2.3. Preparation of Supernatants for Metabolic Analysis

To facilitate biofilm formation, the Xcc bacterial suspension was distributed in Erlenmeyer flasks (50 mL/flask) and incubated for 72 h at 24 °C under a static condition. Next, 5 mL of phages (10⁸ plaque forming-units (PFU)/mL), acid (30 µg/mL) or Xccφ1+HA+C20:0 (10⁸ PFU/mL, 5 mg/mL and 30 µg/mL respectively) were added to each flask. After 3 h incubation at 24 °C, the cultures were collected, centrifuged (13,000 rpm for 20 min) and the supernatants stored at +4 °C for NMR analysis.