Aims: The aim of this study was to investigate the potential of aureocin A53, a staphylococcal antimicrobial peptide, for improving food safety. Methods and Results: The antimicrobial activity of aureocin A53 against strains of Listeria monocytogenes isolated from food was tested and the bacteriocin proved to be bactericidal and bacteriolytic against the listerial strains. Aureocin A53 was neither toxic to eukaryotic cell lines nor haemolytic against sheep erythrocytes. It also exhibited a remarkable stability during storage at different temperatures and sensitivity to both simulated gastric juice and bile salts. When the antibacterial activity of aureocin A53 (256 AU ml(-1)) was tested in skimmed milk artificially inoculated with a L. monocytogenes strain (1.0 x 10(4) CFU ml(-1)) isolated from food, during storage at 4 degrees C, the bacteriocin reduced the viable counts by 7.7 x 7-log(10) units up to 7 days of incubation, when compared with the controls not treated with the bacteriocin. Conclusions: Aureocin A53 exhibited several features considered important for biopreservation and remained fully active in a food matrix. Significance and Impact of the Study: Taken together, the results confirmed that aureocin A53 has potential to be used as a food preservative, representing an alternative to the use of nisin in biopreservation of dairy products.