Alkaline serine protease from the new halotolerant alkaliphilic Salipaludibacillus agaradhaerens strain AK-R: purification and properties

• Published in: 3 Biotech Vol. 9; no. 11; pp. 1 - 11
• Main Authors: Ibrahim, Abdelnasser S. S., Elbadawi, Yahya B., El-Tayeb, Mohamed A., Al-maary, Khalid S., Maany, Dina Abdel Fattah, Ibrahim, Shebl Salah S., Elagib, Atif A.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.11.2019; Springer Nature B.V
• Subjects: Agriculture; Alkaline protease; Bioinformatics; Biomaterials; Biotechnology; Butanol; Calcium chloride; Cancer Research; Chemistry; Chemistry and Materials Science; Detergents; Diethyl ether; Dimethyl ether; Dithiothreitol; Enzymatic activity; Enzyme activity; Enzymes; Ethylenediaminetetraacetic acids; Laundry; Metal ions; Metalloproteinase; Molecular weight; Optimization; Original; Original Article; pH effects; Protease; Proteins; Purification; Salinity tolerance; Serine; Serine proteinase; Stem Cells; Thermal stability; Toluene; Washing powders; Alkaliphilic bacteria; Soda lakes; Alkaline proteases
• ISSN: 2190-572X; 2190-5738
• DOI: 10.1007/s13205-019-1928-9

Herein, we report the purification and characterization of an alkaline protease from the alkaliphilic Salipaludibacillus agaradhaerens (formerly Bacillus agaradhaerens ) strain AK-R, which was previously isolated from Egyptian soda lakes. The purification procedures resulted in enzyme purification up to 13.3-fold, with a recovery yield of 16.3% and a specific activity of 3488 U/mg protein. AK-R protease was a monomeric protein with an estimated molecular weight of 33.0 kDa. The optimum pH and temperature for AK-R protease were pH 10 and 60 °C, respectively. The enzyme thermostability was significantly enhanced in the presence of CaCl 2 by approximately 1.3-fold. Moreover, under optimal conditions, the K m and V max values of the enzyme were 2.63 mg/ml and 4166.7 U/mg, respectively. PMSF caused complete inhibition of the enzyme activity, suggesting that AK-R belongs to the serine protease family. In addition, the enzyme was completely inhibited by EDTA, revealing the requirement of metal ions for AK-R protease activity; hence, it can be classified as a metalloprotease. AK-R protease is a mostly thiol-independent enzyme, since thiol reductants such as β-mercaptoethanol and dithiothreitol had no effect on the enzyme activity. AK-R protease exhibited high stability in several organic solvents, including butanol, amyl alcohol, dimethyl ether, toluene, diethyl ether and methanol. Moreover, AK-R protease showed significant stability to a variety of surfactants and commercial detergents. The features and properties of AK-R alkaline protease are favourable and suggest its potential applications in various industries, particularly in the laundry detergent industry.