Purification and characterization of tannase from the local isolate of Aspergillus niger

Fungi of genus Aspergillus are active producers of extracellular tannase, and characteristics of enzyme production by local Aspergillus species have been well studied. The aim of this experimental study is isolation and partial purification of tannase enzyme from the Aspergillus niger fungus species. The purification was achieved by applying respectively ammonium sulfate (50-70%), dialysis with a specific activity 1227.08 (unit/mg protein), then passed the enzymatic extract through superdex 200 column in the gel filtration chromatography by using ÄKTA Pure 25 apparatus, the activity and the specific activity reached to 525.12 (unit/ml) and 2917.33 (unit/mg protein) respectively, with purification fold of 11.629 and yield 18.40%. One peak was obtained from an enzyme purity, which diagnosed by the absence of denaturation substances for protein SDS. Characteristics of pure enzyme showed that the molecular weight of the pure enzyme was determined, and it was found that the weight of enzyme was 95.49 KDa by using sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis, the enzyme was active in pH range 3 to 6 and temperature of 20 to 50°C. The optimum pH and the temperature for tannase activity were recorded to be pH 5 and 35°C, respectively. Moreover, the tannase activity was inhibited by Cu, Fe and Hg ions while increased by Mg and K ions when added at 1 and 5 mM