A novel alkaline serine protease from bacillus amyloliquefaciens strain S1-13

Bacillus sp. strain S1-13 was identified as Bacillus amyloliquefaciens with 16s rRNA gene (Accession number: JX441363). The strain S1-13 was expressed and secreted alkaline serine protease (called ASP1-13) when growth in nutrient broth containing with 1% skim milk. ASP1-13 was partial purified with a specific activity of 1,324 U/mg and  2% yield. The molecular weight and isoelectric point of ASP1-13 was determined about 40 kDa and 8, respectively. It was indicated as alkaline serine protease with a broad range of activity at alkaline condition (pH 7-12) and completely inhibited with serine protease inhibitor. ASP1-13 was also active in high temperature (50-60°C) and stabilizes with broad range of pH (5-12), surfactant, oxidant, reducing agent and organic solvent. Finally, the  partial amino acid sequence from LC/MS-MS was confirmed similarity with sequence of neutral protease precursor from Bacillus subtilis.