Control of Listeria monocytogenes in Goat's Milk and Goat's Jben by the Bacteriocinogenic Enterococcus faecium F58 Strain

Abstract

The bacteriocinogenic Enterococcus faecium F58 strain, a natural goat's jben cheese isolate, lacks decarboxylase activity involved in most biogenic amine formation. It was also sensitive to 13 antibiotics assayed and free of virulence and vancomycin resistance genes. The F58 strain reached the stationary phase after 12 h of growth in sterile goat's milk, and the production of enterocin F-58 (Ent L50) was first detected after 48 h (400 AU/ml), thereafter remaining stable up to 5 days. The effectiveness of the F58 strain in controlling Listeria monocytogenes serovar 4b in reduced fat and whole goat's milk, and in goat's jben has been examined. Coculture experiments of F58-L. monocytogenes in both types of milk demonstrated that listeriae were not eliminated, although reductions by 1 to 4 log units were found. Nevertheless, when the F58 strain was previously inoculated in whole milk and left to grow for 12 h before contamination, the pathogen was completely eliminated after 130 h of coculture. Production of jben cheese contaminated with L. monocytogenes prior to packaging, using preparations of F58-producer strain, caused a significant decrease in the number of viable listeriae, which were undetectable after 1 week of cheese storage at 22 degrees C. Altogether, results from this study suggest that E. faecium F58 strain may be used as an adjunct culture in cheese to control contamination and growth of L. monocytogenes by in situ enterocin production, thus providing an additional hurdle to enhance control of this pathogen.

Characterization of a bacteriocin-producing strain of Enterococcus faecalis from cow’s milk used in the production of Moroccan traditional dairy foods

“…Enterococci have been described as part of the microbiota of Moroccan white cheese jben (Ouadghiri et al 2005), and an enterocin L50-producing E. faecium strain has been isolated from the cheese and successfully tested to inhibit L. monocytogenes (Achemchem et al 2005(Achemchem et al , 2006. Similarly, strain 2.5 described in the present study could also be of interest in the biocontrol of L. monocytogenes in traditional fermented dairy foods.…”

Enterocins of Enterococcus faecium, emerging natural food preservatives

“…At the end of the ripening period, the pathogen was undetectable in the samples sprayed with E. faecium WHE 81 strain, with no effect on the ripening flora or pigmented bacteria which was in sharp contrast to negative control samples in which the listerial counts increased to about 10 5 CFU/g after 20 days (Izquierdo et al 2009). Similarly, E. faecium 7 C5 (Giraffa and Carminati 1997) and E. faecium F58 (Achemchem et al 2006) also indicated a reduction of listerial counts in Taleggio (Italian soft smear cheese) and Jben (Moroccan fresh cheese), respectively. These results show the potential of using bacteriocinproducing E. faecium strains as a culture adjunct to inhibit L. monocytogenes during cheese manufacturing.…”

The complex microbiota of raw milk

“…A huge variety of other bacteriocins are produced by L. garvieae (Villani et al, 2001;Florez et al, 2012) (Gul et al, 2012), S. macedonicus (Georgalaki et al, 2002(Georgalaki et al, , 2013, enterococci and Leuconostoc spp. (Mathieu et al, 1993;Casaus et al, 1997;Giraffa & Carminati, 1997;Achemchem et al, 2006;Izquierdo et al, 2009;Mirhosseini et al, 2010) and are active against many spoilage and pathogenic microorganisms. In addition to contributing to the control of pathogens and spoilage microorganisms in raw milk and resultant products, these bacteriocins can also be employed, through the addition of producing LAB, fermentates or semi-purified preservatives, to enhance the safety of other foods (Cotter et al, 2005;Deegan et al, 2006).…”