Optimization of alkaline protease production from a locally isolated Bacillus sp. ZR-5: Potential application as a detergent additive

Abstract

The aim of this study was to optimize protease production using a novel Bacillus sp. ZR-5 strainisolated from the soil, and evaluate its application in detergent industry. The proteolytic activityof the strain was demonstrated using gelatin hydrolysis screening test. Protease productionoptimization was carried out using a two-step approach: a conventional method in order toidentify the best carbon and nitrogen sources followed by the application of response surfacemethodology (RSM) to optimize the factors, which include temperature, pH and incubationtime. Glucose or fructose (5 g/L), wheat bran (5 g/L), temperatures of 25 and 55°C, pH 10.0 andan approximate incubation time of 44 h, were determined as the optimal conditions according tooptimization processes. Validation tests were carried out under these conditions and the resultswere in good agreement with RSM predicted data. The in-gel activity (zymogram) test showedtwo hydrolytic zones with 66.2 and 36.5 kDa molecular weight on the casein containingpolyacrylamide gel. The high compatibility in the presence of detergent powder and washingperformance test suggested that the crude enzyme could be an appropriate choice as a detergentadditive in detergent industries.