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1
Absolom, Darryl R. "The role of bacterial hydrophobicity in infection: bacterial adhesion and phagocytic ingestion". Canadian Journal of Microbiology 34, n. 3 (1 marzo 1988): 287–98. http://dx.doi.org/10.1139/m88-054.
Testo completoAbstract (sommario):
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.
2
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. 5 (21 aprile 2022): 551. http://dx.doi.org/10.3390/antibiotics11050551.
Testo completoAbstract (sommario):
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.
3
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. 9 (settembre 2004): 5441–46. http://dx.doi.org/10.1128/aem.70.9.5441-5446.2004.
Testo completoAbstract (sommario):
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.
4
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. 7 (15 luglio 2023): 941. http://dx.doi.org/10.3390/pathogens12070941.
Testo completoAbstract (sommario):
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.
5
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. 8 (25 agosto 2022): e0272329. http://dx.doi.org/10.1371/journal.pone.0272329.
Testo completoAbstract (sommario):
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.
6
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 febbraio 2025): 158. https://doi.org/10.12688/f1000research.159954.1.
Testo completoAbstract (sommario):
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. 1 (26 ottobre 2007): 52–60. http://dx.doi.org/10.1128/aem.01400-07.
Testo completoAbstract (sommario):
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.
8
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. 4 (30 dicembre 2019): 387–97. http://dx.doi.org/10.1177/0954411919898011.
Testo completoAbstract (sommario):
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.
9
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. 8 (16 febbraio 2007): 2653–60. http://dx.doi.org/10.1128/aem.02884-06.
Testo completoAbstract (sommario):
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.
10
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. 20 (21 ottobre 2023): 3863. http://dx.doi.org/10.3390/foods12203863.
Testo completoAbstract (sommario):
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.
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HUI, YEW WOH, e GARY A. DYKES. "Modulation of Cell Surface Hydrophobicity and Attachment of Bacteria to Abiotic Surfaces and Shrimp by Malaysian Herb Extracts". Journal of Food Protection 75, n. 8 (1 agosto 2012): 1507–11. http://dx.doi.org/10.4315/0362-028x.jfp-12-062.
Testo completoAbstract (sommario):
The use of simple crude water extracts of common herbs to reduce bacterial attachment may be a cost-effective way to control bacterial foodborne pathogens, particularly in developing countries. The ability of water extracts of three common Malaysian herbs (Andrographis paniculata, Eurycoma longifolia, and Garcinia atroviridis) to modulate hydrophobicity and attachment to surfaces of five food-related bacterial strains (Bacillus cereus ATCC 14576, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 10145, Salmonella Enteritidis ATCC 13076, Staphylococcus aureus ATCC 25923) were determined. The bacterial attachment to hydrocarbon assay was used to determine bacterial hydrophobicity. Staining and direct microscopic counts were used to determine attachment of bacteria to glass and stainless steel. Plating on selective media was used to determine attachment of bacteria to shrimp. All extracts were capable of either significantly (P < 0.05) increasing or decreasing bacterial surface hydrophobicity, depending on the herb extract and bacteria combination. Bacterial attachment to all surfaces was either significantly (P < 0.05) increased or decreased, depending on the herb extract and bacteria combination. Overall, hydrophobicity did not show a significant correlation (P > 0.05) to bacterial attachment. For specific combinations of bacteria, surface material, and plant extract, significant correlations (R > 0.80) between hydrophobicity and attachment were observed. The highest of these was observed for S. aureus attachment to stainless steel and glass after treatment with the E. longifolia extract (R = 0.99, P < 0.01). The crude water herb extracts in this study were shown to have the potential to modulate specific bacterial and surface interactions and may, with further work, be useful for the simple and practical control of foodborne pathogens.
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Dang, Hongyue, e Charles R. Lovell. "Numerical Dominance and Phylotype Diversity of Marine Rhodobacter Species during Early Colonization of Submerged Surfaces in Coastal Marine Waters as Determined by 16S Ribosomal DNA Sequence Analysis and Fluorescence In Situ Hybridization". Applied and Environmental Microbiology 68, n. 2 (febbraio 2002): 496–504. http://dx.doi.org/10.1128/aem.68.2.496-504.2002.
Testo completoAbstract (sommario):
ABSTRACT Early stages of surface colonization in coastal marine waters appear to be dominated by the marine Rhodobacter group of the α subdivision of the division Proteobacteria (α-Proteobacteria). However, the quantitative contribution of this group to primary surface colonization has not been determined. In this study, glass microscope slides were incubated in a salt marsh tidal creek for 3 or 6 days. Colonizing bacteria on the slides were examined by fluorescence in situ hybridization by employing DNA probes targeting 16S or 23S rRNA to identify specific phylogenetic groups. Confocal laser scanning microscopy was then used to quantify and track the dynamics of bacterial primary colonists during the early stages of surface colonization and growth. More than 60% of the surface-colonizing bacteria detectable by fluorescence staining (Yo-Pro-1) could also be detected with the Bacteria domain probe EUB338. Archaea were not detected on the surfaces and did not appear to participate in surface colonization. Of the three subdivisions of the Proteobacteria examined, the α-Proteobacteria were the most abundant surface-colonizing organisms. More than 28% of the total bacterial cells and more than 40% of the cells detected by EUB338 on the surfaces were affiliated with the marine Rhodobacter group. Bacterial abundance increased significantly on the surfaces during short-term incubation, mainly due to the growth of the marine Rhodobacter group organisms. These results demonstrated the quantitative importance of the marine Rhodobacter group in colonization of surfaces in salt marsh waters and confirmed that at least during the early stages of colonization, this group dominated the surface-colonizing bacterial assemblage.
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Chiang, Chao-Ching, Xinyi Xia, Valentin Craciun, Mateus Garcia Rocha, Samira Esteves Afonso Camargo, Fernanda Regina Godoy Rocha, Sarathy K. Gopalakrishnan, Kirk J. Ziegler, Fan Ren e Josephine F. Esquivel-Upshaw. "Enhancing the Hydrophobicity and Antibacterial Properties of SiCN-Coated Surfaces with Quaternization to Address Peri-Implantitis". Materials 16, n. 17 (22 agosto 2023): 5751. http://dx.doi.org/10.3390/ma16175751.
Testo completoAbstract (sommario):
Peri-implantitis is a major cause of dental implant failure. This disease is an inflammation of the tissues surrounding the implant, and, while the cause is multi-factorial, bacteria is the main culprit in initiating an inflammatory reaction. Dental implants with silicon carbonitride (SiCN) coatings have several potential advantages over traditional titanium implants, but their antibacterial efficiency has not yet been evaluated. The purpose of this study was to determine the anti-bacterial potential of SiCN by modifying the surface of SiCN-coated implants to have a positive charge on the nitrogen atoms through the quaternization of the surface atoms. The changes in surface chemistry were confirmed using contact angle measurement and XPS analysis. The modified SiCN surfaces were inoculated with Streptococcus mutans (S. mutans) and compared with a silicon control. The cultured bacterial colonies for the experimental group were 80% less than the control silicon surface. Fluorescent microscopy with live bacteria staining demonstrated significantly reduced bacterial coverage after 3 and 7 days of incubation. Scanning electron microscopy (SEM) was used to visualize the coated surfaces after bacterial inoculation, and the mechanism for the antibacterial properties of the quaternized SiCN was confirmed by observing ruptured bacteria membrane along the surface.
