Isolation Of Alkaline Protease Producing Strain I13 And Its Enzyme Characterizations

Alkaline protease has been widely applied in detergent, leather and food industries. A strain named 113 with alkaline protease productivity was isolated and identified from soil. The production of alkaline protease was optimized and the enzyme characteristics were studied.Strain 113 producing alkaline protease was isolated from soil. It was Gram negative, straight rod and grew well in the casein plate. The colony was white, round, opaque, smooth and shiny surface, with the neat edge and the bulgeg middle.The optimum identification medium used to isolate the alkaline protease strains was casein yeast medium.Based on single factor experiment and response surface analysis, the optimized culture condition for enzyme production was as follows:1.0% glucose,1.0% yeast extract,0.05% MnCl2,0.1%c asein,1.0% NaCl, initial pH10.0,14.7℃, inoculum 5.3%, and liquid volume 10 mL/50mL. The protease activity was improved to be 321.34U/mL after optimization.The culture supernatant was precipited with (NH4)2SO4 and the supertant was used as crude enzyme. The optimal catalytic conditions of the enzyme were at pH 10.5 and 40 ℃. The enzyme adapted to a wide range of pH and it was stable under different pH. The enzyme had good stability with different surfactants and oxidant. The most important feature of this enzyme was that it was strongly activated by the surfactants and the oxidant.