A detergent stable alkaline serine-protease from Bacillus licheniformis MP1 was purified in three steps: ultrafiltration using a 10 kDa cut-off membrane, Sephadex G-100 gel filtration, and Mono Q-Sepharose ion exchange chromatography with a 3.9-fold increase in specific activity and 48.2% recovery. The N-terminal amino acid sequence of the first 14 amino acids of the purified enzyme was AQTVPYGIPLIKAD. The molecular weight of the purified enzyme was estimated to be 30 kDa. The optimum pH and temperature of the purified protease were 10.0 and 70 degrees C, respectively, using casein as a substrate. It showed high stability towards alkaline pH, non-ionic surfactants and was relatively stable towards SDS. Additionally, the crude enzyme showed higher stability and compatibility with various laundry detergents from Tunisian market, and the addition of MP1 proteolytic preparation (40 U/ml) to wash solution, enhance bloodstain elimination. In addition, when used in shrimp waste deproteinization at E/S = 20 U/mg protein ratio, MP1 proteolytic preparation leads to 75% deproteinization. The aprMP1 gene, encoding the alkaline protease from B. licheniformis MP1, was isolated, and its DNA sequence was determined. The deduced amino acid sequence of the preproenzyme showed high homology with many other known serine protease genes, and some differences that characterize it. (C) 2011 Elsevier Ltd. All rights reserved.