Difco luria bertani medium

Stock K802NR strain was grown on LB-agar plates (Difco Luria-Bertani medium, BD) containing 100 μg mL^–1 ampicillin for 48 h at 37 °C in an incubator (Binder, Camarillo, CA, USA). A single colony from the LB-agar plates was selected and introduced into a 10 mL LB medium containing 100 μg mL^–1 ampicillin and grown overnight at 37 °C with shaking (140 rpm) on a rotary thermo-shaker (Gerhardt, Konigswinter, Germany) to provide aeration. Then, a 20 mL fresh portion of LB medium without antibiotic was inoculated with 20 μL of the inoculum from the overnight culture and re-grown at 30 °C for about 4 h until the early log phase (OD₆₀₀ ≈ 0.2) without shaking. The OD₆₀₀ was determined by Ultrospec 2100 pro spectrophotometer (Amersham, Berks, UK). As for the PAO-JP2 (pKD-rhlA) strain, it was introduced from the stock on LB-agar plates (Difco Luria-Bertani medium, BD) containing 300 μg mL^–1 trimethoprim for 24 h at 37 °C in the incubator (Binder, Camarillo, CA, USA). From the LB-agar plates, a single colony was picked and introduced into 10 mL LB medium supplemented with 300 μg mL^–1 trimethoprim and grown overnight at 37 °C with shaking (140 rpm) on a rotary thermo-shaker (Gerhardt, Konigswinter, Germany). The respective LB-agar plates containing K802NR and PAO-JP2 (pKD-rhlA) strains were stored at 4 °C for future use.

The F. nucleatum strain added to the cell cultures at a human cell:bacterial cell ratio of 1:100. F. nucleatum were grown in Columbia blood agar supplemented with 5 mg/mL hemin, 5% defibrinated sheep blood, and 1 mg/mL vitamin K1 and cultured overnight at 37°C under anaerobic conditions. The commensal E. coli strain DH5a propagated in Difco Luria-Bertani medium (BD Biosciences, California, USA) and cultured overnight at 37°C under anaerobic conditions.