Production, Purification and Physicochemical Properties of an Exo-Polygalacturonase from Aspergillus niger SW06

In this study, exo-polygalacturonase (exo-PG) production from Aspergillus niger SW06 was optimized by central composition design and high amount of 21.51 units mL(-1) could be achieved in optimizing growth conditions. Both gel filtration and ion exchange chromatography revealed a single exo-PG activity peak, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the purified protein showed a single band with a molecular mass of 66.2 kDa. The purified enzyme exhibited maximal activity in the presence of 1% citrus pectin at the temperature of 55 degrees C and pH of 5.0. The enzyme was stable within the pH range of 3.0-5.0 and below 60 degrees C. The Michaelis constant (K-m) and maximum velocity (V-max) of the enzyme was found to be 0.58 mg mL(-1) and 20.66 mu mol (mL min)(-1), respectively. The thermostable and acidic nature for the activity of this exo-PG make it possible to have wide range of industrial applications.