Both phages and tailocins (phage tail-like bacteriocins) are highly specific antibacterials that leave the microbiome unaffected. Their primary specificity determinant is their tail fiber that makes the initial contact with the pathogen. Whereas phages kill a cell through a lytic replication cycle ended by cell lysis, tailocins kill the cell by membrane depolarization. Both phages and tailocins share the potential for customization. In this research proposal we develop an approach starting to rapidly reprogram safe and well-known phages and tailocins towards Shiga-toxin producing Escherichia coli.