Antimicrobial peptides represent the first-line host defence against microbial pathogens and an essential component of innate immunity. They have received growing interest because of their potential use as therapeutic antibiotics. Due to the fact that most antimicrobial peptides are toxic to prokaryotic host cells, they are currently often produced by chemical synthesis. However, this is too costly for them to be used when large quantities of antimicrobial peptides are required for investigations and clinical trials. Thus, the convenience and cost efficiencies of bacterial production of antimicrobial peptides have become a bottleneck problem.