CONTROL OF LISTERIA-MONOCYTOGENES IN THE RIND OF TALEGGIO, A SURFACE-SMEAR CHEESE, BY A BACTERIOCIN FROM ENTEROCOCCOS-FAECIUM-7C5

The aims of this study was to determine the ability of an actively gro wing, bacteriocin-producing culture of Enterococcus faecium 7C5 to inh ibit Listeria monocytogenes on the surface of Taleggio cheese and to e xamine the enhanced antilisterial effect of adding the crude bacterioc in to the cheese surface. Two hatches of Taleggio, an Italian soft-sme ar cheese, were produced: one using the conventional dairy starter as control, and the other with E. faecium as a culture adjunct to the dai ry starter. At the end of ripening, the surface of both batches of che eses was contaminated with 10(2) to 10(3) cfu . cm(-2) of L. monocytog enes (Ohio strain), The pH increase in the rind during ripening allowe d a listerial proliferation on the surface of the control cheeses. An anti-listerial effect was observed on the surface of cheeses contamina ted with 10(2) cfu.cm(-2) listeriae and produced with the E. faecium 7 C5 adjunct, compared to 10(3) cfu.cm(-2) Listeriae, the anti-listerial effect was enhanced when a crude bacteriocin preparation was added to the cheese surface to strengthen the antimicrobial activity in situ. These results demonstrate the efficacy of bacteriocin to reduce the ov erall risks involved in cheese production, especially when high pH dur ing ripening increases the risk of listerial growth.