OPTIMIZATION OF ALKALINE PROTEASE PRODUCTION FROM A LOCALLY ISOLATED BACILLUS SP. ZR-5: POTENTIAL APPLICATION AS A DETERGENT ADDITIVE

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