Pakistan J. Zool., vol. 46(4), pp. 1125-1132, 2014. Characterization of a Thermostable Alkaline Protease from Staphylococcus aureus S-2 Isolated from Chicken Waste Mehwish Akram, 1 Sarah Shafaat, 1 Dilara Abbas Bukhari 2 and Abdul Rehman 1 1 Department of Microbiology and Molecular Genetics, University of the Punjab, New Campus, Lahore 54590, Pakistan 2 Department of Zoology, GC University, Lahore, Pakistan Abstract.- In this study, the protease producing bacterium was isolated from chicken waste and characterized as Staphylococcus aureus through 16S rRNA ribotyping. The protease from S. aureus S-2 showed maximum activity of 360 U/mL. S. aureus S-2 showed optimum growth at 37ºC and pH 7. S. aureus S-2 was able to grow in 1% gram pulse, mung beans and hydrolyzed casein but the maximum growth of the organism was supported by 1% hydrolyzed casein. A comparison of intracellular and extracellular enzyme activity showed that the predominant form of the enzyme was extracellular. The optimal pH and temperature for the protease activity were 8.0 and 50ºC, respectively. The enzyme was active at a broad range of pH (5-9) and temperatures (30-90ºC). The molecular mass of the enzyme was found to be 30 kDa in SDS-polyacrylamide gel electrophoresis. S. aureus S-2 can be exploited for biotechnological and industrial applications. Key words: Azocasein, Staphylococcus aureus, alkaline protease. INTRODUCTION Proteases are single class of enzymes which occupy a pivotal position with respect to their applications in both physiological and commercial fields. Proteolytic enzymes catalyze the cleavage of peptide bonds in other proteins. Proteases are degradative enzymes which catalyze the total hydrolysis of proteins. Advances in analytical techniques have demonstrated that proteases conduct highly specific and selective modifications of proteins such as activation of zymogenic forms of enzymes by limited proteolysis, blood clotting and lysis of fibrin clots, and processing and transport of secretory proteins across the membranes (Fox et al., 1991; Godfrey and West, 1996; Gupta et al., 2002). Of the industrial enzymes, 75% are hydrolytic (Rao and Deshpande, 1998; Rao et al., 1998). Proteases represent one of the three largest groups of industrial enzymes and account for about 60% of the total worldwide sale of enzymes. Proteases have a long history of application in the food and detergent industries (Kumar and Takagi, 1999; Gupta et al., 2002). Their application in the leather industry for ________________________________ * Correspondence author: rehman_mmg@yahoo.com 0030-9923/2014/0004-0000 $ 8.00/0 Copyright 2014 Zoological Society of Pakistan dehairing and bating of hides to substitute currently used toxic chemicals is a relatively new development and has conferred added biotechnological importance (Rao et al., 1998). The vast diversity of proteases, in contrast to the specificity of their action, has attracted worldwide attention in attempts to exploit their physiological and biotechnological applications (Poldermans, 1990; Fox et al., 1991). Proteases are ubiquitous in nature and are found in a wide variety of organisms such as plants, animals and microorganisms. Plant proteases include papain, bromelian and keratinaes (Schechler and Berger, 1967; Bressollier et al., 1999). Most famous proteases of animal origin are pancreatic trypsin, chymotrypsin, pepsin and rennin (Boyer, 1971; Hoffman, 1974). Microbial proteases account for approximately 40% of the total worldwide enzyme sales (Godfrey and West, 1996). Proteases from microbial sources are preferred to the enzymes from plant and animal sources since they possess almost all the characteristics desired for their biotechnological applications. These extracellular enzymes are synthesized by diverse groups of microorganisms, including fungi, yeasts and bacteria. Among extracellular alkaline proteases, those from Bacillus species have wide use and importance in several industrial sectors, such as the