Figure 1.
Changes in mutation rate in E. coli MG1655 induced by different antimicrobial treatments.
Error bars show confidence interval for mutation rate estimation by plating in Rifampicin (100 µg/ml) and using the maximum likelihood method. Each bar represents the mutation rate from 10 independent cultures. All cultures were treated for 4 hours, with their corresponding MIC50 values for each antimicrobial as follow: 3.2 µg/ml of ampicillin, 0.05 µg/ml of ciprofloxacine, 1.6 µg/ml of kanamycin, 6 µg/ml of cecropin A, 12.8 µg/ml of human lysozyme, 8 µg/ml of LL-37, 1.6 µg/ml of melittin, 64 µg/ml of magainin II and 1.6 µg of pexiganan.
Figure 2.
Antimicrobial peptides do not elicit the SOS (top panel) or the rpoS pathway (bottom panel).
Induction of the SOSresponse or rpoS response is shown by a fluorescent ring around the zone of clearance (green for recA::GFP, blue for rpoS::β-gal at the edge of the inhibition zone). Positive controls with antibiotics (Cip: Ciprofloxacin, Ap: Ampicillin) are shown on the left. The bright central disc is a filter paper as source of the antibiotic/antimicrobial [22]. The amount of animicrobials on paper disks consisted of 50 µg of ampicillin, 5 µg of ciprofloxacine, 50 µg of cecropin A (Cec-A), 256 µg of human lysozyme (h-Lys), 50 µg of LL-37, 20 µg of Melittin, 200 µg of magainin II, and 20 µg of pexiganan.