Abstract:The present work was focused on isolating a bacterial strain of Pseudomonas sp. with the ability to synthesise AgNPs rapidly. A strain of Pseudomonas aeruginosa designated JO was found to be a potential candidate for rapid synthesis of AgNPs with a synthesis time of 4h in light, at room temperature which is a shorter time period noticed for the synthesis when compared to the previous reports Biosynthesis of AgNPs was achieved by addition of culture supernatant with aqueous silver nitrate solution (1 mM). The r… Show more
“…1 ) , indicated a surface plasmon resonance (SPR), having nanoparticles with sizes less than 100 nm. This could be due to excitation of electrons in the conductive band around the nanoparticles surface as reported by Busi et al ( 2014 ). Fig.…”
BackgroundEco-friendly synthesis of nanoparticles is viewed as an alternative to the chemical method and initiated the use of microorganisms for synthesis. The present study has been designed to utilize plant pathogenic fungi Sclerotinia sclerotiorum MTCC 8785 strain for synthesis and optimization of silver nanoparticles (AgNPs) production as well as evaluation of antibacterial properties. The AgNPs were synthesized by reduction of aqueous silver nitrate (AgNO3) solution after incubation of 3–5 days at room temperature. The AgNPs were further characterized using UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Reaction parameters including media, fungal biomass, AgNO3 concentration, pH and temperature were further optimized for rapid AgNPs production. The antibacterial efficacy of AgNPs was evaluated against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 by disc diffusion and growth kinetics assay at the concentration determined by the minimum inhibitory concentration (MIC).ResultsAgNPs synthesis was initially marked by the change in colour from pale white to brown and was confirmed by UV–Vis spectroscopy. Optimization studies showed that potato dextrose broth (PDB) media, 10 g of biomass, addition of 2 mM AgNO3, pH 11 and 80 °C temperature resulted in enhanced AgNPs synthesis through extracellular route. TEM data revealed spherical shape AgNPs with size in the range of 10 nm. Presence of proteins capped to AgNPs was confirmed by FTIR. AgNPs showed antibacterial activity against E. coli and S. aureus at 100 ppm concentration, corresponding MIC value.ConclusionS. sclerotiorum MTCC 8785 mediated AgNPs was synthesized rapidly under optimized conditions, which showed antibacterial activity.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2558-x) contains supplementary material, which is available to authorized users.
“…1 ) , indicated a surface plasmon resonance (SPR), having nanoparticles with sizes less than 100 nm. This could be due to excitation of electrons in the conductive band around the nanoparticles surface as reported by Busi et al ( 2014 ). Fig.…”
BackgroundEco-friendly synthesis of nanoparticles is viewed as an alternative to the chemical method and initiated the use of microorganisms for synthesis. The present study has been designed to utilize plant pathogenic fungi Sclerotinia sclerotiorum MTCC 8785 strain for synthesis and optimization of silver nanoparticles (AgNPs) production as well as evaluation of antibacterial properties. The AgNPs were synthesized by reduction of aqueous silver nitrate (AgNO3) solution after incubation of 3–5 days at room temperature. The AgNPs were further characterized using UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Reaction parameters including media, fungal biomass, AgNO3 concentration, pH and temperature were further optimized for rapid AgNPs production. The antibacterial efficacy of AgNPs was evaluated against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 by disc diffusion and growth kinetics assay at the concentration determined by the minimum inhibitory concentration (MIC).ResultsAgNPs synthesis was initially marked by the change in colour from pale white to brown and was confirmed by UV–Vis spectroscopy. Optimization studies showed that potato dextrose broth (PDB) media, 10 g of biomass, addition of 2 mM AgNO3, pH 11 and 80 °C temperature resulted in enhanced AgNPs synthesis through extracellular route. TEM data revealed spherical shape AgNPs with size in the range of 10 nm. Presence of proteins capped to AgNPs was confirmed by FTIR. AgNPs showed antibacterial activity against E. coli and S. aureus at 100 ppm concentration, corresponding MIC value.ConclusionS. sclerotiorum MTCC 8785 mediated AgNPs was synthesized rapidly under optimized conditions, which showed antibacterial activity.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2558-x) contains supplementary material, which is available to authorized users.
