Optimization of Protease Production by Bacillus mojavensis A21 on Chickpea and Faba Bean

Abstract

Response surface methodology (RSM) was employed to optimize the medium composition and culture conditions for the production of alkaline proteases by Bacillus mojavensis A21 on uncommon substrates: chickpea (CF) and faba bean (FF) flours. A significant positive influence of temperature, CF, FF, incubation time and inoculums size on the protease production was evaluated by Plackett Burman Design. Among these, CF was the most influential factor. The enhancement of protease to 9127 U/ml was achieved with the optimization procedure on the medium composed of (g/l): CF, 40; FF 30, NaCl 2.0; KH2PO4 1; K2HPO4 1; CaCl2, 0.1; MgSO4 0.1. The cultures were conducted for 72 hours with an IS of 2%, at 30&degC, an agitation speed of 150 rpm and an initial pH of 8.0. More interestingly, the optimization was accomplished using two cheap and local fermentation substrates, CF and FF, which could result in a significant reduction in the cost of medium constituents. The maximum alkaline protease production was 9127 U/ml after 72 h of incubation and showed 5-fold increase in protease production over the initial level.