Myco-crystallization of silver ions to nanosized particles by live and dead cell filtrates of aspergillus oryzae var. viridis and its bactericidal activity toward staphylococcus aureus KCCM 12256

Abstract

Crystalllization of silver ions to nanosized particles by cell filtrates from live and dead cell filtrates Aspergillus oryzae var. viridis (A. oryzae var. viridis) through bioreduction process was assessed. Strong plasmon resonance of silver nanoparticles was observed around 435 nm. Transmission electron microscopy (TEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD) were performed to examine the formation of silver nanoparticles. Comparing live and dead cell filtrates of A. oryzae var. viridis, the latter showed high silver nanoparticle productivity. The nanoparticles formed were quite uniform in shape and ranged in size from 5 to 50 nm. Organics from the dead cells are believed to be responsible for bioreduction of ionic silver to nanosized silver particles. Organic content of the dead cell filtrate was found to be double the amount of live cell filtrate. High productivity of silver nanoparticles by a metabolically independent process opens up an interesting area of nanoparticle synthesis using waste fungal biomass from industries. The minimum bactericidal concentration (MBC) for the Staphylococcus aureus KCCM 12256 strain was found to be 40 mg/L. © 2010 American Chemical Society.