Bacteriocins are ribosomally synthesized, extracellular released antimicrobial peptides that show activity against closely related bacterial species. Four genes are required to produce bacteriocins: a structural gene encoding a prepeptide, a dedicated immunity gene, a dedicated ABCimmunity gene and a gene encoding the protein necessary for export of the bacteriocin. Bacteriocins are formed as prepeptides in the cell and mature during export from the