure) PDMS samples were layered with Poly-DL-lactic acid (PDLLA) nanosheet of different thickness. Then, the morphology of the surfaces was observed using a scanning electron microscope. The surface of the samples was tested with Staphylococcus aureus and Bacillus with compliance of the ISO 22196 standard to evaluate the antimicrobial activity. Our results revealed, surfaces with snakeskin microstructures displayed a 16% reduction in bacterial adhesion compared to flat PDMS. Whereas the presence of nanosheet does not significantly affect the adhesion of bacteria on the replicated snakeskin. These findings suggest that surfaces with the presence of snakeskin microstructures possess antibacterial property.
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Krebsbach, Meaghen A., e Karim H. Muci-Ku¨chler. "Effect of Initial Surface Concentration on Bacterial Distribution in a Surrogate Ballistic Wound". In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64243.
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In ballistic injuries, contamination can be carried from the environment, clothing, and skin surface into the wound track. Bacteria and contaminated debris can be introduced into the wound by several means, including physical transport by the projectile or by the suction caused by the formation and collapse of the temporary wound cavity. In this paper, the relationship between initial bacterial concentration on the surface and resultant bacterial distribution along the wound channel is examined using a leg surrogate. Escherichia coli strain K-12 was used to represent skin surface contamination. In order to reduce the possibility of contamination by outside bacteria and assist in colony visualization, the E. coli first underwent a transformation protocol to express Green Fluorescent Protein and to be resistant to the antibiotic ampicillin. Different concentrations of bacteria were pipetted onto circular filter paper and placed onto the surface of a ballistic gelatin leg surrogate, and an 11.43-mm (0.45-in) caliber projectile was shot through the contaminated area into the gel. The “wound track” was sliced into small, evenly spaced samples and the permanent cavity was removed using a biopsy punch, liquefied, and grown on selective lysogeny broth media containing ampicillin. Examination of a normalized bacterial colony count and normalized area covered per segment allowed comparison of variations in the initial concentration, and confirmed that within a range the normalized contamination distribution trend along the “wound track” remained similar. This verification allowed additional confidence in results obtained using this bacteria distribution methodology by eliminating concerns over small variations in initial bacterial concentration.
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Park, Eun-Jung, Myoung-Ock Cho e Jung Kyung Kim. "Growth Responses of Swarming and Gliding Bacteria on Substrates With Different Levels of Stiffness". In ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13154.
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We conducted experiments to decipher the interplays among bacterial motility, surface stiffness of culture medium, and growth of colony when bacteria grow on semi-solid substrate. We observed the growth kinetics of two kinds of bacteria, swarming Escherichia coli (E.coli) and gliding Myxococcus Xanthus (M.xanthus), grown on semi-solid agar substrates with different stiffness. The colony of M.xanthus moved by traction force on the surface shows a tendency to grow larger on soft substrate. The colony of E.coli using flagella shows a similar tendency in the early phase but later grows smaller on substrate with lower stiffness. We found that the growth of bacterial colony is affected by the mechanical properties of the substrate and the type of bacterial motility as well.
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Tzeng, Tzuen-Rong J., Yunyan R. Cheng, Reza Saeidpourazar, Siddharth Sanjeev Aphale e Nader Jalili. "Adhesin-Specific Nanomechnical Cantilever Biosensors for Detection of Microorganisms". In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18487.
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Considerable evidence has indicated that lectins (adhesins) on bacterial surfaces play an important role in the initiation of infection by mediating bacterial adherence to epithelial cell, especially in the gastrointestinal and urinary tracts. Many bacteria express adhesins on their surfaces in the form of specialized organelles that seek and bind to cognate receptors on the surface of mucosal cells. Some of these specific receptors have been reported and many of them are carbohydrates in nature. We have explored the use of specific carbohydrate receptors for the functionalization of nanoparticles and demonstrated their binding specificities and their ability to mediate aggregations of targeted bacteria. Based on these binding specificities, here we report the development of adhensin-specific nanomechanical cantilever (microcantilever) biosensors for the detection of their targeted microorganisms.
