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 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 °C and pH of 5.0. The enzyme was stable within the pH range of 3.0-5.0 and below 60 °C. The Michaelis constant (Km) and maximum velocity (Vmax) of the enzyme was found to be 0.58 mg mL and 20.66 μmol (mL min), respectively. The thermostable and acidic nature for the activity of this exo-PG make it possible to have wide range of industrial applications.