Title Purification and Partial Characterization of a Detergent and Oxidizing Agent Stable Alkaline Protease from a Newly Isolated Bacillus subtilis VSG-4 of Tropical Soil
Author Sib Sankar Giri1*, V. Sukumaran1, Shib Sankar Sen2, M. Oviya1, B. Nazeema Banu1, and Prasant Kumar Jena3
Address 1Department of Biotechnology, Periyar Maniammai University, Thanjavur-613403, Tamilnadu, India, 2Department of Pharmaceutical Technology, Jadavpur University, Kolkata-700 032, India, 3Institute of Science, Nirma University, Ahmedabad-382481, Gujarat, India
Bibliography Journal of Microbiology, 49(3),455-461, 2011,
Key Words B. subtilis, alkaline protease, purification, characterization, detergent stability
Abstract An extracellular detergent tolerant protease producing strain VSG-4 was isolated from tropical soil sample and identified as Bacillus subtilis based on morphological, biochemical characteristics as well as 16S-rRNA gene sequencing. The VSG-4 protease was purified to homogeneity using ammonium sulphate precipitation, dialysis and sephadex G-200 gel permeation chromatography with a 17.4 purification fold. The purified enzyme was active and stable over a broad range of pH (8.0-11.0, optimum at 9.0) and temperature (40°C to 60°C, optimum at 50°C). The thermostability of the enzyme was significantly increased by the addition CaCl2. This enzyme was strongly inhibited by PMSF and DFP, suggesting that it belongs to the serine protease superfamily. The purified VSG-4 alkaline protease showed remarkable stability in anionic (5 mM SDS) and ionic (1% Trion X-100 and 1% Tween 80) detergents. It retained 97±2% and 83.6±1.1% of its initial activity after 1 h preincubation in the presence of 1% H2O2 and 1% sodium perborate, respectively. Furthermore, the purified enzyme showed excellent stability and compatibility with some commercial laundry detergents besides its stain removal capacity. Considering these promising properties, VSG-4 protease may find tremendous application in laundry detergent formulations.