Optimization of Alkaline Protease Production by Streptomyces sp. Strain Isolated from Ezzemoul Saltpans, Algeria

The main objective of this work was to formulate a suitable medium for protease production by Streptomyces sp. which was isolated from Ezzemoul saltpans (Algeria). The phenotypic and phylogenetic studies of this strain showed that it represents probably a new species. The fermentation was carried out on two different media, prepared at three pH values. The results showed the presence of an alkaline protease with optimal pH and temperature of 8 and 40°C, respectively. The enzyme was stable up to 90°C, having a residual activity of 79% after 90 min. The enzyme production media were optimized according to statistical methods while using two plans of experience. The first corresponded to the matrices of Plackett and Burman in N=16 experiences and N-1 factors, twelve were real and three errors. The second was the central composite design of Box and Wilson. The analysis of the results allowed the selection of two factors having a significant effect on the production of the enzyme (fructose and malt extract), then defining their optima (7 g/l of fructose and 12 g/l of malt extract). This Study show the high biotechnological potential of this Streptomyces strain for the production of the thermostable alkaline protease.