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Chiang, Wen-Chi, Casper Schroll, Lisbeth Rischel Hilbert, Per Møller e Tim Tolker-Nielsen. "Silver-Palladium Surfaces Inhibit Biofilm Formation". Applied and Environmental Microbiology 75, n. 6 (16 gennaio 2009): 1674–78. http://dx.doi.org/10.1128/aem.02274-08.
Testo completoAbstract (sommario):
ABSTRACT Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under conditions of high bacterial load, biofilm formation occurred upon a layer of surface-associated dead bacteria.
15
Yang, Xiao, Wei Zhang, Xuezhi Qin, Miaomiao Cui, Yunting Guo, Ting Wang, Kaiqiang Wang et al. "Recent Progress on Bioinspired Antibacterial Surfaces for Biomedical Application". Biomimetics 7, n. 3 (4 luglio 2022): 88. http://dx.doi.org/10.3390/biomimetics7030088.
Testo completoAbstract (sommario):
Surface bacterial fouling has become an urgent global challenge that calls for resilient solutions. Despite the effectiveness in combating bacterial invasion, antibiotics are susceptible to causing microbial antibiotic resistance that threatens human health and compromises the medication efficacy. In nature, many organisms have evolved a myriad of surfaces with specific physicochemical properties to combat bacteria in diverse environments, providing important inspirations for implementing bioinspired approaches. This review highlights representative natural antibacterial surfaces and discusses their corresponding mechanisms, including repelling adherent bacteria through tailoring surface wettability and mechanically killing bacteria via engineering surface textures. Following this, we present the recent progress in bioinspired active and passive antibacterial strategies. Finally, the biomedical applications and the prospects of these antibacterial surfaces are discussed.
16
DAS, JAYANTI, JENNIFER A. CHASE, MELISSA L. PARTYKA, EDWARD R. ATWILL e BARBARA LINKE. "An Insight into Surface Topographical Parameters and Bacterial Adhesion: A Case Study of Listeria monocytogenes Scott A Attachment on 304 Stainless Steel". Journal of Food Protection 83, n. 3 (13 febbraio 2020): 426–33. http://dx.doi.org/10.4315/0362-028x.jfp-19-279.
Testo completoAbstract (sommario):
ABSTRACT Bacterial attachment on surfaces is an important biological and industrial concern. Many parameters affect cell attachment behavior, including surface roughness and other topographical features. An understanding of these relationships is critical in the light of recent outbreaks caused by foodborne bacteria. Postharvest packing lines have been identified as a potential source of cross-contamination with pathogens, which can cause subsequent foodborne illness. The objective of this article is to evaluate the influence of surface topographical features on bacterial attachment at various processing temperatures to determine the extent of bacterial colonization. Type 304 stainless steel surfaces and pathogenic Listeria monocytogenes Scott A were used for a detailed investigation. Two commonly used surface types, extruded and ground, were evaluated to determine differences in bacterial attachment on the same type of material. Fifteen surface topography parameters at three processing temperatures were studied to evaluate possible correlations with microbial attachment on these surfaces. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and confocal microscopy were used for both qualitative and quantitative analyses of surfaces. An analysis of variance and multivariate regression analysis were used to predict the attachment behavior of L. monocytogenes Scott A on stainless steel surfaces. Surface isotropy, average surface roughness, surface spacing, and processing temperatures were strongly correlated with bacterial attachment on 304 stainless steel material. HIGHLIGHTS
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UKUKU, DIKE O., e WILLIAM F. FETT. "Relationship of Cell Surface Charge and Hydrophobicity to Strength of Attachment of Bacteria to Cantaloupe Rind†". Journal of Food Protection 65, n. 7 (1 luglio 2002): 1093–99. http://dx.doi.org/10.4315/0362-028x-65.7.1093.
Testo completoAbstract (sommario):
The cantaloupe melon has been associated with outbreaks of Salmonella infections. It is suspected that bacterial surface charge and hydrophobicity may affect bacterial attachment and complicate bacterial detachment from cantaloupe surfaces. The surface charge and hydrophobicity of strains of Salmonella, Escherichia coli (O157:H7 and non-O157:H7), and Listeria monocytogenes were determined by electrostatic and hydrophobic interaction chromatography, respectively. Initial bacterial attachment to cantaloupe surfaces and the ability of bacteria to resist removal by washing with water were compared with surface charge and hydrophobicity. Whole cantaloupes were submerged in inocula containing individual strains or in cocktails containing Salmonella, E. coli, and L. monocytogenes, either as a mixture of strains containing all three genera or as a mixture of strains belonging to a single genus, for 10 min. Inoculated cantaloupes were dried for 1 h in a biosafety cabinet and then stored for up to 7 days at 4°C. Inoculated melons were washed with water, and bacteria still attached to the melon surface, as well as those in the wash water, were enumerated. Initial bacterial attachment was highest for individual strains of E. coli and lowest for L. monocytogenes, but Salmonella exhibited the strongest attachment on days 0, 3, and 7. When mixed-genus cocktails were used, the relative degrees of attachment of the three genera ware altered. The attachment of Salmonella strains was the strongest, but the attachment of E. coli was more extensive than that of L. monocytogenes on days 0, 3, and 7. There was a linear correlation between bacterial cell surface hydrophobicity (r2 = 0.767), negative charge (r2 = 0.738), and positive charge (r2 = 0.724) and the strength of bacterial attachment to cantaloupe surfaces.
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Niazi, Parwiz, Abdul Wahid Monib, Hamidullah Ozturk, Mujibullah Mansoor, Azizaqa Azizi e Mohammad Hassan Hassand. "Review on Surface Elements and Bacterial Biofilms in Plant-Bacterial Associations". Journal for Research in Applied Sciences and Biotechnology 2, n. 1 (9 marzo 2023): 204–14. http://dx.doi.org/10.55544/jrasb.2.1.30.
Testo completoAbstract (sommario):
In recent years, there has been increasing interest in the function of bacterial surface elements and functional signals in biofilm formation. Plant-associated bacteria can significantly affect the health and productivity of a plant because they are found in many different areas of the plant, including roots, transport channels, stems, and leaves. The management of these compounds by plants is still unknown, although biofilm production on plants is associated with both symbiotic and pathogenic responses. While some of the bacteria found in biofilm matrices trigger pathogenesis, others can promote plant thriving and serve as biocontrol agents for phytopathogens. This detailed review discusses in depth the various elements and methods involved in the production of bacterial biofilms on plant surfaces and their attachment, as well as the relationship between these factors and bacterial activity and survival.
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Chen, Chao, e Monica Ek. "Antibacterial evaluation of CNF/PVAm multilayer modified cellulose fiber and cellulose model surface". Nordic Pulp & Paper Research Journal 33, n. 3 (25 settembre 2018): 385–96. http://dx.doi.org/10.1515/npprj-2018-3050.
