Mycofabrication of gold nanoparticles: Optimization, characterization, stabilization and evaluation of its antimicrobial potential on selected human pathogens

In this study, aqueous fungus extract from edible mushroom Agaricus bisporus was prepared and utilized as reducing and stabilizing agents towards a green synthesis of gold nanoparticles (Au NPs). The biophysical characterization of Au NPs was done by UV-Vis absorption spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and High Resolution Transmission Electron Microscopy (TEM). The mycosynthesized Au NPs were primarily confirmed by the color change from yellow to dark violet in 72 h of reaction due to the reduction of Au3+ ions to Au-0. A sharp peak at 540 nm in the UV-Visible spectrum proved the synthesis of Au NPs. The different parameters viz., the concentration of gold chloride, ratio of gold chloride concentrations with a volume of a mushroom extract, pH, temperature, reaction mode, and the reaction time were optimized for the mycosynthesis of Au NPs. The stability of Au NPs was well proved in the in-vitro stability test under various conditions viz., 10 % NaCl; 0.2 M Cysteine; different pH; sterilized conditions (121 degrees C at 15 lbs for 20 min) and unsterilized. The mycosynthesized Au NPs have significantly inhibited the growth of clinically important pathogenic Gram-positive bacteria (Streptococcus pyogenes & Staphylococcus aureus); Gram-negative bacteria (Klebsiella pnemoniae & Shigella flexneri) and pathogenic fungi (Candida albicans & Aspergillus fumigatus). This study suggests that the mycosynthesized Au NPs could be used as novel drug against various human pathogens and also a promising candidate for many biomedical applications.