3.4.3. The Minimum Inhibitory Concentration

The minimum inhibitory concentrations (MICs) of purified antimicrobial peptides against St. aureus ACCC 10499, B. cereus ACCC 04315, and Sa. enterica ACCC 01996 were determined by the double dilution method [21,22]. The indicator bacteria cultures were diluted to an OD₆₀₀ of 0.5 respectively, of which 50 μL of them were added into the sterile 96-well plate, and then 50 μL antimicrobial peptide samples with different concentrations were mixed with each indicator bacterium at a 1:1 ratio. The experiment was performed in three parallel sets. After incubation at 37 °C for 12–18 h, the OD₆₀₀ value was determined by an Automatic growth curve analyzer (Bioscreen C, Turku, Finland), and the minimum concentration of 100% inhibition of indicator bacteria growth was used as the minimum inhibitory concentration [23].