UTTAR PRADESH JOURNAL OF ZOOLOGY

Proteases are the foremost important hydrolytic enzyme that plays a vital role in the metabolism and physiological activities of every organism. There is an increasing demand for protease enzyme worldwide. An extracellular protease producing strain was isolated from the gut of Portunus pelagicus and was identified as Bacillus subtilis. The stability of crude protease in various solid laundry detergents was investigated. The enzyme had an optimum activity at pH 9.0-10.0 and temperature 55-60°C. The protease was found to be stable towards non-ionic (Triton X-100, Tween 20, Tween 80, Brij 35) and ionic detergents (0.1% SDS) and were relatively stable in bleaching agents such as 1% H₂O₂ and 1% sodium perborate which retained 74% and 63% of their initial activity respectively. Except for acetone, all other organic solvents showed more than 70% of total activity in 10% of solvents (methanol, 2-propanol, xylene, toluene, and benzene). Moreover, the alkaline crude enzyme extract showed its stability and compatibility with commercial solid detergents. Wash performance analysis, stability in pH, temperature, thermal stability and the stability in the presence of surfactants, bleaching agents and organic solvents, suggest its application as a laundry additive.