scholarly journals Enhanced Antimicrobial Activity of N-Terminal Derivatives of a Novel Brevinin-1 Peptide from The Skin Secretion of Odorrana schmackeri

Toxins ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 484 ◽  
Author(s):  
Xiaowei Zhou ◽  
Yue Liu ◽  
Yitian Gao ◽  
Yuanxing Wang ◽  
Qiang Xia ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antimicrobial Activity ◽  
Bacterial Infections ◽  
Therapeutic Index ◽  
Skin Secretion ◽  
Amphibian Skin ◽  
Transmission Electron ◽  
Conventional Antibiotics ◽  
Therapeutic Alternatives ◽  
Promising Source

Antimicrobial peptides (AMPs) are promising therapeutic alternatives compared to conventional antibiotics for the treatment of drug-resistant bacterial infections. However, the application of the overwhelming majority of AMPs is limited because of the high toxicity and high manufacturing costs. Amphibian skin secretion has been proven to be a promising source for the discovery and development of novel AMPs. Herein, we discovered a novel AMP from the skin secretion of Odorrana schmackeri, and designed the analogues by altering the key factors, including conformation, net charge and amphipathicity, to generate short AMPs with enhanced therapeutic efficacy. All the peptides were chemically synthesised, followed by evaluating their biological activity, stability and cytotoxicity. OSd, OSe and OSf exhibited broad-spectrum antibacterial effects, especially OSf, which presented the highest therapeutic index for the tested bacteria. Moreover, these peptides displayed good stability. The results from scanning electron microscopy and transmission electron microscopy studies, indicated that brevinin-OS, OSd, OSe and OSf possessed rapid bactericidal ability by disturbing membrane permeability and causing the release of cytoplasmic contents. In addition, OSd, OSe and OSf dramatically decreased the mortality of waxworms acutely infected with MRSA. Taken together, these data suggested that a balance between positive charge, degrees of α-helicity and hydrophobicity, is necessary for maintaining antimicrobial activity, and these data successfully contributed to the design of short AMPs with significant bactericidal activity and cell selectivity.

scholarly journals Potential Decontamination of Drinking Water Pathogens through k-Carrageenan Integrated Green Bottle Fly Bio-Synthesized Silver Nanoparticles

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1936 ◽  
Author(s):  
M. A. Abu-Saied ◽  
Mohamed Elnouby ◽  
Tarek Taha ◽  
Muhammad El-shafeey ◽  
Ali G. Alshehri ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Drinking Water ◽  
Pathogenic Bacteria ◽  
Polymeric Nanoparticles ◽  
Wide Distribution ◽  
Spectrophotometric Analysis ◽  
Transmission Electron ◽  
Green Bottle

The wide distribution of infections-related pathogenic microbes is almost related to the contamination of food and/or drinking water. The current applied treatments face some limitations. In the current study, k-carrageenan polymer was used as supporting material for the proper/unreleased silver nanoparticles that showed strong antimicrobial activity against six pathogenic bacteria and yeast. The bio-extract of the pupa of green bottle fly was used as the main agent for the synthesis of silver nanoparticles. The qualitative investigation of biologically synthesized silver nanoparticles was determined using UV-Vis spectrophotometric analysis; however, the size of nanoparticles was in range of 30–100 nm, as confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle size analyzer. The proper integration of silver nanoparticles into the polymeric substrate was also characterized through fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), SEM, and tensile strength. The antimicrobial activity of k-carrageenan/silver nanoparticles against Gram positive, Gram negative, and yeast pathogens was highly effective. These results indicate the probable exploitation of the polymeric/nanoparticles composite as an extra stage in water purification systems in homes or even at water treatment plants.

scholarly journals Multifunctional Epoxy/Nanocomposites Based on Natural Moroccan Clays with High Antimicrobial Activity: Morphological, Thermal and Mechanical Properties

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
M. Monsif ◽  
A. Zerouale ◽  
N. Idrissi Kandri ◽  
R. Bertani ◽  
A. Bartolozzi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antimicrobial Activity ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Clay Nanocomposites ◽  
Mechanical And Thermal Properties ◽  
Clay Dispersion ◽  
Mechanical Stirring ◽  
Antimicrobial Materials ◽  
Transmission Electron

