ε polylysine

After the single- and mixed-species biofilms were formed on coupons over 120 h of incubation, they were rinsed and air-dried as described above, and then immersed in WK2 (16 µg/mL) or ε-polylysine (Sigma-Aldrich, 16 µg/mL) solutions for 5, 30, and 60 min. After treatment, residual biofilms were rinsed three times, sonicated, serially diluted, and 100 µL of samples were plated in duplicate on MacConkey agar, as described above. The colonies were counted after incubation at 37 °C for 18 h. The minimum limit of detection by the direct plating method was 0.7 log CFU/mL.

Persian gum was collected from wild almond shrubs in Shiraz, Iran. It contained 7.92% moisture, 2.21% ash, 0.18% fat, 0.22% protein, 87.88% total sugar, and 9.68% uronic acid. The average molecular weight of Persian gum was 4.15 × 10⁶ Da. Poly (ethylene oxide) (average molecular weight = 9 × 10⁵ Da) and ε-Polylysine were acquired from Sigma-Aldrich (St. Louis, MO, USA). The nutrient agar culture was obtained from Merck Chemicals Co. (Darmstadt, Germany). E. coli and S. aureus were procured from the Persian Type Culture Collection (PTCC).