scholarly journals Near-atomic size highly positive silver nanoparticles are bactericidal targeting cell wall and adherent fimbriae expression

2021 ◽  
Author(s):  
Lok Pokhrel ◽  
Zachary Jacobs ◽  
Dmitriy Dikin ◽  
Shaw Akula
Keyword(s):  
Silver Nanoparticles ◽  
Cell Wall ◽  
Health And Safety ◽  
Next Generation ◽  
Atomic Size ◽  
E Coli ◽  
Bactericidal Effects ◽  
Patient Health ◽  
Hospital Acquired ◽  
Positively Charged

Abstract To tackle growing antibiotic resistance (AR) and hospital-acquired infections (HAIs), novel antimicrobials are warranted that are effective against HAIs and safer for human use. We hypothesize that near-atomic size positively charged silver nanoparticles (AgNPs) could specifically target bacterial cell wall and adherent fimbriae expression, serving as the next generation antimicrobial agent. Herein we show positively charged, 5 nm NH2–AgNPs were bactericidal; negatively charged, 45 nm Citrate–AgNPs were nontoxic; and Ag+ ions were bacteriostatic forming honeycomb-like potentially resistant phenotype, at 10µg Ag/mL in E. coli dh5a. Further, adherent fimbriae were expressed with Citrate–AgNPs, whereas NH2–AgNPs (0.5–10µg/mL) or Ag+ ions (10µg/mL) inhibited fimbriae expression. Potent bactericidal effects demonstrated by biocompatible NH2–AgNPs and the lack of toxicity of Citrate–AgNPs lend credence to the hypothesis that near-atomic size, positively charged AgNPs may serve as a next-generation antibacterial agent, potentially addressing the rising HAIs and patient health and safety.

scholarly journals Rapid Method for Detecting Bactericidal Effects of Mangrove Derived Silver Nanoparticles Using Resazurin Microdilution Assay

2021 ◽  
Vol 9 (8) ◽  
pp. 2438-2442
Author(s):  
Asmathunisha N
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Antimicrobial Agents ◽  
Antimicrobial Activities ◽  
Vital Role ◽  
Bacterial Strains ◽  
E Coli ◽  
Inhibition Concentration ◽  
Resazurin Assay ◽  
Bactericidal Effects

Abstract: Nanoparticles plays a vital role in the field of antimicrobial agents against pathogenic microorganisms. Screening of nanoparticles for antimicrobial activities is a time consuming and cumbersome process. Recently, a simple technique of using the dye resazurin has been used as an indicator of bacterial growth for testing antimicrobial activity on microtitre plate. However, this technique does not quantify the microbial load. Therefore, the present work was attempted to find a new antibacterial method employing the dye resazurin assay and haemocytometric counting of microbes for testing silver nanoparticles synthesised from Xylocarpus mekongensis .The bacterial strains E. coli, S. aureus and P. aeruginosa (multi-drug resistant strain) were used to evaluate the screening of mangrove extracts. Minimum inhibition concentration (MIC) was also calculated for the silver nanoparticles using ciproflaxcin as reference antibiotic. The antibacterial activity Xylocarpus mekongensis was carried out against all the three bacteria by the same method and the values were compared with reference antibiotic. The present study has suggested a rapid, dependable, easy and inexpensive method, suitable for testing the antibacterial activity of silver nanoparticles which are promising to develop as new antibacterials. Keywords: Mangroves, Silver, Nanoparticles, Resazurin, Antibacterials

scholarly journals Bioinformatics and Functional Assessment of Toxin-Antitoxin Systems in Staphylococcus aureus

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 473 ◽  
Author(s):  
Gul Habib ◽  
Qing Zhu ◽  
Baolin Sun
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Virulence Genes ◽  
Type I ◽  
Mycobacterial Species ◽  
Nosocomial Pathogen ◽  
E Coli ◽  
Persistent Infections ◽  
Inhibition Of Growth ◽  
Bactericidal Effects

Staphylococcus aureus is a nosocomial pathogen that can cause chronic to persistent infections. Among different mediators of pathogenesis, toxin-antitoxin (TA) systems are emerging as the most prominent. These systems are frequently studied in Escherichia coli and Mycobacterial species but rarely explored in S. aureus. In the present study, we thoroughly analyzed the S. aureus genome and screened all possible TA systems using the Rasta bacteria and toxin-antitoxin database. We further searched E. coli and Mycobacterial TA homologs and selected 67 TA loci as putative TA systems in S. aureus. The host inhibition of growth (HigBA) TA family was predominantly detected in S. aureus. In addition, we detected seven pathogenicity islands in the S. aureus genome that are enriched with virulence genes and contain 26 out of 67 TA systems. We ectopically expressed multiple TA genes in E. coli and S. aureus that exhibited bacteriostatic and bactericidal effects on cell growth. The type I Fst toxin created holes in the cell wall while the TxpA toxin reduced cell size and induced cell wall septation. Besides, we identified a new TA system whose antitoxin functions as a transcriptional autoregulator while the toxin functions as an inhibitor of autoregulation. Altogether, this study provides a plethora of new as well as previously known TA systems that will revitalize the research on S. aureus TA systems.

