scholarly journals Imposed Environmental Stresses Facilitate Cell-Free Nanoparticle Formation by Deinococcus radiodurans

2017 ◽  
Vol 83 (18) ◽  
Author(s):  
Angela Chen ◽  
Lydia M. Contreras ◽  
Benjamin K. Keitz
Keyword(s):  
Gold Nanoparticles ◽  
Silver Nanoparticles ◽  
Environmental Remediation ◽  
Deinococcus Radiodurans ◽  
Environmental Stresses ◽  
Pure Gold ◽  
Metal Reduction ◽  
Content Type ◽  
Nanoparticle Production ◽  
Nanoparticle Formation

ABSTRACT The biological synthesis of metal nanoparticles has been examined in a wide range of organisms, due to increased interest in green synthesis and environmental remediation applications involving heavy metal ion contamination. Deinococcus radiodurans is particularly attractive for environmental remediation involving metal reduction, due to its high levels of resistance to radiation and other environmental stresses. However, few studies have thoroughly examined the relationships between environmental stresses and the resulting effects on nanoparticle biosynthesis. In this work, we demonstrate cell-free nanoparticle production and study the effects of metal stressor concentrations and identity, temperature, pH, and oxygenation on the production of extracellular silver nanoparticles by D. radiodurans R1. We also report the synthesis of bimetallic silver and gold nanoparticles following the addition of a metal stressor (silver or gold), highlighting how production of these particles is enabled through the application of environmental stresses. Additionally, we found that both the morphology and size of monometallic and bimetallic nanoparticles were dependent on the environmental stresses imposed on the cells. The nanoparticles produced by D. radiodurans exhibited antimicrobial activity comparable to that of pure silver nanoparticles and displayed catalytic activity comparable to that of pure gold nanoparticles. Overall, we demonstrate that biosynthesized nanoparticle properties can be partially controlled through the tuning of applied environmental stresses, and we provide insight into how their application may affect nanoparticle production in D. radiodurans during bioremediation. IMPORTANCE Biosynthetic production of nanoparticles has recently gained prominence as a solution to rising concerns regarding increased bacterial resistance to antibiotics and a desire for environmentally friendly methods of bioremediation and chemical synthesis. To date, a range of organisms have been utilized for nanoparticle formation. The extremophile D. radiodurans, which can withstand significant environmental stresses and therefore is more robust for metal reduction applications, has yet to be exploited for this purpose. Thus, this work improves our understanding of the impact of environmental stresses on biogenic nanoparticle morphology and composition during metal reduction processes in this organism. This work also contributes to enhancing the controlled synthesis of nanoparticles with specific attributes and functions using biological systems.

scholarly journals Isolation and Optimization of Culture Conditions of Thraustochytrium kinnei for Biomass Production, Nanoparticle Synthesis, Antioxidant and Antimicrobial Activities

2021 ◽  
Vol 9 (6) ◽  
pp. 678
Author(s):  
Kaliyamoorthy Kalidasan ◽  
Nabikhan Asmathunisha ◽  
Venugopal Gomathi ◽  
Laurent Dufossé ◽  
Kandasamy Kathiresan
Keyword(s):  
Antimicrobial Activity ◽  
Gold Nanoparticles ◽  
Silver Nanoparticles ◽  
Biomass Production ◽  
Petroleum Ether Extract ◽  
Antimicrobial Activities ◽  
Culture Conditions ◽  
Gold And Silver Nanoparticles ◽  
Optimization Of Culture Conditions ◽  
Antioxidant And Antimicrobial Activities

This work deals with the identification of a predominant thraustochytrid strain, the optimization of culture conditions, the synthesis of nanoparticles, and the evaluation of antioxidant and antimicrobial activities in biomass extracts and nanoparticles. Thraustochytrium kinnei was identified as a predominant strain from decomposing mangrove leaves, and its culture conditions were optimized for maximum biomass production of 13.53 g·L−1, with total lipids of 41.33% and DHA of 39.16% of total fatty acids. Furthermore, the strain was shown to synthesize gold and silver nanoparticles in the size ranges of 10–85 nm and 5–90 nm, respectively. Silver nanoparticles exhibited higher total antioxidant and DPPH activities than gold nanoparticles and methanol extract of the strain. The silver nanoparticles showed higher antimicrobial activity than gold nanoparticles and petroleum ether extract of the strain. Thus, Thraustochytrium kinnei is proven to be promising for synthesis of silver nanoparticles with high antioxidant and antimicrobial activity.

