Three culture media were studied for the bacteriocin like substance (BLS) production from Carnobacterium piscicola L 103 in a batch and continuous culture system. The efficacy of the antagonistic substance against Listeria monocytogenes was tested on vacuum packaged salmon. BLS was produced in a 1.0 L bioreactor by batch and continuous culture using D-MRS, mod. D-MRS and APT as nutrient broths. Salmon fillets were inoculated with BLS (200 AU mL -1 and 800 AU mL in D-MRS and mod. D-MRS broth, and of 400 AU mL -1 in APT broth. During continuous culture BLS activity increased to 6400 AU mL -1 in both types of MRS broths, while in APT the activity decreased to 50 AU mL -1 , indicating a clear advantage of the first two culture media and also of the continuous culture system. BLS had a bacteriostatic effect on L. monocytogenes when inoculated on salmon, with counts of 6.0 x 10 3 cfu cm -2 after 15 days. No significant differences were found between the two BLS activities used. In the control without BLS, L. monocytogenes counts increased to 1.0 x 10 6 cfu cm -2 after 15 days of storage.