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Purification and biochemical characterization of a novel detergent-stable serine alkaline protease from Bacillus safensis strain RH12
1 , 1 , 1 , 2 , 2 , 3 , 2 , * 2
1  Laboratory of Microbial Biotechnology and Engineering Enzymes (LMBEE), Centre of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour Km 6, PO Box 1177, Sfax 3018, Tunisia
2  Laboratory of Microbial Biotechnology and Engineering Enzymes (LMBEE), Centre of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour Km 6, P.O. Box 1177, Sfax 3018, Tunisia
3  STE JMAL (EJM)-Laundry Detergent Industry, Z.I. Avenue August 13, Z.I. Poudriere 1, P.O. Box 407, Boustene, Sfax 3000, Tunisia

Abstract:

Enzymes are fascinating the researchers because of their enormous power of catalysis and eco-friendly nature. In biotechnological processes, diversity of microbes is studied, and different metabolic reactions entitle a potential repository that direct valuable production of desirable products. Although tremendous scientific and technological advances have been made by researchers and industrial enzyme producers, and despite the large flow of data on bacterial proteases, little data is currently available on the purification and characterization of proteases and keratinases from B. safensis. Accordingly, the present study reports on the purification and biochemical characterization of a novel detergent-stable protease (SAPRH) from B. safensis strain RH12 isolated from offshore sediment in the Gulf of Gabes (Tunisia). A novel extracellular protease (SAPRH) was hyper-produced (9,000 U/mL) from Bacillus safensis RH12. The enzyme was purified to homogeneity using salt-precipitation, heat-treatment, and FPLC anion-exchange chromatography. The purified enzyme is a monomer of molecular mass of ~28 kDa. The NH2-terminal 23 amino-acid sequence of SAPRH showed high homology with those of Bacillus-proteases. SAPRH showed optimal activity at pH 9 and 60°C. It is strongly inhibited by PMSF and DFP, showing that it belongs to the serine-proteases family. Moreover, SAPRH was extremely stable at a broad range of temperature and pH retaining 85% of its activity at 50°C and 75% at pH 11. The enzyme exhibited excellent-stability and compatibility with surfactants and commercial detergents, showing 90% stability with SDS and 100% stability with Class commercial laundry detergent. One of the distinguishing properties is its catalytic efficiency, which is higher than that of Alcalase 2.5 L, type DX (commercial enzyme) and SAPB from B. pumilus strain CBS. Interestingly, the results of the wash performance analysis demonstrated considerably good de-staining at 40°C for 30 min with low supplementation (500 U/mL). Accordingly, such protease can be considered as a good detergent-additive in detergent industry.

Keywords: Protease; Bacillus safensis; Offshore oil field; Detergent; Wash performance.
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