In vitro antibacterial activity of OBPgp279, PVP-SE1gp146 and 201φ2-1gp229 without (A) and with (B) the OM permeabilizer EDTA against different Gram-negative species, compared to P. aeruginosa phage endolysins KZ144 and EL188.

Cell cultures (initial cell density of 106 cells/ml) were incubated for 30 min with 1.5 µM OBPgp279, 5 µM PVP-SE1gp146, 3 µM 201φ2-1gp229, 3 µM EL188 and 3 µM KZ144 alone (a) and in combination with 0.5 mM EDTA (b). Antibacterial reduction is calculated in logarithmic units ( = log10(N0/Ni) with N0 = number of untreated cells and Ni = number of treated cells counted after incubation). Averages and standard deviations of three repeated and independent experiments are shown.