3.4. Validation of the optimized fed batch fermentation
To verify the modeling results, experiments were done in triplicate, using the optimized conditions to represent the maximum point of the cell dry weight in the course of fed batch fermentation. The predicted maximum dry cell weight was 76.79 g/L, and the average value obtained in the experiments was 77.50 g/L. This is an improvement of concentration by about 280% relative to that in batch fermentation (20.37 g/L). The good correlation between the predicted and experimental values after optimization justified the validity of the response model and the existence of an optimum point. At this point, the maximum concentration of JAA was 0.574 g/L, which is an improvement of the concentration by about 44% relative to that in batch fermentation. The dry cell weight value of 77.50 g/L was higher than those reported for fed batch fermentation by some B. subtilis variants using an optimized feeding strategy for the substrate