“…The biopolymer forms a ligand-shell surrounding AgNPs at the core, forming a silver polymer core-shell structure. The polymeric shell decreases the surface potential that is responsible for accumulation of the silver nanoparticles to larger aggregates (Busi et al, 2014). Frequently, microbes are considered dead when they cannot be cultured.…”
Introduction Nanotechnology is relatively a new science of study in which a set of sciences, including the STEM (science, technology, engineering, and mathematics) disciplines, are involved to synthesize nanomaterials of about 1-100 nm. At the nanoscale level, materials have distinct chemical, physical, optical, magnetic, and electrical properties due to their large surface area to volume ratio (Chaturvedi et al., 2012). One of the most important aspects of nanotechnology is the synthesis of nanoparticles (NPs), which form the essence of nanomaterials (Ishida et al., 2014). NPs exhibit new properties based on specific characteristics such as size, distribution, and morphology. Today NPs are used in many fields, including manufacturing and materials, environmental sciences, energy and electronics, and medicine. Multidrug-resistant (MDR) microbes are a growing problem in the treatment of infectious diseases due to the widespread use of broad-spectrum antibiotics, which has resulted in the production of antibiotic resistance for many human bacterial pathogens (Franci et al., 2015). Advances in nanotechnology have opened new horizons in nanomedicine, allowing the synthesis of NPs, which are now considered a viable alternative to antibiotics and seem to have high potential in solving the problem of the emergence of microbial multidrug resistance (Rai et al., 2012). During the last decade, increased interest has been paid to biological systems for the synthesis of NPs compared with other methods, i.e. physical and chemical methods. The latter approaches are expensive and have many limitations; therefore, scientists are developing clean, economical, and ecofriendly biological approaches as an alternative for NP synthesis (Rai et al., 2009; Seshadri et al., 2011; Wei et al., 2012). Microorganisms (mainly bacteria, yeasts, and molds) have efficiently proven their ability to absorb and accumulate inorganic metallic ions from the surrounding environment. More importantly, the ability of a biological entity to use its inherent biochemical processes to transform inorganic metallic ions into metal NPs has led to a relatively new and largely unexplored field of research. Among microbes, filamentous fungi are widely used as biocatalysts in NP preparation (
“…Many bacteria have been shown to produce AgNPs when exposed to light, and some require light to occur. (68,70,72,78,108,111,113) Wei et al (140) have demonstrated that solar radiation intensity influenced the biosynthesis of nanoparticles in CFE. Sunlight caused the reaction rate to increase in an intensity-dependent manner.…”
Silver nanoparticles (AgNPs) have potential uses in many applications, but current chemical production methods are challenged by scalability, limited particle stability, and the use of hazardous chemicals. The biological processes present in bacteria to mitigate metallic contaminants in their environment present a potential solution to these challenges. Before commercial exploitation of this technology can be achieved, the quality of bacteriogenic AgNPs needs to be improved for certain applications. While the colloidal and morphological stabilities of biogenic AgNPs are widely regarded as superior to chemogenic particles, little control over the synthesis of particle morphologies has been achieved in biological systems. This article reviews a range of biosynthetic reaction conditions and how they affect AgNP formation in bacteria to understand which are most influential. While there remains uncertainty, some general trends are emerging: higher Ag + concentrations result in higher AgNP production, up to a point at which the toxic effects begin to dominate; the optimal temperature appears to be heavily species-dependent and linked to the optimal growth temperature of the organism. However, hotter conditions generally favour higher production rates, while colder environments typically give greater shape diversity. Little attention has been paid to other potentially important growth conditions including halide concentrations, oxygen exposure, and irradiation with light. To fully exploit biosynthetic production routes as alternatives to chemical methods, hurdles remain with controlling particle morphologies and require further work to elucidate and harness. By better understanding the factors influencing AgNP production a foundation can be laid from which shape-controlled production can be achieved.
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