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Bunpot - Sirinutsomboon, Michael J Delwiche e Glenn M Young. "Effect of Surface Microstructure on Bacterial Attachment". In 2010 Pittsburgh, Pennsylvania, June 20 - June 23, 2010. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2010. http://dx.doi.org/10.13031/2013.30009.
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Litvinenko, V. V., E. V. Vasilieva, M. A. Abdulkadieva, E. V. Sysolyatina e S. A. Ermolaeva. "THE USE OF BACTERIAL MOTILITY CHARACTERISTICS FOR RAPID ASSESSMENT OF ANTIBIOTIC SENSITIVITY". In X Международная конференция молодых ученых: биоинформатиков, биотехнологов, биофизиков, вирусологов и молекулярных биологов — 2023. Novosibirsk State University, 2023. http://dx.doi.org/10.25205/978-5-4437-1526-1-193.
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Motile bacteria are capable of converting chemical energy into directed movement. The characteristics of motility (trajectories, average speeds, average time spent in a layer, etc.) depend on the morphology of the bacterial cell (number and arrangement of flagella), the presence of chemical stimuli in the environment, distance from the surface, and bacterial concentration. Changes in motility parameters can be used as a prognostic indicator of bacterial cell metabolism disorders.
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Zheng, Zhouyuan, Parth Bansal e Yumeng Li. "Numerical Study on Antibacterial Effects of Bio-Inspired Nanostructured Surface". In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23594.
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Abstract Natural bactericidal surfaces are found on the wings of cicada and dragonfly that compose of nanopatterns such as nanopillar arrays. Experimental studies have unveiled that the nanopillars can penetrate the bacterial walls or stretch them, resulting in the cell death. This offers an attractive “chemical-free” and wide-spectrum strategy to fight against bacteria-related infections and fouling, especially for implant-associated infections (IAIs). However, what is the fundamental mechanism and key factors governing the bactericidal performance of the nanostructured surface is the critical research questions need to be answered to realize its full potential. In this work, we developed mechanical single cell model of bacteria based on finite element analysis (FEA) to simulate the interactions between different strains of bacteria and the nanostructured surface. The nanostructured surface contains nanopillar arrays, which are made of polymer materials. Different strains of bacteria are simulated by adopting the corresponding geometry and material properties from experimental values. The mechanical responses of the bacteria cell on the nanopillar arrays with various configurations are studied based on estimated stress and strain distributions within the cell.
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Steager, Edward, M. Selman Sakar, U. Kei Cheang, David Casale, Vijay Kumar, George J. Pappas e Min Jun Kim. "Galvanotactic Control of Self-Powered Microstructures". In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-66647.
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We are examining microactuation techniques by employing the electrokinetic and galvanotactic behavior of certain bacteria. We cultured selected strains of swarming Serratia marcescens which were attached to microstructures using a blotting technique that creates a bacterial monolayer carpet. These bacterial carpets naturally self-coordinate to propel the microstructures. The microstructures were placed in an open channel and a voltage was applied and polarity was switched. We have demonstrated directional control of the motion of the microstructures patterned with bacteria. This mobility is due to the patterning of bacteria on the microstructure surface and arises from a combination of electrokinetic effects and galvanotaxis.
Relatórios de organizações sobre o assunto "Bacterial surface"
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Apte, Shruti, Smita Bhutda, Sourav Ghosh e Anirban Banerjee. Ubiquitination of bacterial surface proteins act as novel innate pathogen sensing strategy. Peeref, junho de 2023. http://dx.doi.org/10.54985/peeref.2306p5609776.
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Alvarez, Rene, Alexander J. Burdette, Xiaomeng Wu, Christian Kotanen, Yiping Zhao e Ralph A. Tripp. Rapid Identification of Bacterial Pathogens of Military Interest Using Surface-Enhanced Raman Spectroscopy. Fort Belvoir, VA: Defense Technical Information Center, junho de 2014. http://dx.doi.org/10.21236/ada605244.
