Bacteriocin-producing lactobacilli in Spanish-style fermented sausages: Characterization of bacteriocins

Three bacteriocins were studied. Sakacin K, a bacteriocin from Lactobacillu s sake CTC494 was purl fled to homogeneity by a four-step system involving ammonium sulphate precipitation binding to a cation exchanger, hydrophobic interaction and reverse phase chromatography in FPLC (fast performance liqu id chromatography) system. The peptide sequence was determined by Edman deg radation. The first 30 amino acid residues from the N-terminus of sakacin K were identical to those of curvacin A from Lactobacillus curvatus LTH1174 and sakacin A from Lactobacillus sakei Lb706 The structural gene of sakacin K in Lb. sake CTC494 was located on a 60 Kbp plasmid (as has been previous ly reported) by curvacin A in Lb. curvatus LTH1174 and sakacin A in Lb. sak ei Lb706. Plantaricin D, a bacteriocin-like compound isolated from Lb. plan tarum CTC305 was purified and sequenced using the same procedure as describ ed for sakacin K. The first 15 amino acid residues of plantaricin 5) were i dentical to those obtained from the bacteriocin inducer peptide (termed pla ntaricin A) of the bacteriocinogenic system in Lb. plantarum CII. The struc tural gene of the plantaricin D peptide was located on a similar EcoRI chro mosomal fragment when compared to plantaricin A in Lb, plantarum Cli! These two isolated bacteriocin-like peptides (sakacin K and plantaricin DJ were purified from two new different strains obtained from fermented meat, confi rming the ecological importance of these substances. Lactobacillus sakei CT C372, the third bacteriocinogenic strain selected in this study from fermen ted sausages, produced a bacteriocin named sakacin T The bacteriocin is not found free in the supernatant of the cells, it is active against Listeria monocytogenes and Staphylococcus aureus. The genetic determinant of this ba cteriocin was localized in a 84.4 Kbp plasmid by conjugative transfer and c uring assays. (C) 2000 Academic Press.