In this study, a series of new epoxy/clay nanocomposites (ECN) has been prepared and characterized in order to investigate the properties and compare the effect of the unmodified Moroccan clay on the structure and properties of the composite materials. Five natural clays have been used to reinforce the neat epoxy resin with 1% wt and 5% wt achieving the clay dispersion only through strong milling and mechanical stirring without previous organic modifications of the clays. The quality of clay dispersion in the epoxy matrix and the morphology of nanocomposites have been studied by transmission electron microscopy (TEM), environmental scanning electron microscopy (ESEM), and X-ray diffraction (XRD). The mechanical and thermal properties have also been investigated. The antimicrobial activity of the nanocomposites has been tested against E. coli and S. aureus in order to evaluate their applicability as advanced antimicrobial materials. The results showed that the epoxy/crude clay nanocomposites exhibited a high inhibition action attending 99% against both bacteria in the case of the clay labeled A5.

scholarly journals Ultrastructural Study of Elaeis guineensis (Oil Palm) Leaf and Antimicrobial Activity of its Methanol Extract against Staphylococcus Aureus

2016 ◽  
Vol 12 (3) ◽  
pp. 419-423 ◽  
Author(s):  
Amala Rajoo ◽  
Sreenivasan Sasidharan ◽  
Subramanion L Jothy ◽  
Surash Ramanathan ◽  
Sharif M Mansor
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Staphylococcus Aureus ◽  
Transmission Electron Microscopy ◽  
Antimicrobial Activity ◽  
Methanol Extract ◽  
Elaeis Guineensis ◽  
Transmission Electron ◽  
Inhibition Concentration ◽  
Scanning Electron

Purpose: To evaluate the antimicrobial activity of the methanol extract of Elaeis guineensis leaf against Staphylococcus aureus and to determine the effect of extract treatment on the microstructure of the microbeMethods: The antimicrobial activity of the methanol leaf extract of the plant against S. aureus was examined using disc diffusion and broth dilution methods. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were carried out to determine the major alterations in the microstructure of S. aureus after treatment with the extract.Results: The extract showed a good antimicrobial activity against S. aureus with a minimum inhibition concentration (MIC) of 6.25 mg/mL and for Chloramphenicol was 30.00 ìg/mL. The main changes observed under SEM and TEM were structural disorganization of the cell membrane which occurred after 12 h and total collapse of the cell 36 h after exposure to the extract.Conclusion: We concluded that the methanolic extract of E. guineensis leaf exhibited good antimicrobial activity against S. aureus and this is supported by SEM and TEM.Keywords: Antimicrobial activity, Elaeis guineensis, Staphylococcus aureus, Scanning electron microscopy, Transmission electron microscopy

The ultrastructure of hypersymbionts on the monogenean Gyrodactylus salaris infecting Atlantic salmon Salmo salar

2006 ◽  
Vol 80 (4) ◽  
pp. 377-386 ◽  
Author(s):  
T.A. Bakke ◽  
J. Cable ◽  
M. Østbø
Keyword(s):  
Electron Microscopy ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Structural Damage ◽  
Bacterial Infections ◽  
Control Strategies ◽  
Feeding Activity ◽  
Transmission Electron ◽  
Infected Wounds ◽  
Sensory Structures

AbstractThere is increasing pressure to develop alternative control strategies against the pathogen Gyrodactylus salaris, which has devastated wild Atlantic salmon Salmo salar in Norway. Hyperparasitism is one option for biological control and electron microscopy has revealed two ectosymbionts associated with G. salaris: unidentified rod-shaped bacteria, and the protist, Ichthyobodo necator. No endosymbionts were detected. The flagellate I. necator occurred only occasionally on fish suffering costiosis, whereas bacterial infections on the tegument of G. salaris were observed throughout the year, but at variable densities. Bacteria were seldom observed attached to fish epidermis, even when individuals of G. salaris on the same host were heavily infected. Wounds on salmon epidermis caused by the feeding activity of bacteria-infected G. salaris did not appear to be infected with bacteria. On heavily infected gyrodactylids, bacteria were most abundant anteriorly on the cephalic lobes, including the sensory structures, but no damaged tissue was detected by transmission electron microscopy in the region of bacterial adherence. Furthermore, transmission and survival of infected G. salaris on wild salmon did not appear to be influenced by the bacterial infection. The lack of structural damage and impact on G. salaris biology indicates that these bacteria are not a potential agent for control of gyrodactylosis. However, this may not be the case for all gyrodactylid–bacterial interactions and a review of bacterial infections of platyhelminths is presented.

