Oxidant and SDS-stable alkaline protease from Bacillus clausii I-52: production and some properties

Aims: An investigation was carried out on an oxidative and SDS-stable alkaline protease secreted by Bacillus clausii of industrial significance. Methods and Results: Maximum enzyme activity was produced when the bacterium was grown in the medium containing (g l−1): soyabean meal, 15; wheat flour, 10; liquid maltose, 25; K2HPO4, 4; Na2HPO4, 1; MgSO4·7H2O, 0·1; Na2CO3, 6. The enzyme has an optimum pH of around 11 and optimum temperature of 60°C. The alkaline protease showed extreme stability towards SDS and oxidizing agents, which retained its activity above 75 and 110% on treatment for 72 h with 5% SDS and 10% H2O2, respectively. Inhibition profile exhibited by phenylmethylsulphonyl fluoride suggested that the protease from B. clausii belongs to the family of serine proteases. Conclusions: Bacillus clausii produced high levels of an extracellular protease having high stability towards SDS and H2O2. Significance and Impact of the Study: The alkaline protease from B. clausii I-52 is significant for an industrial perspective because of its ability to function in broad pH and temperature ranges in addition to its tolerance and stability in presence of an anionic surfactant, like SDS and oxidants like peroxides and perborates. The enzymatic properties of the protease also suggest its suitable application as additive in detergent formulations.