Determination of the bacteriocin-like substances produced by some lactic acid bacteria isolated from Turkish dairy products

Inhibitory effect of cell-free filtrates of Lactobacillus bulgaricus (6 strains), L. casei (4 strains), L. plantarum (2 strains), L. acidophilus (2 strains), L. brevis (2 strains), L. fermentum (1 strain), L. lactis (1 strain), and L. helveticus (1 strain) isolated from Turkish dairy products were determined against test bacteria (Staphylococcus aureus, Escherichia coli, Yersinia enterocolitica). All strains showed antimicrobial activity against test bacteria. Bacteriocin-like substances producing strains were determined under conditions eliminating the effects of organic acids and hydrogen peroxide. As a result, it was observed that inhibitory activities of three strains were due to bacteriocin-like substances. They were resistant to heat (100 °C for 10 and 20 min). The inhibitory activity of bacteriocin-like substances was not lost after 10 and 20 min at 100 °C. The inhibition observed in these studies could not have been due to the probable hydrogen peroxide production, since it was unaffected by catalase. The purified bacteriocin-like substances were identified as 29 kDa peptide by sodium dodecyl sulfate-polyacrylamide gel (SDS-PAGE). Molecular weights of bacteriocin-like substances were found the same in all three strains. This bacteriocin-like substances might be useful as a natural preservative.