Sequential Optimization Approach for Enhanced Production of Antimicrobial Compound from Streptomyces rochei BKM-4

The main objective of the present work is to demonstrate the efficiency of multi-factorial experimental designs to elucidate factors affecting the antimicrobial compound production by Streptomyces rochei BKM-4 isolated from an Eastern Ghats soil. Combinations of Plackett-Burman design (PBD) and Box-Behnken design (BBD) have been carried out for the optimization of various factors for antimicrobial production. Among 9 factors, yeast extract, D-glucose and incubation periods were selected due to significant positive effect on antimicrobial compound production. Box-Behnken design, a response surface methodology, was used for further optimization of these selected factors for better output. Data were analyzed, a second order polynomial model was established to identify the relationship between the compound yield and the selected factors. The media formulations were optimized having the factors such as yeast extract 1.10%, D-glucose 0.98% and incubation periods 9.05 days. The maximum experimental response for antimicrobial compound production was 262.42 μg/mL whereas the predicted value was 261.35 μg/mL. The high correlation among the predicted and observed values indicated the validity of the statistical design. The combined statistical method enabled rapid identification and integration of key medium parameters for optimizing secondary metabolite production and might be very useful in pharmaceutical screening programs.