Synthesis of Silver Nanoparticles by a Bryophilous Rhizoctonia Species

Abstract

We demonstrate the synthesis of silver nanoparticles by a potentially benign species of bryophilous Rhizoctonia in two different media. The first medium supports fungal growth and the up-regulation of nitrate reductase, while the second medium supports fungal growth and the repression of nitrate reductase. For both media, the resulting silver nanoparticles were ca. 25–50nm and were subglobose to broadly ellipsoidal in shape. The optical analysis of the silver nanoparticles from both media demonstrated plasmon resonance at 415nm, confirming their metallic properties. The liquid colour change typically observed for extracellular silver nanoparticle formation was absent in both media. The silver nanoparticles in the two different media displayed different chemical associations; fewer associated chemicals were found with the media, which supported the up-regulation of nitrate reductase. Another difference included plate-like silver nanoparticle conglomerations, which were only encountered on hyphae from the medium that repressed nitrate reductase. There was also a noticeable difference in the capping agent formations between each media. The Rhizoctonia isolate examined in this study is suitable for large-scale industrial applications because it does not produce spores and would have minimal impact on air quality.