Colicin M (ColM) and related bacteriocins degrade Lipid II, blocking both peptidoglycan biosynthesis and C55-P recycling. This project, recently supported by the FRM (2017-2020), is dedicated to the biochemical and functional characterization of ColM-related bacteriocins, particularly from pathogenic bacteria, and to the engineering of these bacteriocins to modify/control their antibacterial spectrum of action. Chimeras between these bacteriocins and other molecules are thus generated to target certain pathogenic species. The mechanisms deployed by bacteria to resist the action of these bacteriocins are also studied: production of immunity proteins, polymorphism of the import system and modification of lipid II.