微生物および生化学技術ジャーナル

概要

Development of Bacillus subtilis Mutants for Overproduction of Protease

Mohsin I, Muhammad A and Fareeha B

Proteases are widely used in leather processing, silk industry, diary meat processing, and preparation of organic fertilizer as well as for the liberation of silver from recycled X-ray films. Ultraviolet radiation mutagenesis of Bacillus subtilis IBL-04 was carried out for hyper producing strain development. Mutants of Bacillus subtilis were isolated and screened for selection of hyper producing mutant. Production of protease by the selected mutant BS-90 (treated for 90 min) was optimized by varying pH, temperature, and inoculum size and fermentation time simultaneously in Response Surface Method (RSM) under Central Composite Design (CCD). The mathematical response model is considered to be reliable with an R2 value of 0.9842. The adjusted R2 value was 0.9695 suggesting a significant model by determining the close relationship to the actual R2 value. Predicted R2 value shown in this model was 0.9133. The "Pred R-Squared" of 0.9133 is close as to the "Adj R-Squared" of 0.9695 as expected. The ratio of 22.60 attained in this model represents an adequate signal. The calculated C.V was 3.25 which indicate the good level of model precision and reliability. The maximum enzyme activity was 95.89 (IU/mL) at optimum conditions pH 8, Temperature 50°C, Inoculum size 2.5 mL and fermentation time 72 h. These characteristics render its potential use in detergent industries for detergent formulation.