Testo completoAbstract (sommario):
Abstract Earlier studies have shown that 3-layer-modified cellulose fibers with poly(acrylic acid) (PAA) as the middle layer between two cationic polyelectrolyte polyvinylamine (PVAm) layers have strong antibacterial efficacy in terms of both bacteria adsorption and bacterial growth inhibition. In the present work, the fossil-based PAA middle layer was replaced by sustainable wood-based cellulose nano-fibrils (CNF), i. e., the fibers were modified by a 3-layer PVAm/CNF/PVAm system. Interestingly, the antibacterial efficacy of this system was greater than that of the previous PVAm/PAA/PVAm system. A higher salt concentration and lower assembly pH in the multilayer build-up resulted in better bacterial reduction. As the surface of a cellulose fiber is heterogeneous, making it difficult to characterize and visualize at high resolution, more homogeneous cellulose model surfaces were prepared by spin coating the dissolved cellulose fiber onto a silica surface to model the fiber surface. With increasing ionic strength, more aggregated and heterogeneous structures can be observed on the PVAm/CNF/PVAm modified model surfaces. The adsorbed bacteria distributed on the structured surfaces were clearly seen under fluorescence microscopy. Adsorbed amounts of bacteria on either aggregate or flat regions were quantified by scanning electron microscopy (SEM). More adsorbed bacteria were clearly seen on aggregates than on the flat regions at the surfaces. Degrees of bacteria deformation and cell damage were also seen under SEM. The surface roughness of the modified model surfaces was examined by atomic force microscopy (AFM), and a positive correlation was found between the surface roughness and the bacterial adhesion. Thus, an additional factor that controls adhesion, in addition to the surface charge, which is probably the most dominant factor affecting the bacteria adhesion, is the surface structures, such as roughness.
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Wandiyanto, Jason V., Vi Khanh Truong, Mohammad Al Kobaisi, Saulius Juodkazis, Helmut Thissen, Olha Bazaka, Kateryna Bazaka, Russell J. Crawford e Elena P. Ivanova. "The Fate of Osteoblast-Like MG-63 Cells on Pre-Infected Bactericidal Nanostructured Titanium Surfaces". Materials 12, n. 10 (14 maggio 2019): 1575. http://dx.doi.org/10.3390/ma12101575.
Testo completoAbstract (sommario):
Biomaterials that have been newly implanted inside the body are the substratum targets for a “race for the surface”, in which bacterial cells compete against eukaryotic cells for the opportunity to colonize the surface. A victory by the former often results in biomaterial-associated infections, which can be a serious threat to patient health and can undermine the function and performance of the implant. Moreover, bacteria can often have a ‘head start’ if implant contamination has taken place either prior to or during the surgery. Current prevention and treatment strategies often rely on systemic antibiotic therapies, which are becoming increasingly ineffective due to a growing prevalence of antibiotic-resistant bacteria. Nanostructured surfaces that kill bacteria by physically rupturing bacterial cells upon contact have recently emerged as a promising solution for the mitigation of bacterial colonization of implants. Furthermore, these nanoscale features have been shown to enhance the adhesion and proliferation of eukaryotic cells, which is a key to, for example, the successful osseointegration of load-bearing titanium implants. The bactericidal activity and biocompatibility of such nanostructured surfaces are often, however, examined separately, and it is not clear to what extent bacterial cell-surface interactions would affect the subsequent outcomes of host-cell attachment and osseointegration processes. In this study, we investigated the ability of bactericidal nanostructured titanium surfaces to support the attachment and growth of osteoblast-like MG-63 human osteosarcoma cells, despite them having been pre-infected with pathogenic bacteria. MG-63 is a commonly used osteoblastic model to study bone cell viability, adhesion, and proliferation on the surfaces of load-bearing biomaterials, such as titanium. The nanostructured titanium surfaces used here were observed to kill the pathogenic bacteria, whilst simultaneously enhancing the growth of MG-63 cells in vitro when compared to that occurring on sterile, flat titanium surfaces. These results provide further evidence in support of nanostructured bactericidal surfaces being used as a strategy to help eukaryotic cells win the “race for the surface” against bacterial cells on implant materials.
21
O. Bello, Olorunjuwon, Favour T. Martins, Temitope K. Bello, Bamikole W. Osungbemiro e Adebanke M. Ajagunna. "Detection and Control of Bacterial Biofilms". International Journal of Advanced Engineering Research and Science 10, n. 3 (2023): 049–63. http://dx.doi.org/10.22161/ijaers.103.6.
Testo completoAbstract (sommario):
A biofilm is a clump of bacteria living in a self-produced matrix of extracellular polymeric substances (EPS) linked to a biotic or abiotic surface, indicating that biofilms can exist on a variety of biotic and abiotic surfaces. Abiotic surfaces include floors, walls, drains, equipment, and food-contact surfaces, as well as biotic surfaces like meat, the oral cavity, the intestine, the urogenital tract, and the skin. Humans are a good source of biotic microenvironments for biofilm and bacterial growth, which leads to infectious diseases in most cases. The optimum biotic environment for bacteria to thrive requires a supply of nutrients, humidity, and the right temperature. Biofilms originate on inert surfaces or dead tissue, and they're frequent on medical devices and dead tissue fragments, but they can also form on living tissues. Biofilms' tolerance to harsh environments provides a favorable habitat for microbial populations, allowing for a more efficient flow of chemicals and information amongst microorganisms. As a result, biofilm resistance is a self-protective strategy for microbial development. Bacterial biofilms are detectable by direct and indirect methods and they could be controlled. Bacterial biofilm is a major cause of antimicrobial-resistant bacteria's development and spread, causing severe infections and increased mortality rates.
22
Pacha-Olivenza, Miguel Ángel, Ricardo Tejero, María Coronada Fernández-Calderón, Eduardo Anitua, María Troya e M. Luisa González-Martín. "Relevance of Topographic Parameters on the Adhesion and Proliferation of Human Gingival Fibroblasts and Oral Bacterial Strains". BioMed Research International 2019 (10 febbraio 2019): 1–13. http://dx.doi.org/10.1155/2019/8456342.
Testo completoAbstract (sommario):
Dental implantology allows replacement of failing teeth providing the patient with a general improvement of health. Unfortunately not all reconstructions succeed, as a consequence of the development of infections of bacterial origin on the implant surface. Surface topography is known to modulate a differential response to bacterial and mammalian cells but topographical measurements are often limited to vertical parameters. In this work we have extended the topographical measurements also to lateral and hybrid parameters of the five most representative implant and prosthetic component surfaces and correlated the results with bacterial and mammalian cell adhesion and proliferation outcomes. Primary human oral gingival fibroblast (gum cells) and the bacterial strains: Streptococcus mutans, Streptococcus sanguinis and Aggregatibacter actinomycetemcomitans, implicated in infectious processes in the oral/implant environment were employed in the presence or absence of human saliva. The results confirm that even though not all the measured surface is available for bacteria to adhere, the overall race for the surface between cells and bacteria is more favourable to the smoother surfaces (nitrided, as machined or lightly acid etched) than to the rougher ones (strong acid etched or sandblasted/acid etched).
23
Yıldırım, Musa, e Hacer Bilir Özhan. "EFFECT OF BACTERIAL CURING AND BACTERIAL ADDITIVE ON CONCRETE PROPERTIES". Advances in Civil and Architectural Engineering 14, n. 27 (21 settembre 2023): 32–43. http://dx.doi.org/10.13167/2023.27.3.