scholarly journals Metagenomic Analysis of Stress Genes in Microbial Mat Communities from Antarctica and the High Arctic

2011 ◽  
Vol 78 (2) ◽  
pp. 549-559 ◽  
Author(s):  
Thibault Varin ◽  
Connie Lovejoy ◽  
Anne D. Jungblut ◽  
Warwick F. Vincent ◽  
Jacques Corbeil
Keyword(s):  
High Arctic ◽  
Environmental Stresses ◽  
The Arctic ◽  
Functional Responses ◽  
Protein Coding ◽  
Content Type ◽  
Stress Genes ◽  
Cyanobacterial Genes ◽  
Shock Proteins ◽  
The Antarctic

ABSTRACTPolar and alpine microbial communities experience a variety of environmental stresses, including perennial cold and freezing; however, knowledge of genomic responses to such conditions is still rudimentary. We analyzed the metagenomes of cyanobacterial mats from Arctic and Antarctic ice shelves, using high-throughput pyrosequencing to test the hypotheses that consortia from these extreme polar habitats were similar in terms of major phyla and subphyla and consequently in their potential responses to environmental stresses. Statistical comparisons of the protein-coding genes showed similarities between the mats from the two poles, with the majority of genes derived fromProteobacteriaandCyanobacteria; however, the relative proportions differed, with cyanobacterial genes more prevalent in the Antarctic mat metagenome. Other differences included a higher representation ofActinobacteriaandAlphaproteobacteriain the Arctic metagenomes, which may reflect the greater access to diasporas from both adjacent ice-free lands and the open ocean. Genes coding for functional responses to environmental stress (exopolysaccharides, cold shock proteins, and membrane modifications) were found in all of the metagenomes. However, in keeping with the greater exposure of the Arctic to long-range pollutants, sequences assigned to copper homeostasis genes were statistically (30%) more abundant in the Arctic samples. In contrast, more reads matching the sigma B genes were identified in the Antarctic mat, likely reflecting the more severe osmotic stress during freeze-up of the Antarctic ponds. This study underscores the presence of diverse mechanisms of adaptation to cold and other stresses in polar mats, consistent with the proportional representation of major bacterial groups.

scholarly journals Silver Nanomaterial-Immobilized Desalination Systems for Efficient Removal of Radioactive Iodine Species in Water

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 660 ◽  
Author(s):  
Ha Shim ◽  
Jung Yang ◽  
Sun-Wook Jeong ◽  
Chang Lee ◽  
Lee Song ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Radioactive Iodine ◽  
Deinococcus Radiodurans ◽  
Single Photon ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Cellulose Acetate Membrane ◽  
High Concentration ◽  
Iodine Species ◽  
Radiation Resistant

Increasing concerns regarding the adverse effects of radioactive iodine waste have inspired the development of a highly efficient and sustainable desalination process for the treatment of radioactive iodine-contaminated water. Because of the high affinity of silver towards iodine species, silver nanoparticles immobilized on a cellulose acetate membrane (Ag-CAM) and biogenic silver nanoparticles containing the radiation-resistant bacterium Deinococcus radiodurans (Ag-DR) were developed and investigated for desalination performance in removing radioactive iodines from water. A simple filtration of radioactive iodine using Ag-CAM under continuous in-flow conditions (approximately 1.5 mL/s) provided an excellent removal efficiency (>99%) as well as iodide anion-selectivity. In the bioremediation study, the radioactive iodine was rapidly captured by Ag-DR in the presence of high concentration of competing anions in a short time. The results from both procedures can be visualized by using single-photon emission computed tomography (SPECT) scanning. This work presents a promising desalination method for the removal of radioactive iodine and a practical application model for remediating radioelement-contaminated waters.

scholarly journals Coexisting properties of thermostability and ultraviolet radiation resistance in the main S-layer complex of Deinococcus radiodurans

2018 ◽  
Vol 17 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Domenica Farci ◽  
Chavdar Slavov ◽  
Dario Piano
Keyword(s):  
Ultraviolet Radiation ◽  
Radiation Resistance ◽  
Deinococcus Radiodurans ◽  
Environmental Stresses

Deinococcus radiodurans is well known for its unusual resistance to different environmental stresses.

