Fig. 5.

Antimicrobial action of combined p1 and p3. (A) The checkerboard assay was used to assess synergy between p1 and p3 following an overnight incubation with varying ratios of both peptides to either WT E. coli (top) or ΔrecA mutant (bottom). Numbers at the boundary of the zone of inhibition and zone of growth represent FIC indices calculated from the corresponding wells. Values correspond to the mean collected on three duplicates (n = 3). (B) p1 and p3 at sub-inhibitory concentrations were used either alone or in combination to treat E. coli. Growth was inhibited when the ΔrecA mutant was treated with both p1 and p3. Data are representative of three duplicates (n = 3).