Isolation and characterization of a broad pH- and temperature-active, solvent and surfactant stable protease from a new strain of Bacillus subtilis

Bacillus subtilis BUU1 from marine sediment collected in the Gulf of Thailand produced an extracellular protease. The enzyme was purified by 14.36-fold using 80–90% ammonium sulfate precipitation and Sephadex G-75. Molecular mass of the purified protease was estimated at 32 kDa on SDS-PAGE. The enzyme was highly active in a pH range of 3.0–12.0, the optimum being 11.0. After 6 h of incubation at different pH, the enzyme retained more than 80% of its activity at alkali pHs (7.0–12.0). The enzyme exhibited optimum activity over a broad temperature range (10–80 °C) with the maximum at 50 °C. The enzyme was stable between 60 and 80 °C for 72 h, showed excellent stability towards surfactants and was relatively compatible with oxidizing and bleaching agents. It was partially inhibited by metal salts and displayed remarkable stability towards a range of hydrophobic organic solvents. These promising properties make this enzyme a candidate biocatalyst for future use in biotechnological applications.