Optimization of thermotolerant alkaline protease production from Brevibacillus brevis strain BT2 using surface response methodology

An efficient thermotolerant alkaline protease producer, strain Brevibacillus brevis BT2 was isolated from waste water effluents from textile dyeing industry. Effect of variables, i.e. soybean meal, soluble starch, inoculums, temperature and pH and their mutual interaction were analyzed by Box-Behnken design (BBD) for optimizing their levels in the medium and effect of their mutual interaction on thermotolerant alkaline protease production. All the above variables were found significantly influencing protease activity individually and also in interaction with other variables. The model predicted maximal protease production of 121.1 (U ml−1) at the soybean meal 7.46 (gL−1), soluble starch 10.00 (gL−1), inoculums 1.76%, temperature 49.3 °C, and pH 9.1. The maximum protease production obtained experimentally was found to be 128.5 U/ml. The result was coincident with the predicted value and the model was proven to be adequate.