scholarly journals Bacteria Exposed to Silver Nanoparticles Synthesized by Laser Ablation in Water: Modelling E. coli Growth and Inactivation

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 653 ◽  
Author(s):  
Lucija Krce ◽  
Matilda Šprung ◽  
Ana Maravić ◽  
Polona Umek ◽  
Krešimir Salamon ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Bacterial Growth ◽  
Growth Curves ◽  
Dynamic State ◽  
Lag Phase ◽  
The Novel ◽  
Minimal Inhibitory Concentrations ◽  
E Coli ◽  
Main Effect

This study is aimed to better understand the bactericidal mode of action of silver nanoparticles. Here we present the production and characterization of laser-synthesized silver nanoparticles along with growth curves of bacteria treated at sub-minimal and minimal inhibitory concentrations, obtained by optical density measurements. The main effect of the treatment is the increase of the bacterial apparent lag time, which is very well described by the novel growth model as well as the entire growth curves for different concentrations. The main assumption of the model is that the treated bacteria uptake the nanoparticles and inactivate, which results in the decrease of both the nanoparticles and the bacteria concentrations. The lag assumes infinitive value for the minimal inhibitory concentration treatment. This apparent lag phase is not postponed bacterial growth. It is a dynamic state in which the bacterial growth and death rates are close in value. Our results strongly suggest that the predominant mode of antibacterial action of silver nanoparticles is the penetration inside the membrane.

scholarly journals Study of a Natural Mutant SHV-Typeβ-Lactamase, SHV-104, fromKlebsiella pneumoniae

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Nahed Ben Achour ◽  
Omrane Belhadj ◽  
Moreno Galleni ◽  
Mohamed Ben Moussa ◽  
Paola Sandra Mercuri
Keyword(s):  
Salt Bridge ◽  
Conjugative Plasmid ◽  
Military Hospital ◽  
The Novel ◽  
Minimal Inhibitory Concentrations ◽  
E Coli ◽  
Novel Variant ◽  
The Military

Klebsiella pneumoniaeML2011, a multiresistant isolate, was isolated from the Military Hospital of Tunis (Tunisia). The determination of the minimal inhibitory concentrations exhibited byK. pneumoniaeML2011 was performed by Etest. The crude extract of the isolates contains four differentβ-lactamases with pI 5.5, 7.3, 7.6, and 8.6. Only theβ-lactamases with pI 7.3 and pI 8.6 were transferred by transformation and conjugation experiment. Molecular characterization of these genes was performed by PCR and sequencing. The chromosomalβ-lactamases are TEM (pI 5.5) and SHV-1 (7.6). CTX-M-28 (pI 8.6) and the novel variant of SHV named SHV-104 (pI 7.3) were encoded byblagene located on a 50 kb highly conjugative plasmid. The SHV-104β-lactamase was produced inE. coliand purified. Its profile of activity was determined. Compared to SHV-1, SHV-104 contains one mutation, R202S. Their kinetic parameters were similar except for cefotaxime. The analysis of the predicted structure of SHV-104 indicated that the R202S mutation suppresses a salt bridge present in SHV-1. Therefore, the overall flexibility of the protein increased and might improve the hydrolysis of cefotaxime. We can conclude that the multiresistant phenotype ofK. pneumoniaeML2011 strain is mainly linked to the production of CTX-M-28 since SHV-104 possesses a narrow spectrum of activity.

Optimization and Characterization of Biogenic Silver Nanoparticles Synthesized by Leaves Extract of Alphonsea Madraspatana

2021 ◽  
Vol 17 ◽  
Author(s):  
Amita Sahu ◽  
Sudhanshu Shekhar Swain ◽  
Goutam Ghosh ◽  
Deepak Pradhan ◽  
Dipak Kumar Sahu ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Volume Ratio ◽  
Xrd Analysis ◽  
Biofilm Inhibition ◽  
Nano Silver ◽  
E Coli ◽  
Biogenic Silver Nanoparticles ◽  
Icp Ms ◽  
Anti Oxidant

