Aspergillus terreus NCFT 4269.10 was used for extracellular protease production under liquid static surface (LSSF) and solid-state fermentation (SSF) using powder of chickling vetch peels as the substrate. Maximum production of protease was noticed at 30°C incubated for 96h. The crude protease obtained was purified by ammonium sulphate precipitation, dialysis followed by size-exclusion chromatography using Sephadex G-100 column. The purified protease was subjected to characterization. The characterization of purified protease revealed that enzyme was most stable at pH 5.0, temperature of 60°C and at substrate concentration of 1.0%. The enzyme was thermostable at 70°C for 20 min with optimum enzyme-substrate reaction time of 50 min. Sodium dodecyl sulfate and commercial detergents did not significantly affect protease activity during 30 min of incubation at 30°C. Maximum protease activity was noticed in the presence of Zn2+ followed by Mn2+ out of all the metal ions studied. Protease activity was not considerably affected in the presence of sodium lauryl sulfate and Triton X-100. Phenylmethylsulfonyl fluoride (1 mM), urea and β-mercaptoethanol drastically inhibited the activity of protease. The notable constancy of this enzyme with detergents, additives, inhibitors and metal ions contributes uniqueness to protease and makes it a potential enzyme for noteworthy biotechnological exploitation.

Keywords: Aspergillus terreus, liquid static surface fermentation, pearl millet, protease, solid-state fermentation