title: Protease production with sweet potato residue by solid state fermentation.
abstract: The sweet potato residue being at the initial moisture content 50-58%, initial pH 3.5-4.3, supplemented with rice bran, and minerals, and incubated at 20-26 degrees C for 5 days was the optimal conditions for protease production with Aspergillus niger NTU-AM-1 by solid state fermentation. Protease could be recovered by shaking at room temperature for one hour and extracted with five times volume of 0.1% NaCl solution. The yield of protease was 814 units per gram dry weight of substrate. Partially purified protease with DEAE-Sephacel column chromatography was thermally stable and able to retain 80-100% of activity in pH 4.0-5.5 at 55 degrees C for 40 minutes. In addition, the activity of protease was stimulated by the presence of EDTA and cysteine, but was inhibited by the addition of HgCl2.
mesh_terms: D001234:Aspergillus niger / Q000378:metabolism*; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000378:metabolism; D010447:Peptide Hydrolases / Q000096:biosynthesis* / Q000302:isolation & purification; D010758:Phosphorus / Q000494:pharmacology; D013696:Temperature; D014675:Vegetables
chemical_list: D010758:Phosphorus; D010447:Peptide Hydrolases; D009584:Nitrogen