2.2.2. Agar-Well Diffusion Assay of Polymer Solutions and Nisin Z

The antibacterial activity of SA, GN, SAGN, and Nisin Z solutions was assessed against S. aureus via the Kirby–Bauer method [2]. Solutions were prepared in the concentrations employed for fiber production: 2 wt% for SA and ≈1 wt% for GN, and then combined at a polymer ratio of 70:30 v/v (for SA and GN, respectively). Nisin Z was examined at MIC, 2 × MIC and 3 × MIC. 0.33 mL of the bacterium inoculum, adjusted to 1.0 × 10⁷ CFUs/mL in TSB, were collected and added to 4.67 mL of TSA warmed at approximately 45 °C. The 5 mL bacterial solution was casted into 55 mm diameter sterilized Petri dishes. After agar solidification, 6 mm diameter holes were made at the center of each bacteria-containing agar plate using a sterilized puncher, and 40 μL of each testing solution were introduced in the respective holes. Plates were incubated at 37 °C for 24 h. After this period, zones of inhibition (ZoIs) were observed and measured (mm) to verify the antibacterial efficiency of the solutions.