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.

scholarly journals Experimental Evolution of Extreme Resistance to Ionizing Radiation inEscherichia coliafter 50 Cycles of Selection

2019 ◽  
Vol 201 (8) ◽  
Author(s):  
Steven T. Bruckbauer ◽  
Joseph D. Trimarco ◽  
Joel Martin ◽  
Brian Bushnell ◽  
Katherine A. Senn ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Repair ◽  
Ionizing Radiation ◽  
Experimental Evolution ◽  
Deinococcus Radiodurans ◽  
Bacterial Species ◽  
Genomic Sequencing ◽  
Novel Mutations ◽  
Content Type ◽  
Resistance To Ionizing Radiation

ABSTRACTIn previous work (D. R. Harris et al., J Bacteriol 191:5240–5252, 2009, https://doi.org/10.1128/JB.00502-09; B. T. Byrne et al., Elife 3:e01322, 2014, https://doi.org/10.7554/eLife.01322), we demonstrated thatEscherichia colicould acquire substantial levels of resistance to ionizing radiation (IR) via directed evolution. Major phenotypic contributions involved adaptation of organic systems for DNA repair. We have now undertaken an extended effort to generateE. colipopulations that are as resistant to IR asDeinococcus radiodurans. After an initial 50 cycles of selection using high-energy electron beam IR, four replicate populations exhibit major increases in IR resistance but have not yet reached IR resistance equivalent toD. radiodurans. Regular deep sequencing reveals complex evolutionary patterns with abundant clonal interference. Prominent IR resistance mechanisms involve novel adaptations to DNA repair systems and alterations in RNA polymerase. Adaptation is highly specialized to resist IR exposure, since isolates from the evolved populations exhibit highly variable patterns of resistance to other forms of DNA damage. Sequenced isolates from the populations possess between 184 and 280 mutations. IR resistance in one isolate, IR9-50-1, is derived largely from four novel mutations affecting DNA and RNA metabolism: RecD A90E, RecN K429Q, and RpoB S72N/RpoC K1172I. Additional mechanisms of IR resistance are evident.IMPORTANCESome bacterial species exhibit astonishing resistance to ionizing radiation, withDeinococcus radioduransbeing the archetype. As natural IR sources rarely exceed mGy levels, the capacity ofDeinococcusto survive 5,000 Gy has been attributed to desiccation resistance. To understand the molecular basis of true extreme IR resistance, we are using experimental evolution to generate strains ofEscherichia coliwith IR resistance levels comparable toDeinococcus. Experimental evolution has previously generated moderate radioresistance for multiple bacterial species. However, these efforts could not take advantage of modern genomic sequencing technologies. In this report, we examine four replicate bacterial populations after 50 selection cycles. Genomic sequencing allows us to follow the genesis of mutations in populations throughout selection. Novel mutations affecting genes encoding DNA repair proteins and RNA polymerase enhance radioresistance. However, more contributors are apparent.

Homotopy perturbation method for peristaltic motion of gold-blood nanofluid with heat source

2019 ◽  
Vol 30 (6) ◽  
pp. 3121-3138 ◽  
Author(s):  
Abdelhalim Ebaid ◽  
Abdulrahman F. Aljohani ◽  
Emad H. Aly
Keyword(s):  
Gold Nanoparticles ◽  
Heat Source ◽  
Perturbation Method ◽  
Homotopy Perturbation Method ◽  
Human Cancer ◽  
Content Type ◽  
Homotopy Perturbation ◽  
Blood Temperature ◽  
Flow And Heat Transfer ◽  
Diagnosis Therapy

PurposeThis paper aims to investigate the impacts of the gold nanoparticles on the peristaltic flow and heat transfer of blood in the presence of heat source. This element has been chosen because on comparing with the other common nanoparticles, gold nanoparticles are preferred due to their unique properties in absorbing the temperature when a heat source exists.Design/methodology/approachOn simplifying the governing equations under the assumption of long-wavelength and low-Reynolds number approximations, the resulted system has been solved by applying the homotopy perturbation method. Then, detailed physical discussion has been introduced through several plots while focusing on the consequences of the current results on the treatment of cancer.FindingsThe present results revealed that the heat source has a great effect on the blood velocity, blood temperature and concentration of the gold nanoparticles within the artery/vein cavity when represented as asymmetric channel. Moreover, the accuracy of the current solutions was validated through several plots of the remainder error for each studied phenomenon.Originality/valueThe current idea gives some light on the attempts of using the gold nanoparticles in the treatment of cancer and therefore may lead to possible applications for diagnosis/therapy of the human cancer. To the best of authors’ knowledge, this is novel, very efficient and applicable.

