Evaluation of live-culture-producing lacticin 3147 as a treatment for the control of Listeria monocytogenes on the surface of smear-ripened cheese

Abstract

Aims: A live Lactococcus lactis culture, producing the two‐component broad spectrum bacteriocin lacticin 3147, was assessed for ability to inhibit the food pathogen Listeria monocytogenes on the surface of smear‐ripened cheese. Methods and Results: In initial experiments, the addition of Listeria to a lacticin 3147‐containing fermentate produced with L. lactis DPC4275 (a transconjugant strain derived from L. lactis DPC3147) resulted in at least a 4 log reduction of the pathogen in 30 min. Two separate trials were performed in order to assess the most suitable method for application of the potential protective culture to smear‐ripened cheese. In the initial trial, the L. lactis was sprayed onto the surface of the cheese either before or after Listeria was deliberately applied. Application of the culture following Listeria challenge, yielded up to a 1000‐fold reduction of the pathogen in contrast to the pretreatment where Listeria numbers were unaffected. In a further trial, three applications of the live lacticin 3147‐producing culture was used on a cheese surface containing Listeria. Listeria numbers were found to be up to 100‐fold lower than in the cheese treated with L. lactis DPC4268 (control). Conclusion: While application of the live lacticin 3147 producer did not give complete elimination of the pathogen the results nonetheless demonstrate the potential of the bioprotectant for improving the safety of smear‐ripened cheeses and particularly those that contain low level contamination with Listeria. Significance and Impact of the Study: The application of lacticin 3147 as a live‐culture can serve as a bioprotectant for the control of L. monocytogenes on the surface of smear‐ripened cheese.

Bacteriophage biocontrol ofListeria monocytogeneson soft ripened white mold and red-smear cheeses

“…21,22,24,[35][36][37][38] In most cases, however, not phages but "anti-Listeria cultures" or bacteriocins were used, and the different experimental setups and various types of cheeses employed make it difficult to compare these data. Important parameters which affect the results include the Listeria strain(s) and contamination levels used, type of phage or bacteriocin applied, time point of application, type of cheese, ripening conditions and packaging conditions.…”

Microbial interactions in cheese: implications for cheese quality and safety

“…For example, LAB cultures were used to prevent and control L. monocytogenes and spoilage microorganisms including Clostridium tyrobutyricum, within the framework of hurdle technology (e.g. milk pasteurisation, use of defined starter and ripening cultures) [24,25,26]. Protective cultures are used because they produce antagonistic metabolites such as bacteriocins, peptides and/or low-weight non-proteinaceous compounds (organic acids, fatty acids, H 2 O 2 , etc.)…”

“…The effects of the omission of one, two or three yeasts on the Enterocin A and B Enterococcus faecium Adjunct culture in brine and smearing solution [48] Lacticin 3147 Lactococcus lactis Smeared on the cheese surface [26] Nisin and Pediocin PA-1…”

Recent developments in cheese cultures with protective and probiotic functionalities

“…No decrease in in situ produced lacticin activity was detected in Cheddar cheese over 6 months of ripening [119]. However, the application of the lacticin 3147 producer strain on surfaces of smear-ripened cheese as a pretreatment for controlling L. monocytogenes contamination was not effective [102].…”