In Situ Synthesis of Entrapped Silver Nanoparticles by a Fungus-Penicillium purpurogenum

Intracellular silver nanoparticles are produced by exposing silver nitrate to a fungus-Penicillium purpurogenum. The formation of silver nanoparticles is greatly influenced by the secretion of proteins and more specifically secretion of nitrate reductase enzyme by the fungus. The UV-visible spectra show a broad band at 420 nm for spherical silver nanoparticles. The X-ray diffraction analysis indicates that the structure of the nanoparticles is face centered cubic. Results of transmission and scanning electron microscopy show that the silver nanoparticles are embedded within fungal mycelia. Finally, the biomass embedded nanoparticles are evaluated for their antimicrobial activity. They show significant antimicrobial activity against pathogenic gram negative bacteria like Escherichia coli and Pseudomonas aeruginosa, and gram positive bacteria like Staphylococcus aureus.