Smearing of soft cheese with Enterococcus faecium WHE 81, a multi-bacteriocin producer, against Listeria monocytogenes

Abstract

Enterococcus faecium WHE 81, a multi-bacteriocin producer, was tested for its antimicrobial activity on Listeria monocytogenes in Munster cheese, a red smear soft cheese. The naturally delayed and superficial contamination of this type of cheese allowed the use of E. faecium WHE 81 at the beginning of the ripening as a surface culture. A brine solution inoculated at 10 5 CFU of E. faecium WHE 81 per mL was sprayed on the cheese surface during the first smearing operation. On day 7, smearing of cheese samples with a brine solution at 10 2 CFU of L. monocytogenes per mL yielded initial cell counts of approximately 50 CFU g −1 of the pathogen on the cheese surface. Although, in some instances, L. monocytogenes could survive (<50 CFU g −1) in the presence of E. faecium WHE 81, it was unable to initiate growth. In control samples however, L. monocytogenes counts often exceeded 10 4 CFU g −1. In other respects, E. faecium WHE 81, which naturally existed in Munster cheese, did not adversely impact on the ripening process.