| Abstract | Provedena je karakterizacija pojedinih sojeva autohtone populacije bakterija mliječne kiseline (BMK), izoliranih iz tradicionalno proizvedenog sira u salamuri, kao probiotičkih starter kultura. Iz svježeg sira odabrano je 19 različitih autohtonih izolata koji su identificirani kao predstavnici BMK, te su provedena istraživanja probiotičkog koncepta. Kako bi se isključila mogućnost širenja antibiotičke rezistencije, ispitana je i osjetljivost autohtonih izolata BMK na različite skupine antibiotika. Autohtoni izolati BMK su osjetljivi na ispitane antibiotike, osim na vankomicin, za koji predstavnici Lactobacillus vrsta imaju urođenu rezistenciju. Uspješno preživljavanje u gastrointestinalnom traktu (GIT) jedan je od glavnih kriterija pri izboru probiotika. Ispitano je preživljavanje autohtonih izolata BMK u simuliranim uvjetima GIT. Većina autohtonih izolata BMK podnosi nepovoljne uvjete GIT in vitro, a osobito visok stupanj preživljavanja pri pH vrijednosti želučanog soka 2,5, pokazali su bakterijski sojevi: BGGO11-3, BGGO11-47, te BGAL 1-1, BGAL 1-5, BGAL1-39, BGLE 1-14 i BGLE 1-16. Adhezija na površinu epitelnih stanica je bitan preduvjet za kolonizaciju probiotičkih sojeva u GIT jer omogućava dugotrajnije djelovanje probiotičkih bakterija na crijevnu mikrofloru i imunološki sustav domaćina, te spriječava kolonizaciju nepoželjnih patogenih bakterija. Ispitana je stoga i adhezija autohtonih izolata BMK na Caco-2 epitelne stanice. Prema dobivenim rezultatima, adhezija sojeva BGG07-25 i BGG011-17 pokazala se najuspješnom. Ispitana je i antimikrobna aktivnost supernatanata kultura autohtonih izolata prema bakteriji Salmonella enterica s. Typhimurium FP1. Inhibicijsko djelovanje autohtonih izolata BMK prema S. Typhimurium FP1 osobito je bilo izraženo kada je pH vrijednost supernatanta kulture bila u kiselom području, dok su supernatanti kultura, autohtonih izolata BGAL1-1, BGAL1-14, BGAL1-39 i BGLE1-6 uspješno inhibirali rast S. Typhimurium FP1 i kada je pH vrijednost supernatanta kulture podešena na 6,5, odnosno kada je uklonjen inhibicijsku učinak mliječne kiseline, što može upućivati na bakteriocinsku aktivnost. |
| Abstract (english) | The characterization of the different autochthonous lactic acid bacteria (LAB) strains, naturally present in traditional made white pickled cheese, was undertaken in order to define potential probiotic starter cultures. 19 different autochthonous isolates were selected from white pickled cheese, which were previously identified as representatives of LAB and were further examined by probiotic concept investigations. In order to exclude possibility of spreading an antibiotic resistance, selected isolates were tested for their antibiotic susceptibility. Autochthonous LAB were found susceptible to all of the antibiotics tested excluding vancomycin, for which representatives of the Lactobacillus species are known to poses an innate resistance. Survival in a high bacterial count in the gastrointestinal tract (GIT) is one of the most important criteria in probiotic selection. Autochthonous LAB strains were examined for their ability to survive harsh simulated GIT conditions in vitro. Autochthonous LAB strains mostly survived well harsh GIT conditions in vitro, and especially the high level of recovery showed strains BGGO11-3, BGGO11-47, BGAL 1-1, BGAL 1-5, BGAL1-39, BGLE 1-14 and BGLE 1-16, even when pH level of simulaeted gastric juice was 2,5. Adhesion on epithelial cell sirface is a major prerequisite for the colonisation of the GIT by probiotic strain what enables longer influence of the probiotic on intestial microflora and imunostimulation of the host and aditionally inhibits colonistion of the pathogens. Hence adhesion of the autochthonous LAB to Caco-2 epithelial cells was investigated. According to the results, strains BGG07-25 and BGG011-17 adhered the best to Caco-2 epithelial cells. Antimicrobial acitivity of the culture supernatans of 19 strauins against Salmonella enterica s. Typhimurium FP1 was tested. Antimicrobial activity of autochthonous LAB against S. Typhimurium FP1 was especially pronouced when pH of the culture supernantant was acid, while culture supernatants of the isolates BGAL1-1, BGAL1-14, BGAL1-39 and BGLE1-6 inhibitated S. Typhimurium FP1 growth even when pH of the culture supernatant was set up at 6,5, i.e. when inhibiotion influence of lactis acid was eliminated. This could indicate on bacteriogenic activity of the these strains. |
