Optimization of growth conditions and production of extracellular protease by Bacillus subtilis DC5
Keywords:Bacillus subtilis DC5, extracellular protease, protease productivity
The strain Bacilus subtilis DC5 having high productivity of extracellular amylase and protease was determined as based on its 16S rDNA gene sequence. Cultivating strain B. subtilis DC5 in optimum basic medium supplemented with soluble starch or yeast extract increased protease productivity (0.423 HP/ml and 0.528 HP/ml, respectively). However, protease productivity of this strain was not increased in case combination of these nitrogen and carbon sources in the culture medium. The highest protease activity was 0.649 HP/ml when cultivating the strain in medium containing 0.75% soluble starch. Study on effect of physical conditions indicated that protease activity of B. subtilis DC5 was obtained at the highest when cultivated at initial pH 7, temperature of 35oC after 22 hours of cultivation.