Abstract

The increase in agricultural practices has necessitated the judicious use ofagricultural wastes into value added products. In this study, an extracellular, organic solvent and oxidant stable, serine protease was produced by Aspergillus flavusMTCC 9952 under solid state fermentation. Maximum protease yield was obtained when the strain was grown under wheat bran and corn cob mixture (1:1) incubated for 48 h at pH 9.0 and temperature 37°C with 50% of initial moisture content. The partially purified enzyme showed wide range of pH optima (8.0-12.0) and pH stability (7.0-12.0), whereas, optimum temperature was 40°C and was stable over a wide range of temperature 30-45°C. The protease was extremely stable towards several organic solvents. The enzyme retained 80% of its original activity in the presence of non ionic and ionic surfactants and 100% with 10% H₂O₂ after 1 h of incubation at 30°C. In addition, the enzyme showed excellent compatibility with some commercial powder detergents. The compatibility of our protease with several detergents, oxidants and organic solvents suggests its possible use in detergent industry and peptide synthesis.

Key words: Alkaline protease, solid state fermentation, PMSF, organic solvent.

Abbreviation

SmF, Submerged fermentation; SSF, solid-state fermentation;PMSF, phenylmethylsulfonyl fluoride; TCA, trichloroacetic acid; EDTA, ethylene-diaminetetraacetic acid; SDS, Sodium dodecyl sulphate.