Background: Literature evidences as well as traditional uses of genus Alphonsea reveal significant antimicrobial and anti-oxidant activity, which encourages to consider A. madraspatana to have potent antimicrobials, there by offering potential adjuncts to synthesize improved antimicrobial Silver nanoparticles (AgNPs). The objective of the present exposition is to optimize reaction parameters to synthesize antimicrobial Biogenic Silver nanoparticles (BAgNPs) from extract of A. madraspatana leaves (AML) and to evaluate the effect against bacteria. Methods: BAgNPs was synthesized by optimized reaction. The Synthesized nanoparticles were characterized by UV, IR, ICP-MS and XRD analysis. The antibacterial potency of optimized BAgNPs was evaluated against E. coli by comparing with positive controls. Results: Results of optimization process indicate nanoscale BAgNPs were produced at operating temp. of 45°C for 120 min at pH 8 with 1:5 volume ratio of AgNO3 and extract. Optimized BAgNPs exhibits relatively higher antimicrobial activity (31±1mm) compared to Ciprofloxacin (27±1mm) and marketed nano silver (28± 2 mm). The developed BAgNPs shows comparable biofilm inhibition (86.50%) as compared to marketed nano silver (88.10%) and Ciprofloxacin (83.10%). Conclusion: Experimental evidence suggests methanolic extract of AML under predefined conditions successfully generate nano-template of silver with better antibacterial response against E. coli.

Characterization of novel ybjG and dacC variants in Escherichia coli

2013 ◽  
Vol 62 (11) ◽  
pp. 1728-1734 ◽  
Author(s):  
Dongguo Wang ◽  
Enping Hu ◽  
Jiayu Chen ◽  
Xiulin Tao ◽  
Katelyn Gutierrez ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Multiple Drug Resistance ◽  
Multiple Drug ◽  
The Novel ◽  
Conventional Pcr ◽  
E Coli ◽  
Novel Variants ◽  
Restriction Sites ◽  
Genetic Structures

A total of 69 strains of Escherichia coli from patients in the Taizhou Municipal Hospital, China, were isolated, and 11 strains were identified that were resistant to bacitracin, chloramphenicol, tetracycline and erythromycin. These strains were PCR positive for at least two out of three genes, ybjG, dacC and mdfA, by gene mapping with conventional PCR detection. Conjugation experiments demonstrated that these genes existed in plasmids that conferred resistance. Novel ybjG and dacC variants were isolated from E. coli strains EC2163 and EC2347, which were obtained from the sputum of intensive care unit patients. Genetic mapping showed that the genes were located on 8200 kb plasmid regions flanked by EcoRI restriction sites. Three distinct genetic structures were identified among the 11 PCR-positive strains of E. coli, and two contained the novel ybjG and dacC variants. The putative amino acid differences in the ybjG and dacC gene variants were characterized. These results provide evidence for novel variants of ybjG and dacC, and suggest that multiple drug resistance in hospital strains of E. coli depends on the synergistic function of ybjG, dacC and mdfA within three distinct genetic structures in conjugative plasmids.

scholarly journals Green ultrasonic synthesis, Characterization and Antibacterial activity of Silver and Gold Nanoparticles mediated by Ganoderma lucidum extract

2020 ◽  
Vol 4 (2) ◽  
Keyword(s):  
Gold Nanoparticles ◽  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Metal Nanoparticles ◽  
Cytotoxic Activities ◽  
Gold And Silver Nanoparticles ◽  
Silver And Gold Nanoparticles ◽  
E Coli ◽  
Inhibition Zones

