Antifungal potentiality of mycogenic silver nanoparticles capped with chitosan produced by endophytic Amesia atrobrunnea
Samiyah Saeed Al-Zahrani, Saleh Mohammed Al-Garni
Abstract
This research reports the fabrication of silver nanoparticles (AgNPs) from endophytic fungus, Amesia atrobrunnea isolated from Ziziphus spina-christi (L.). Influencing factors for instance, thermal degree of incubation, media, pH, and silver nitrate (AgNO3) molarity were optimized. Then, the AgNPs were encapsulated with chitosan (Ch-AgNPs) under microwave heating at 650W for 90s. Characterization of nanoparticles was performed via UV-visible (UV-vis) spectrophotometer, Fourier-transform infrared spectrophotometer (FTIR), zeta potential using dynamic-light scattering (DLS), and field-emission-scanning electron microscope (FE-SEM). Anti-fungal activity of Ch-AgNPs at (50, 25, 12.5, 6.25mg/L) was tested against Fusarium oxysporum, Curvularia lunata, and Aspergillus niger using the mycelial growth inhibition method (MGI). Results indicated that Czapek-dox broth (CDB) with 1mM AgNO3, an acidic pH, and a temperature of 25–30°C were the optimum for AgNPs synthesis. (UV-vis) showed the highest peak at 435nm, whereas Ch-AgNPs showed one peak for AgNPs at 405nm and another peak for chitosan at 230nm. FTIR analysis confirmed that the capping agent chitosan was successfully incorporated and interacted with the AgNPs through amide functionalities. Z-potential was -19.7mV for AgNPs and 38.9mV for Ch-AgNPs, which confirmed the significant stability enhancement after capping. FES-SEM showed spherical AgNPs and a reduction in the nanoparticle size to 44.65nm after capping with chitosan. The highest mycelial growth reduction using fabricated Ch-AgNPs was 93% for C. lunata followed by 77% for A. niger and 66% F. oxysporum at (50mg/L). Biosynthesis of AgNPs using A. atrobrunnea cell-free extract was successful. Capping with chitosan exhibited antifungal activity against fungal pathogens.