ANTILISTERIAL ACTIVITY OF CARNOCIN-54, A BACTERIOCIN FROM LEUCONOSTOC-CARNOSUM

Carnocin 54, a bacteriocin produced by Leuconostoc carnosum LA54A acts very rapidly in a bactericidal manner on Listeria cells. The killing kinetics strongly depend on bacteriocin concentration and pH. At a hig h concentration, more than 99.99% of the cells were killed within I mi n. Lowering carnocin concentration and increasing pH from 4.9 to 6.5 r esulted in a slower reduction of Listeria viable counts. Carnocin was able to inactivate Listeria cells to the same extent at pH 4.5 and 6.5 within 5 h. After 24 h, however, a slight resurgence of Listeria was observed at pH 6.5. The bactericidal efficiency was Listeria strain de pendent, but was not influenced by the growth phase. At a given bacter iocin concentration, the level of inactivation of Listeria was not aff ected by the initial cell number.