DETECTION OF PEDIOCIN PA-1-PRODUCING PEDIOCOCCI BY RAPID MOLECULAR-BIOLOGY TECHNIQUES

Five bacteriocinogenic lactic acid bacteria strains (347, X13, Z102, A 172 and P20) independently isolated from fermented sausages were ident ified as Pediococcus acidilactici by carbohydrate fermentation pattern s and other biochemical characteristics This fact, together with their activity against Listeria monocytogenes, suggested that they could be pediocin PA-1 producers. Rapid molecular biology techniques were used to detect the pediocin PA-1 operon in these strains. PCR, dot-blot an d Southern hybridization, and DNA sequencing results confirmed that al l of them had the genetic determinants for pediocin PA-1 biosynthesis encoded in a 9.4 kb plasmid. The bacteriocin produced by P. acidilacti ci 347 has been purified by a procedure that included ammonium sulphat e precipitation and cation exchange, hydrophobic-interaction and rever se-phase chromatography. The amino acid sequence of this bacteriocin w as identical to pediocin PA-1, confirming the expression of the pedioc in PA-1 genes. (C) 1997 Academic Press Limited.