극한성 미생물Deinococcus geothermalis 유래 재조합 글루코아밀레이즈의 전분 분해 활성 특징

Characterization of the Starch Degradation Activity of recombinant glucoamylase from Extremophile Deinococcus geothermalis

This work focused on characterization of the starch degradation activity from extremophile strain Deinococcus geothermalis. Glucoamylase gene from D. geothermalis was cloned and overexpressed by pET-21a vector using E. coli BL21 (DE3). In order to characterize starch degrading activity of recombinant glucoamylase, enzyme was purified using HisPur Ni-NTA column. The recombinant glucoamylase from D. geothermalis exhibited the optimum temperature as 45°C for starch degradation activity. And highly acido-stable starch degrading activity was shown at pH 2. For further optimization of starch degrading activity with metal ion, various metal ions (AgCl 2 , HgCl 2 , MnSO 4⦁ 4H 2 O, CoCl 2⦁ 6H 2 O, MgSO 4 , ZnSO 4⦁ 7H 2 O, K 2 SO 4 , FeCl 2⦁ 4H 2 O, NaCl, or CuSO 4 ) were added for enzyme reaction. As results, it was found that FeCl 2⦁ 4H 2 O or MnSO 4⦁ 4H 2 O addition resulted in 17% and 9% improved starch degrading activity, respectively. The recombinant glucoamylase from D. geothermalis might be used for simultaneous saccharification and fermentation (SSF) process at high acidic conditions.