Determination the Effect of Silver Nanoparticles on Gram-Positive Bacterial Cells by Atomic Force Microscopy

The atomic force microscope (AFM) was employed to study the significant effects of silver (Ag) nanoparticles-treated on the elastic cell wall of bacteria. In this study, the exposed Staphylococcus aureus was grown at 37 °C for 14 h. The cultures were centrifuged and cell pellets were resuspended in Milli-Q water to prepare final bacterial suspensions. A drop of bacterial suspension was deposited on polydimethylsiloxane (PDMS) sheet and allowed to air dry at room temperature before imaging. The cell suspension was collected at certain time intervals from the beginning of the test. The morphology of the cell surface compares between without treatment and Ag-treated cell suspension was investigated. The force mappings were obtained for the PDMS substrate and for the bacteria while scanning obliquely. The contribution of the internal osmotic pressure, to obtain a quantitative measure for the elasticity of the cell wall, had to be estimated. The pyramid-shaped AFM tip indented into a soft cell and the resulting bacterial surface was flat, and irreversible changed of bacterial cell structure. The investigation is attempted to understand pronounced effect of Ag nanoparticles on the individual gram-positive bacterial cell after treated with Ag nanoparticles.

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Telavancin, a Multifunctional Lipoglycopeptide, Disrupts both Cell Wall Synthesis and Cell Membrane Integrity in Methicillin-Resistant Staphylococcus aureus

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.3.1127-1134.2005 ◽

2005 ◽

Vol 49 (3) ◽

pp. 1127-1134 ◽

Cited By ~ 291

Author(s):

Deborah L. Higgins ◽

Ray Chang ◽

Dmitri V. Debabov ◽

Joey Leung ◽

Terry Wu ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

Membrane Potential ◽

Cell Membrane ◽

Bactericidal Activity ◽

Bacterial Cell ◽

Cell Membrane Potential ◽

Gram Positive ◽

Methicillin Resistant ◽

Bacterial Cell Membrane

ABSTRACTThe emergence and spread of multidrug-resistant gram-positive bacteria represent a serious clinical problem. Telavancin is a novel lipoglycopeptide antibiotic that possesses rapid in vitro bactericidal activity against a broad spectrum of clinically relevant gram-positive pathogens. Here we demonstrate that telavancin's antibacterial activity derives from at least two mechanisms. As observed with vancomycin, telavancin inhibited late-stage peptidoglycan biosynthesis in a substrate-dependent fashion and bound the cell wall, as it did the lipid II surrogate tripeptideN,N′-diacetyl-l-lysinyl-d-alanyl-d-alanine, with high affinity. Telavancin also perturbed bacterial cell membrane potential and permeability. In methicillin-resistantStaphylococcus aureus, telavancin caused rapid, concentration-dependent depolarization of the plasma membrane, increases in permeability, and leakage of cellular ATP and K+. The timing of these changes correlated with rapid , concentration-dependent loss of bacterial viability, suggesting that the early bactericidal activity of telavancin results from dissipation of cell membrane potential and an increase in membrane permeability. Binding and cell fractionation studies provided direct evidence for an interaction of telavancin with the bacterial cell membrane; stronger binding interactions were observed with the bacterial cell wall and cell membrane relative to vancomycin. We suggest that this multifunctional mechanism of action confers advantageous antibacterial properties.

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Revealing Silver Effects on Bacterial Cell Structure by Atomic Force and Scanning Electron Microscopies

10.21203/rs.3.rs-547371/v1 ◽

2021 ◽

Author(s):

Reem Tambosi ◽

Jamila Djafari ◽

Sylviane Liotenberg ◽

Soufian Ouchane ◽

Nouari Kebaili

Keyword(s):

Bacterial Cell ◽

Metal Toxicity ◽

Food Industry ◽

Cell Structure ◽

Silver Ions ◽

Electron Microscopies ◽

Atomic Force ◽

Morphology And Structure ◽

Damage Membrane ◽

Photosynthesis And Respiration

Abstract The use of silver (Ag+) as an antimicrobial under different forms and at different scales, appears in numerous applications such as in health care, food industry, clothing, fabrics and disinfectants. Yet, there is still important gaps regarding the complete comprehension of the mechanisms of its actions on bacteria. In a previous work, we demonstrated that, silver and copper severly damage membrane proteins involved in photosynthesis and respiration in bacteria exposed to metal excess. Here, we are presenting complementary data using AFM and SEM microscopies, that reveals (i) the drastic effects of Ag+ ions on the morphology and structure of cell membrane and (ii) the formation of Ag+ aggregates that adhere to the bacterial cell surface in Rubrivivax (R.) gelatinosus . Impacts of Ag+ ions on R. gelatinosus are compared to those on the most commonly studied bacteria (Escherichia (E.) coli and Bacillus (B.) subtilis ), while considering the effect of culture grown media on the modification of silver ions. Altogether, these results reveal other levels and subtle aspects of Ag+ toxicity to be taken into account in understanding the general mechanisms of metal toxicity in bacteria.