The plasma-chemical formation of polysorbate 80-coated silver nanoparticles and composite materials for water treatment

2019 ◽  
Vol 48 (5) ◽  
pp. 431-438 ◽  
Author(s):  
Margarita Ivanovna Skiba ◽  
Viktoria Vorobyova
Keyword(s):  
Silver Nanoparticles ◽  
Water Treatment ◽  
Low Temperature ◽  
Polysorbate 80 ◽  
Low Temperature Plasma ◽  
Colloidal Solutions ◽  
Ag Nps ◽  
Temperature Plasma ◽  
Content Type ◽  
Water Treatment Process

Purpose This paper aims to propose a simple, eco-friendly method for obtaining colloidal solutions of silver nanoparticles (Ag NPs) by using of contact non-equilibrium low-temperature plasma in presents polysorbate-80 and to assess their antibacterial activity in composite materials (beads) for water treatment process. Design/methodology/approach Silver nanoparticles were prepared in aqueous AgNO3 solution by using of contact non-equilibrium low-temperature plasma in the present of nonionic surfactant polysorbate-80 (Tween 80) as capping agent. Ultraviolet–visible (UV) spectroscopy, X-ray diffraction and zeta potential analysis were used to study the formation and properties of silver nanoparticles. Findings The formation of silver colloidal solutions in the presence of capping agent under plasma discharge is characterized by the presence of peak λmax = 380 – 402 nm in the spectra. The addition of sodium alginate into the reaction mixture allows synthesizing stable colloidal silver solutions. The average size of formed silver particles is up to 50 nm. Ag NPs exhibited an excellent bactericidal activity against both gram-positive and gram- negative bacteria. Composite beads prepared using nonionic surfactant were found to be effective in disinfecting the Staphylococcus aureus to different extents. Research limitations/implications Further studies are necessary for confirmation of the practical application, especially of the toxicity of Ag NPs, as well as the sorption properties of the alginate beads with Ag NPs. Practical implications The method provides a simple and practical solution to improving the synthesis of colloidal solutions of Ag NPs for water treatment process. Originality/value Contact nonequilibrium low-temperature plasma can be used as an effective technique for synthesis of nanomaterials.

scholarly journals Modulatory Effect of Citrate Reduced Gold and Biosynthesized Silver Nanoparticles on α-Amylase Activity

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Kantrao Saware ◽  
Ravindra Mahadappa Aurade ◽  
P. D. Kamala Jayanthi ◽  
Venkataraman Abbaraju
Keyword(s):  
Gold Nanoparticles ◽  
Silver Nanoparticles ◽  
Amylase Activity ◽  
Temperature Stability ◽  
Fold Increase ◽  
Free Enzyme ◽  
Catalytic Function ◽  
Ficus Benghalensis ◽  
Novel Approach ◽  
Immobilization Of Enzymes

Amylase is one of the important digestive enzymes involved in hydrolysis of starch. In this paper, we describe a novel approach to study the interaction of amylase enzyme with gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) and checked its catalytic function. AuNPs are synthesized using citrate reduction method and AgNPs were synthesized using biological route employing Ficus benghalensis and Ficus religiosa leaf extract as a reducing and stabilizing agent to reduce silver nitrate to silver atoms. A modulatory effect of nanoparticles on amylase activity was observed. Gold nanoparticles are excellent biocompatible surfaces for the immobilization of enzymes. Immobilized amylase showed 1- to 2-fold increase of activity compared to free enzyme. The biocatalytic activity of amylase in the bioconjugate was marginally enhanced relative to the free enzyme in solution. The bioconjugate material also showed significantly enhanced pH and temperature stability. The results indicate that the present study paves way for the modulator degradation of starch by the enzyme with AuNPs and biogenic AgNPs, which is a promising application in the medical and food industry.

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