Characterization of Lactobacillus species isolated from traditionally produced cheese

U ovom radu provedena je izolacija autohtonih izolata iz tradicionalno proizvedenog sira s ciljem odabira predstavnika Lactobacillus vrsta kao potencijalnih probiotičkih starter kultura. Odabrani autohtoni izolati su pomoću klasičnih mikrobioloških metoda okarakterizirane kao gram-pozitivni, katalaza-negativni, nesporogeni, štapići, koji uspješno spuštaju pH vrijednost hranjive podloge, te sintetiziraju visoke koncentracije mliječne kiseline što su karakteristike bakterija mliječne kiseline (BMK). Identifikacija sekvencioniranjem 16S rRNA gena pokazala je da među odabranim autohtonim BMK prisutno 14 različitih bakterijskih sojeva iz roda Lactobacillus. Autohtoni BMK BGGO 5-3, ZG 2-42, ZG 2-25 i ZG 3-17 najuspješnije preživljavaju simulirane uvjete gastrointestinalnog trakta. Ispitana je ojetljivost bakterija na antibiotike, te je utvrđeno da Lactobacillus pentosus BGGO 5-3 nije osjetljiv na neomicin, streptomicin i vankomicin, kao i sojevi Lactobacillus pentosus ZG2-42 i Lactobacillus pentosus ZG2-25, dok Lactobacillus pentosus ZG3-17 nije osjetljiv na neomicin i streptomicin. Analizom površinskih proteina autohtonih BMK pomoću SDS-PAGE utvrđeno je da soj BGGO 7-28 posjeduje S-layer protein koji može imati važnu ulogu u probiotičkim svojstvima ovog soja.In this paper an isolation, of the autochthonous isolates from traditionally produced cheese was performed aimed to select representatives of Lactobacillus species with a potential as probiotic starter cultures. Selected autochthonous isolates were characterized as gram-positive, catalase-negative rods by conventional microbiological methods, which were successfully in lowering pH value of the medium and synthesized high concentrations of lactic acid what are main characteristics of lactic acid bacteria (LAB). Identification performed by 16S rRNA gene sequencing revealed that between selected autochthonous LAB 14 different strains were identified as representatives of Lactobacillus. Autochthonous LAB BGGO 5-3, ZG 2-42, ZG 3-17 and ZG 2-25 showed high survival rates in simulated gastrointestinal tract conditions. Investigation of the susceptibility to different antibiotics revealed that Lactobacillus pentosus BGGO 5-3, Lactobacillus pentosus ZG2-42 and Lactobacillus pentosus ZG 2-25 were not sensitive to neomycin, streptomycin and vancomycin, while strain Lactobacillus pentosus ZG 3-17 was resistant to neomycin and streptomycin. The analysis of surface proteins of the autochthonous LAB using SDS-PAGE showed that the strain BGGO 7-28 posses S-layer protein which could be important in the probiotic properties of this strain