The main objective of this study was the isolation and selection of lactic acid bacteria capable of showing antagonistic activity against Listeria. The main factors contributing to such activity were examined and characterized and strains with superior antilisterial activity were selected and identified as well. Furthermore, a PCR analysis of genomic DNA isolated from strains with relevant antilisterial activity was performed in order to determine, whether these bacteria are capable of producing class IIa antilisterial bacteriocins. Five different polish artisanal cheeses were chosen as a source of isolation of baterial strains: bundz, bryndza, non-smoked golka, smoked golka and warkocze. The isolated microorganisms were primarily cultivated on MRS and M17 media. The antilisterial activity was evaluated by diffusion tests against an indicator strain – Listeria innocua. Phylogenetic identification of the strains with highest antilisterial activity was performed by 16S rDNA sequencing. The presence of class IIa bacteriocin coding gene within the genome of selected strains was detected using a panel of degenerate PCR primers. About 1000 cultures of lactic acid bacteria were obtained during the studies presented in this paper. Nearly one third of these cultures showed an antagonistic activity against Listeria. The greatest number of active strains were among the lactic acid bacteria isolated from bryndza and non-smoked golka and these strains were able to synthetize mainly hydrogen peroxide and organic acids. Only less than 1% of examined bacteria showed the ability of synthesizing other metabolites with antilisterial activity – the bacteriocins. Strains identified as Lactococcus garvieae, Leuconostoc mesenteroides and Lactobacillus plantarum showed the ability to synthetize such metabolites. Furthermore, the presence of class IIa bacteriocin coding gene within the genomic DNA of these bacteria was also detected. The structure, modes of action and biosynthesis pathways of bacteriocins synthetized by Lc. garvieae, Leu. mesenteroides and Lb. plantarum are still examined by the authors.

27-44