The experiments were performed according to the protocol described previously . In short, Nylon66 syringe filters were used as a simplified model for sterilizing the membrane surfaces. First, refreshed E. coli BL21 (OD600 = 0.9) or B. subtilis DSM 5547 (OD600 = 1.27) suspensions were diluted in the TM buffer to obtain the concentration of bacteria about 10 5 CFU/mL. The Nylon66 filters were flushed with 5 mL of such bacterial cultures. The same volume was flushed through the filter twice. Then, the filters were filled with 1 mL of the following samples and exposed to the following conditions: 1) control (TM buffer); 2) TM buffer and 10 minutes of UV exposure; 3) TM buffer and T4/Phi29 phages; 4) BB; 5) TM buffer, T4/Phi29, and UV; 6) BB, and UV; 7) T4/Phi29 and BB; 8) T4/Phi29, BB, and UV. The final concentrations were around 10 4 PFU/mL of T4/Phi29 phages, 0.1% BB. The samples were incubated for 20 minutes at room temperature and then exposed for 10 minutes to UV radiation within the laminar hood (Thermo Scientific MSC-ADVANTAGE; 36 W, 254 nm UV). The filters were washed with 1 mL of TM buffer solution to recover bacterial cells. The number of bacteria was estimated using the plating method. After the overnight incubation at 37°C, colonies were counted. For both control samples, a concentration of about 5 × 10 4 CFU (i.e., 5 mL of 10 4 CFU/mL suspension) was introduced, while approximately 4.8 × 10 4 CFU was recovered.