Combined effect of bacteriocins on the survival of various Listeria species in broth and meat system

The antilisterial efficiency of three bacteriocins from lactic acid bacteri a, lactocin 705 (produced by L. casei CRL705, 17000 AU/ml), enterocin CRL35 (produced by E. faecium CRL35, 17000 AU/ml), and nisin (2000 IU/ml), was t ested in broth, individually and in combination against Listeria monocytoge nes and Listeria innocua. Both Listeria species showed an initial decrease in viable counts followed by the regrowth of the survivors after 1 h in the presence of each bacteriocin. A greater antilisterial effect was observed when the bacteriocins were combined in pairs, maximal inhibition being reac hed when nisin was involved. When a mix of the three bacteriocins was used, no survivors were observed after 24 h of incubation. Similar results were obtained when the bacteriocin combinations were tested in a meat system, in dicating that the use of more than one LAB bacteriocin in combination may b e effective in preventing the spontaneous emergence of a bacteriocin-resist ant Listeria population.