Anti-Listeria activity of lactic acid bacteria isolated from golka, a regional cheese produced in Poland

Eight hundred lactic acid bacteria (LAB) strains isolated from golka, one of the oldest and most popular regional cheese produced in Poland, were screened for anti-Listeria activity. Nearly one third of isolates showed antagonistic activity against Listeria monocytogenes. Seven strains produced other substances active against L. monocytogenes. These substances were detected in neutralized cell-free supernatant fluids and were classified as bacteriocins. 16S rDNA identification of the selected bacteriocin-producing bacteria was performed. By using primers specific to a fragment of class IIa bacteriocin-coding genes, developed by the authors, presence of the bacteriocin structural gene was confirmed for all Lactococcus garvieae strains, Leuconostoc mesenteroides 453Lab and Lactobacillus plantarum Lab572. Presence of the class IIa bacteriocin-coding genes within genomes of non-bacteriocin-producing strains Lactococcus lactis subsp. lactis was also detected. Bacteriocins with the highest activity against Listeria, i.e. bacteriocins of L. garvieae Lab428, Lc. mesenteroides Lab25 and Lb. plantarum Lab572 strains, were partially characterized. The bacteriocins did not adhere to surface of the producer cells and exhibit a bactericidal mode of action. Bacteriocin of L. garvieae 428Lab was produced at much higher levels (12.800 AU/ml), as compared to the other bacteriocins (3.200 AU/ml). Our results indicate that golka cheese is a rich source of LAB active against L. monocytogenes. The bacteriocinogenic isolates from golka described in this work may potentially find application as starter or protective cultures and could constitute a superb genetic pool for production of new bacteriocins.