Phenotypic and genotypic characterization of lactic acid bacterial strains for the production of probiotics and functional starter cultures

Cilj ovog rada bio je izolacija, identifikacija i karakterizacija prirodno prisutnih sojeva bakterija mliječne kiseline, odgovornih za autentičan okus i teksturu tradicionalnog svježeg sira, kako bi se koristile kao funkcionalne starter kulture s probiotičkim djelovanjem ili kao dodatak starter kulturama. Posebno je istraženo antimikrobno djelovanje s naglaskom na bakteriocinsku aktivnost izoliranih sojeva kao važno svojstvo u suzbijanju nepoželjnih mikroorganizama tijekom biotehnološke proizvodnje fermentiranih proizvoda, a također i važno probiotičko svojstvo pri natjecanju za mjesta vezanja i nutrijente u gastrointestinalnom traktu domaćina. Fenotipski i genotipski okarakterizirani sojevi bakterija mliječne kiseline su proizvedeni kao suhe aktivne kulture, postupkom liofilizacije, pri čemu je istražen zaštitni učinak različitih lioprotektora na njihovo preživljavanje. Provedena je i mikroinkapsulacija odabranih sojeva, u različitim nosačima, uz ispitivanje zaštitnog utjecaja mikroinkapsulacije u stresnim uvjetima. Svježi sirevi, proizvedeni s autohtonim sojevima pojedinačno ili u kombinaciji s komercijalnom starter kulturom su uspoređeni sa svježim sirom proizvedenim samo s komercijalnom starter kulturom te s tradicionalnim svježim sirom.The aim of this study was isolation, identification and characterization of autochthonous lactic acid bacterial strains, responsible for the authentic aroma and texture of traditional fresh cheese, to use it as functional starter cultures with probiotic activity or as adjunct to the starter cultures. Antimicrobial activity, with a focus to bacteriocinogenic activity of isolated lactic acid bacteria strains was especially investigated because of its relevance in the inhibition of undesirable microorganisms during the biotechnological production of fermented products and as it is important probiotic property at competition for the nutrients and binding sites in the gastrointestinal tract. Phenotypically and genotypically characterised lactic acid bacterial strains were produced as dry active cultures with lyophilisation where protective role of lyoprotectors on the strain viability was investigated. In addition, microencapsulation of the selected lactic acid bacteria was performed in several carriers. The protective role of microencapsulation under different stress conditions was investigated, too. Fresh cheeses produced with autochthonous strains, singly or in combination with commercial starter, were compared with fresh cheese produced only with commercial starter culture and with traditional fresh cheese