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Green Synthesis, Characterization and Antimicrobial Activities of Silver Nanoparticles by Streptomyces viridodiastaticus SSHH-1 as a Living Nanofactory: Statistical Optimization of Process Variables

Author(s): Attiya Mohamedin, Noura El-Ahmady El-Naggar, Sarah Shawqi Hamza, A.A. Sherief.

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Abstract:

Microbial synthesis of nanoparticles has a potential to develop simple, cost-effective and eco-friendly methods for production of technologically important materials. Silver nanoparticles are playing an important role in biomedical and various applications. In this study, we present a biological method for synthesis of silver nanoparticles (AgNPs) using cell-free supernatant. 40 actinomycete isolates were screened for their ability to synthesize silver nanoparticles. Among them, isolate SSHH-1, was selected and identified as Streptomyces viridodiastaticus SSHH-1 on the basis of morphological, cultural and physiological properties, together with 16S rRNA sequence. Sequencing product was deposited in the GenBank database under accession number KJ676475. Response surface methodology (RSM) was employed for optimization of different nutritional and physical parameters for the production of AgNPs by Streptomyces viridodiastaticus in submerged fermentation. Initial screening of production parameters was performed using a Plackett- Burman design and the variables with statistically significance effects on AgNPs production were identified. Among the 14 variables tested, inoculum age, medium volume, and peptone concentration were identified as the most significant factors for AgNPs production (confidence level above 99%). These variables were selected for further optimization studies using a Box-Behnken design. The statistical optimization by RSM resulted in a 4.43- fold increase in the production of AgNPs by Streptomyces viridodiastaticus. The synthesized AgNPs were characterized using UV-visible spectroscopy (UV-vis), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), and Energy Dispersive X-ray (EDX) spectroscopy. TEM study indicated spherical silver nanoparticles in the size range of 15-45 nm. The biosynthesized AgNPs significantly inhibited the growth of Gram -positive (Staphylococcus aureus), Gram -negative bacteria (E. coli) and yeast (Candida albicans).

Keywords: Antimicrobial activity, Box-Behnken design, characterization, green synthesis, identification, Plackett-Burman design, Silver nanoparticles, Streptomyces viridodiastaticus.

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Article Details

VOLUME: 11
ISSUE: 5
Year: 2015
Page: [640 - 654]
Pages: 15
DOI: 10.2174/1573413711666150309233939
Price: $58