Testo completoAbstract (sommario):
In this study, calcium carbonate was formed on the surfaces and inner structure of concrete using the microbially induced carbonate precipitation method. Bacillus megaterium bacteria were supplemented into the curing water and concrete mixtures. Three types of concrete were tested: control concrete, bacteria-containing concrete, and concrete cured in bacterial liquid. Compressive strength, water absorption, capillary water absorption, scanning electron microscopy (SEM), and mapping analyses were conducted to investigate the effects of bacterial additive or bacterial curing to concrete specimens. Bacteria spore added to the concrete mixture and curing in bacterial media increased the compressive strengths of concrete by up to 9,52 % at the end of 28 days of curing. Bacterial curing and the addition of bacteria spores caused a reduction in water absorption rates owing to changes in the concrete structures. Calcite only formed on the surfaces of the samples treated with bacterial curing liquid, thereby limiting its effect on capillary water absorption. In contrast, capillary water absorption in the bacterial concrete decreased by 50 % compared to the control concrete. The crystalline structures of calcium carbonate and bacterial concrete were analysed through SEM imaging. Mapping analysis revealed that the primary elements of calcite were considerably more concentrated on the surface of bacterial concrete than in the control concrete.
24
Zhurlov, Oleg, e Maria Zhurlova. "The effectiveness of bacterial contamination of beetles during their transfer to wheat bran". BIO Web of Conferences 130 (2024): 07004. http://dx.doi.org/10.1051/bioconf/202413007004.
Testo completoAbstract (sommario):
The study of the mechanisms of transfer of bacteria during contamination of insect surfaces during food invasion is of current interest. Additionally, the increasing antibiotic resistance of clinical bacterial strains over the past decade has highlighted the importance of understanding the mechanisms of bacterial circulation among insects, especially antibiotic-resistant strains. Our modeling study demonstrates that the transfer of the Escherichia coli Rif (+) marker strain on the surface and inside the intestine of adult beetles Tenebrio molitor contributes to bacterial contamination of wheat bran. The isolation of E. coli Rif (+) in high titers from the beetle’s surface and feces continued for three days. The ability of beetles to carry allochthonous bacteria on their surface and inside their intestines can contribute to contamination of grains, flour, and wheat bran with antibiotic-resistant bacterial strains. In the future, the use of the Escherichia coli Rif (+) strain may help to better understand the mechanisms of how insects transfer antibiotic-resistant bacteria from one place to another during their invasion of food sources.
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Fierer, Noah, Micah Hamady, Christian L. Lauber e Rob Knight. "The influence of sex, handedness, and washing on the diversity of hand surface bacteria". Proceedings of the National Academy of Sciences 105, n. 46 (12 novembre 2008): 17994–99. http://dx.doi.org/10.1073/pnas.0807920105.
Testo completoAbstract (sommario):
Bacteria thrive on and within the human body. One of the largest human-associated microbial habitats is the skin surface, which harbors large numbers of bacteria that can have important effects on health. We examined the palmar surfaces of the dominant and nondominant hands of 51 healthy young adult volunteers to characterize bacterial diversity on hands and to assess its variability within and between individuals. We used a novel pyrosequencing-based method that allowed us to survey hand surface bacterial communities at an unprecedented level of detail. The diversity of skin-associated bacterial communities was surprisingly high; a typical hand surface harbored >150 unique species-level bacterial phylotypes, and we identified a total of 4,742 unique phylotypes across all of the hands examined. Although there was a core set of bacterial taxa commonly found on the palm surface, we observed pronounced intra- and interpersonal variation in bacterial community composition: hands from the same individual shared only 17% of their phylotypes, with different individuals sharing only 13%. Women had significantly higher diversity than men, and community composition was significantly affected by handedness, time since last hand washing, and an individual's sex. The variation within and between individuals in microbial ecology illustrated by this study emphasizes the challenges inherent in defining what constitutes a “healthy” bacterial community; addressing these challenges will be critical for the International Human Microbiome Project.
26
Bashan, Yoav, e Hanna Levanony. "Factors affecting adsorption of Azospirillum brasilense Cd to root hairs as compared with root surface of wheat". Canadian Journal of Microbiology 35, n. 10 (1 ottobre 1989): 936–44. http://dx.doi.org/10.1139/m89-155.
Testo completoAbstract (sommario):
Electron microscopy of wheat (Triticum aestivum) roots inoculated with Azospirillum brasilense Cd revealed massive adsorption of bacterial cells to the root surface and less adsorption to root hairs. Quantitative analysis of A. brasilense Cd adsorption to root surface and to root hairs, confirmed qualitatively by light microscopy observations, revealed a bacterial adsorption ratio of 5 (+2): 1 (root surface: root hairs). Extreme bacterial adsorption ratios were recorded when bacteria were previously grown in the presence of KNO3 (27:1) or when bacterial cells were inoculated under hydroponic plant growth conditions (80:1). Adsorption of A. brasilense Cd to roots was directly related to the bacterial growth phase, with logarithmic phase cultures demonstrating a greater adsorption than stationary phase cultures. Adsorption to root hairs was dependent mainly on the number of root hairs developed under certain growth conditions. When very few root hairs had developed, most of the bacterial cells were adsorbed to the root surface. Factors such as starvation, bacteria grown in culture in the presence of KNO3, addition of several nutrients, and protease or NaEDTA treatments of bacterial cells before the adsorption assay decreased bacterial adsorption to root hairs. Other factors such as microaerophilic growth conditions, addition of several bacterial chemoattractants, and cellulase-treated root hairs enhanced bacterial adsorption. It is proposed that although A. brasilense Cd adsorbed to every part of the root system, more cells adsorbed to the root surface of wheat than to the root hairs.Key words: associative bacteria, Azospirillum, bacterial adsorption, beneficial bacteria, rhizosphere bacteria, root-hair colonization.
27
Chathoth, Kanchana, Louis Fostier, Bénédicte Martin, Christine Baysse e Fabrice Mahé. "A Multi-Skilled Mathematical Model of Bacterial Attachment in Initiation of Biofilms". Microorganisms 10, n. 4 (23 marzo 2022): 686. http://dx.doi.org/10.3390/microorganisms10040686.
Testo completoAbstract (sommario):
The initial step of biofilm formation is bacteria attachment to biotic or abiotic surfaces and other bacteria through intra or interspecies interactions. Adhesion can be influenced by physicochemical conditions of the environment, such as iron. There is no available mathematical model of bacterial attachment giving realistic initiation rather than random adhesion. We describe a simple stochastic attachment model, from the simplest case in two dimensions with one bacterial species attaching on a homogeneous flat surface to more complex situations, with either several bacterial species, inhomogeneous or non-flat surfaces, or in three dimensions. The model depends on attachment probabilities (on the surface, laterally, or vertically on bacteria). Effects of each of these parameters were analyzed. This mathematical model is then applied to experimental oral microcolonies of Porphyromonas gingivalis, Streptococcus gordonii, and Treponema denticola, either as mono-, two, or three species, under different iron concentrations. The model allows to characterize the adhesion of three bacterial species and explore the effect of iron on attachment. This model appears as a powerful tool for initial attachment analysis of bacterial species. It will enable further modeling of biofilm formation in later steps with biofilm initialization more relevant to real-life subgingival biofilms.
28
Taylor, Gordon T., e Jeanne D. Gulnick. "Enhancement of marine bacterial growth by mineral surfaces". Canadian Journal of Microbiology 42, n. 9 (1 settembre 1996): 911–18. http://dx.doi.org/10.1139/m96-117.
