Inhibition of Listeria monocytogenes by enterocin 4 during the manufacture and ripening of Manchego cheese.

The inhibitory effect of enterocin 4, a bacteriocin produced by Enterococcus faecalis INIA 4, on Listeria monocytogenes strains Ohio and Scott A during the manufacture and ripening of Manchego cheese was investigated. Raw ewe's milk was inoculated with ca 10(5) cfu ml-1 of L. monocytogenes and with 1% of a commercial lactic starter, 1% of an Ent. faecalis INIA 4 culture, or 1% of each culture. Manchego cheeses were manufactured according to usual procedures. Listeria monocytogenes Ohio counts decreased by 3 log units after 8 h and by 6 log units after 7 d in cheese made from milk inoculated with Ent. faecalis INIA 4 or with both cultures, whereas no inhibition was recorded after 60 d in cheese made from milk inoculated with commercial lactic starter. Listeria monocytogenes Scott A was not inhibited by enterocin 4 during cheese manufacture, but decreases of 1 log unit after 7 d and of 2 log units after 60 d were achieved in cheese made from milk inoculated with both commercial lactic starter and Ent. faecalis INIA 4.