Fig. 9. Concentration dependence of the effects of amino acids on escapin's antimicrobial activity. (A) Plate assay of growth inhibition. E. coli cells were grown at 37°C on a plate in minimal medium, (M9+glucose) in the presence of amino acids and escapin, or in hydrogen peroxide alone (without escapin) at concentrations from 3 to 50 mmol l^-1. (B) Bactericidal assay. E. coli cells were grown in M9+glucose containing 3 x10⁸ cells ml^-1, then incubated at 37°C with escapin (60 µg ml^-1) in M9+glucose with L-lysine, L-arginine, or L-tyrosine at 3-50 mmol l^-1. Values are means ± S.E.M., N=3.