Testo completoAbstract (sommario):
The effects of sorptive inert surfaces on growth of marine bacteria and metabolism, as well as partitioning of organic substrates, were examined in microcosms inoculated with bacterioplankton from a local salt marsh. Introduction of organic-free glass beads to a dilute seawater medium (tryptic soy broth) increased yields of ATP, a surrogate for bacterial biomass, by 187% within the entire microcosm (attached + free-living). Growth efficiencies (bacterial C/media C) were 30% for bacteria grown in microcosms with beads compared with 16% without beads. Surface enrichment increased rates of proteolytic enzyme activity and cell-specific [3H]leucine incorporation into protein by factors of 6.8 and 2.2, respectively. Scanning electron microscopy revealed obvious organic coatings on all beads after 2 h of exposure, but few strongly attached bacteria were evident, even after 40 h of exposure. Results support the hypothesis that mineral surfaces facilitate bacterial utilization of complex organic matter through physical–chemical processes that increase conversion efficiencies of labile substrate despite possible kinetic limitations. Furthermore, firm attachment by bacteria to these surfaces is apparently not a requirement to produce surface-enhanced activity.Key words: epibacteria, sorption, interfaces, hydrolytic enzymes, growth efficiency.
29
Yee, Foong Choi, e Saiful Izwan Abd Razak. "Surface Modification of Bacterial Cellulose Film". Materials Science Forum 889 (marzo 2017): 71–74. http://dx.doi.org/10.4028/www.scientific.net/msf.889.71.
Testo completoAbstract (sommario):
Bacterial cellulose (BC) is the cellulose which is produced by specific bacteria such as Acetobacter xylinum, Agrobacterium, Gluconacetobacter, Rhizobium, Achromobacter, Alcaligenes, Aerobacter, Azotobacter, Salmonella, Esherichia, and Sarcina. Surface modification of bacterial cellulose (BC) by coating with synthetic biodegradable polyester on it was reported. BC films were coated with the polymer at different concentrations in order to improve the surface structure of BC. Tear and burst indices of the BC film were increased with such modification.
30
Tetz, V. V., V. P. Korobov, N. K. Artemenko, L. M. Lemkina, N. V. Panjkova e G. V. Tetz. "Extracellular phospholipids of isolated bacterial communities". Biofilms 1, n. 3 (luglio 2004): 149–55. http://dx.doi.org/10.1017/s147905050400136x.
Testo completoAbstract (sommario):
We have made a comparative analysis of the extracellular phospholipid composition of biofilms of Gram-negative and Gram-positive bacteria. The surface film of a growing bacterial community contains small membrane vesicles and a bilipid layer covering the entire surface of that community. These supracommunity films containing the bilipid layer can cover the entire surface of a Petri dish and form a boundary between bacterial communities and the environment. A mixed bacterial lawn, formed by unrelated bacteria, also becomes covered with a single film containing a lipid bilayer. The phospholipid compositions of the bacterial cell and surface film bilipid layer reflect the nature of the bacterial strains forming the community, but have some specific differences.
31
Lee, Hanna, e Jun Kyun Oh. "Durable, Photostable Omniphobic Synthetic Leather Surfaces with Anti-Biofouling Properties for Hygienic Applications". Polymers 16, n. 14 (11 luglio 2024): 1983. http://dx.doi.org/10.3390/polym16141983.
Testo completoAbstract (sommario):
Globally, the public health domain is increasingly emphasizing the need for surfaces that can resist bacterial contamination, as the consumption of bacteria-infected substance may cause illnesses. Thus, this study aimed to modify polyurethane (PU) synthetic leather surfaces by coating their upper layer with fluorine-functionalized nano-silica particles (FNPs). This simple modification imparted omniphobic characteristics, realizing anti-biofouling and self-cleaning properties. The effectiveness in preventing bacterial adhesion was confirmed by the dip-inoculation method using Escherichia coli O157:H7 and Staphylococcus epidermidis. Bacterial adhesion was evaluated based on bacterial counts using the pour plate method and by directly enumerating from scanning electron microscopy images. The attachment of bacteria to the modified omniphobic FNPs-coated PU leather surface decreased by over 98.2% compared to that on the bare surface. We expect that the method developed in this study will significantly reduce or even eliminate the potential risks associated with various biological cross-contamination scenarios, thereby enhancing hygiene standards.
32
Pacha-Olivenza, Miguel Ángel, Abraham Rodríguez-Cano, M. Luisa González-Martín e Amparo M. Gallardo-Moreno. "Kinetic of Adhesion of S. epidermidis with Different EPS Production on Ti6Al4V Surfaces". BioMed Research International 2019 (26 novembre 2019): 1–8. http://dx.doi.org/10.1155/2019/1437806.
Testo completoAbstract (sommario):
Controlling initial bacterial adhesion is essential to prevent biofilm formation and implant-related infection. The search for surface coatings that prevent initial adhesion is a powerful strategy to obtain implants that are more resistant to infection. Tracking the progression of adhesion on surfaces from the beginning of the interaction between bacteria and the surface provides a deeper understanding of the initial adhesion behavior. To this purpose, we have studied the progression over time of bacterial adhesion from a laminar flow of a bacterial suspension, using a modified Robbins device (MRD). Comparing with other laminar flow devices, such as the parallel plate flow chamber, MRD allows the use of diverse substrata under the same controlled flow conditions simultaneously. Two different surfaces of Ti6Al4V and two strains of Staphylococcus epidermidis with different exopolymer production were tested. In addition, the modified Robbins device was examined for its convenience and suitability for the purpose of this study. Results were analyzed according to a pseudofirst order kinetic. The values of the parameters obtained from this model make it possible to discriminate the adhesive behavior of surfaces and bacteria. One of the fitting parameters depends on the bacterial strain and the other only on the surface properties of the substrate.
33
Bislimi, Fuat, Jagoda Bajevska, Mrinmoy Garai e Arianit A. Reka. "A study on the bacterial adhesion of Streptococcus mutans in various dental ceramics: In vitro study". Open Chemistry 18, n. 1 (4 novembre 2020): 1334–38. http://dx.doi.org/10.1515/chem-2020-0070.
Testo completoAbstract (sommario):
AbstractStreptococcus mutans (S. mutans) has been identified as a major etiologic agent of human dental caries and forms a significant proportion of oral streptococci in carious lesions. This study investigates the correlation of surface properties (effect of contact angle [CA] and free surface energy) on three restorative materials (zirconia, nickel–chromium–molybdenum alloy and composites) used in dental prosthetics with bacterial adhesion to S. mutans. Ten samples of each material (zirconia, nickel–chromium–molybdenum alloy and composites) of 8 mm diameter and 2.5 mm thickness were used. Aqueous CA measurements, free surface energy and bacterial adhesion to the sample surfaces were performed. Bacterial adhesion is determined by planting samples in the blood agar cultures and using an electron microscope (scanning electron microscopy [SEM]). The highest values of bacterial adhesion are found in composites, followed by the metal alloy, while the lowest values are observed in zirconia. Measurements show that zirconia has 17 bacteria; Ni–Cr–Mo alloy has 65, while the composite has 80 bacteria. The composites showed the highest degree of bacterial adhesion, compared to the other investigated materials, which correlates with the free surface energy of the samples (24.31 mJ/m2 for zirconia, 31.78 mJ/m2 for Ni–Cr–Mo alloy and 48.82 mJ/m2 for the composite).
