Effect of nisin-producing Lactococcus lactis starter cultures on the inhibition of two pathogens in ripened cheeses

摘要: The effect of Lactococcus lactis nisin-producing strains, isolated from Italian fermented foods, onthe survival two foodborne pathogens namely Listeria monocytogenes and Staphylococcus aureuswas investigated in experimental cheese production. One the three Lactobacillus nisin inn-oculated as starters, 41FL1 lowered S. aureus count by 1.73 log colony-formingunits (cfu)/g within first 3 days, reaching highest reduction, 3.54 cfu/g, end ofripening period 60 days. There was no on L. monocytogenes. application lactis41FL1 bioprotective culture controlling shows considerable promise.Keywords lactis, nisin, aureus, monocytogenes, Cheese.INTRODUCTIONLactic acid bacteria (LAB) are widely used forthe fermentation preservation a widerange milk, meat vegetable foods.Among LAB isextensively starter dairyindustry, potential applications thesestrains food production well documented.In particular, recent years, great interest wasfocused possible use certain productsof their metabolism, called bacteriocins, aspotential biopreservatives foods (O’Sullivanet al. 2002).Bacteriocins proteinaceous antimicrobialcompounds ribosomially synthesised bacteriaand able to inhibit high number potentialpathogens among which monocytogenesand (Cotter et 2005).The current technologies employed inacti-vate bacterial not alwaysefficient often represent particular treatmentsthat may modify fisical chemical proper-ties products. Therefore, newapproaches combat pathogenic spoilagemicroorganisms needed. In last fewyears, bacteriocins have been thor-oughly characterised tested systemsas new preservatives (Stiles 1996).Although many charac-terised, most foodindustry biopreservative (Class I,lantibiotic) pediocin II). Nisin is thebacteriocin with longest history safe usein industry. It has shown be effec-tive for microbial control ofdairy products also assessed incheese manufacturing (Ross 2002). Inmost cases, bacteriocin incorporatedinto product dried concentrated powder(O’Sullivan 2002), but currently, useof or costarter culturesseems an alternative way incorporatingthe (e.g. cheesemaking process)(Sobrino-Lopez Marton-Belloso 2008).Among potentiallyassociated dairy andL. cause numerous