PRODUCTION OF PEDIOCIN ACH BY LACTOBACILLUS-PLANTARUM WHE-92 ISOLATEDFROM CHEESE

Among 1,962 bacterial isolates from a smear-surface soft cheese (Munst er cheese) screened for activity against Listeria monocytogenes, six p roduced antilisterial compounds other than organic acids. The bacteria l strain WHE 92, which displayed the strongest antilisterial effect, w as identified at the DNA level as Lactobacillus plantarum. The protein aceous nature, narrow inhibitory spectrum, and bactericidal mode of ac tion of the antilisterial compound produced by this bacterium suggeste d that it was a bacteriocin, Purification to homogeneity and sequencin g of this bacteriocin showed that it was a 4.6-kDa, 44-amino-acid pept ide, the primary structure of which was identical to that of pediocin AcH produced by different Pediococcus acidilactici strains, We report the first case of the same bacteriocin appearing naturally with bacter ia of different genera, Whereas the production of pediocin AcH from P, acidilactici H was considerably reduced when the final pH of the medi um exceeded 5.0, no reduction in the production of pediocin AcH from L . plantarum WHE 92 was observed when the pH of the medium was up to 6. 0. This fact is important from an industrial angle, As the pH of dairy products is often higher than 5.0, L. plantarum WHE 92, which develop s particularly well in cheeses, could constitute an effective means of biological combat against L. monocytogenes in this type of foodstuff.