Optimization of a culture medium for streptomycin production using response-surface methodology

The effects of all ingredients of a culture medium designed for streptomycin production were evaluated in order to select the variables which influenced antibiotic production. Among them, glucose, beer-yeast autolyzate, sodium chloride and dibasic potassium phosphate showed a substantial effect on this parameter and were therefore selected. The optimum concentration for each variable was determined using an orthogonal-central composite experimental design and the response-surface methodology. The determination coefficient (R2) of the fitted second-order model was 0·9384. Applying this model, the optimum concentration of the four variables was obtained and with this optimized medium the streptomycin titre was increased by 52% with respect to the original medium, using an industrial strain of Streptomyces griseus.