Abstract: Provided herein are vectors having a polynucleotide encoding a polycistronic mRNA operably linked to a heterologous promoter, where the polycistronic mRNA includes at least two coding regions encoding a first and a second antimicrobial peptide. In one embodiment, the heterologous promoter is controlled by a modulatory protein, such as a GadR, PROTEON, or PROTEOFF modulatory protein. Also provided is a genetically modified microbe that includes a vector described herein, and methods of using the genetically modified microbe. The methods include increasing activity of antimicrobial peptides against a microbial pathogen, reducing development of resistance of a microbial pathogen, and treating a subject having a pathogenic microbe.