Application of a bacteriocin-like inhibitory substance producing Enterococcus durans E204 strain, isolated from camel milk, to control Listeria monocytogenes CECT 4032 in goat jben

Abstract

Enterococcus durans E204 is a bacteriocin-like inhibitory substance (BLIS)-producing strain. It was isolated from camel’s milk in Morocco. Enterococcus durans shows interesting features such as the susceptibility to vancomycin and other clinically relevant antibiotics. In this study, we have shown that E. durans lacks haemolytic activity. Its performance as a protective culture was evaluated against Listeria monocytogenses CECT 4032 in goat jben, a Moroccan traditional fresh cheese. Ten liters of goats’ milk, originating from one farm in M’diq (northern Morocco), were pasteurised and used to make 12 small cheeses. Enterococcus durans E204 at approximately 106 CFU/ml was added in the preparation of six jben samples and six others were made without E. durans. Before packaging, two groups of four jbens were contaminated with brine solutions at 106 and 104 CFU/ml of L. monocytogenes. During storage, E. durans E204 was given time to multiply in jben and produce BLIS. In jben batches prepared with E. durans, Listeria counts decreased progressively from the beginning of storage and were undetectable at 8 and 6 days post-contamination with 106 and 104 CFU/ml, respectively. On the other hand, a substantial amount of BLIS activity (240 AU/ml) was detected from the start of the experiment and was stable during the storage. These data suggest that E. durans E204 can be used as a protective culture to inhibit growth of L. monocytogenes in cheese.