Medium Optimization for Protease Production via Moderately Halotolerant Virgibacillus Pantothenticus Using Response Surface Methodology

Abstract

Virgibacillus pantothenticus is an industrially promising, yet scarcely studied, moderately halotolerant microorganism (up to 10% NaCl) with high activity protease production potential. Following Response Surface Methodology, we employed a Central Composite Design for the experiments and constructed a second order polynomial model to represent the resulting data. For medium optimization for protease production we optimized the resulting model. 32 experiments (following the central composite design scheme) where, carbon (glucose), nitrogen (ammonium sulfate), potassium (potassium phosphate monobasic) and magnesium (magnesium sulfate) sources were studied in the media. Bacterial growth, residual glucose and protease activities were determined at the 48 th hour of each experiment. The model was optimized and the concentrations were found for each parameter. Under the optimum conditions, the predicted protease activity is also experimentally verified and the model prediction was in very good agreement with experimental results. The interactions between medium components and their effect on cell growth and protease production are also sought. This work reports the improvements on protease production of a potentially interesting industrial host, Virgibacillus pantothenticus.