scholarly journals Antimicrobial nanospheres thin coatings prepared by advanced pulsed laser technique

2014 ◽  
Vol 5 ◽  
pp. 872-880 ◽  
Author(s):  
Alina Maria Holban ◽  
Valentina Grumezescu ◽  
Alexandru Mihai Grumezescu ◽  
Bogdan Ştefan Vasile ◽  
Roxana Truşcă ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Bacterial Infections ◽  
Pulsed Laser ◽  
Antimicrobial Effect ◽  
Average Diameter ◽  
Laser Evaporation ◽  
Laser Technique ◽  
Thin Coatings ◽  
Transmission Electron ◽  
Good Biocompatibility

We report on the fabrication of thin coatings based on polylactic acid-chitosan-magnetite-eugenol (PLA-CS-Fe3O4@EUG) nanospheres by matrix assisted pulsed laser evaporation (MAPLE). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) investigation proved that the homogenous Fe3O4@EUG nanoparticles have an average diameter of about 7 nm, while the PLA-CS-Fe3O4@EUG nanospheres diameter sizes range between 20 and 80 nm. These MAPLE-deposited coatings acted as bioactive nanosystems and exhibited a great antimicrobial effect by impairing the adherence and biofilm formation of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) bacteria strains. Moreover, the obtained nano-coatings showed a good biocompatibility and facilitated the normal development of human endothelial cells. These nanosystems may be used as efficient alternatives in treating and preventing bacterial infections.

scholarly journals Evaluation of Samarium Doped Hydroxyapatite, Ceramics for Medical Application: Antimicrobial Activity

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
C. S. Ciobanu ◽  
S. L. Iconaru ◽  
C. L. Popa ◽  
M. Motelica-Heino ◽  
D. Predoi
Keyword(s):  
Electron Microscopy ◽  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
Enterococcus Faecalis ◽  
Medical Application ◽  
Inhibitory Effect ◽  
Linear Increase ◽  
High Antibacterial Activity ◽  
Hydroxyapatite Ceramics ◽  
Transmission Electron

Samarium doped hydroxyapatite (Sm:HAp),Ca10-xSmx(PO4)6(OH)2(HAp), bionanoparticles with differentxSmhave been successfully synthesized by coprecipitation method. Detailed characterization of samarium doped hydroxyapatite nanoparticles (Sm:HAp-NPs) was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The biocompatibility of samarium doped hydroxyapatite was assessed by cell viability. The antibacterial activity of the Sm:HAp-NPs was tested against Gram-negative bacteria (Pseudomonas aeruginosaandEscherichia coli) and Gram-positive bacteria (Enterococcus faecalisandStaphylococcus aureus). A linear increase of antimicrobial activity ofP. aeruginosahas been observed when concentrations of Sm:HAp-NPs in the samples withxSm=0.02were higher than 0.125 mg/mL. For Sm:HAp-NPs withxSm=0.05a significant increase of antibacterial activity onE. coliwas observed in the range 0.5–1 mg/mL. For low concentrations of Sm:HAp-NPs (xSm=0.05) from 0.031 to 0.125 mg/mL a high antibacterial activity onEnterococcus faecalishas been noticed. A growth of the inhibitory effect onS. aureuswas observed for all concentrations of Sm:HAp-NPs withxSm=0.02.

scholarly journals Click-correlative light and electron microscopy (click-AT-CLEM) for imaging and tracking azido-functionalized sphingolipids in bacteria

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Simon Peters ◽  
Lena Kaiser ◽  
Julian Fink ◽  
Fabian Schumacher ◽  
Veronika Perschin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antimicrobial Activity ◽  
Outer Membrane ◽  
Light And Electron Microscopy ◽  
Super Resolution ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Gram Negative ◽  
Array Tomography ◽  
Transmission Electron

