Purification and Characterization of a Cold Alkaline Protease from a Psychrophilic Pseudomonas aeruginosa HY1215

A novel alkaline protease was purified from Pseudomonas aeruginosa HY1215 using ammonium sulfate, DEAE-Sepharose and Sephacryl S-200 gel filtration chromatographic techniques. The protease had a relative molecular weight of 32.8 KDa by SDS-PAGE, and the optimal temperature and pH for excellent stability and activity were determined as 25 °C and 10.0, respectively. Within the pH range of 7.0–11.0, the protease had a good stability, which could retain more than 80 % of its original activity; in the temperature range of 15–35 °C, the protease had a higher activity, and its activity at 20 °C could amount to 85 % of the maximum activity at 25 °C. Besides, the enzyme activity showed a valuable stability towards several commercially available surfactants (Tween-80, Tween-40, and Triton X-100) and bleaches (H2O2) even when their concentrations ranged up to 2.0 and 1.6 %.