Optimization of cellulase production by Aspergillus niger NCIM 1207.

Aspergillus niger NCIM 1207 produces high levels of extracellular beta-glucosidase and xylanase activities in submerged fermentation. Among the nitrogen sources, ammonium sulfate, ammonium dihydrogen orthophosphate, and corn-steep liquor were the best for the production of cellulolytic enzymes by A. niger. The optimum pH and temperature for cellulase production were 3.0-5.5 and 28 degrees C, respectively. The cellulase complex of this strain was found to undergo catabolite repression in the presence of high concentrations of glucose. Glycerol at all concentrations caused catabolite repression of cellulase production. The addition of glucose (up to 1% concentration) enhanced the production of cellulolytic enzymes, but a higher concentration of glucose effected the pronounced repression of enzymes. Generally the growth on glucose- or glycerol-containing medium was accompanied by a sudden drop in the pH of the fermentation medium to 2.0.