AbstractSphingolipids, including ceramides, are a diverse group of structurally related lipids composed of a sphingoid base backbone coupled to a fatty acid side chain and modified terminal hydroxyl group. Recently, it has been shown that sphingolipids show antimicrobial activity against a broad range of pathogenic microorganisms. The antimicrobial mechanism, however, remains so far elusive. Here, we introduce ‘click-AT-CLEM’, a labeling technique for correlated light and electron microscopy (CLEM) based on the super-resolution array tomography (srAT) approach and bio-orthogonal click chemistry for imaging of azido-tagged sphingolipids to directly visualize their interaction with the model Gram-negative bacterium Neisseria meningitidis at subcellular level. We observed ultrastructural damage of bacteria and disruption of the bacterial outer membrane induced by two azido-modified sphingolipids by scanning electron microscopy and transmission electron microscopy. Click-AT-CLEM imaging and mass spectrometry clearly revealed efficient incorporation of azido-tagged sphingolipids into the outer membrane of Gram-negative bacteria as underlying cause of their antimicrobial activity.

scholarly journals Stachybotrys chartarum: A Novel Biological Agent for The Extracellular Synthesis of Silver Nanoparticles and Their Antimicrobial Activity

2015 ◽  
Vol 18 (2) ◽  
pp. 75 ◽  
Author(s):  
Abdel Ghany Tarek Mohamed
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Stachybotrys Chartarum ◽  
Capping Agent ◽  
Extracellular Synthesis ◽  
Transmission Electron

Microbial assisted biosynthesis of nanoparticles is a rapidly progressing area of nanobiotechnology. Inthis paper Stachybotrys chartarum assisted extracellular synthesis of silver nanoparticles (AgNPs) is reportedwhen challenged with 1mM silver nitrate (AgNO3). The characterization of AgNPs was carried out visualobservation and UV-Vis spectrophotometry. Further analysis carried out by Fourier Transform InfraredSpectroscopy (FTIR), provides evidence for the presence of proteins as capping agent, which helps in increasingthe stability of the synthesized AgNPs. Transmission Electron Microscopy (TEM) investigations confi rmedthat AgNPs were formed. The synthesized silver nanoparticles were found in the range of 65-108 nm. Finally,the antimicrobial susceptibility of AgNPs synthesized was investigated which exhibited more potent activityagainst bacteria than fungi compared with using silver nitrate at concentration 1mM. Keywords: Antimicrobial activity, Stachybotrys chartarum, Silver nanoparticles

scholarly journals Antimicrobial Activity of Silver Nanoparticles Synthesized Using Goat Milk against Pathogens of Selected Vegetables

2019 ◽  
pp. 1-10 ◽  
Author(s):  
T. A. Ihum ◽  
C. C. Iheukwumere ◽  
I. O. Ogbonna ◽  
G. M. Gberikon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Goat Milk ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

This study was carried out to determine the antimicrobial activity of silver nanoparticles synthesized using goat milk against pathogens of selected vegetables. Synthesis of Silver nanoparticles was done using Goat milk, and characterized using Ultra Violet-Visible absorption spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X- ray diffraction (XRD) and Transmission Electron Microscopy (TEM). Maximum absorbance of Goat milk synthesized AgNPs was observed at 417 nm, with FTIR peaks at 3455 cm−1, 1628 cm−1, 1402 cm−1, 1081 cm−1 and 517 cm−1, indicating that proteins in Goat milk (GM) were the capping and stabilization molecules involved the synthesis of AgNPs. Transmission electron microscopy analysis showed that the biosynthesized particles were spherical in shape having a size of 10-100 nm, X- ray diffraction (XRD) pattern agreed with the crystalline nature and face-centered cubic phase of AgNPs. Evaluation of the antimicrobial activity of AgNPs synthesized using GM against the indicator strains (Staphylococcus aureus CIP 9973, Pectobacterium carotovorum Pec1, Enterobacter cloacae AS10, Klebsiella aerogenes OFM28, Proteus mirabilis UPMSD3 and Escherichia coli 2013C-3342) isolated from selected vegetables, was carried out using the Agar diffusion assay at different concentrations of 25, 75 and 100 µl/ml. The present study demonstrated that the AgNPs synthesized using Goat milk have potent biological activities, which can find applications in diverse areas.

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