*2.6. Antimicrobial Activity*

The antimicrobial activity of MgO-NPs synthesized by fungal metabolites was investigated against various pathogenic microbes, including *Staphylococcus aureus* ATCC 6538, *Bacillus subtilis* ATCC 6633 (Gram-positive strains), *Pseudomonas aeruginosa* ATCC 9022, *Escherichia coli* ATCC 8739 (Gram-negative strains), and unicellular fungi *Candida albicans* ATCC 10231. The bacterial strains were subcultured on nutrient agar media (containing g L–1: peptone, 5; beef extract, 3; NaCl, 5; agar, 20; distilled water, 1000 mL) while *C. albicans* was subcultured on yeast extract peptone dextrose (YEPD) agar media (containing g L–1: glucose, 20; peptone, 20; yeast extract, 10; agar, 20; distilled water, 1000 mL) for 24 h. To check antimicrobial activity, each strain was homogenously streaked over Mueller-Hinton agar (for bacterial strains) and YEPD agar plates (for *C. albicans)* using a sterilized cotton swab. Three wells (0.7 cm diameter) were cut in the streaked Mueller-Hinton plates and filled with 100 µL of biosynthesized MgO-NPs (200 µg mL–1). The minimum inhibitory concentration (MIC) was assessed by using different concentrations of MgO-NPs (150, 100, 50, and 25 µg mL–1). The loaded Mueller-Hinton plates were kept in the refrigerator for 1 h before being incubated at 35 ◦C for 24 h. The results were recorded as a zone of inhibitions (ZOIs) around each well by mm [36]. The experiment was achieved in triplicate.