34
Gupta, Akash, Ryan F. Landis e Vincent M. Rotello. "Nanoparticle-Based Antimicrobials: Surface Functionality is Critical". F1000Research 5 (16 marzo 2016): 364. http://dx.doi.org/10.12688/f1000research.7595.1.
Testo completoAbstract (sommario):
Bacterial infections cause 300 million cases of severe illness each year worldwide. Rapidly accelerating drug resistance further exacerbates this threat to human health. While dispersed (planktonic) bacteria represent a therapeutic challenge, bacterial biofilms present major hurdles for both diagnosis and treatment. Nanoparticles have emerged recently as tools for fighting drug-resistant planktonic bacteria and biofilms. In this review, we present the use of nanoparticles as active antimicrobial agents and drug delivery vehicles for antibacterial therapeutics. We further focus on how surface functionality of nanomaterials can be used to target both planktonic bacteria and biofilms.
35
Busalmen, J. P., S. R. de Sánchez e D. J. Schiffrin. "Ellipsometric Measurement of Bacterial Films at Metal-Electrolyte Interfaces". Applied and Environmental Microbiology 64, n. 10 (1 ottobre 1998): 3690–97. http://dx.doi.org/10.1128/aem.64.10.3690-3697.1998.
Testo completoAbstract (sommario):
ABSTRACT Ellipsometric measurements were used to monitor the formation of a bacterial cell film on polarized metal surfaces (Al-brass and Ti). Under cathodic polarization bacterial attachment was measured from changes in the ellipsometric angles. These were fitted to an effective medium model for a nonabsorbing bacterial film with an effective refractive index (nf ) of 1.38 and a thickness (df ) of 160 ± 10 nm. From the optical measurements a surface coverage of 17% was estimated, in agreement with direct microscopic observations. The influence of bacteria on the formation of oxide films was monitored by ellipsometry following the film growth in situ. A strong inhibition of metal oxide film formation was observed, which was assigned to the decrease in oxygen concentration due to the presence of bacteria. It is shown that the irreversible adhesion of bacteria to the surface can be monitored ellipsometrically. Electrophoretic mobility is proposed as one of the factors determining bacterial attachment. The high sensitivity of ellipsometry and its usefulness for the determination of growth of interfacial bacterial films is demonstrated.
36
Vymazal, J., J. Balcarová e H. Doušová. "Bacterial dynamics in the sub-surface constructed wetland". Water Science and Technology 44, n. 11-12 (1 dicembre 2001): 207–9. http://dx.doi.org/10.2166/wst.2001.0830.
Testo completoAbstract (sommario):
Constructed wetlands have been shown to be capable of removing a wide variety of contaminants, including bacterial pollution. However, only limited information exists on the distribution of bacteria on roots of macrophytes growing in constructed wetlands. Constructed wetland with sub-surface horizontal flow at Nucÿice near Prague, Czech Republic, was put in operation in 1996. The system treats municipal sewage from 650 PE and the total area of the beds, planted with Phalaris arundinacea and Phragmites australis in alternate stripes perpendicular to the flow direction, is 3,224 m2 (2 beds 62×26 m each). Pea gravel (8/16 mm) was used as a filtration material. During the period 1998-1999, distribution of total aerobic and anaerobic bacteria, coliform bacteria and fecal streptococci was monitored in wastewater as well as on roots of both macrophyte species. Counts of bacteria on root surface in the system at Nucÿice indicate that there is a steep decrease in bacterial numbers within the first few metres of the bed and that there is significantly more bacteria on roots of Phragmites as compared to Phalaris. There was no statistically significant influence of the season on the bacterial counts on roots of macrophytes.
37
Çulha, Mustafa, M. Müge Yazıcı, Mehmet Kahraman, Fikrettin Şahin e Sesin Kocagöz. "Surface-Enhanced Raman Scattering of Bacteria in Microwells Constructed from Silver Nanoparticles". Journal of Nanotechnology 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/297560.
Testo completoAbstract (sommario):
Whole bacterial cell characterization is critically important for fast bacterial identification. Surface-enhanced Raman scattering (SERS) is proven to be powerful technique to serve such a goal. In this study, the characterization of whole bacterial cells in the microwells constructed from colloidal silver nanoparticles (AgNPs) with “convective-assembly” method is reported. The proper size of the microwells for the model bacteria,Escherichia coliandStaphylococcus cohnii, is determined to be 1.2 μm from their electron microscopy images. A minimum dilution factor of 20 is necessary for the bacterial samples collected from growth media to diminish the bacterial aggregation to place the bacterial cells into the microwells. The constructed microwell structures are tested for their bacterial SERS performance and compared to the SERS spectra obtained from the samples prepared with a simple mixing of bacteria and AgNPs for the same bacteria. The results indicate that microwell structures not only improve the spectral quality but also increase the reproducibility of the SERS spectra.
38
ABDALLAH, MARWAN, CORINNE BENOLIEL, CHARAFEDDINE JAMA, DJAMEL DRIDER, PASCAL DHULSTER e NOUR-EDDINE CHIHIB. "Thermodynamic Prediction of Growth Temperature Dependence in the Adhesion of Pseudomonas aeruginosa and Staphylococcus aureus to Stainless Steel and Polycarbonate". Journal of Food Protection 77, n. 7 (1 luglio 2014): 1116–26. http://dx.doi.org/10.4315/0362-028x.jfp-13-365.
Testo completoAbstract (sommario):
This study investigated the effect of growth temperature changes (20, 30, and 37°C) on the adhesion behavior of Pseudomonas aeruginosa and Staphylococcus aureus to stainless steel and polycarbonate. Adhesion assays were performed under static conditions at 20°C. In addition, the validity of the thermodynamic and extended Derjaguin, Landau, Verwey, and Overbeek theories as predictive tools of bacterial adhesion were studied. The surface properties of the bacterial cells and the substrates of attachment were characterized, and atomic force microscopy was used to analyze the surface topography. The results indicated that the highest adhesion rate of P. aeruginosa and S. aureus on both surfaces was observed when the cells were grown at 37°C. The bacterial adhesion to stainless steel was found to be two times higher than to polycarbonate for both bacteria, whatever the condition used. The present study underlined that the thermodynamic and the extended Derjaguin, Landau, Verwey, and Overbeek theories were able to partially predict the empirical results of P. aeruginosa adhesion. However, these theories failed to predict the adhesion behavior of S. aureus to both surfaces when the growth temperature was changed. The results of the microbial adhesion to solvent indicated that the adhesion rate to abiotic surfaces may correlate with the hydrophobicity of bacterial surfaces. The effect of surface topography on bacterial adhesion showed that surface roughness, even on the very low nanometer scale, has a significant effect on bacterial adhesion behavior.
39
Wilson-Nieuwenhuis, Joels, Nina Dempsey-Hibbert, Christopher M. Liauw e Kathryn A. Whitehead. "The Effect of Human Blood Plasma Conditioning Films on Platelet Transfusion Bag Surface Properties". Applied Sciences 12, n. 22 (9 novembre 2022): 11358. http://dx.doi.org/10.3390/app122211358.
