Biogenic antimicrobial silver nanoparticles produced by fungi
Aspergillus tubingensis and Bionectria ochroleuca showed excellent extracellular ability to synthesize silver nanoparticles (Ag NP), spherical in shape and 35 ± 10 nm in size. Ag NP were characterized by transmission electron microscopy, X-ray diffraction analysis, and photon correlation spectroscopy for particle size and zeta potential. Proteins present in the fungal filtrate and in Ag NP dispersion were analyzed by electrophoresis (sodium dodecyl sulfate polyacrylamide gel electrophoresis). Ag NP showed pronounced antifungal activity against Candida sp, frequently occurring in hospital infections, with minimal inhibitory concentration in the range of 0.11–1.75 μg/mL. Regarding antibacterial activity, nanoparticles produced by A. tubingensis were more effective compared to the other fungus, inhibiting 98.0 % of Pseudomonas. aeruginosa growth at 0.28 μg/mL. A. tubingensis synthesized Ag NP with surprisingly high and positive surface potential, differing greatly from all known fungi. These data open the possibility of obtaining biogenic Ag NP with positive surface potential and new applications.
KeywordsSilver nanoparticles Antimicrobial activity Aspergillus tubingensis Bionectria ochroleuca Mangrove
This study was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo. Dr. A. Leyva helped with the English editing of the manuscript and Prof. Nelson Durán with PCS equipment.
Conflict of interest
The authors declare that they have no conflict of interest.
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