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Frymier, P. D. Jr. Bacterial migration and motion in a fluid phase and near a solid surface. Office of Scientific and Technical Information (OSTI), janeiro de 1995. http://dx.doi.org/10.2172/573237.
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Branch, Darren W., Dale L. Huber, Susan Marie Brozik e Thayne L. Edwards. Shear horizontal surface acoustic wave microsensor for Class A viral and bacterial detection. Office of Scientific and Technical Information (OSTI), outubro de 2008. http://dx.doi.org/10.2172/1028915.
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Lindow, Steven, Isaac Barash e Shulamit Manulis. Relationship of Genes Conferring Epiphytic Fitness and Internal Multiplication in Plants in Erwinia herbicola. United States Department of Agriculture, julho de 2000. http://dx.doi.org/10.32747/2000.7573065.bard.
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Most bacterial plant pathogens colonize the surface of healthy plants as epiphytes before colonizing internally and initiating disease. The epiphytic phase of these pathogens is thus an important aspect of their epidemiology and a stage at which chemical and biological control is aimed. However, little is known of the genes and phenotypes that contribute to the ability of bacteria to grow on leaves and survive the variable physical environment in this habitat. In addition, while genes such as hrp awr and others which confer pathogenicity and in planta growth ability have been described, their contribution to other aspects of bacterial epidemiology such as epiphytic fitness have not been addressed. We hypothesized that bacterial genes conferring virulence or pathogenicity to plants also contribute to the epiphytic fitness of these bacteria and that many of these genes are preferentially located on plasmids. We addressed these hypotheses by independently identifying genes that contribute to epiphytic fitness, in planta growth, virulence and pathogenicity in the phytopathogenic bacterium Erwinia herbicola pv gypsophilae which causes gall formation on gypsophila. This species is highly epiphytically fit and has acquired a plasmid (pPATH) that contains numerous pathogenicity and virulence determinants, which we have found to also contribute to epiphytic fitness. We performed saturation transposon mutagenesis on pPATH as well as of the chromosome of E.h. gypsophilae, and identified mutants with reduced ability to grow in plants and/or cause disease symptoms, and through a novel competition assay, identified mutants less able to grow or survive on leaves. The number and identity of plasmid-borne hrp genes required for virulence was determined from an analysis of pPATH mutants, and the functional role of these genes in virulence was demonstrated. Likewise, other pPATH-encoded genes involved in IAA and cytokinin biosynthesis were characterized and their pattern of transcriptional activity was determined in planta. In both cases these genes involved in virulence were found to be induced in plant apoplasts. About half of avirulent mutants in pPATH were also epiphytically unfit whereas only about 10% of chromosomal mutants that were avirulent also had reduced epiphytic fitness. About 18% of random mutants in pPATH were avirulent in contrast to only 2.5% of random chromosomal mutants. Importantly, as many as 28% of pPATH mutants had lower epiphytic fitness while only about 10% of random chromosomal mutants had lower epiphytic fitness. These results support both of our original hypotheses, and indicate that genes important in a variety of interactions with plant have been enriched on mobile plasmids such as pPATH. The results also suggest that the ability of bacteria to colonize the surface of plants and to initiate infections in the interior of plants involves many of the same traits. These traits also appear to be under strong regulatory control, being expressed in response to the plant environment in many cases. It may be possible to alter the pattern of expression of such genes by altering the chemical environment of plants either by genetic means or by additional or chemical antagonists of the plant signals. The many novel bacterial genes identified in this study that are involved in plant interactions should be useful in further understanding of bacterial plant interactions.
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Kozlowski, Mark, Joshua Orlicki, Randall Hughes e Randi Pullen. Peptide and Hydrophobin Interactions with Polymeric Substrates Screened by a Bacterial Surface Display Method. Aberdeen Proving Ground, MD: DEVCOM Army Research Laboratory, setembro de 2021. http://dx.doi.org/10.21236/ad1150281.
