Isolation and Optimization of Bacillus subtilis W1 Strain with High Neutral/Alkaline Protease Activity
Article
Figures
Metrics
Preview PDF
Reference
Related
Cited by
Materials
Abstract:
To obtain the bacteria strain with high protease activity, high-protease-producing strain W1 was isolated from soybean products by casein plate method, and identified as Bacillus subtilis subsp. subtilis by phenotypical characteristics and 16S rDNA sequences. The strain W1 exhibited both neutral protease activity and alkaline protease activity, which were 28.99 U/mL and 33.19 U/mL, respectively. The single factor experiment was selected for preliminary optimization. The orthogonal experimental design was used to optimize the culture condition of Bacillus subtilis W1 strain based on the single factor results and the total protease activity was selected as an indicator. The optimal conditions were as follow: the initial pH 9.0 in the medium, 4% inoculation, culture temperature 37 ℃, and culture time 60 h. In the above conditions, the activity of neutral protease, alkaline protease and total protease were 40.39 U/mL, 52.02 U/mL and 92.41 U/mL, respectively. Thought optimization, the corresponding protease activities increased by 39.3%, 56.7% and 48.6%, respectively. These results will be helpful to further study the protease characteristics of the Bacillus subtilis W1 strain, and also enrich the resource library of Bacillus subtilis with protease activity.