Metal nanoparticles possess an extensive scientific and technological significance due to their unique physiochemical properties and their potential applications in different fields like medicine. Silver and gold nanoparticles have shown to have antibacterial and cytotoxic activities. Conventional methods used in the synthesis of the metal nanoparticles involve use of toxic chemicals making them unsuitable for use in medical field. In our continued effort to explore for simple and eco-friendly methods to synthesize the metal nanoparticles, we here describe synthesis and characterization of gold and silver nanoparticles using Gonaderma lucidum, wild non-edible medicinal mushroom. G. lucidum mushroom contain bioactive compounds which can be involved in the reduction, capping and stabilization of the nanoparticles. Antibacterial activity analysis was done on E. coli and S. aureus. The synthesis was done on ultrasonic bath. Characterization of the metal nanoparticles was done by UV-VIS., High Resolution Transmission Electron Microscope (HRTEM) and FTIR. HRTEM analysis showed that both silver and gold nanoparticles were spherical in shape with an average size of 15.82±3.69 nm for silver and 24.73±5.124nm for gold nanoparticles (AuNPs). FTIR analysis showed OH and -C=C- stretching vibrations, an indication of presence of functional groups of biomolecules capping both gold and silver nanoparticles. AgNPs showed inhibition zones of 15.5±0.09mm and 13.3±0.14mm while AuNPs had inhibition zones of 14.510±0.35 and 13.3±0.50mm on E. coli and S. aureus respectively. The findings indicate the potential use of AgNPs and AuNPs in development of drugs in management of pathogenic bacteria.

More than simply microbial growth curves

2016 ◽  
Vol 1 (2) ◽  
pp. 63 ◽  
Author(s):  
Ji-Dong Gu
Keyword(s):  
Bacterial Growth ◽  
Microbial Growth ◽  
Growth Curves ◽  
Lag Phase ◽  
Growth Data ◽  
Phase Growth ◽  
Simple Task ◽  
Wide Range ◽  
Comparative Results ◽  
Comparative Information

Bacterial growth is a very important piece of information in a wide range of investigation and, in most of the time the data are simply shown directly without any further processing. In a single factor investigation without comparative information to be extracted, this simple approach can be used together with other data to form a comprehensive set of results. When comparison is involved, such direct showing of bacterial growth curves without processing cannot warrant a meaningful comparison thoroughly and further processing of data is necessary. In addition, there is little, if any, quantitative data for the comparison from the display of growth curves and description of a number of curves is not a simple task, especially in a meaningful way for assimilation of the data to readers. With this in mind, I would like to remind of those who plan to show such data as growth curves for their potential publication to carry this further to generate comparative results for a much meaningful interpretation by modeling and calculation from the raw growth data over time of incubation. By calculating with existing equations, the lag phase, growth rate and the biomass can be derived from a series of growth curves for a more effective and meaningful analysis. This approach is not new, but remembrance of such available tool is more important so that research data are shown professionally and also scientifically for meaning presentation and effective assimilation.

scholarly journals Development and Characterization of Bioactive Polypropylene Films for Food Packaging Applications

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3478
Author(s):  
Adrian Krzysztof Antosik ◽  
Urszula Kowalska ◽  
Magdalena Stobińska ◽  
Paulina Dzięcioł ◽  
Magdalena Pieczykolan ◽  
...  
Keyword(s):  
Food Packaging ◽  
Antimicrobial Properties ◽  
The Novel ◽  
E Coli ◽  
Synthetic Product ◽  
Natural Agents ◽  
Plastic Materials ◽  
Study Results ◽  
Oregano Oil

Bioactive polypropylene (PP) films with active agents) presence for food packaging application have been prepared and characterized. The novel modified PP films were obtained via PP/additives systems regranulation and cast extrusion. The influence of two types of plasticizers (natural agents as well as commercial synthetic product) and bioactive additives on final features, e.g., mechanical properties, was evaluated. Moreover, the biocidal activity of the films was determined. Due to their functional properties, they are developed as additives to packaging plastic materials such as polyolefins. The study results presented in our work may indirectly contribute to environmental protection by reducing food waste. The aim of the work was to obtain innovative, functional packaging materials with an ability to prolong the shelf life of food products. The best antimicrobial properties were observed for the sample based on 5 wt.% oregano oil (OO) and 5 wt.% cedar oil (OC) in PP matrix. A microbial test revealed that the system causes total reduction in the following microorganisms: B. subtilis, E. coli, S. aureus, P. putida, C. albicans, A. alternata, F. oxysporum.

