Alkaline protease from a new halotolerant alkaliphilic Bacillus agaradhaerens strain ak-r isolated from egyptian soda lakes


  • Abdelnasser Salah Shebl Ibrahim 1- King Saud University
  • Ali A Al-Salamah King Saud University
  • Yahya B Elbadawi King Saud University
  • Mohamed A El-Tayeb King Saud University
  • Khalid S Almaary King Saud University
  • Atif A. Elagib King Saud University
  • Abdelnasser Salah Shebl Ibrahim National Centre for Research



Bacillus agaradhaerens, Soda lakes, Alkaline protease, Enzyme production, 16S rDNA, Fermentation


Alkaline proteases are hydrolytic enzymes that cleave peptide bonds in proteins and peptides in alkaline conditions, which occupy a pivotal importance with respect to their industrial applications. This study aimed to isolate new alkaline protease producing alkaliphilic bacteria from Egyptian soda lakes and optimize the fermentation process to enhance the enzyme production. The extensive screening process of the samples collected from Egyptian soda lakes resulted in isolation of a potent alkaline protease producing alkaliphilic strain AK-R. The isolate was identified as Bacillus agaradhaerens strain AK-R based on 16S rRNA gene analysis (99%). Wheat bran and gelatin supported maximum alkaline protease production as carbon and nitrogen sources, respectively. Strain AK-R is halo-tolerant thermo-tolerant alkaliphilic bacterium in nature, as it can grow over a wide range of NaCl concentrations (up to 25%) and up to 55 °C, with maximal growth and enzyme production at 2.5-5%, and pH 11 at 35 °C. Among the tested cations, only Mg2+ and Ca2+ ions significantly enhanced the enzyme production by about 1.2, and 1.3 fold compared to control, respectively. Alkaline protease secretion was coherent with the growth pattern, reaching maximal yield after about 32 h (mid stationary phase). In conclusion a new halo-tolerant thermo-tolerant alkaliphilic alkaline protease producing Bacillus agaradhaerens strain AK-R was isolated from Egyptian soda lakes. Optimization of the nutritional and cultivation conditions resulted in increase of enzyme yield by 20 fold. Strain AK-R and its extracellular alkaline protease with salt, pH and temperature, tolerance signify their potential application in laundry and pharmaceuticals industries.


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Author Biography

Abdelnasser Salah Shebl Ibrahim, 1- King Saud University

Associate Professor

1-Department of Botany and Microbiology, College of Science, King Saud University, Riyadh - 11451, Saudi Arabia

2-Department of Chemistry of Natural and Microbial Products, Pharmaceutical Industries Research division, National Research Center, El-Buhouth St., Dokki, Cairo 12311, Egypt




How to Cite

IBRAHIM, A.S.S., AL-SALAMAH, A.A., ELBADAWI, Y.B., EL-TAYEB, M.A., ALMAARY, K.S., ELAGIB, A.A. and IBRAHIM, A.S.S.., 2016. Alkaline protease from a new halotolerant alkaliphilic Bacillus agaradhaerens strain ak-r isolated from egyptian soda lakes . Bioscience Journal [online], vol. 32, no. 6, pp. 1604–1618. [Accessed19 April 2024]. DOI 10.14393/BJ-v32n1a2016-33251. Available from:



Biological Sciences