CHARACTERIZATION OF BACTERIOCINS FROM ENTEROCOCCUS-FAECIUM WITH ACTIVITY AGAINST LISTERIA-MONOCYTOGENES

Laboratory cultures and environmental isolates of bacteria were screen ed for antagonism towards Listeria monocytogenes using an agar spot te st. Seven of the 163 strains that were tested, one Streptococcus bovis , one Enterococcus casseliflavus, two E. avium and three E. faecium, c onsistently displayed antilisterial activity. Cell-free, pH-neutralize d supernatants prepared from the three E. faecium strains (JBL1061, JB L1083 and JBL1351) exhibited strong antilisterial activity against L. monocytogenes, and were subjected to more detailed analyses. The antag onistic factors produced by these three strains were sensitive to chlo roform and several proteolytic enzymes, resistant to heat (121-degrees -C, 20 min), and stable over a wide pH range (3.0-10.0). Moreover, the y were listericidal without causing cell lysis. These data suggest tha t a bacteriocin(s) is involved in the inhibition of L. monocytogenes b y E. faecium JBL1061, JBL1083 and JBL1351.