Fig. 4

The effect of protease on the bactericidal activity of polybia-MPI and D-MPI. Peptides were incubated with the same volume of PBS (Left) or trypsin (Right) at 37 °C for 4 h. The enzyme was heat inactivated at 60 °C for 20 min, and E. coli suspension was added and co-incubated for 3 h. Then, the mixtures were plated onto MH broth ager and incubated for 18–24 h. Pictures of each plate were photographed