scholarly journals Ultrastructural changes in methicillin-resistant Staphylococcus aureus induced by positively charged silver nanoparticles

2015 ◽  
Vol 6 ◽  
pp. 2396-2405 ◽  
Author(s):  
Dulce G Romero-Urbina ◽  
Humberto H Lara ◽  
J Jesús Velázquez-Salazar ◽  
M Josefina Arellano-Jiménez ◽  
Eduardo Larios ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Silver Nanoparticles ◽  
Cell Wall ◽  
Molecular Mechanisms ◽  
Antibacterial Properties ◽  
Silver Ions ◽  
Ultrastructural Changes ◽  
Future Research ◽  
Methicillin Resistant ◽  
Positively Charged

Silver nanoparticles offer a possible means of fighting antibacterial resistance. Most of their antibacterial properties are attributed to their silver ions. In the present work, we study the actions of positively charged silver nanoparticles against both methicillin-sensitive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. We use aberration-corrected transmission electron microscopy to examine the bactericidal effects of silver nanoparticles and the ultrastructural changes in bacteria that are induced by silver nanoparticles. The study revealed that our 1 nm average size silver nanoparticles induced thinning and permeabilization of the cell wall, destabilization of the peptidoglycan layer, and subsequent leakage of intracellular content, causing bacterial cell lysis. We hypothesize that positively charged silver nanoparticles bind to the negatively charged polyanionic backbones of teichoic acids and the related cell wall glycopolymers of bacteria as a first target, consequently stressing the structure and permeability of the cell wall. This hypothesis provides a major mechanism to explain the antibacterial effects of silver nanoparticles on Staphylococcus aureus. Future research should focus on defining the related molecular mechanisms and their importance to the antimicrobial activity of silver nanoparticles.

scholarly journals Synthesis of colloidal silver nanoparticles and their bactericidal effects on E. coli, S. epidermidis and oral plaque

2020 ◽  
Vol 1541 ◽  
pp. 012017
Author(s):  
Juan Fernando Ramirez ◽  
Juliana Ortiz ◽  
Jorge Andrés Cuellar ◽  
Carlos Andrés Naranjo ◽  
Francy Nelly Jiménez ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Colloidal Silver ◽  
E Coli ◽  
Colloidal Silver Nanoparticles ◽  
Bactericidal Effects

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Isolation of post operative hospital acquired infections in a private hospital of Bangladesh and identification of clonal relatedness of E. coli by using Pulse filed gel electrophoresis

2012 ◽  
Vol 6 (2) ◽  
pp. 7-10
Author(s):  
Mohammad Murshed ◽  
Sabeena Shahnaz ◽  
Md. Abdul Malek
Keyword(s):  
Private Hospital ◽  
Isolation And Identification ◽  
College Hospital ◽  
Hospital Acquired Infection ◽  
E Coli ◽  
Hospital Acquired Infections ◽  
Medical College ◽  
Clonal Relatedness ◽  
Hospital Acquired ◽  
Dressing Materials

Isolation and identification of post operative hospital acquired infection was carried out from July 2008 to December 2008 in Holy Family Red Crescent Medical College Hospital (private hospital). The major pathogen of wound infection was E. coli. A total; of 120 samples were collected from the surrounding environment of post operative room like floor, bed sheets, instruments, dressing materials, catheter, nasogastric and endotracheal tube. E. coli (40%) was the predominant organism followed by S. aureus (24%). DNA fingerprinting analysis using pulsed field gel electreopheresis of XbaI restriction digested genomic DNA showed that clonal relatedness between the two clinical nd environmental isolates were 100%.DOI: http://dx.doi.org/10.3329/bjmm.v6i2.19369 Bangladesh J Med Microbiol 2012; 06(02): 7-10

Antimicrobial Activity of Silver Nanoparticles Prepared Under an Ultrasonic Field

2011 ◽  
Vol 4 (3) ◽  
pp. 1491-1496
Author(s):  
Umadevi M ◽  
Rani T ◽  
Balakrishnan T ◽  
Ramanibai R
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Reduction Method ◽  
Therapeutic Potential ◽  
Chemical Reduction ◽  
Ultrasonic Field ◽  
Great Promise ◽  
Chemical Reduction Method ◽  
E Coli

Nanotechnology has great promise for improving the therapeutic potential of medicinal molecules and related agents. In this study, silver nanoparticles of different sizes were synthesized in an ultrasonic field using the chemical reduction method with sodium borohydride as a reducing agent. The size effect of silver nanoparticles on antimicrobial activity were tested against the microorganisms Staphylococcus aureus (MTCC No. 96), Bacillus subtilis (MTCC No. 441), Streptococcus mutans (MTCC No. 497), Escherichia coli (MTCC No. 739) and Pseudomonas aeruginosa (MTCC No. 1934). The results shows that B. subtilis, and E. coli were more sensitive to silver nanoparticles and its size, indicating the superior antimicrobial efficacy of silver 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.

