Caracterization of antilisterial proteins produced by Lactobacillus sakei subsp sakei 2a, a bacteriocinogenic strain isolated from a Brazilian meat product..

KATIA GIANNI DE CARVALHO LIMA; MONIKA FRANCISCA KRUGER; JAMIL OLIVEIRA; FELIPE HENRIQUE DA SILVA BAMBIRRA; MARCELO PORTO BEMQUERER; JACQUES NICOLI; BERNADETTE DORA GOMBOSSY DE MELO FRANCO

Bologna, Italia

Congreso; Food Micro 2006; 2006

Bacteriocins produced by lactic acid bacteria are gaining increased importance due to their activity against undesirable microorganisms, especially Listeria monocytogenes, an important psicrothrofic foodborne pathogen. Previous reports have shown that strain Lactobacillus sakeisubsp. sakei 2a, isolated from a Brazilian pork meat product (linguiça), is bacteriocinogenic, and presents antilisterial activity in vitro and in situ. In this paper, we report more details about the antibacterial properties of this strain. After submitting a culture supernatant to extraction with acid (100mmol NaCl pH 1.5), the extract was submitted to further purification by ionic exchange and reversed phase, using a C18 column. Compounds were eluted with TFA 1% at 1.0mL.min-1 by a linear gradient and those with a peak at 280nm were assayed against L. monocytogenes and Enterococcus faecalis. Nine compounds presented activity, and were submitted to characterization by protein sequencing and ESI-mass spectrometry. Based on theBasic Local Alignment Search Tool (BLAST) program, which finds regions of local similarity between sequences, one of the active peptides is a Class II bacteriocin identical to sakacin 674 and bavaricin A. A second peptide is similar to a ribossomal protein of L. monocytogenes, suggesting an activity on the microbial ribosome and, possibly, inhibition of protein synthesis. The third peptide isa histone and the remaining six active peptides present similarity to 30S ribossomal proteins of L. sakei subsp. sakei. The molecular of these compounds varied from 6kDa to 13kDa. These results suggest that the antagonist activity of L. sakei subsp. sakei 2a can be attributed to more than one peptide with distinct mechanisms of action.