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

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.

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

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 ◽  
E Coli ◽  
Electron Microscopies ◽  
Atomic Force ◽  
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.

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

2012 ◽  
Vol 506 ◽  
pp. 202-205
Author(s):  
O. Ketchart ◽  
A. Treetong ◽  
P. Na-Ubon ◽  
N. Supaka
Keyword(s):  
Cell Wall ◽  
Cell Suspension ◽  
Ag Nanoparticles ◽  
Bacterial Cell ◽  
Cell Structure ◽  
Quantitative Measure ◽  
Bacterial Suspension ◽  
Bacterial Cells ◽  
Gram Positive ◽  
Atomic Force

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.

Antimicrobial Activity of Silver Nanoparticles Synthesized by Streptomyces Species JF714876

2012 ◽  
Vol 5 (1) ◽  
pp. 1638-1642 ◽  
Author(s):  
Vidyasagar G M ◽  
Shankaravva B ◽  
R Begum ◽  
Imrose ◽  
Sagar R ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Silver Ions ◽  
Human Beings ◽  
Streptomyces Species ◽  
Force Microscopy ◽  
E Coli ◽  
Extracellular Synthesis ◽  
Atomic Force ◽  
Uv Visible

Microorganisms like fungi, actinomycetes and bacteria are considered nanofactories and are helpful in the production of nanoparticles useful in the welfare of human beings. In the present study, we investigated the production of silver nanoparticles from Streptomyces species JF714876. Extracellular synthesis of silver nanoparticles by Streptomyces species was carried out using two different media. Silver nanoparticles were examined using UV-visible, IR and atomic force microscopy. The size of silver nanoparticles was in the range of 80-100 nm. Antimicrobial activity of silver nanoparticle against bacteria such as E. coli, S. aureus, and dermatophytes like T. rubrum and T. tonsurans was determined. Thus, this study suggests that the Streptomyces sp. JF741876 can produce silver ions that can be used as an antimicrobial substance.

scholarly journals Gel Formation in Low Concentrated Solutions of Glycyram and Amino Acids in the Presence of Silver Nitrate

2021 ◽  
Vol 7 (11) ◽  
pp. 11-21
Keyword(s):  
Amino Acids ◽  
Silver Nitrate ◽  
Food Industry ◽  
Silver Ions ◽  
Electrolyte Solutions ◽  
Low Molecular Weight ◽  
Gel Formation ◽  
Recent Past ◽  
Concentrated Solutions ◽  
Low Concentrations

Abstract. Research relevance: low molecular weight supramolecular hydrogels are unique objects that can solve many pressing problems in medicine, food industry and other sectors of the national economy. Research objectives: in recent past, it was discovered that low-concentration solutions of L-cysteine and silver nitrate (CSN) can form, when electrolyte solutions are added to hydrogels. We were faced with the task of obtaining hydrogels from dilute solutions of glycyram (GC) by adding CSN, since GC, due to its poor solubility, has low bioavailability. Materials and research methods: using the method of isomolar series, a comparative study of the formation of hydrogels by dilute GC solutions with the addition of CSN and GCP was carried out. It has been found that most durable hydrogels were obtained using CSN. Thus, GC hydrogels were obtained at a concentration of 10−3 M after adding CSN and GCP, which have a supramolecular character and combine the properties of GC, amino acids, and silver ions. Research results: glycyram hydrogels were obtained at its concentration equal to 10−3 M by mixing it with silver amino acids L-cysteine (CSN) and L-glutamic acid (GCP) solutions in same low concentrations. Conclusions: hydrogels with glycyram form silver solutions of those amino acids that are capable of giving frame structures at a ratio of amino acid: silver nitrate of 1.25.

scholarly journals Silver Nanoparticles Stimulates Spermatogenesis Impairments and Hematological Alterations in Testis and Epididymis of Male Rats

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1063 ◽  
Author(s):  
Janet Olayemi Olugbodi ◽  
Oladipupo David ◽  
Ene Naomi Oketa ◽  
Bashir Lawal ◽  
Bamidele Joseph Okoli ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Hematological Parameters ◽  
Silver Ions ◽  
Thiol Group ◽  
Sperm Parameters ◽  
Male Rats ◽  
Ag Nps ◽  
Hematological Indices ◽  
Electron Microscopies ◽  
Pharmaceutical Application

