Investigation of the probiotic activity of autochthonous lactic acid bacteria

Za razvoj probiotičkih proizvoda važno je svojstvo probiotičkih bakterija da utječu na prisutnu mikrofloru u gastrointestinalom ekosustavu, svojom enzimskom aktivnošću i drugim proizvodima svog metabolizma. Stoga su iz autohtonih sireva izolirane bakterije mliječne kiseline (BMK), te su istražena njihova probiotička svojstva. 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. Preživljavanje u nepovoljnim uvjetima gastrointestinalnog trakta (GIT) jedan je od glavnih kriterija pri izboru probiotika. Autohtoni izolati BMK, odabrani na temelju in vitro testa simuliranih gastrointestinalnih uvjeta, preživljavaju proces liofilizacije u većem broju kad su prisutni lioprotektori obrano mlijeko i inulin. Izolat BGLE1-6 preživljava bolje u prisutnosti inulina, dok izolati BGAL1-1 i ZG3-17 bolje preživljavaju proces liofilizacije u obranom mlijeku u prahu.The ability of probiotic bacteria to influence the activity of colonizing microflora in the gastrointestinal ecosystem to deliver the functional enzymes or other byproducts is the rationale for the development of probiotic-containing products. Therefore, lactic acid bacteria isolated from autochthonous cheeses where explored for their probiotic properties. 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 the most important criteria in probiotic selection. Indigenous isolates of LAB, selected on the basis on in vitro simulated gastrointestinal tract conditions test, survive freezedrying process in greater numbers when they are present lyoprotector skim milk or inulin. Isolate BGLE1-6 survives better in the presence of inulin, while isolates BGAL1-1 and ZG3- 17 better survive freeze-drying process in skimmed milk powder