scholarly journals Green Synthesis and Characterization of Silver Nanoparticles using Crude Extract of Crotalaria burhia

2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Khalil Ahmad ◽  
Raeesa Noor ◽  
Muhammad Younus ◽  
Akram Chohan ◽  
Ume Habiba ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Zeta Potential ◽  
Green Synthesis ◽  
Crude Extract ◽  
Bacterial Infections ◽  
Synthesis And Characterization ◽  
Phytochemical Analysis ◽  
E Coli

Background: Appearance of antibiotic resistance has raised the demand to find alternative therapies and modified drug delivery system of medicinal plants to treat bacterial infections. Objective: The aim of this study is the green synthesis and characterization of silver nanoparticles by using crude extract of Crotalaria burhia and to evaluate their antibacterial potential. Methods: The roots and stems of plant were used to prepare the crude extract. The phytochemical analysis of different compounds in extract was performed. 1mM AgNO3 and different concentrations of plant extract were used for the green synthesis of silver nanoparticles. The particles size and zeta potential were measured by zeta sizer while surface morphology of silver nanoparticles was observed with Scanning Electron Microscope (SEM). The antibacterial activity of silver nanoparticles was performed by 96 well microdilution plate method. Results: The particle size and zeta potential of optimized formulation was 92 nm and -24.8 mV. The SEM analysis showed that silver nanoparticles are irregular and spherical shape. The antibacterial activity showed that MIC value of silver nanoparticles was lower for E. coli than S. aureus. Conclusion: Silver nanoparticles possess potent bactericidal activity against E. coli and moderate activity against S. aureus. It had been concluded that these nanoparticles can be used against multi-drug resistant bacterial infections.

Integrated approach to evaluating the toxicity of novel cysteine-capped silver nanoparticles to Escherichia coli and Pseudomonas aeruginosa

The Analyst ◽  
2014 ◽  
Vol 139 (5) ◽  
pp. 954-963 ◽  
Author(s):  
John H. Priester ◽  
Aditi Singhal ◽  
Binghui Wu ◽  
Galen D. Stucky ◽  
Patricia A. Holden
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Silver Nanoparticles ◽  
Bacterial Growth ◽  
Ag Nanoparticles ◽  
Cell Membranes ◽  
Integrated Approach ◽  
E Coli ◽  
Particle Dissolution ◽  
Measured Particle

The toxicity of cysteine capped Ag nanoparticles toE. coliandP. aeruginosawas evaluated using an integrated approach that measured particle dissolution, bacterial growth, and effects on cell membranes.

Synthesis of Silver Nanoparticles Using the Leaf Extract of Vitex negundo and its Anti-Bacterial Effect

2013 ◽  
Vol 678 ◽  
pp. 301-305 ◽  
Author(s):  
Gunasekaran Bhavani ◽  
Paulsamy Muthuselvam ◽  
Subramanian Geetha
Keyword(s):  
Silver Nanoparticles ◽  
Synthesis Method ◽  
Nanoparticle Synthesis ◽  
Cost Effective ◽  
Klebsiella Pneumonia ◽  
The Novel ◽  
Vitex Negundo ◽  
X Ray Diffraction ◽  
Leaf Extracts

Silver nanoparticles are known to have antimicrobial activity. The green synthesis method of nanoparticle synthesis is one of the most cost effective and eco friendly method. The present study is based on the synthesis of silver nanoparticles by the self reduction of silver nitrate by the leaf extracts of Vitex negundo which is one of the novel methods used in developing nanoparticles. The characterization of the particle was done by UV-Vis spectrophotometer, Fourier Transform Infra Red Spectroscopy, X-ray Diffraction analysis and the size of the synthesized nanoparticle was analyzed in the Scanning Electron Microscopy. The size of the particle was found to be 56 nm. The obtained silver nanoparticles showed anti-microbial activity against E.coli and Klebsiella pneumonia.

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