ISOLATION AND CHARACTERIZATION OF PEDIOCIN L50, A NEW BACTERIOCIN FROM PEDIOCOCCUS-ACIDILACTICI WITH A BROAD INHIBITORY SPECTRUM

Lactic acid bacteria were isolated from Spanish dry-fermented sausages and screened for bacteriocin production. About 10% of the isolates pr oduced antimicrobial substances when grown on solid media, put only 2% produced detectable activity in liquid media. Strain L50, identified as Pediococcus acidilactici, showed the strongest inhibitory activity and was active against members of all of the gram-positive genera test ed. The strain produced a heat-stable bacteriocin when grown at 8 to 3 2 degrees C but not at 45 degrees C. The bacteriocin was purified to h omogeneity. Its mass was determined to be 5,250.11 +/- 0.30 by electro spray mass spectrometry. The N terminus of the bacteriocin was blocked for sequencing by Edman degradation, but a partial sequence of 42 ami no acids was obtained after cleavage of the peptide by cyanogen bromid e. The sequence showed no similarity to those of other bacteriocins. P ediocin L50 appears to contain modified amino acids but ndt lanthionin e or methyl-lanthionine.