Composition and properties of autochthonus population of lactic acid bacteria in traditionally produced cheeses in brine

Autohtonu populaciju bakterija mliječne kiseline (BMK) u tradicionalno proizvedenom siru u salamuri čine bakterijske vrste koje pripadaju rodovima Lactococcus, Enterococcus, Leuconostoc i Lactobacillus. Odabrano je 14 autohtonih izolata koji su pomoću klasičnih mikrobioloških metoda okarakterizirani kao gram-pozitivni, katalaza-negativni, štapići i koki, koji spuštaju pH vrijednost hranjive podloge, jer proizvode mliječnu kiselinu u visokim koncentracijama. Autohtoni sojevi BGRE2-24 I BGRE2-43 najuspješnije preživljavaju simulirane uvjete gastrointestinalnog trakta. Ispitana je i osjetljivost bakterija na 12 antibiotika, te je utvrđeno da je večina bakterijkih sojeva osjetljiva na sve ispitivane antibiotike. Međutim, sojevi VL1-13 i VL1-24 nisu bili osjetljivi na neomicin, vankomicin i streptomicin, sojevi BGBU1-41, BGRE2-24 i BGRE2-57 na neomicin i streptomicin, sojevi BGBU1-42, BGRE2-21 i BGRE2-43 na streptomicin, a soj BGBU1-16 nije bio osjetljiv na neomicin. Analizom površinskih proteina autohtonih BMK pomoću SDS-PAGE utvrđeno je da se svi sojevi BMK međusobno razlikuju prema dobivenom proteinskom profilu.Autochthonus population of lactic acid bacteria (LAB) in traditionally produced cheeses in brine belongs to the genera Lactococcus, Enterococcus, Leuconostoc and Lactobacillus. Selected 14 autochthonous isolates were characterized as gram-positive, catalase-negative rods and cocci by conventional microbiological methods. Bacterial strains were successful in lowering pH value of the medium and synthesized high concentrations of lactic acid. According to the results, autochthonous LAB BGRE2-24 and BGRE2-43 have shown high survival rates in simulated gastrointestinal tract conditions. Investigation of the susceptibility to 12 different antibiotics revealed that most of tested isolates were susceptible to all tested antibiotics. Strains VL1-13 and VL1-24 were not sensitive to neomycin, vancomycin and streptomycin, strains BGBU1-41, BGRE2-24 and BGRE2-57 were resistant to neomycin and streptomycin, strains BGBU1-42, BGRE2-21 and BGRE2-43 were not sensitive to streptomycin, while strain BGBU1-16 was resistant to neomycin. The analysis of surface proteins of the autochthonous LAB using SDS-PAGE showed that all strains LAB are different according to the obtained protein profile