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Phisalaphong, Muenduen, e Neeracha Sanchavanakit. Development of bacterial cellulose for temporary skin substitute. Chulalongkorn University, 2006. https://doi.org/10.58837/chula.res.2006.74.
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Thin films of bacterial cellulose (BC) from nata de coco culture system were developed, characterized and investigated for the growth of human keratinocytes and fobroblasts. The average pore diameter and total surface area of the dried BC films estimated by BET were 224 [aungstrom] degree Celsius A and 12.62 m[superscript 2] /g, respectively. With the film thickness 0f 0.12 mm, the average tensile strength and break strain of the dried films were 5.21 MPa and 3.75 % while those of the wet films were 1.56 MPa and 8.00 %, respectively. The water absorption capacity of air-dried film was 5.09 g water/g dried films. For the uses in the therapy of skin wounds, the potential biological mechanism of action of BC film was evaluated by using human keratinocytes and fibroblasts. Our results were the first direct demonstration that BC film supported the growth, spreading and migration of human keratinocytes, but not those of human fibroblasts. Expressions of E-cadherin and alpha-3 chain of laminin confirmed the phenotype of human keratinocyte on BC film.
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Gottlieb, Yuval, Bradley Mullens e Richard Stouthamer. investigation of the role of bacterial symbionts in regulating the biology and vector competence of Culicoides vectors of animal viruses. United States Department of Agriculture, junho de 2015. http://dx.doi.org/10.32747/2015.7699865.bard.
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Symbiotic bacteria have been shown to influence host reproduction and defense against biotic and abiotic stressors, and this relates to possible development of a symbiont-based control strategy. This project was based on the hypothesis that symbionts have a significant impact on Culicoides fitness and vector competence for animal viruses. The original objectives in our proposal were: 1. Molecular identification and localization of the newly-discovered symbiotic bacteria within C. imicola and C. schultzei in Israel and C. sonorensis in California. 2. Determination of the prevalence of symbiotic bacteria within different vector Culicoides populations. 3. Documentation of specific symbiont effects on vector reproduction and defense: 3a) test for cytoplasmic incompatibility in Cardinium-infected species; 3b) experimentally evaluate the role of the symbiont on infection or parasitism by key Culicoides natural enemies (iridescent virus and mermithid nematode). 4. Testing the role(s) of the symbionts in possible protection against infection of vector Culicoides by BTV. According to preliminary findings and difficulties in performing experimental procedures performed in other insect symbiosis systems where insect host cultures are easily maintained, we modified the last two objectives as follows: Obj. 3, we tested how symbionts affected general fitness of Israeli Culicoides species, and thoroughly described and evaluated the correlation between American Culicoides and their bacterial communities in the field. We also tried alternative methods to test symbiont-Culicoides interactions and launched studies to characterize low-temperature stress tolerances of the main US vector, which may be related to symbionts. Obj. 4, we tested the correlation between EHDV (instead of BTV) aquisition and Cardinium infection. Culicoides-bornearboviral diseases are emerging or re-emerging worldwide, causing direct and indirect economic losses as well as reduction in animal welfare. One novel strategy to reduce insects’ vectorial capacity is by manipulating specific symbionts to affect vector fitness or performance of the disease agent within. Little was known on the bacterial tenants occupying various Culicoides species, and thus, this project was initiated with the above aims. During this project, we were able to describe the symbiont Cardinium and whole bacterial communities in Israeli and American Culicoides species respectively. We showed that Cardinium infection prevalence is determined by land surface temperature, and this may be important to the larval stage. We also showed no patent significant effect of Cardinium on adult fitness parameters. We showed that the bacterial community in C. sonorensis varies significantly with the host’s developmental stage, but it varies little across multiple wastewater pond environments. This may indicate some specific biological interactions and allowed us to describe a “core microbiome” for C. sonorensis. The final set of analyses that include habitat sample is currently done, in order to separate the more intimately-associated bacteria from those inhabiting the gut contents or cuticle surface (which also could be important). We were also able to carefully study other biological aspects of Culicoides and were able to discriminate two species in C. schultzei group in Israel, and to investigate low temperature tolerances of C. sonorensis that may be related to symbionts. Scientific implications include the establishment of bacterial identification and interactions in Culicoides (our work is cited in other bacteria-Culicoides studies), the development molecular identification of C. schultzei group, and the detailed description of the microbiome of the immature and matched adult stages of C. sonorensis. Agricultural implications include understanding of intrinsic factors that govern Culicoides biology and population regulation, which may be relevant for vector control or reduction in pathogen transmission. Being able to precisely identify Culicoides species is central to understanding Culicoides borne disease epidemiology.
