Effect of Selected Lab on L. Monocytogenes during Production of Traditionally Fermented Sausages

Within the project “Safety of traditional fermented sausages: Research on protective cultures and bacteriocins” the task of Work Package 5 (WP5) was to produce traditional fermented sausages inoculated with pathogens using selected protective cultures and/or bacteriocins. As a result from previous work packages, three strains of Lactobacillus sakei (I-151, I-154 and I-155) showed bacteriocin-based antimicrobial activity against Listeria monocytogenes only. The Task 5.1. was production of fermented sausages inoculated with L. monocytogenes, together with the three selected protective cultures. Three batches of the indigenous sausages were prepared according to original recipes. For each batch four groups of sausages were produced: a positive control group (sausages inoculated only with L. monocytogenes), and three groups of sausages inoculated with L. monocytogenes and one of the three protective strains of Lb. sakei (I-151, I-154 and I-155). A slight advantage of the strain I-151 over the other two was observed in antilisterial activity, which may suggests that the three investigated strains represented just three isolates of the same bacteria. This hypothesis was supported by results of genetic investigation of bacteriocin determinants of the isolates carried out in WP3, where it was verified that all the Italian strains are subclones of the same population. Having in mind these results, it may be suggested to use only Lb. sakei I-151 as a protective starter culture in further experimental investigation.