Green synthesis of silver nanoparticles using tree oyster mushroom Pleurotus ostreatus and its inhibitory activity against pathogenic bacteria

The present study reports the biological synthesis of silver nanoparticles (AgNPs) using the aqueous extract of fresh basidiocarps of the tree oyster mushroom, Pleurotus ostreatus. The AgNPs solution exhibited an absorption maximum at 440 nm, corresponding to surface plasmon resonance of AgNPs. The field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) analyses revealed that the synthesised AgNPs were spherical in shape and the particle size was less than 40 nm. The energy dispersive x-ray analysis (EDX) spectrum showed peaks for the presence of silver, carbon and oxygen atoms in the range of 2.8-3.2 keV. Fourier transform infra-red spectroscopy (FTIR) results showed the binding properties of bio-constituents responsible for capping and stabilizing the nanoparticles. The synthesised AgNPs significantly (p < 0.05) inhibited the growth of all bacterial species tested. The MIC of the tested bacterial spp. were in the range 13-27 mu g/mL. The results of this study indicated that the synthesised AgNPs may be developed as an effective agent against bacterial infections.