The gram-negative bacterial strains Escherichia coli (KCTC 1682) and Acinetobacter baumannii (KCCM 40203) were purchased from the Korean Collection for Type Cultures (Korea) and the Korean Culture Center of Microorganisms (Korea), respectively. The MDR gram-negative strains Escherichia coli CCARM 1229, Escherichia coli CCARM 1238, Acinetobacter baumannii CCARM 12010, and Acinetobacter baumannii CCARM 12220 were obtained from the Culture Collection of Antibiotic-Resistant Microbes at Seoul Women’s University (South Korea).
The antibacterial properties of all peptides were determined by measuring the Minimum Inhibitory Concentration (MIC) as described previously [22 (link)]. In brief, the MIC was defined as the concentration of peptides that inhibited 99% of the bacterial growth. Two-fold serial dilutions of respective peptides were inoculated in 96-well plates in Mueller-Hinton medium, followed by the addition of bacterial suspensions (2 × 105 CFU/ml) at the log growth phase. The plates were incubated at 37°C for 16 h, and absorbance was read at 600 nm using a SpectraMAX microplate reader (Molecular Devices, USA).
The antibacterial properties of all peptides were determined by measuring the Minimum Inhibitory Concentration (MIC) as described previously [22 (link)]. In brief, the MIC was defined as the concentration of peptides that inhibited 99% of the bacterial growth. Two-fold serial dilutions of respective peptides were inoculated in 96-well plates in Mueller-Hinton medium, followed by the addition of bacterial suspensions (2 × 105 CFU/ml) at the log growth phase. The plates were incubated at 37°C for 16 h, and absorbance was read at 600 nm using a SpectraMAX microplate reader (Molecular Devices, USA).