Purification and characterization of thermo stable DNase of Staphylococcus gallinarum isolated from burns

Abstract

Abstract One hundred samples from various clinical sources were obtained. Sixty isolates of Staphylococcus aureus and one isolate of Staphylococcus gallinarum have been identified. The Capability of S. gallinarum was phenotypically tested on DNase agar medium and also by quantitative assay which showed that S. gallinarum has been able to generate the thermostable DNase. DNase was extracted, the activity and specific activity of the crude was 36 (U/ml) and 240(U/mg) respectively. The purification of the enzyme was done by precipitation with ammonium sulphate at saturation (65–85%) then by using ion exchange chromatography in CM cellulose and gel filtration by in Sephadex G150.The activity and specific activity Purified DNase was 35 (U/ml) and 3500(U/mg) respectively. The optimal PH for DNase was found to be 8 while the enzyme was stable at broad pH range (7, 8, 9 and 10) with remaining activity 94%, 100%, 97%, 86% respectively. The optimal temperature for DNase activity and stability was at 37 °C. The results indicate that DNase activity increased when 10 mM of each MnCl2, KCl, NaCl MgCl2 and CaCl2 were incubated with the enzyme. The molecular weight of DNase was estimated by gel filtration and found that it was approximately 27 KDa.