Screening and characterization of proteases produced by deep-sea cold seep bacteria

Fifty protease-producing strains were screened from sediment of deep-sea cold seep, and divided into four different categories: Bacillus, Pseudoalteromonas, Vibrio, and Alteromonas according to the sequences of 16s rRNA. Their abilities to produce protease, amylase, and lipase were determined, and a Bacillus strain gcc-1 displayed very strong alkaline protease activity and stability under different thermal and acidic conditions. The purification of the protease produced by strain gcc-1 was carried out by precipitation with ammonium sulfate, and sequentially chromatographed by anion exchange column and gel filtration. The purified protease showed a single band at the molecular weight of 28 kDa by SDS-PAGE. The characterization results show that the purified protease exhibited a considerable activity and stability in a wide thermal range of 10–80 °C and a wide acidic range of pH 6.5–11.5, and displayed highest activity at 40 °C and pH 8.5. Notably, the protease still maintained high activity even at low to 10 °C. Furthermore, the protease exhibited good stability in presence of different surfactants, organic solvents, oxidizing agent H2O2, and commercial detergents. Therefore, the protease produced by gcc-1 is a cold active and high stable enzyme, and has a promising potential in laundry detergent as an additive.