Extracellular biosynthesis of silver nanoparticles using cell suspension of Rhodococcus fascians

Biosynthesis of metallic nanoparticles using biological systems such as bacteria has become an important nanobiotechnology area. In this report, we present the first extracellular biosynthesis of silver nanoparticles (AgNPs) using the gram positive bacterium Rhodococcus fascians. The AgNPs underwent characterization through various analytical techniques, encompassing UV visible spectroscopy, X ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM). UV visible spectroscopy revealed the emergence of an absorbance peak at 430 nm due to the synthesis of AgNPs. R. fascians started producing AgNPs after 12 h of incubation, with the highest yield after 48 h. The extent of synthesis was higher when cultures were grown in the dark than in the light. According to TEM and SEM, the AgNPs had a uniform spherical morphology of diameter 10 to 80 nm. The AgNPs exhibited antifungal efficacy against the virulent filamentous fungi Rhizoctonia solani, Botrytis cinerea, and Fusarium graminearum, which cause root rot, soft rot and head blight on plants, respectively. This research provides evidence on the ability of R. fascians to generate AgNPs from silver nitrate, as well as their subsequent assembly and potential for controlling vascular wilt disease.