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Choudhary, Ruplal, Victor Rodov, Punit Kohli, Elena Poverenov, John Haddock e Moshe Shemesh. Antimicrobial functionalized nanoparticles for enhancing food safety and quality. United States Department of Agriculture, janeiro de 2013. http://dx.doi.org/10.32747/2013.7598156.bard.
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Original objectives The general goal of the project was to utilize the bactericidal potential of curcumin- functionalizednanostructures (CFN) for reinforcement of food safety by developing active antimicrobial food-contact surfaces. In order to reach the goal, the following secondary tasks were pursued: (a) further enhancement of the CFN activity based on understanding their mode of action; (b) preparing efficient antimicrobial surfaces, investigating and optimizing their performance; (c) testing the efficacy of the antimicrobial surfaces in real food trials. Background to the topic The project dealt with reducing microbial food spoilage and safety hazards. Cross-contamination through food-contact surfaces is one of the major safety concerns, aggravated by bacterial biofilm formation. The project implemented nanotech methods to develop novel antimicrobial food-contact materials based on natural compounds. Food-grade phenylpropanoidcurcumin was chosen as the most promising active principle for this research. Major conclusions, solutions, achievements In agreement with the original plan, the following research tasks were performed. Optimization of particles structure and composition. Three types of curcumin-functionalizednanostructures were developed and tested: liposome-type polydiacetylenenanovesicles, surface- stabilized nanoparticles and methyl-β-cyclodextrin inclusion complexes (MBCD). The three types had similar minimal inhibitory concentration but different mode of action. Nanovesicles and inclusion complexes were bactericidal while the nanoparticlesbacteriostatic. The difference might be due to different paths of curcumin penetration into bacterial cell. Enhancing the antimicrobial efficacy of CFN by photosensitization. Light exposure strengthened the bactericidal efficacy of curcumin-MBCD inclusion complexes approximately three-fold and enhanced the bacterial death on curcumin-coated plastic surfaces. Investigating the mode of action of CFN. Toxicoproteomic study revealed oxidative stress in curcumin-treated cells of E. coli. In the dark, this effect was alleviated by cellular adaptive responses. Under light, the enhanced ROS burst overrode the cellular adaptive mechanisms, disrupted the iron metabolism and synthesis of Fe-S clusters, eventually leading to cell death. Developing industrially-feasible methods of binding CFN to food-contact surfaces. CFN binding methods were developed for various substrates: covalent binding (binding nanovesicles to glass, plastic and metal), sonochemical impregnation (binding nanoparticles to plastics) and electrostatic layer-by-layer coating (binding inclusion complexes to glass and plastics). Investigating the performance of CFN-coated surfaces. Flexible and rigid plastic materials and glass coated with CFN demonstrated bactericidal activity towards Gram-negative (E. coli) and Gram-positive (Bac. cereus) bacteria. In addition, CFN-impregnated plastic material inhibited bacterial attachment and biofilm development. Testing the efficacy of CFN in food preservation trials. Efficient cold pasteurization of tender coconut water inoculated with E. coli and Listeriamonocytogeneswas performed by circulation through a column filled with CFN-coated glass beads. Combination of curcumin coating with blue light prevented bacterial cross contamination of fresh-cut melons through plastic surfaces contaminated with E. coli or Bac. licheniformis. Furthermore, coating of strawberries with CFN reduced fruit spoilage during simulated transportation extending the shelf life by 2-3 days. Implications, both scientific and agricultural BARD Report - Project4680 Page 2 of 17 Antimicrobial food-contact nanomaterials based on natural active principles will preserve food quality and ensure safety. Understanding mode of antimicrobial action of curcumin will allow enhancing its dark efficacy, e.g. by targeting the microbial cellular adaptation mechanisms.
