Biosynthetic Reduction of Gold Ions to Gold Nanoparticles by Nocardia farcinica

The biological synthesis of Gold nanoparticles (GNPs) using Nocardia farcinica exudates present in medium, as reducing and stabilizing agent is reported in this paper. On treating Nocardia farcinica extract with gold salt, rapid reduction of gold ions was observed resulting in the formation of highly stable GNPs. Inherent pH of the bacterial exudates, high temperature (100o C) and 100 ppm aqueous solution of aurochlorate were found to be the optimum parameters for synthesis of GNPs. The results were verified using UV-Visible spectroscopy, Transmission electron microscopy (TEM) and X-ray diffraction (XRD) studies TEM images show monodispersed spherical gold nanoparticles of 15-20 nm diameters. Moreover, the nitrate reductase activity of exudates was found to get reduced from 1.020 mmole/min/ml to 0.14 mmole/min/gram when added to the aqueous solution of aurochlorate that resulted into bio fabrication of gold nanoparticles. Key words: Biosynthesis, Nocardia farcinica, Gold nanoparticles, XRD, Nitrate reductase