Control of Listeria monocytogenes in Cheese by Bacteriocinogenic Strains of Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch

FRANCO B.; VERA PINGITORE E.; NADER FURTADO D.; TODOROV S. D.; SESMA F.

Congreso; International Association for Food Protection; 2010

Introduction: Bacteriocins are antimicrobial peptides produced by several bacteria. For control of Listeria monocytogenes in foods, they can be supplemented with bacteriocins, or inoculated with bacteriocinogenic strains for in situ production of bacteriocins. Purpose: The aim was to evaluate the capability of two bacteriocinogenic strains Enterococcus mundtii CRL35 (bac+) and Enterococcus faecium ST88Ch (bac+), isolated from cheeses, to control the growth of Listeria monocytogenes 426 in experimentally contaminated fresh bovine cheese over 10 days of storage at 8°C. Methods: Cheeses were prepared with pasteurized milk, lactic acid, calcium chloride and commercial rennet. Four sets were prepared: two made with milk containing one of the two bac+ strains (106CFU/ml), one with milk containing a bac- strain (E. faecium ATCC19443) and one added of nisin (12,5mg/l). Other appropriate control cheeses were also prepared. L. monocytogenes 426 was added to cheeses during the manufacturing, in order to obtain 103UFC/g. Counts of lactic acid bacteria and L. monocytogenes in the cheeses stored at 8°C were done every other day for 10 days. Results: After 10 days at 8°C, counts of L. monocytogenes 426 in the cheeses containing the bac+ and the bac- strains of E. faecium decreased in a similar manner (2.63-log and 2.87-log, respectively), showing that inhibition might have occurred due to another factor than the production of bacteriocin. In the cheeses prepared with E. mundtii CRL35 bac+, the counts of L. monocytogenes decreased 4.69-log, and in those containing nisin, only a 0.75-log reduction was observed. Significance: The study showed that the strain E. mundtii CRL35 bac+ was more effective than E. faecium ST88Ch bac+ for the control of growth of L. monocytogenes in cheeses stored at 8°C. E. mundtii CRL35 bac+ was even more effective than nisin. This research underlines the potential of application of different bacteriocins in the control of nisin-resistant variants of L. monocytogenes in cheese.