Enhanced Production and Characterization of a Highly Stable Extracellular Protease from an Extreme Halophilic Isolate Salicola marasensis

Owing to their superior catalytic activity in the extreme conditions, extremozymes have found the potential biotechnological applications for industrial purposes. A robust extracellular protease activity was detected in the culture broth of Salicola marasensis, an extreme halophilic bacterium, after a 48 h-incubation. The effect of different media ingredients in a liquid state fermentation was followed with the aim of improving the enzyme production yield. Fractional factorial and Box-Behnken designs were applied to get a 3.4 fold (from 6.0 to 20.3 U mL−1) improvement of protease production. The distinguishing features of this enzyme were stability at a wide range of pH (5.0–11.0) and temperature (25–60 °C), significant compatibility towards organic solvents, metal ions, chemicals, and surfactants, and hydrolysis of a variety of substrates. The properties of this enzyme can be of tremendous help in terms of the halophilic proteolytic extract’s industrial applications.