An antimicrobial peptide having potent antibacterial activity against Listeria monocytogenes and Staphylococcus aureus is described. Also described is an isolated Lactobacillus salivarius DPC6502 strain as deposited with the National Collection of Industrial and Marine Bacteria under the Accession No. NCIMB 41840, and variants thereof, wherein the isolated bacteria and variants thereof express an antimicrobial peptide of the invention.