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Production, purification and biochemical characterization of an exo-polygalacturonase from Aspergillus niger MTCC 478 suitable for clarification of orange juice

Anand, Gautam, Yadav, Sangeeta, Yadav, Dinesh
3 Biotech 2017 v.7 no.2 pp. 122
Aspergillus niger, acetone, chromatography, clarification (processing), copper, enzyme activity, fungi, industrial applications, molecular weight, orange juice, pH, polygalacturonase, silver, solid state fermentation, tea, temperature, wheat bran
Polygalacturonases (PG) represent an important member of pectinases group of enzymes with immense industrial applications. A fungal strain Aspergillus niger MTCC478 was used for the production of polygalacturonase both under submerged and solid-state fermentation condition. Further its production was optimized under solid-state fermentation condition with media comprising of wheat bran and tea extract. Purification of an exo-PG was achieved by acetone precipitation (60–90%) and CM-cellulose column chromatography revealing 15.28-fold purification with a specific activity of 33.47 U/mg protein and 1.2% yield. A relative molecular mass of purified PG was approximately 124.0 kDa. The pH and temperature optimum was found to be 4 and 50 °C, respectively. The k cₐₜ and K ₘ value for degradation of PGA by the purified enzyme was found to be 194 s⁻¹ and 2.3 mg/mL, respectively. Cu²⁺ was found to enhance the PG activity while Ag⁺ completely inhibited the enzyme activity. The application of the purified PG in orange juice clarification was elucidated.