Efficacy of Silver Nanoparticles Synthesized from Hymenocallis species (Spider Lilly) Leaf Extract as Antimicrobial Agents

2019 ◽  
Vol 12 (5) ◽  
pp. 4644-4647
Author(s):  
K.K. Gupta ◽  
Neha Kumari ◽  
Neha Sinha ◽  
Akruti Gupta
Keyword(s):  
Silver Nanoparticles ◽  
Leaf Extract ◽  
Antimicrobial Agents ◽  
Color Change ◽  
Bacterial Species ◽  
Antimicrobial Property ◽  
Biogenic Synthesis ◽  
E Coli ◽  
Light Yellow ◽  
Antibiotic Property

Biogenic synthesis of silver nanoparticles synthesized from Hymenocallis species (Spider Lilly) leaf extract was subjected for investigation of its antimicrobial property against four bacterial species (E. coli, Salmonella sp., Streptococcus sp. & Staphylococcus sp.). The results revealed that synthesized nanoparticles solution very much justify the color change property from initial light yellow to final reddish brown during the synthesis producing a characteristics absorption peak in the range of 434-466 nm. As antimicrobial agents, their efficacy was evaluated by analysis of variance in between the species and among the different concentration of AgNPs solution, which clearly showed that there was significant variation in the antibiotic property between the four different concentrations of AgNPs solution and also among four different species of bacteria taken under studies. However, silver nanoparticles solution of 1: 9 and 1:4 were proved comparatively more efficient as antimicrobial agents against four species of bacteria.

Green Synthesis of Silver Nanoparticles Using Artocarpus hirsutus Seed Extract and its Antibacterial Activity

2020 ◽  
Vol 21 (10) ◽  
pp. 980-989
Author(s):  
Sampath Shobana ◽  
Sunderam Veena ◽  
S.S.M. Sameer ◽  
K. Swarnalakshmi ◽  
L.A. Vishal
Keyword(s):  
Silver Nanoparticles ◽  
Cell Wall ◽  
Antibacterial Activity ◽  
Listeria Monocytogenes ◽  
Nanoparticle Synthesis ◽  
Enterobacter Aerogenes ◽  
Seed Extract ◽  
Diffusion Method ◽  
Multi Drug Resistance ◽  
Gastrointestinal Bacteria

Aims: To evaluate the antibacterial activity of Artocarpus hirsutus mediated seed extract for nanoparticle synthesis. Background: Gastrointestinal bacteria are known for causing deadly infections in humans. They also possess multi-drug resistance and interfere with clinical treatments. Applied nanotechnology has been known to combat such infectious agents with little interference from their special attributes. Here we synthesize silver nanoparticles from Artocarpus hirsutus seed extract against two gastro-intestinal bacterial species: Enterobacter aerogenes and Listeria monocytogenes. Objective: To collect, dry, and process seeds of Artocarpus hirsutus for nanoparticle synthesis. To evaluate the morphological interaction of silver nanoparticles with bacteria. Methods: Artocarpus hirsutus seeds were collected and processed and further silver nanoparticles were synthesized by the co-precipitation method. The synthesized nanoparticles were characterized using XRD, UV, FTIR, and SEM. These nanoparticles were employed to study the antibacterial activity of nanoparticles against Enterobacter aerogenes and Listeria monocytogenes using well diffusion method. Further, morphological interaction of silver nanoparticles on bacteria was studied using SEM. Result: Silver nanoparticles were synthesized using Artocarpus hirsutus seed extract and characterization studies confirmed that silver nanoparticles were spherical in shape with 25-40 nm size. Antibacterial study exhibited better activity against Enterobacter aerogenes with a maximum zone of inhibition than on Listeria monocytogenes. SEM micrographs indicated that Enterobacter aerogenes bacteria were more susceptible to silver nanoparticles due to the absence of cell wall. Also, the size and charge of silver nanoparticles enable easy penetration of the bacterial cell wall. Conclusion: In this study, silver nanoparticles were synthesized using the seed extract of Artocarpus hirsutus for the first time exploiting the fact that Moraceae species have high phytonutrient content which aided in nanoparticle synthesis. This nanoparticle can be employed for large scale synthesis which when coupled with the pharmaceutical industry can be used to overcome the problems associated with conventional antibiotics to treat gastrointestinal bacteria.

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