Modeling of the last stage of production phase of oxytetracycline fermentation processes

In an attempt to disclose the reason why, during the last stage of FBOFP (fed-batch oxytetracycline fermentation processes) its specific production rate in general decreases notably, the authors started with the modeling of the process based on operation data, and thus reached the conclusion that this is due to too low residual nitrogen in the substrate. This inference is quite unacceptable to the current practice of the process operations. It was finally realized that the trouble lies in that our old measurement method of residual nitrogen is misleading. Upon using improved measuring method, it was found that while the total residual nitrogen is plentiful, the available nitrogen notably decreases with time, and thus confirmed the authors' conclusions. Experiments on industrial fermentators showed that the product can be increased by 1%, and the titer reaches 3200 micrograms/ml.