Isolation,Identification And Products Characterization Of Strain SD-142 Producing Thermostable Alkaline Protease

381 strains of bacteria were isolated from soil in Tibet and 97 strains were isolated as the thermostable alkaline protease producers. Among them a thermophilic and alkaliphilic bacterial strain producing a large amount of thermostable alkaline protease was selected. By testing morphologic and physiological-biochemical characteristics the strain was identified as Bacillus sp. .We call it SD-142.The cells of the strain are Gram-positive and the shape of single cell is pole. The strain has endospore shape of which is oval and the sporangium is swelling. SD-142 can grow in the temperature range 25-60℃ and its salt-resisting is under 14%. It can grow in the pH range 5-11 and its optimum pH is 6-8. The strain can make use of Glucose to produce acid and gas. It also can make use of D-aeabinose. D-xylose, D-mannose, D-galactose. D-lactose, D-fructose, D-maltose, D-sucrose, D-sorbose and D-rhamnose to produce acid.Studying on the effects of carbon sources and other influence factorsoptimized the protease fermentation condition for the strains. The optimal medium composition for the strain growth is(%) Matose 2%, peptone 0.5%, KH2PO4 0.1%, MgSO4 0.05%. The optimal medium composition for protease producing is(%) Matose 6%, Soyapower 3%, Bran 3%, Na2HPO4 0.4%, MgSO4 0.02%, CaCl2 0.02%. The optimal conditions for protease producing are inoculation for 10%, seeds age for 12h, culture medium volumes for 10 mL in 100 mL flask, initial pH7.2. cultivated at 45℃ with an aeration rate of 180rpm for 48h. Then a maximum yield of 650u/mL was obtained.By studying on the supernatant of the culture fluids, the enzymatic characteristics were concluded. The optimum temperature and pH for protease activity was 60℃ and pH9.5. It was stable in the pH range 6.5-11.0 and had good thermal stability. The enzyme retains 100% of activity after 24h of heat treatment at 40℃ and the half-lives was 30min at 60℃. Addition of CaCl2 (10mM) and glycine (1M), individually and in combination improve the themostability of enzyme. The enzyme retained more than 50% of its maximum activity after 1h at 60℃ in the presence of glycine.The enzyme retained about 58.3% of its maximum activity after 10min at 40℃ in the presence of SDS. The extracellular production of the enzyme, its thermostable nature and compatibility with most commercial detergents are features that suggest its application in detergent industry. We have also studied the ability of the enzyme in unhairing, which is the foundation of the further research.