CHARACTERIZATION OF THE BACTERIOCINS CURVACIN-A FROM LACTOBACILLUS-CURVATUS LTH1174 AND SAKACIN-P FROM L-SAKE LTH673

Two bacteriocin producing strains, one of Lactobacillus curvatus and one of L. sake have been isolated employing a catalase-containing bacteriocin-screening-medium for lactobacilli. Both bacteriocins were produced in the late exponential growth phase, and were not only active against closely related lactobacilli but also against the opportunistic food pathogens Listeria monocytogenes and Enterococcus faecalis. The inhibitory compounds were only slightly affected by heat treatment but distroyed by proteinase K and trypsin. Both bacteriocins were purified to homogeneity by ammonium sulfate precipitation, cation exchange, hydrophobic interaction and reversed phase chromatography. The bacteriocins from L. curvatus LTH1174 and L. sake LTH673 were termed curvacin A and sakacin P, respectively. Amino acid composition analysis and automated protein sequencing revealed that curvacin A and sakacin P are small peptides of 38-41 and 41 amino acid residues, respectively. No unusual amino acids were detected. In the N-terminal region curvacin A and sakacin P share the similar segment - Tyr-Gly-Asn-Gly-Val -. No sequence similarity was detected to previously characterized bacteriocins indicating that these bacteriocins are novel.