*2.6. Bacterial Strains, Growth Media, and Culture Conditions*

Five of the most relevant foodborne pathogen bacteria were tested for antibacterial activity of PEP: *Campylobacter jejuni* NCTC11168, *Escherichia coli* ATCC®25922™, *Staphylococcus aureus* ATCC®25923™, *Listeria monocytogenes* CECT935, and *Salmonella enterica* subsp. enterica serovar Typhimurium ATCC® 14028™. All bacteria strains were stored at −80 ◦C in Brucella Broth (BB) (Becton, Dickinson, & Co, Madrid, Spain) plus 20% glycerol. The agar-plating medium consisted of Müeller-Hinton agar supplemented with 5% defibrinated sheep blood (MHB) (Becton, Dickinson, & Co), and liquid growth medium consisted of BB. Bacteria cultures were prepared as follows: The frozen stored strains were reactivated by inoculation in MHB and incubation under aerobic conditions (*E. coli*, *S. aureus*, *L. monocytogenes*, and *S. typhimurium*) and microaerophilic conditions (*C. jejuni*) using a Variable Atmosphere Incubator (85% N2, 10% CO2, 5% O2) (VAIN, MACS-VA500, Don Whitley Scientific, Bingley, UK) at 37 ◦C for 24–48 h. Isolated colonies were inoculated into 50 mL of BB and incubated in the conditions described above following stirring (150 rpm) for 24–48 h until the late exponential phase, and used as experimental inoculum. These bacterial inoculum cultures ~1 × 108 colony forming units (CFU/mL) were used for the different experimental assays.
