Purification and characterization of the bacteriocin produced by Lactobacillus sakei MBSa1 isolated from Brazilian salami

Aims The study aimed at determining the biochemical characteristics of the bacteriocin produced by Lactobacillus sakei MBSa1, isolated from salami, correlating the results with the genetic features of the producer strain. Methods and Results Identification of strain MBSa1 was performed by 16S rDNA sequencing. The bacteriocin was tested for spectrum of activity, heat and pH stability, mechanism of action, molecular mass and amino acid sequence when purified by cation-exchange and reversed-phase HPLC. Genomic DNA was tested for bacteriocin genes commonly present in Lact.sakei. Bacteriocin MBSa1 was heat-stable, unaffected by pH 2 center dot 0 to 6 center dot 0 and active against all tested Listeria monocytogenes strains. Maximal production of bacteriocin MBSa1 (1600AUml(-1)) in MRS broth occurred after 20h at 25 degrees C. The molecular mass of produced bacteriocin was 4303 center dot 3Da, and the molecule contained the SIIGGMISGWAASGLAG sequence, also present in sakacin A. The strain contained the sakacin A and curvacin A genes but was negative for other tested sakacin genes (sakacins T-alpha, T-beta, X, P, G and Q). Conclusions In the studied conditions, Lact.sakei MBSa1 produced sakacin A, a class II bacteriocin, with anti-Listeria activity. Significance and Impact of the Study The study covers the purification and characterization of the bacteriocin produced by a lactic acid bacteria isolated from salami (Lact.sakei MBSa1), linking genetic and expression information. Its heat-resistance, pH stability in acid conditions (pH 2 center dot 0-6 center dot 0) and activity against L.monocytogenes food isolates bring up a potential technological application to improve food safety.