Antimicrobial peptides from dairy propionibacteria; Gene regulation, Expression and Distribution, with Emphasis on Future Application

A large variety of microorganisms play important roles in food industry. The elassical propionibacteria have an extensive history of use in dairy fermentations, especially in the produetion of Swiss-type cheeses, where they are responsible of flavor aud o f the forniation of the characteristic eyes. Propionibacteria produce several antimicrobial metabolites, among them bacteriocins and other antimicrobial peptides and proteins. Bacteriocins are antimierobial peptides produced by several bacteria species, a nd bacteriocins from propionibacteria are interesting due to their potential application in food preservation. Propionicin Ti is a bacteriocin isolated troni Propionibacteria thoenii aud it is active against all other tesred propionibacteri&except Propion ibactcrium freudenreichii ssp. PAMP is a protease activated antimierobial peptide isolated from Propionibacteriumjensenii, aud is active against otber propionibaiteria and lactobacilli. Propionicin Ti and PAMP are the first antimierobial peptides from pr opionibacteria characteriied ot the inolecular levd. This projeet will further elucidate the produetion, regulation and applications of thesetwo antimicrobiai ~ompounds. The other major goal is to develop molecular metbods and vehieles suitable for propio nibacteria e.g. food grade plasmid veito~s containing bacteriocin genes as genetie markers. Sueb genetic markers will also be of importande in further phylogenetic ~. Iåssifications of our colleetion of propionibacteria.