A new report of Nocardiopsis valliformis strain OT1 from alkaline Lonar crater of India and its use in synthesis of silver nanoparticles with special reference to evaluation of antibacterial activity and cytotoxicity

Abstract

The authors report the biological synthesis of silver nanoparticles (AgNPs) by alkaliphilic actinobacterium Nocardiopsis valliformis OT1 strain isolated for the first time from Lonar crater, India. The primary detection of silver NPs formation was made by colour change from colourless to dark brown and confirmed by UV–Vis spectrum of AgNPs at 423 nm, specific for AgNPs. Further, AgNPs were characterized by nanoparticle tracking analysis, Zeta sizer, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) analyses. FTIR analysis showed the presence of proteins as capping agent. TEM analysis revealed the formation of spherical and polydispersed AgNPs within the size range of 5–50 nm. The antimicrobial activity of silver nanoparticles against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis was evaluated. The AgNPs showed the maximum antibacterial activity against B. subtilis (Gram positive) and the minimum against E. coli (Gram negative). The minimal inhibitory concentration values of AgNPs for the tested bacteria were found to be in the range of 30–80 µg/mL. The AgNPs demonstrated higher antibacterial activity against all the bacteria tested as compared with the commercially available antibiotics. The cytotoxicity of biosynthesized AgNPs against in vitro human cervical cancer cell line (HeLa) demonstrated a dose–response activity. The IC50 value was found to be 100 µg/mL of AgNPs against cancer HeLa cell line.

Antimicrobial and cytotoxic activity of silver nanoparticles synthesized from two haloalkaliphilic actinobacterial strains alone and in combination with antibiotics

“…Spectrophotometer analysis showed that AgNPs due to their SPR had a maximum absorbance peak within the wavelength range of 380–450 nm, which is characteristic for AgNPs (Rathod et al . ; Wypij et al . ).…”

Evaluation of cytotoxicity, immune compatibility and antibacterial activity of biogenic silver nanoparticles

“…Those properties are very crucial in maintenance of cellular barrier function on various levels: epithelial, endothelial or intestinal [58]. Studies confirm that AgNPs as well as silver ions are responsible for inducing toxicity in organisms [59, 60]. Many authors suggested that ROS plays central role in silver nanoparticle-induced cell death [61].…”

Synthesis, characterization and evaluation of antimicrobial and cytotoxic activities of biogenic silver nanoparticles synthesized from Streptomyces xinghaiensis OF1 strain

“…The search for the closest phylogenetic neighbours based on 16S rRNA gene similarity was performed using the EzTaxon server ( http://eztaxon-e.ezbiocloud.net/ ; Kim et al 2012 ). The DNA extraction, PCR amplification and sequencing reactions were performed as previously described by Golinska et al ( 2013 ) and Rathod et al ( 2016 ).…”