Testo completoAbstract (sommario):
Transfusion-associated bacterial infections continue to occur which may be due to the formation of bacterial biofilms on the inner surface of the blood bag. Plasticized poly (vinyl chloride) (p-PVC) platelet storage bags in three surface roughness states (rough, smooth and flattened) were used to determine the effect that a conditioning film (CF) of human plasma had on surface properties and its interaction with Staphylococcus epidermidis and Serratia marcescens. SEM and optical profilometry determined changes in surface roughness, whilst EDX and ATR-FTIR determined surface chemistry. The physicochemistry of the surfaces and bacteria was assessed using contact angle measurements and MATH assays respectively. When applied to a rougher surface, the CF reduced the surface topography, masked certain surface chemistry features and made the surfaces more hydrophilic. The CF reduced the adhesion of the bacteria to most of the hydrocarbons. When human plasma was combined with bacteria, most of the physicochemical properties changed similarly to those of human plasma alone, with the most significant changes observed after 24 h especially with Ser. marcescens. The results demonstrated that the presence of human plasma had a significant effect on the surface properties of the platelet bags and also on microbial interactions with the bag surface.
40
Chang, Yow-Ren, Eric R. Weeks e William A. Ducker. "Surface Topography Hinders Bacterial Surface Motility". ACS Applied Materials & Interfaces 10, n. 11 (22 febbraio 2018): 9225–34. http://dx.doi.org/10.1021/acsami.7b16715.
Testo completo
41
Anderson, Brett N., Albert M. Ding, Lina M. Nilsson, Kaoru Kusuma, Veronika Tchesnokova, Viola Vogel, Evgeni V. Sokurenko e Wendy E. Thomas. "Weak Rolling Adhesion Enhances Bacterial Surface Colonization". Journal of Bacteriology 189, n. 5 (22 dicembre 2006): 1794–802. http://dx.doi.org/10.1128/jb.00899-06.
Testo completoAbstract (sommario):
ABSTRACT Bacterial adhesion to and subsequent colonization of surfaces are the first steps toward forming biofilms, which are a major concern for implanted medical devices and in many diseases. It has generally been assumed that strong irreversible adhesion is a necessary step for biofilm formation. However, some bacteria, such as Escherichia coli when binding to mannosylated surfaces via the adhesive protein FimH, adhere weakly in a mode that allows them to roll across the surface. Since single-point mutations or even increased shear stress can switch this FimH-mediated adhesion to a strong stationary mode, the FimH system offers a unique opportunity to investigate the role of the strength of adhesion independently from the many other factors that may affect surface colonization. Here we compare levels of surface colonization by E. coli strains that differ in the strength of adhesion as a result of flow conditions or point mutations in FimH. We show that the weak rolling mode of surface adhesion can allow a more rapid spreading during growth on a surface in the presence of fluid flow. Indeed, an attempt to inhibit the adhesion of strongly adherent bacteria by blocking mannose receptors with a soluble inhibitor actually increased the rate of surface colonization by allowing the bacteria to roll. This work suggests that (i) a physiological advantage to the weak adhesion demonstrated by commensal variants of FimH bacteria may be to allow rapid surface colonization and (ii) antiadhesive therapies intended to prevent biofilm formation can have the unintended effect of enhancing the rate of surface colonization.
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Hsu, Lillian C., Jean Fang, Diana A. Borca-Tasciuc, Randy W. Worobo e Carmen I. Moraru. "Effect of Micro- and Nanoscale Topography on the Adhesion of Bacterial Cells to Solid Surfaces". Applied and Environmental Microbiology 79, n. 8 (15 febbraio 2013): 2703–12. http://dx.doi.org/10.1128/aem.03436-12.
Testo completoAbstract (sommario):
ABSTRACTAttachment and biofilm formation by bacterial pathogens on surfaces in natural, industrial, and hospital settings lead to infections and illnesses and even death. Minimizing bacterial attachment to surfaces using controlled topography could reduce the spreading of pathogens and, thus, the incidence of illnesses and subsequent human and financial losses. In this context, the attachment of key microorganisms, includingEscherichia coli,Listeria innocua, andPseudomonas fluorescens, to silica and alumina surfaces with micron and nanoscale topography was investigated. The results suggest that orientation of the attached cells occurs preferentially such as to maximize their contact area with the surface. Moreover, the bacterial cells exhibited different morphologies, including different number and size of cellular appendages, depending on the topographical details of the surface to which they attached. This suggests that bacteria may utilize different mechanisms of attachment in response to surface topography. These results are important for the design of novel microbe-repellant materials.
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Noureddine, Mahmoudi. "Study of composite-based natural fibers and renewable polymers, using bacteria to ameliorate the fiber/matrix interface". Journal of Composite Materials 53, n. 4 (2 luglio 2018): 455–61. http://dx.doi.org/10.1177/0021998318785965.
Testo completoAbstract (sommario):
In this paper, bacteria belonging to the species Acetobacter xylinum were used to modify the surface of natural fibers by depositing nanosized bacterial cellulose around natural fibers which enhances their adhesion to renewable polymers. Single fiber tensile test was used in order to determine their mechanical properties and surface. The practical adhesion between the modified fibers and the renewable polymers cellulose acetate butyrate is quantified using the single fiber pullout test. Simple weight gain measurements before and after the modification show that about 4 and 6% bacterial cellulose adheres to the fibers as a result of the bacterial modification procedure. Scanning electron microscopy micrographs confirm the presence of attached bacterial cellulose on the surfaces of natural fibers.
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Robles, Daniel, Aritza Brizuela, Manuel Fernández-Domínguez e Javier Gil. "Osteoblastic and Bacterial Response of Hybrid Dental Implants". Journal of Functional Biomaterials 14, n. 6 (13 giugno 2023): 321. http://dx.doi.org/10.3390/jfb14060321.
Testo completoAbstract (sommario):
Bacterial infections in dental implants generate peri-implantitis disease that causes bone loss and the mobility of the dental implant. It is well known that specific ranges of roughness favor the proliferation of bacteria, and it is for this reason that new dental implants called hybrids have appeared. These implants have a smooth area in the coronal part and a rough surface in the apical part. The objective of this research is the physico-chemical characterization of the surface and the osteoblastic and microbiological behavior. One-hundred and eighty discs of titanium grade 3 with three different surfaces (smooth, smooth–rough, and completely rough) were studied. The roughness was determined by white light interferometry, and the wettability and surface energy by the sessile drop technique and the application of Owens and Wendt equations. Human osteoblast SaOS-2 was cultured to determine cell adhesion, proliferation, and differentiation. Microbiological studies were performed with two common bacterial strains in oral infection, E. faecalis and S. gordonii, at different times of culture. The roughness obtained for the smooth surface was Sa = 0.23 and for the rough surface it was 1.98 μm. The contact angles were more hydrophilic for the smooth surface (61.2°) than for the rough surface (76.1°). However, the surface energy was lower for the rough surface (22.70 mJ/m2) in both its dispersive and polar components than the smooth surface (41.77 mJ/m2). Cellular activity in adhesion, proliferation, and differentiation was much higher on rough surfaces than on smooth surfaces. After 6 h of incubation, the osteoblast number in rough surfaces was more than 32% higher in relation to the smooth surface. The cell area in smooth surfaces was higher than rough surfaces. The proliferation increased and the alkaline phosphatase presented a maximum after 14 days, with the mineral content of the cells being higher in rough surfaces. In addition, the rough surfaces showed greater bacterial proliferation at the times studied and in the two strains used. Hybrid implants sacrifice the good osteoblast behavior of the coronal part of the implant in order to obstruct bacterial adhesion. The following fact should be considered by clinicians: there is a possible loss of bone fixation when preventing peri-implantitis.
