Statistical, optimization, and thermodynamic studies on the production of alkaline protease using new local isolate of Bacillus sp

Abstract

Investigation of alkaline protease production under different fermentation conditions using one factor at a time involving temperature, pH, incubation time as well as different carbon and organic nitrogen sources. The results showed that the maximum activity (470U/ml) was obtained at peptone 7.5 (g/L), glucose 5 (g/L), pH 10, 24h incubation time and 35 o C. Further more, Two sequential statistical designs were used to optimize these physiochemical parameters (pH, temperature, incubation time, glucose, peptone, and MgSO 4 .7H 2 O, K 2 HPO 4 ) for enzyme production. Firstly, the Plackett Burman factorial design was applied followed by Box-Behnken experimental design. The results showed that the best protease production (580 U/ml) was obtained at peptone 10 (g/L), glucose 12.5 (g/L), pH 11, 24h incubation time and 35 o C. The level of significance was studied using the three significant variables on the enzyme production (pH, glucose and peptone conc.) and the results indicated the integration of these parameters on protease production. The thermodynamic parameters of crude enzyme were also investigated and they proved the superior thermal stability of the B. amyloliquefaciens protease