Microbial ecology of artisanal products from North West of Italy and antimicrobial activity of the autochthonous populations

A total of about 1000 autochthonous strains were isolated from fresh and fermented artisanal products (cheese and meat) of the Piedmont area (Northwest of Italy) and screened for their antimicrobial activity. Among them, 98 bacteriocin-producing strains were detected and identified by molecular methods and genetic determinants encoding the antimicrobial proteins were targeted by PCR. The bacteriocins produced by isolates showed antimicrobial activity towards different spoilage and pathogenic microorganisms such as Listeria monocytogenes, Staphylococcus aureus, Clostridium tyrobutyricum and Brochothrix thermosphacta. Identification of the bacteriocin producing strains resulted in a large number of Lactococcus and Enterococcus strains with a broad spectrum of activity towards more that one spoilage and/or pathogenic microorganisms tested. In several strains it was possible to detect a combination of different genes responsible for the bacteriocin activity. These newly isolated bacteriocin-producing strains represent potential starters or co-starters to be used in food stabilization using the approach of the biopreservation.