Mycosynthesis and Characterization of Gold and Silver Nanoparticles Using Biomolecules of Pleurotus ostreatus as Antibacterial Agent against Some Selected Pathogens

The study aims to investigate the biosynthesis and characterization of gold (AuNPs) and sil¬ver nanoparticles (SNPs) using biomolecules: exopolysaccharides (EPS), culture-free filtrate (CFF) and fruiting body extract (FBE) of Pleurotus ostreatus (PO), and to evaluate the antibacterial potential of the nanoparticles against some pathogens. The nanoparticles were characterized by UV-visible spectra, FTIR and SEM. Nanoparticles formation was confirmed by changes in colour; colour changes from pale yellow to purple, cloudy colourless to purple and yellow to dark purple indicate, respectively, POEPSAuNPs, POCFFAuNPs and POFBEAuNPs formation. Colour changes from pale yellow, cloudy colourless and yel¬low to dark brown indicate POEPSSNPs, POCFFSNPs and POFBESNPs formation, respectively. Surface plasmon resonance (SRP) peaks were observed at 400 nm. SEM revealed POEPSAuNPs, POCFFAuNPs and POCFFAuNPs as polymorphic with sizes ranging from 0.5 – 2.6 μm, 0.08 - 1.00 μm, and 0.2 – 2.4 μm. POEPSSNPs, POCFFSNPs and POFBESNPs were aggregate particles with sizes of 0.2 - 3.0 μm, 0.2 - 2.8 μm, and 0.1 – 3.2 μm. FTIR showed that amide, carboxyl and hydroxyl groups contributed to nanoparticles biosynthesis. The AuNPs exhibited a broad spectrum of activity against the tested pathogens compared to the SNPs. POEPSAuNPs and POFBEAuNPs had the highest inhibitory activity against E. coli while POF¬BEAuNPs had the highest inhibitory activity against Micrococcus sp. with MIC of 0.2 at 200 μg/mL, and POEPSSNPs and POCFFSNPs had the highest inhibitory activity against S. aureus with MIC of 0.05 at 50 μg/mL. In conclusion, biomolecules from P. ostreatus supported the biosynthesis of nanoparticles with enhanced therapeutic properties.