Optimization of production of subtilisin in solid substrate fermentation using response surface methodology

Subtilisin (EC 3.4.21.62) is a type of serine protease that is of high commercial importance. It is mainly produced by Bacillus species as an extra cellular enzyme. Subtilisin being stable over a wide range ofpH and temperature is exploited as a detergent enzyme and also favoured by its non-specificity. The yield of this enzyme needs to be optimized for cost effective production of subtilisin for commercialization. Here, various solid substrates were screened for the production of subtilisin using Bacillus subtilis MTCC 441 and the maximum yield was found with green gram husk. Response surface methodology (RSM) was used to optimize pH, temperature, and moisture content. The optimal conditions were obtained after solving the polynomial equation using inverse matrix. The optimum pH, temperature and moisture content obtained under the conditions of study were 7.00, 30.04°C, and 73.38% respectively. The predicted response under these conditions was to be 571.73 U/mg proteinwhereas the actual response was found to be 571.32 U/mg protein