Biogenic Synthesis of Silver Nanoparticles UsingStreptomycesspp. and their Antifungal Activity AgainstFusarium verticillioides

The present study reports the synthesis of silver nanoparticles (AgNPs) using haloalkaliphilicStreptomycesspp. characterization, and antifungal activity thereof. The UV visible spectra of synthesized AgNPs showed a characteristic absorption peak at 430 nm, due to the excitation of Surface Plasmon Resonance. Scanning electron microscopy and transmission electron microscopy images showed spherical shape NPs with an average particle size of 16.4 +/- 2.2 nm. The crystalline structure of the AgNPs was confirmed by X-ray diffraction (XRD). Zeta potential analyses revealed that NPs were negatively charged (- 8.12 +/- 3.87 mV). The synthesized AgNPs are significantly active against phytopathogenic fungi,Fusarium verticillioidesandUstilago maydis. Microscopic, histo- and bio-chemical investigation of AgNPs againstF. verticillioidesrevealed that AgNPs at 100 mu g concentration inhibits the hyphal growth and conidia germination, and similar to 42.85% reduction of ergosterol biosynthesis. The results of propidium iodide staining and high relative cell membrane conductivity confirmed AgNPs mediated damage to the membrane. Moreover, the AgNPs synthesized byStreptomycesspp. inhibit the growth ofF. verticillioidescould be due to the inhibition of ergosterol biosynthesis and membrane damage. In our knowledge, this is the first report demonstrating the antiF. verticillioidesactivity of AgNPs synthesized byStreptomycesspp.