Production, characterization, and immobilization of partially purified surfactant-detergent and alkali-thermostable protease from newly isolated Aeromonas caviae

摘要

Proteolytic Aeromonas caviae P-1-1 growing at wide-ranging pH (7.0-11.0) and moderate salinity (0-5% NaCl) was isolated from cattle shed of Thanjavur, India. It produced lipase, gelatinase, and polyhydroxybutyrate. Different culture conditions, incubation time, carbon and nitrogen sources, vitamins, amino acids, surfactants, and metal ions for optimal growth and protease production of P-1-1 were examined. Maximum protease (0.128U/mL) production was achieved with 1% fructose, 1% yeast extract, 0.1% ammonium sulfate, 3% NaCl, 0.1% CaCl(2)2H(2)O, 1% glycine, 0.1% vitamin E, and 0.1% Tween-40 at pH 8.0 after 42hr of incubation at 37 degrees C. It was active over broad range of pH (7.0-12.0), temperature (15-100 degrees C), and salinity (0-9% NaCl) with optima at pH 10.0, 55 degrees C, and 3% NaCl. It retained 65 and 48% activities at pH 12.0 and 100 degrees C, respectively. Partially purified protease was highly stable (100%) within pH range 7.0-12.0 and salinities of 0-5% NaCl for 48hr. Cu2+, Mn2+, Co2+, and Ca2+ did not inhibit its activity. Its stability at extreme pHs, temperatures, and in the presence of surfactants and commercial detergents suggests its possible application in laundry detergents. Partially purified protease was immobilized and reused. This is the first report of alkali-thermotolerant, surfactant-detergent-stable partially purified extracellular protease from A. caviae.