Alkaline protease production using eggshells and membrane-based substrates: Process modeling, optimization, and evaluation of detergent potency

摘要

This study focused on the use and eggshells and associated membranes (ESM) as a substrate for producing alkaline protease (AlkP). Furthermore, the study was performed to optimize the production process and check the feasibility of using the enzyme as a detergent. Bacillus mojavensis was used as a biological agent for fermentative enzyme production. The process was optimized with four factors at three levels using response surface methodology (RSM) coupled with the Box–Behnken design. Through RSM, optimal parameters for the production of AlkP were found to be the following: pH 9.08, temperature 39.74 °C, and ESM 197.8 g/l or 19.78% (w/v) with an incubation time of 48 h. Thereafter, the obtained enzyme was partially characterized. It retained more than 93.97% of its original activity in the pH range between 8 and 10, with optimal activity at pH 10. The minimum residual activity of AlkP was 39.6% of its original activity at pH 6.0. AlkP was found to be active at temperatures between 30 and 80 °C, but maximal at 60 °C. Residual activities were found to be 67.4%, 71.7%, 75.7%, 78.7%, and 78.7% in solutions with NaCl concentrations of 1.0, 1.5, 2, 2.5, and 3.0 M, respectively, at pH 8.0. A detergent compatibility study revealed that the obtained AlkP is quite effective as a detergent.