Assessing the antifungal resistance of synthesized tannic acid-modified silver nanoparticles against Aspergillus niger isogenic mutants

In the present study, the chemical synthesis and characterization of silver (Ag) nanoparticles, as well as their effects on the growth and inhibition of the filamentous fungus Aspergillus niger, were examined. Tannic acid-modified silver nanoparticles (TA-AgNPs) with a size 13.6 nm were synthesized and characterized before being exposed to antimicrobial assessments. The preparation involved mixing an aqueous solution of silver nitrate with an aqueous tannic acid solution. Antimicrobial assessmsents included the exposure of the nanoparticles to the A. niger, and five isogenic mutant strains (MA2.34, TLF93, TLF95, TLF96,TLF39), each lacking a distinct combination of genes. were analyzed to assess the effects of four different concentrations (30, 60, 90, and 120 ppm) of Ag nanoparticles. Statistical analysis of the experimental data confirmed that Ag nanoparticles reduce fungal growth rates and inhibit growth across all strains. However, due to genetic differences among the mutant strains, the extent of growth varied depending on the specific strain. The TLF96 mutant (ΔkusA::DR-amdS-DR, ΔcrhA-G, ΔagsA) exhibited greater sensitivity to chemically synthesized silver nanoparticles than TLF39 (ΔkusA::DR-amdS-DR, ΔcrhA-G), indicating that deletion of the agsA gene increases A. niger susceptibility by compromising α-glucan-mediated cell wall integrity. The findings of this study offer valuable insights into the antifungal properties of silver nanoparticles, highlighting their potential effectiveness in overcoming fungal resistance.