Statistical optimization of media for enhanced azadirachtin production from redifferentiated zygotic embryo cultures of neem (Azadirachta indica A. Juss.)

Callus cultures from zygotic embryos of neem (Azadirachta indica) were initiated and analyzed for azadirachtin production. Medium components were screened and optimized using the statistical techniques of Plackett-Burman and response surface methodology. The Plackett-Burman design, with five medium components (Murashige and Skoog major salts, sucrose, casein hydrolysate, indole-3-acetic acid, and N-6-benzylaminopurine), was performed to screen the variables that significantly affected azadirachtin production. The three variables-Murashige and Skoog major salts, sucrose, and N-6-benzylaminopurine-significantly affected azadirachtin production and were significant factors for optimization using response surface methodology. The experimental results were fitted to a second-order polynomial model with a correlation coefficient (R (2)) of 0.9582. The optimal concentrations of variables for maximum azadirachtin production were full-strength Murashige and Skoog major salts, 5.68% sucrose, and 10.42 mu M N-6-benzylaminopurine. The maximum azadirachtin production by the predicted model was 5.13 mg/g dry weight, which was in agreement with the actual experimental value of 4.97 mg/g dry weight.