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Xiaoxia, S., T. Y. Peng e P. S. Olavi. "Direct force measurement of bacteria adhesion on metal in aqueous media". Water Science and Technology 54, n. 9 (1 novembre 2006): 17–25. http://dx.doi.org/10.2166/wst.2006.866.
Testo completoAbstract (sommario):
The adhesion of bacteria on metal surfaces in aqueous media and the development of biofilm and resultant biofouling are important phenomena in both the natural environment and engineering systems. This work reports on the use of a force microscopy technique to measure bacterial metal adhesion by two anaerobic sulphate-reducing bacteria (Desulfovibrio desulfuricans and a local marine isolate) and an aerobe (Pseudomonas sp.). Using a modified bacteria tip, the atomic force microscope was able to quantify the attraction and repulsion force in the nano-Newton range between the bacteria cell and metal surface in aqueous media. Results show that increasing surface hydrophobicity of the metal, and increasing the ionic strength of the aqueous medium both enhance the adhesion force. The adhesion forces were also influenced by the physiological properties of the bacterium, such as the bacterial surface charges and hydrophobicity.
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Droumpali, Ariadni, Jörg Hübner, Lone Gram e Rafael Taboryski. "Fabrication of Microstructured Surface Topologies for the Promotion of Marine Bacteria Biofilm". Micromachines 12, n. 8 (3 agosto 2021): 926. http://dx.doi.org/10.3390/mi12080926.
Testo completoAbstract (sommario):
Several marine bacteria of the Roseobacter group can inhibit other microorganisms and are especially antagonistic when growing in biofilms. This aptitude to naturally compete with other bacteria can reduce the need for antibiotics in large-scale aquaculture units, provided that their culture can be promoted and controlled. Micropatterned surfaces may facilitate and promote the biofilm formation of species from the Roseobacter group, due to the increased contact between the cells and the surface material. Our research goal is to fabricate biofilm-optimal micropatterned surfaces and investigate the relevant length scales for surface topographies that can promote the growth and biofilm formation of the Roseobacter group of bacteria. In a preliminary study, silicon surfaces comprising arrays of pillars and pits with different periodicities, diameters, and depths were produced by UV lithography and deep reactive ion etching (DRIE) on polished silicon wafers. The resulting surface microscale topologies were characterized via optical profilometry and scanning electron microscopy (SEM). Screening of the bacterial biofilm on the patterned surfaces was performed using green fluorescent staining (SYBR green I) and confocal laser scanning microscopy (CLSM). Our results indicate that there is a correlation between the surface morphology and the spatial organization of the bacterial biofilm.
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Liu, Qiao, Mengmeng Liu, Qi Zhang, Yanlin Bao, Na Yang, Yuanzi Huo e Peimin He. "Epiphytic bacterial community composition on the surface of the submerged macrophyte Myriophyllum spicatum in a low-salinity sea area of Hangzhou Bay". Oceanological and Hydrobiological Studies 48, n. 1 (26 marzo 2019): 43–55. http://dx.doi.org/10.1515/ohs-2019-0005.
Testo completoAbstract (sommario):
Abstract In this study, we conducted a comparative analysis of the abundance and diversity of bacteria on the surface of the submerged macrophyte Myriophyllum spicatum, as well as in the surrounding water column and sediment in the low-salinity area of Hangzhou Bay, China. Bacterial clones from three clone libraries were classified into 2089 operational taxonomic units (OTUs), most of which affiliated with bacterial divisions commonly found in marine ecosystems. Alphaproteobacteria, Cyanobacteria and Gammaproteobacteria were the most abundant groups of bacteria on the surface of plants, in the water column and sediment, respectively. Epiphytic bacterial communities were more closely related to those in the sediment than bacterioplankton, and some species of epiphytic bacteria were found only on the surface of M. spicatum. The relative abundance of epiphytic bacterial genera associated with breakdown of organic compounds and with cellulose digestion was higher in October than that in July. These results suggested that bacterial communities on the surface of M. spicatum may originate from sediment bacterial communities and their specific structure was gradually formed on the surface of M. spicatum after being cultivated in low-salinity seawater.
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Santo, Christophe Espírito, Nadine Taudte, Dietrich H. Nies e Gregor Grass. "Contribution of Copper Ion Resistance to Survival of Escherichia coli on Metallic Copper Surfaces". Applied and Environmental Microbiology 74, n. 4 (21 dicembre 2007): 977–86. http://dx.doi.org/10.1128/aem.01938-07.
Testo completoAbstract (sommario):
ABSTRACT Bacterial contamination of touch surfaces poses a serious threat for public health. The use of bactericidal surface materials, such as copper and its alloys, might constitute a way to aid the use of antibiotics and disinfectants, thus minimizing the risk of emergence and spread of multiresistant germs. The survival of Escherichia coli on metallic copper surfaces has been studied previously; however, the mechanisms underlying bacterial inactivation on copper surfaces have not been elucidated. Data presented in this study suggest that bacteria are killed rapidly on dry copper surfaces. Several factors, such as copper ion toxicity, copper chelators, cold, osmotic stress, and reactive oxygen species, but not anaerobiosis, influenced killing rates. Strains deleted in copper detoxification systems were slightly more sensitive than was the wild type. Preadaptation to copper enhanced survival rates upon copper surface exposure. This study constitutes a first step toward understanding the reasons for metallic copper surface-mediated killing of bacteria.
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Kumar, Neeraj. "Bacterial Growth on the Surface of used Mobile Phone". International Journal of Science and Research (IJSR) 10, n. 1 (27 gennaio 2021): 491–93. https://doi.org/10.21275/sr21106224028.
Testo completo
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Karlsson, Christofer, Matthias Mörgelin, Mattias Collin, Rolf Lood, Marie-Louise Andersson, Artur Schmidtchen, Lars Björck e Inga-Maria Frick. "SufA – a bacterial enzyme that cleaves fibrinogen and blocks fibrin network formation". Microbiology 155, n. 1 (1 gennaio 2009): 238–48. http://dx.doi.org/10.1099/mic.0.021311-0.
Testo completoAbstract (sommario):
Finegoldia magna is a member of the normal human bacterial flora on the skin and other non-sterile body surfaces, but this anaerobic coccus is also an important opportunistic pathogen. SufA was the first F. magna proteinase to be isolated and characterized. Many bacterial pathogens interfere with different steps of blood coagulation, and here we describe how purified SufA efficiently and specifically cleaves fibrinogen in human plasma. SufA is both secreted by F. magna and associated with the bacterial surface. Successful gene targeting has previously not been performed in anaerobic cocci, but in order to study the role of the SufA that is present at the bacterial surface, we constructed an F. magna mutant that expresses a truncated SufA lacking proteolytic activity. In contrast to wild-type bacteria that delayed the coagulation of human plasma, mutant bacteria had no such effect. Wild-type and mutant bacteria adhered to keratinocytes equally well, but in a plasma environment only wild-type bacteria blocked the formation of fibrin networks surrounding adherent bacteria. The effective cleavage of fibrinogen by SufA suggests that the interference with fibrin network formation represents an adaptive mechanism of F. magna with potential implications also for pathogenicity.