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Purification and Characterization of Polygalacturonase Produced by Aspergillus niger AN 07 in Solid State Fermentation

Polygalacturonase, an industrial enzyme has been produced from various fungal isolates using solid state and submerged fermentation techniques. The challenge has been yield, extraction and cost of production. In the present study, a low cost solid substrate, dried papaya peel was employed for polygalacturonase production using Aspergillus niger AN07. Polygalacturonase enzyme from Aspergillus niger AN07 was purified to 24.8 fold with a 52.6% recovery through anion exchange chromatography on DEAE-cellulose and gel filtration chromatography using Sephadex G200. The SDS-PAGE revealed that the enzyme was monomeric with a molecular weight of 64.5 kDa. The optimum pH and temperature were 5.0 and 55°C, respectively. This enzyme was stable over a wide pH range (4.0–7.0) and relatively high temperature of 55°C for 1 h. The Km and Vmax values of polygalacturonase for polygalacturonic acid were 2.6 mg/l and 181.8 μmol/ml/min, respectively. The purified enzyme could digest the polygalacturonic acid into oligosaccharides with a small amount of galacturonic acid as visualized on thin layer chromatography.