Occurrence of indigenous bacteriocin-producing Lactococcus lactis strains from an artisanal cheese produced in “malga” of the Val Venosta area.

Appreciated artisanal raw milk cheeses are manufactured following traditional procedures during summer season in the “malga” of the Vallevenosta area (Bolzano, Italy). Since no starter cultures are added, the adventitious natural microflora conduct fermentation and ripening processes. This cheese could be, therefore, an interesting source of microbial biodiversity that can be explored to select indigenous strains with peculiar technological and functional properties. During an investigation on the microbial ecology of these cheeses, we have isolated, identified and characterized a large number of lactic acid bacteria strains. In this study, the ability of producing bacteriocins by the Lactococcus lactis isolates was examined. Both classical agar spot tests and PCR assays to detect bacteriocin-encoding genes were applied. Several strains showed an inhibitory activity toward Listeria and, among these, some harboured the genetic determinant for nisin. It could be presumed a contribution of these protective strains in maintaining the safety of this artisanal cheese.