The identification and/or design of novel antibacterial agents are hot topics, because of the increasing bacterial resistance against antibiotics. Some natural proteins and peptides can be considered promising antimicrobials because acting through different and complementary mechanisms. Lysozyme and ovotransferrin are two proteins known for its activity against bacteria. We are interested on its ability to disturb the outer and/or the inner membranes. Indeed, the membrane permeabilization is an interesting mechanism because it causes bacterial cell death, while limiting the development of bacterial resistance. The understanding of the mechanisms by which different protein can have different antibacterial activity could help goal-oriented screening and design of new antimicrobial compounds. For this propose, we develop a strategy based on the use of lipid monolayer to decompose the mechanism of the antimicrobial activity. In this presentation, we will present results .