PURIFICATION, CHARACTERIZATION AND APPLICATIONS OF THERMOSTABLE ALKALINE PROTEASE FROM MARINE STREPTOMYCES SP. D1

Abstract

An extracellular alkaline protease from marine Streptomyces sp. D1 was isolated and characterized. The protease was purified using ammonium sulfate precipitation method, followed by dialysis and Sephadex G-100 gel chromatography, with an 8.82-fold increase in specific activity and a 12.8% recovery. The molecular weight was found to be 28 kDa, determined by SDS-PAGE. The purified enzyme was completely inhibited by phenylmethylsulphonyl fluoride, indicating presence of a serine protease. Protease enzyme was found to have maximum activity at 45⁰C and pH 10, respectively. The enzyme was stable in pH range 8-10 and temperature 45-60⁰C. The enzyme was found to be halotolerant, retains 92.5% of its initial activity after 6 h. The alkaline protease was found stable in presence of non-ionic surfactant (1% Triton X-100) retains 81.5% residual activity after 48 h and 92.57 % residual activity after 6 h with oxidizing agent (1% H₂O₂). The protease inhibited the growth of several pathogenic organisms such as B. subtilis, E. coli, P. aeruginosa and S. aureus. Enzyme also exhibited good hair removal activity from goat skin. These unique properties make this protease an ideal choice in food, pharmaceutical, leather and detergent industries.