Biosynthesis of gold nanoparticles by extracellular molecules produced by the phytopathogenic fungus Botrytis cinerea

The biosynthesis of gold nanoparticles (AuNPs) by extracellular components of the phytopathogenic fungus Botrytis cinerea was observed. Chloroauric acid (HAuCl4) reduction and the formation of AuNPs were evidenced by a color change in the free-mycelium culture filtrate, from a pale yellow to a dark purple, and through an absorbance peak of 540 nm due to surface plasmon resonance of AuNPs. Characterization of the AuNPs showed triangular, hexagonal, spherical, decahedral, and pyramidal shapes of approximate sizes ranging from 1 to 100 nm. The experimental data presented in this study demonstrates that extracellular putative NADH-dependent reductase activity participates in reduction of HAuCl4 and in the subsequent formation of AuNPs. However, this reductase is not the only active component secreted by the fungus in this process as the formation of AuNPs also occurs in conditions of high denaturation. The present study is the first to report on a rapid and eco-friendly method for the production of AuNPs by B. cinerea. (C) 2013 Elsevier B.V. All rights reserved.