Anti-Listeria effect of enterocin A, produced by cheese-isolated Enterococcus faecium EFM01, relative to other bacteriocins from lactic acid bacteria

Enterocin A produced by Enterococcus faecium EFM01 displayed a narrow antim icrobial spectrum, mainly directed against Listeria spp. In particular, the bacteriocin was extremely active against 13 Listeria monocytogenes strains . This high specificity of action of enterocin A for Listeria spp. relative to lactic acid bacteria, together with its broad range of activity from pH 4.0 to pH 9.0, are factors which may be of great interest with respect to the potential antilisterial use of this bacteriocin in fermented foods. Ass essment of the effect of enterocin A concentration on the extent and kineti cs of bactericidal activity on L. monocytogenes Lm 6 (10(7) cfu ml(-1) in c ulture broth), suggested that viability losses of higher than 5 log(10), an d time intervals necessary for maximum loss of viability of less than 2 h, could not be obtained. Moreover, it was shown that both parameters are clos ely dependent on the Listeria strain used. On the other hand, at concentrat ions inducing destruction of approximately 2 log(10) cycles, maximum loss o f viability was achieved within time intervals which varied widely from one lactic acid bacteria bacteriocin to another.