Antibacterial Potential of Silver Nanoparticles Synthesized Using Aspergillus hortai

This is a first-time report of structural characterization and assessment of the antibacterial activity of silver nanoparticles synthesized using the fungus Aspergillus hortai isolated from domestic wastewater. Silver nanoparticles were synthesized using cell-free filtrate of Aspergillus hortai cultured in potato dextrose broth at 60 degrees C in the presence of 2-mM silver nitrate for 24 h. The appearance of reddish brown color and a surface plasmon resonance peak at 420 nm confirmed the formation of the silver nanoparticles. Dynamic light scattering analysis reported an average particle size of 57 nm having a polydispersity index of 0.21 and zeta potential of -19 mV. Transmission electron micrographs confirmed almost spherical shape of the nanoparticles and the selected area electron diffraction pattern corresponded to the crystal lattice structure of silver. The antibacterial potential of the silver nanoparticles was evaluated using a growth curve assay, well diffusion method, and DREAM assay on Escherichia coli (ATCC 35218) and Staphylococcus aureus (ATCC 25923). The assessment of the antibacterial potential of the silver nanoparticles demonstrated activity comparable to that of streptomycin, which was used as a positive control in all the experiments.