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Factors That Affect the Enlargement of Bacterial Protoplasts and Spheroplasts

International Journal of Molecular Sciences ◽

10.3390/ijms21197131 ◽

2020 ◽

Vol 21 (19) ◽

pp. 7131

Author(s):

Hiromi Nishida

Keyword(s):

Cell Wall ◽

Plasma Membrane ◽

Bacterial Cell ◽

Metal Ion ◽

Bacterial Species ◽

Bacterial Cells ◽

Cell Enlargement ◽

Ion Composition ◽

Gene Manipulation ◽

Peptidoglycan Biosynthesis

Cell enlargement is essential for the microinjection of various substances into bacterial cells. The cell wall (peptidoglycan) inhibits cell enlargement. Thus, bacterial protoplasts/spheroplasts are used for enlargement because they lack cell wall. Though bacterial species that are capable of gene manipulation are limited, procedure for bacterial cell enlargement does not involve any gene manipulation technique. In order to prevent cell wall resynthesis during enlargement of protoplasts/spheroplasts, incubation media are supplemented with inhibitors of peptidoglycan biosynthesis such as penicillin. Moreover, metal ion composition in the incubation medium affects the properties of the plasma membrane. Therefore, in order to generate enlarged cells that are suitable for microinjection, metal ion composition in the medium should be considered. Experiment of bacterial protoplast or spheroplast enlargement is useful for studies on bacterial plasma membrane biosynthesis. In this paper, we have summarized the factors that influence bacterial cell enlargement.

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The Microstructure and Mechanical Properties of Poplar Catkin Fibers Evaluated by Atomic Force Microscope (AFM) and Nanoindentation

Forests ◽

10.3390/f10110938 ◽

2019 ◽

Vol 10 (11) ◽

pp. 938 ◽

Cited By ~ 4

Author(s):

Wu ◽

Shi ◽

Chen ◽

Wang ◽

...

Keyword(s):

Mechanical Properties ◽

Cell Wall ◽

Cell Structure ◽

Large Cell ◽

Populus Tomentosa ◽

Thin Wall ◽

Cell Lumen ◽

Atomic Force ◽

Microstructure And Mechanical Properties ◽

Wall Cell

In this study, the microstructure and mechanical properties of poplar (Populus tomentosa) catkin fibers (PCFs) were investigated using field emission scanning electron microscope, atomic force microscopy (AFM), X-ray diffraction, and nanoindentation methods. Experimental results indicated that PCFs had a thin-wall cell structure with a large cell lumen and the hollow part of the cell wall took up 80 percent of the whole cell wall. The average diameters of the fiber and cell lumen, and the cell wall thickness were 5.2, 4.2, and 0.5 µm, respectively. The crystallinity of fibers was 32%. The AFM images showed that the orientation of microfibrils in cell walls was irregular and their average diameters were almost between 20.6–20.8 nm after being treated with 2 and 5 wt.% potassium hydroxide (KOH), respectively. According to the test of nanoindentation, the average longitudinal-reduced elastic modulus of the PCF S2 layer was 5.28 GPa and the hardness was 0.25 GPa.

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Analysis of the Crushing Effect about Ultrasound on E. coli and B. subtilis

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.260-261.1017 ◽

2012 ◽

Vol 260-261 ◽

pp. 1017-1021

Author(s):

Xin Ying Wang ◽

Yong Tao Liu ◽

Min Hui ◽

Ji Fei Xu

Keyword(s):

Escherichia Coli ◽

Cell Wall ◽

Bacillus Subtilis ◽

Bacterial Cell ◽

Logarithmic Phase ◽

Growth Stages ◽

Bacterial Cells ◽

E Coli ◽

Different Growth Stages ◽

Main Factor

Escherichia coli and Bacillus subtilis as objects of the study, ultrasonic fragmentation acted on the bacterial cells in different growth stages, results showed that, it’s similar to the crushing effect of ultrasound on E. coli and B. subtilis cells of different growth stages, the highest crushing rate in the logarithmic phase, reached to 95.8% and 94.3% respectively, the crushing rate of adjustment phase is lowest, maintained at around 60%, the crushing rate stability cell was centered, which can be achieved 90%. The structure of the bacterial cell wall didn’t the main factor to decide the ultrasonic fragmentation effect, but different growth periods of bacterial cells did the determinant.

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Identification of Bacterial Cell Wall Lyases via Pseudo Amino Acid Composition

BioMed Research International ◽

10.1155/2016/1654623 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8 ◽

Cited By ~ 44

Author(s):

Xin-Xin Chen ◽

Hua Tang ◽

Wen-Chao Li ◽

Hao Wu ◽

Wei Chen ◽

...

Keyword(s):

Cell Wall ◽

Bacterial Cell ◽

Pathogenic Bacteria ◽

Antimicrobial Agents ◽

Cell Structure ◽

Bacterial Cell Wall ◽

Computational Method ◽

Support Vector ◽

Feature Subset ◽

Feature Selection Technique

Owing to the abuse of antibiotics, drug resistance of pathogenic bacteria becomes more and more serious. Therefore, it is interesting to develop a more reasonable way to solve this issue. Because they can destroy the bacterial cell structure and then kill the infectious bacterium, the bacterial cell wall lyases are suitable candidates of antibacteria sources. Thus, it is urgent to develop an accurate and efficient computational method to predict the lyases. Based on the consideration, in this paper, a set of objective and rigorous data was collected by searching through the Universal Protein Resource (the UniProt database), whereafter a feature selection technique based on the analysis of variance (ANOVA) was used to acquire optimal feature subset. Finally, the support vector machine (SVM) was used to perform prediction. The jackknife cross-validated results showed that the optimal average accuracy of 84.82% was achieved with the sensitivity of 76.47% and the specificity of 93.16%. For the convenience of other scholars, we built a free online server calledLypred. We believe thatLypredwill become a practical tool for the research of cell wall lyases and development of antimicrobial agents.

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