Green synthesis of silver nanoparticles: Another honor for the yeast model Saccharomyces cerevisiae

Authors

1 Infectious Disease Research Science, Golestan University of Medical Sciences, Gorgan, Iran

2 Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran

3 Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

4 Invasive Fungi Research Centre, Department of Medical Mycology & Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran

Abstract

Background and Purpose: Microorganism-based synthesis of nanostructures has recently been noted as a green method
for the sustainable development of nanotechnology. Nowadays, there have been numerous studies on the emerging
resistant pathogenic bacteria and fungal isolates, the probable inability of bacteria and fungi to develop resistance against
silver nanoparticles’ (SNPs) antibacterial, antifungal, antiviral and, particularly antibacterial activities. In this study, we
aim to use the yeast Saccharomyces cerevisiae model for synthesis of SNPs and to investigate its antifungal activity against
some isolates of Candida albicans.
Materials and Methods: A standard strain of S. cerevisiae was grown in liquid medium containing mineral salt then,
it was exposed to 2 mM AgNO3. The reduction of Ag+ ions to metal nanoparticles was virtually investigated by tracing
the color of the solution, which turned into reddish-brown after 72 hours. Further characterization of synthesized SNPs
was performed afterwards. In addition, antifungal activity of synthesized SNPs was evaluated against fluconazolesusceptible
and fluconazole-resistant isolates of Candida albicans.
Results: The UV-vis spectra demonstrated a broad peak centering at 410 nm, which is associated with the particle sizes
much less than 70 nm. The results of TEM demonstrated fairly uniform, spherical and small in size particles with
almost 83.6% ranging between 5 and 20 nm. The zeta potential of SNPs was negative and equal to -25.0 (minus 25) mv
suggesting that there was not much aggregation. Silver nanoparticles synthesized by S. cerevisiae, showed antifungal
activity against fluconazole-susceptible and fluconazole-resistant Candida albicans isolates, and exhibited MIC90 values
of 2 and 4 &mug/ml, respectively.
Conclusion: The yeast S. cerevisiae model demonstrated the potential for extracellular synthesis of fairly monodisperse
silver nanoparticles

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