Hydrothermal assisted biosynthesis of silver nanoparticles from Streptomyces sp. GUT 21 (KU500633) and its therapeutic antimicrobial activity

Abstract

In the present investigation we report unique biological green synthesis of nanoparticles (AgNPs) by secondary metabolites of Streptomyces supernatant extract acting as reducing agents in hydrothermal process. Various divergent techniques like sonication, microven, heating and hydrothermal (autoclaving) techniques were employed to produce silver nanoparticles through microbe-mediated assistance. The Streptomyces sp. GUT 21 was isolated from the field soil sampled neighbouring the campus of Gulbarga University. Morphological and biochemical characterization of the strain was performed and its taxonomical genus identification was determined by 16s rDNA technique. The formation of nanoparticles was first monitored by measuring the surface plasmon resonance (SPR) band at 410 nm through UV-Visible absorption spectroscopy. FTIR analysis revealed that many efficient clusters of functional biomolecules are playing significant role in capping and synthesis process during hydrothermal method. The crystalline structure of the AgNPs and the presence of elemental silver nanoparticles were confirmed by powder X-ray diffraction (PXRD) and scanning electron microscopy. Our results indicated that, nanoparticles are spherical in shape with an average of 23-48 nm in size. The biosynthesized AgNPs exhibited significant antibacterial activity against Escherichia coli (MTCC 9537), Klebsiella pneumoniae (MTCC 109), Pseudomonas aeruginosa (MTCC1688) and Staphylococcus aureus (MTCC 96). This biotechnological development of synthesis of nanoparticles can further be exploited as ''new-generation of antimicrobials'' against multi-drug resistant bacteria (MDR) for various medical diagnostic applications.

Exploring the potentials of halophilic prokaryotes from a solar saltern for synthesizing nanoparticles: The case of silver and selenium

“…The results were confirmed by their PDI value (0.27 vs 0.36). In comparison to some silver and selenium nanoparticles produced by non-halophiles such as Actinotalea (551.1 nm) [36], Streptomyces (44 nm) [14], and Zooglea (30-150 nm) [34] with PDI values of 0.5, 0.4, and 0.43, the current nanoparticles were more uniform.…”

“…The mixtures were then autoclaved at 121˚C under 15 psi pressure for 20 min. The uninoculated 10% and 20% SW broth media supplemented with equal concentrations of silver nitrate and sodium selenite were used as the control [14]. A part of the cell-free supernatant (CFS) was freeze-dried (Freeze dryer, Christ Alpha 1.2 LD Plus, Germany) and applied for FTIR analysis.…”

“…Desai et al also successfully biosynthesized AgNPs by autoclaving Streptomyces sp. GUT21 supernatant [14].…”

“…The images revealed that silver and selenium produced by bacterial (mean size 24.8 nm) and archaeal strains (mean size 96.45 nm) had a smaller size compared to silver and selenium produced by the archaeal and bacterial strains, respectively. It was observed that larger particles formed due to aggregation of nanoparticles which might be attributed to the difficulty of precise cantilever tip attachment to the exact sample end during AFM set up, which might have increased discrepancy and variation in particles size [14]. FTIR analysis revealed the presence of C = O, C = C, N-H, C-N, and C-H groups of organic compounds suggesting the possible presence of amino acids, peptides, and aldehyde compounds on the surface of these nanoparticles.…”

Permutation Entropy as a Parameter of Characterizing the Surface of a Thin Film

“…It also has the highest electrical and thermal conductivity and optical reflectivity of all metals [6]. Some of its applications include optics [7][8][9], nanophotonic [10], flexible transparent electrodes [11], antioxidant [12][13][14], solar cells [15] protein sensors [16], biosensors [17], and fluorescence imaging of single molecules [18]. There are distinct techniques explaining the surface growth of the silver thin films.…”