| Popis: |
U proizvodnji egzopolisaharida (EPOL) u posljednje vrijeme se posebno istražuju bakterije mliječne kiseline (BMK) s ciljem poboljšanja svojstava proizvoda i unaprjeđenja kvalitete ljudskog zdravlja. Također, neki sojevi bakterija mliječne kiseline sintezom egzopolisaharida pridonose poboljšanju teksture i viskoznosti fermentiranih proizvoda. Stoga je cilj ovog završnog rada bio ispitati sposobnost različitih sojeva BMK da sintetiziraju egzopolisaharide u MRS hranjivoj podlozi suplementiranoj s različitim izvorima ugljika (2% w/v fruktoza, galaktoza). Soj Lactobacillus fermentum D12 se pokazao kao najbolji producent egzopolisaharida. Nakon provedenog uzgoja L. fermentum D12, slijedila je izolacija egzopolisaharida s površine stanica L. fermentum D12 te iz supernatanta ove bakterijske kulture nakon čega je izračunata masa egzopolisaharida. Čistoća egzopolisaharida na prisutnost proteina se provjerila UV-spektrofotometrijom pri valnoj duljini od 190 do 350 nm. Koncentracija prisutnih proteina kod uzoraka egzopolisaharida izoliranih s površine stanica bila je puno veća, u odnosu na one izolirane iz supernatanta kulture. In the recent years, lactic acid bacteria (LAB) have been specifically investigated in the frame of the exopolysaccharide production, because of its impact in improving product properties and improving the quality of human health. In addition, several lactic acid bacterial species, that synthesis exopolisaccharides, contribute to improving texture and viscosity of fermented products. Therefore, the aim of this final study was to examine the ability of several LAB to synthesis exopolisaccharides in MRS nutrient medium supplemented with different carbon sources (2% w/v fructose, galactose). Lactobacillus fermentum D12 has been shown, as the best exopolisaccharides producer among tested strains. After producing cultivation of L. fermentum D12, isolation and mass calculation of the exopolisaccharides from the cell surface and from the culture supernatant, was performed. The purity of the exopolisaccarides on the presence of the proteins was verified by UV spectrophotometry at wavelenngthsfrom 190 to 350 nm. The concentration of proteins of exopolisaccharides samples isolated from the surface of the cell was much higher than those isolated from the culture supernatant. |