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Splitter, Gary, e Menachem Banai. Microarray Analysis of Brucella melitensis Pathogenesis. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7709884.bard.
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Original Objectives 1. To determine the Brucella genes that lead to chronic macrophage infection. 2. To identify Brucella genes that contribute to infection. 3. To confirm the importance of Brucella genes in macrophages and placental cells by mutational analysis. Background Brucella spp. is a Gram-negative facultative intracellular bacterium that infects ruminants causing abortion or birth of severely debilitated animals. Brucellosis continues in Israel, caused by B. melitensis despite an intensive eradication campaign. Problems with the Rev1 vaccine emphasize the need for a greater understanding of Brucella pathogenesis that could improve vaccine designs. Virulent Brucella has developed a successful strategy for survival in its host and transmission to other hosts. To invade the host, virulent Brucella establishes an intracellular niche within macrophages avoiding macrophage killing, ensuring its long-term survival. Then, to exit the host, Brucella uses placenta where it replicates to high numbers resulting in abortion. Also, Brucella traffics to the mammary gland where it is secreted in milk. Missing from our understanding of brucellosis is the surprisingly lillie basic information detailing the mechanisms that permit bacterial persistence in infected macrophages (chronic infection) and dissemination to other animals from infected placental cells and milk (acute infection). Microarray analysis is a powerful approach to determine global gene expression in bacteria. The close genomic similarities of Brucella species and our recent comparative genomic studies of Brucella species using our B. melitensis microarray, suqqests that the data obtained from studying B. melitensis 16M would enable understanding the pathogenicity of other Brucella organisms, particularly the diverse B. melitensis variants that confound Brucella eradication in Israel. Conclusions Results from our BARD studies have identified previously unknown mechanisms of Brucella melitensis pathogenesis- i.e., response to blue light, quorum sensing, second messenger signaling by cyclic di-GMP, the importance of genomic island 2 for lipopolysaccharide in the outer bacterial membrane, and the role of a TIR domain containing protein that mimics a host intracellular signaling molecule. Each one of these pathogenic mechanisms offers major steps in our understanding of Brucella pathogenesis. Strikingly, our molecular results have correlated well to the pathognomonic profile of the disease. We have shown that infected cattle do not elicit antibodies to the organisms at the onset of infection, in correlation to the stealth pathogenesis shown by a molecular approach. Moreover, our field studies have shown that Brucella exploit this time frame to transmit in nature by synchronizing their life cycle to the gestation cycle of their host succumbing to abortion in the last trimester of pregnancy that spreads massive numbers of organisms in the environment. Knowing the bacterial mechanisms that contribute to the virulence of Brucella in its host has initiated the agricultural opportunities for developing new vaccines and diagnostic assays as well as improving control and eradication campaigns based on herd management and linking diagnosis to the pregnancy status of the animals. Scientific and Agricultural Implications Our BARD funded studies have revealed important Brucella virulence mechanisms of pathogenesis. Our publication in Science has identified a highly novel concept where Brucella utilizes blue light to increase its virulence similar to some plant bacterial pathogens. Further, our studies have revealed bacterial second messengers that regulate virulence, quorum sensing mechanisms permitting bacteria to evaluate their environment, and a genomic island that controls synthesis of its lipopolysaccharide surface. Discussions are ongoing with a vaccine company for application of this genomic island knowledge in a Brucella vaccine by the U.S. lab. Also, our new technology of bioengineering bioluminescent Brucella has resulted in a spin-off application for diagnosis of Brucella infected animals by the Israeli lab by prioritizing bacterial diagnosis over serological diagnosis.