An organic solvent stable, alkaline serine protease (Bsubap-I) with molecular mass of 33.1 kDa, purified from Bacillus subtilis DM-04 showed optimum activity at temperature and pH range of 37-45 degrees C and 10.0-10.5, respectively. The enzyme activity of Bsubap-I was significantly enhanced in presence of Fe(2+). The thermal resistance and stability and of Bsubap-I in presence of surfactants, detergents, and organic solvents, and its dehairing activity supported its candidature for application in laundry detergent formulations, ultrafiltration membrane cleaning, peptide synthesis and in leather industry. The broad substrate specificity and differential antibacterial property of Bsubap-I suggested the natural ecological role of this enzyme for the producing bacterium. (C) 2008 Elsevier Ltd. All rights reserved.