THE ANTI-ASPERGILLUS POTENTIAL OF OPTIMIZED BIOSYNTHESIZED REDUCED GRAPHENE OXIDE/SILVER NANOCOMPOSITE USING ESCHERICHIA COLI D8 (MF062579)

Abstract

Conventional antifungal agents have failed to treat several infectious diseases of many Aspergillus strains. These strains have been linked to the production of high-potency mycotoxins, which cause mould diseases on fruits and vegetables and have negative health consequences. The current study aimed to develop new effective nanomaterials using efficient methods that were stable and antifungal. The current work has been carried out to use the free cell supernatant of Escherichia coli D8 (MF062579) in the biosynthesis of reduced graphene oxide/silver nanocomposite (rGO/AgNC). At room temperature, the nanocomposite was prepared by an economical and simple one-step approach. Different parameters were optimized in the biofabrication of rGO/AgNC such as silver nitrate concentration, bacterial supernatant concentration, pH value, and temperature. Ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Zeta analyses were used to evaluate the optimized rGO/AgNC. The biosynthesis process was performed within minutes in the incidence of solar irradiation. The mean size of silver nanoparticles (AgNPs) was estimated to be 9-18 nm. The biogenesis of spherical-shaped, well-dispersed AgNPs was validated by TEM images. AgNPs have a positive potential value, as seen by the zeta potential graph. rGO/AgNC had a harmful effect on the ultrastructure of rGO/AgNC-treated Aspergillus including membranes damage, malformation, and complete lysis of fungal cells in addition to enzymatic inhibition in lactate dehydrogenase activity. This study states a well-designed approach to develop a new antimicrobial agent, rGO/AgNC, against pathogenic human and phytopathogenic Aspergillus spp. in addition to a probable mechanism for the nanomaterial’s antimicrobial action.