Aims: The aim of this research was to investigate the antimicrobial activity produced by Brevibacterium linens ATCC 9175. Methods and Results: A bacteriocin produced by the red smear cheese bacterium B. linens ATCC 9175 was identified. The antimicrobial activity was first produced at the exponential growth phase. A crude bacteriocin obtained from the culture supernatant fluid was inhibitory to some indicator strains. It inhibited the growth of Listeria monocytogenes ATCC 7644, B. linens ATCC 9172 and Corynebacterium fimi NCTC 7547, but was inactive against the Gram-negative bacteria and yeast tested. The bacteriocin was stable at 30degreesC but the activity was lost when the temperature reached 50degreesC. It was sensitive to the proteolytic action of trypsin, papain and pronase E and was active between pH 6.0 and 9.0. The bacteriocin was bactericidal to L. monocytogenes at 40 AU ml(-1). Bacteriostasis was observed for a low dose of bacteriocin (20 AU ml(-1)). Conclusions: An antibacterial peptide produced by B. linens was characterized, presenting potential for use as a biopreservative in food systems: Significance and Impact of the Study: The identification of a novel bacteriocin active against L. monocytogenes addresses an important aspect of food protection against pathogens and spoilage micro-organisms.