The potential pharmaceutical application of nanoparticles has led to the toxicity within the male reproductive system. In the present study, the effects of silver nanoparticles (Ag-NPs) on hematological parameters, free radical generation, antioxidant system, sperm parameters, and organ histo-morphometry in male rats were investigated. Ag-NPs were produced by the reduction of silver ions, while the formation of which was monitored by UV–visible spectrophotometry. Zeta potential, transmission, and scanning electron microscopies were applied for the characterization of AgNPs. A total of 30 rats were divided into 6 groups and were sub-dermally exposed to Ag-NPs at the dosage of 0 (control), 10, and 50 mg/kg bodyweight (bw) doses for either 7 or 28 days. Ag-NP administration altered hematological indices and caused dose-dependent decreases in sperm motility, velocity, kinematic parameters, concentrations of luteinizing hormone, follicle-stimulating hormone, and testosterone. In the epididymis and testis, the concentrations of malondialdehyde and peroxide increases while superoxide dismutase, catalase, reduced glutathione, and total thiol group decreases. These findings suggest that Ag-NP triggered hormonal imbalance and induce oxidative stress in testis and epididymis; which negatively affect sperm parameters of male rats.

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

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 938 ◽  
Author(s):  
Wu ◽  
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.

scholarly journals Electrostatic shape control of a charged molecular membrane from ribbon to scroll

2019 ◽  
Vol 116 (44) ◽  
pp. 22030-22036 ◽  
Author(s):  
Changrui Gao ◽  
Sumit Kewalramani ◽  
Dulce Maria Valencia ◽  
Honghao Li ◽  
Joseph M. McCourt ◽  
...  
Keyword(s):  
Shape Control ◽  
Electrostatic Interactions ◽  
Debye Length ◽  
Electron Microscopies ◽  
Atomic Force ◽  
Length Relationship ◽  
Transmission Electron ◽  
Nacl Concentration ◽  
Large Length ◽  
And Control

Bilayers of amphiphiles can organize into spherical vesicles, nanotubes, planar, undulating, and helical nanoribbons, and scroll-like cochleates. These bilayer-related architectures interconvert under suitable conditions. Here, a charged, chiral amphiphile (palmitoyl-lysine, C16-K1) is used to elucidate the pathway for planar nanoribbon to cochleate transition induced by salt (NaCl) concentration. In situ small- and wide-angle X-ray scattering (SAXS/WAXS), atomic force and cryogenic transmission electron microscopies (AFM and cryo-TEM) tracked these transformations over angstrom to micrometer length scales. AFM reveals that the large length (L) to width (W) ratio nanoribbons (L/W > 10) convert to sheets (L/W → 1) before rolling into cochleates. A theoretical model based on electrostatic and surface energies shows that the nanoribbons convert to sheets via a first-order transition, at a critical Debye length, with 2 shallow minima of the order of thermal energy at L/W >> 1 and at L/W = 1. SAXS shows that interbilayer spacing (D) in the cochleates scales linearly with the Debye length, and ranges from 13 to 35 nm for NaCl concentrations from 100 to 5 mM. Theoretical arguments that include electrostatic and elastic energies explain the membrane rolling and the bilayer separation–Debye length relationship. These models suggest that the salt-induced ribbon to cochleate transition should be common to all charged bilayers possessing an intrinsic curvature, which in the present case originates from molecular chirality. Our studies show how electrostatic interactions can be tuned to attain and control cochleate structures, which have potential for encapsulating, and releasing macromolecules in a size-selective manner.

scholarly journals Examining Bacterial Cell Interactions using Atomic Force Microscopy

2015 ◽  
Vol 108 (2) ◽  
pp. 633a
Author(s):  
Ronald Aucapina ◽  
Nadia Ouedraogo ◽  
Megan A. Ferguson
Keyword(s):  
Atomic Force Microscopy ◽  
Bacterial Cell ◽  
Cell Interactions ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Identification of Bacterial Cell Wall Lyases via Pseudo Amino Acid Composition

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
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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