Određivanje strukture netopljivog dekstrana proizvedenog s pomoću bakterije Leuconostoc mesenteroides NRRL B-1149 u prisutnosti maltoze ; Structural Characterization of Insoluble Dextran Produced by Leuconostoc mesenteroides NRRL B-1149 in the Presence of Maltose

Leuconostoc mesenteroides NRRL B-1149 proizvodi dekstran s 52 % α-(1→6) i 40 % α-(1→3) veza. Mala topljivost dekstrana u vodi u svezi je s velikim udjelom α-(1→3) veza. Leuconostoc mesenteroides NRRL B-1149 proizvodi dva tipa enzima, dekstran saharazu, koja se aktivira u prisutnosti saharoze, i fruktan saharazu, koja djeluje u prisutnosti rafinoze, što je potvrđeno bojenjem s Coomasie brilijant plavom bojom. Netopljivi je dekstran sintetiziran pomoću djelomično pročišćene dekstran saharaze u prisutnosti maltoze. Pomoću istog je enzima proizveden i dekstran topljiv u vodi. Netopljivi je dekstran pročišćen taloženjem alkoholom i zatim okarakteriziran FTIR, 1H NMR i 13C NMR spektroskopijom. Spektralnim je analizama potvrđeno da je netopljivi dekstran, proizveden s pomoću Leuconostoc mesenteroides NRRL B-1149, povezan α-(1→6) i α-(1→3) vezama. Pomoću skenirajućeg elektronskog mikroskopa (SEM) utvrđeno je da osušeni i mljeveni dekstran ima vlaknastu strukturu. ; Leuconostoc mesenteroides NRRL B-1149 is known to produce dextran with 52 % α-(1→6) and 40 % α-(1→3) linkages. Low solubility of dextran in water is associated with the presence of high percentage of α-(1→3) linkages. Leuconostoc mesenteroides NRRL B-1149 produces two types of enzymes, dextransucrase and fructansucrase, which are active with sucrose and raffinose, respectively, as confirmed by the activity staining. The insoluble dextran was synthesized using partially purified dextransucrase in the presence of maltose. A water-soluble dextran was also produced by dextransucrase from Leuconostoc mesenteroides NRRL B-1149. The produced insoluble dextran was purified by alcohol precipitation, and then structurally characterized using FTIR, 1H NMR, and 13C NMR spectroscopic techniques. From the spectral analysis, it was confirmed that the insoluble dextran produced by Leuconostoc mesenteroides NRRL B-1149 contained dextran with α-(1→6) linkages and α-(1→3) branched linkages. The surface morphology of dried and powdered dextran studied using scanning electron ...