ANTIBACTERIAL POTENTIAL OF ENTEROCOCCUS-FAECIUM STRAINS ISOLATED FROM SOUS-VIDE COOKED FISH FILLETS

Nineteen isolates of Enterococcus faecium were isolated from sous-vide cooked cod fillets stored 3-8 weeks at 3 degrees C. Fourteen. isolates produced proteinaceous substances inhibitory to different strains of Listeria monocytogenes, other pathogenic bacteria and spoilage bacteria. The isolates had similar growth profiles in broth at 0, 3, and 5 degrees C. In the presence of 10(7) cfu ml(-1) E. faecium, L. monocytogenes (10(2) cfu ml(-1)) was strongly inhibited at 3 degrees C and partially at 5 degrees C and 15 degrees C. When cultivated with 10(4) cfu ml(-1) E. faecium, L. monocytogenes (10(2) cfu ml(-1)) was only slightly inhibited at 15 degrees C and not at 3 degrees C or 5 degrees C. Spontaneous resistance phenomena were observed at 15 degrees C after 11 days. The isolates of E. faecium did not produce off-odours in shrimp extracts or sous-vide cooked fish. The potential use of the isolated strains of E. faecium as biopreservation is suggested.