ANTILISTERIAL ACTIVITY BY ENTEROCOCCI IN A MODEL PREDICTING THE TEMPERATURE EVOLUTION OF TALEGGIO, AN ITALIAN SOFT CHEESE

Enterococcus ssp. produced broad-spectrum bacteriocins, which were act ive against Listeria innocua and Listeria monocytogenes. Inhibition of L. innocua in milk by different starter cultures was evaluated. Milk was inoculated with a conventional starter (Streptococcus salivarius s sp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus mixed c ultures) as a sole starter or in combination with inhibitory starter c ultures (Enterococcus ssp., bacteriocin-producing strains). Tests were performed under a temperature gradient that reproduced the first 55 h of Taleggio cheese manufacturing and in the presence of rennet. Resul ts indicated that satisfactory inhibition of L. innocua was linked to the combined synergistic antimicrobial effect of pH decrease and bacte riocin production. Overall, data suggested that a potential existed fo r use of the antagonistic activity from enterococci for protection of Taleggio cheese during ripening, when L. monocytogenes may often reach dangerous concentrations.