ABSTRACT
Biosynthetic metals have attracted global attention because of their safety, affordability, and environmental friendliness. As a consequence, the cell-free filtrate (CFF) of Dill leaf-derived endophytic fungus Aspergillus luchuensis was employed for the extracellularly synthesis silver nanoparticles (AgNPs). A reddish-brown color shift confirmed that AgNPs were successfully produced. The obtained AgNPs were characterized by UV-Vis (ultraviolet-visible spectroscopy), Transmission electron microscopy (TEM), FTIR, EDX, and zeta potential. Results demonstrated the creation of crystalline AgNPs with a spherical shape at 427.81 nm in the UV-Vis spectrum, and size ranged from 16 to 18 nm as observed by TEM. Additionally, the biogenic AgNPs had a promising antibacterial activity versus multidrug-resistant bacteria, notably, S. aureus, E. coli, and S. typhi. The highest growth reduction was recorded in the case of E. coli. Furthermore, the biosynthesized AgNPs demonstrated potent antifungal potential versus a variety of harmful fungi. The maximum growth inhibition was evaluated from A. brasinsilles, followed by C. albicans as compared to cell-free extract and AgNO3. In addition, data revealed that AgNPs possess powerful antioxidant activity, and their ability to scavenge radicals increased from 33.0 to 85.1% with an increment in their concentration from 3.9 to 1,000 µg/mL. Furthermore, data showed that AgNPs displayed high catalytic activity of safranin under light irradiation. The maximum decolorization percentage (100%) was observed after 6 h. Besides, the biosynthesized AgNPs showed high insecticidal potential against 3rd larval instar of Culex pipiens. Taken together, data suggested that endophytic fungus, A. luchuensis, is an attractive candidate as an environmentally sustainable and friendly fungal nanofactory.
ABSTRACT
Toxigenic fungi infect fruits and vegetables either during harvest or storage and create mycotoxins as secondary metabolites, which pose a serious threat to human and animal health throughout the food chain. Therefore, the objective of this study was to determine the inhibitory effect of OZO against the growth and spore germination of the Alternaria alternata fungal strain. Additionally, evaluation of the synthesis inhibition of Alternaria toxins (ATs), among which are alternariol (AOH), alternariol-9-methyl ether (AME), and tenuazonic acid (TeA) in the potato dextrose broth (PDB) medium and orange fruit after harvest. The results indicated that the inhibition zone was 29.0 ± 1.2 mm at 20 mg/L of OZO. The MIC and MFC values were recorded at 0.186 and 1.57 mg/mL, respectively. In this regard, OZO prevented conidia germination at 98.8% with the treatment of 5 mg/mL. OZO at 20 mg/mL was efficacious in producing a high loss in ATs production in the PDB medium, reaching 73.4, 76, and 67.1% for AOH, AME, and TeA, respectively. In addition, OZO prevents the biosynthesis of AOH and AME during the storage of orange fruits compared with the positive control sample. In contrast, 20 mg/mL reduced TeA accumulation and the appearance of Alternaria brown spot (ABS) in orange. To the best of our knowledge, this is the first report that studies OZO to control ATs in vitro in orange fruits.
