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Keywords:

  • coconut pith;
  • Aspergillus niger;
  • cellulase;
  • cellobiase;
  • CMCase;
  • solid state fermentation;
  • inoculum size;
  • particle size;
  • nutrient level;
  • fermentation time

Abstract

Coconut coir pith, available in abundance especially in tropical countries, was studied as a substrate for the production of cellulase[1,4(1,3;1,4)-β-D-glucan 4-glucanohydrolase, EC 3.2.1.4] and β-D-glucosidase(β-D-glucoside glucohydrolase, EC 3.2.1.21) in solid state fermentation. The effects of fermentation time, nutrient level, substrate particle size and inoculum size have been examined for optimal production of these enzymes by the fungal strain Aspergillus niger NCIM 1005. The highest filter paper activity (FPA) of 4.11 IU g−1, carboxyl methyl cellulose (CMCase) activity of 15·55 IU g−1 and cellobiase activity of 9·31 IU g−1 were obtained after 7 to 8 days of fermentation. Reese and Mandel's mineral solution in the substrate to mineral solution ratio of 1:10 (w/v) supported high cellulase and cellobiase activities. An inoculum size of 20–50% (v/v) based on the volume of mineral medium and substrate average particle size of 375 μm were optimum for enzyme production.