EFFECT OF CULTURE CONDITIONS ON PRODUCTION OF THERMOSTABLE EXTRACELLULAR PROTEASE FROM Streptomyces sp. CNXK100

Abstract

Thermostable proteases are widely used in various industrial applications because of their high catalytic activity at high temperatures. In recent years, more and more studies on actinomycetes-derived thermostable proteases have been done to explore their remarkable biological characterstics such as thermostability, ability to catalyze in extreme pH, and in presence of inhibitors. In this study, extracellular protease from Streptomyces sp. CNXK100 was proved to display highest activity at 75℃. Cell-free culture of Streptomyces sp. CNXK100 shown the highest of proteolytic activity (2943.21±12.1 U/ml) when this strain was cultured in modified Gause I medium supplemented with 1.0% skim milk, 1.0% lactose, and 0.1% NaNO₃ under shaking conditions at 150 rpm at 30-35℃, initial medium pH 7.0-8.0. With definded culture conditions, thermostable protease from Streptomyces sp. CNXK100 will be subsequently used for many potential applications in industries.