Journal of Pure and Applied MicrobiologyVol. 8 No. Special Edition Nov. 2014

Optimization of Production and Factors Affecting the Stability of a New Protease Produced by a Thermohaloalkali Tolerant Halobacillus Strain

Mohammed I.A. Ali1, Wael N. Hozzein2,3*, Ahmed M. Reyad3,4 and Mohammed S. Abdel Hameed3,4

1Department of Botany, Faculty of Science, Cairo University, Giza, Egypt. 2Bioproducts Research Chair (BRC), Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia. 3Botany Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt; 4Biology Department, Faculty of Sciences, Jazan University, Saudi Arabia.

Received on 21 August 2014 and accepted on 10 October 2014



The optimized conditions for the production of a protease produced by a thermohaloalkali tolerant Halobacillus strain were determined. The results showed that the optimum temperature for enzyme activity was 65ÂșC and the highest proteolytic activity was obtained at 10% NaCl. Also, the enzyme exhibited proteolytic activity over a broad pH range from 5 to 13 and the highest activity achieved in the range from 9 to 12. However, casein, glycerol and glucose as carbon sources supported the highest growth, but protease production was not supported by them similarly and the highest protease activity was obtained with galactose. The highest protease activity was obtained also with NH4Cl as a nitrogen source. On the other hand, the maximum protease stability was obtained at 30oC and remained stable till 65oC after which the stability decreased gradually and beyond 75oC the activity decreased sharply. Surprisingly, the stability of the protease decreased with the increase of NaCl concentrations. The stability of the protease was maximum at pH 7 and remained highly stable up to pH 11. These results clearly indicated the thermohaloalkali tolerant nature of the enzyme.

Keywords : Protease, production optimization, stability, thermohaloalkali tolerant, Halobacillus sp.