Production of Acid Protease by Aspergillus niger Using Solid State Fermentation

The study is concerned with the isolation and screening of Aspergillus niger strains for the biosynthesis of acid protease using solid state fermentation. Thirteen A. niger strains capable of producing proteases were isolated from the soil. Of all the isolates, Aspergillus niger IHG9 was found to be the best producer of protease. Different agricultural by-products were evaluated as fermentation substrate and maximum enzyme biosynthesis (5.2U/g) was obtained when sunflower meal was used as a substrate. Optimum temperature, pH and fermentation period for the production of protease were 30°C (7.2 U/g), 4.5(7.0 U/g) and 72 hrs (7.2 U/g), respectively. The growth and production of protease by Aspergillus niger IHG9 was also studied by varying the carbon and nitrogen sources. Fructose (7.8 U/g) and beef extract (8.5 U/g) were found as best carbon and nitrogen sources, respectively. A spore inoculum at a level of 10% was found best for protease production (8.6U/g) by Aspergillus niger IGH9 under solid state fermentation conditions.