Profit optimization for mycelia fed-batch cultivation

The goal of bioprocess-control and-scheduling is to maximize the profit of the whole process. Maximizing of the profit implies the optimal coordination among the subindices such as productivity, yield and duality of the product. These three subindices often interact with each other since the manipulating variables may influence them simultaneously. Therefore, the best way to control the process is to optimize the profit index directly. In this paper, it is illustrated by an example of industrial penicillin fed-batch production how the profit index, named as profit function, is established. The profit function is an objective description of a process under the aspect of economy. In reality, it may be found that the profit function is often different from batch to batch. Such a fluctuation is demonstrated by gibberellic acid, penicillin and cephalosporin fed-batch processes. This suggests that optimal scheduling of process time may be an effective way to enhance the total profit. Based on a database which consists of the characteristic description of the profit function of earlier batches, the procedures of classification and optimal scheduling decision are described in details. On-line profit optimization may be done in particular if a process model is available. This is demonstrated with cephalosporin C fed-batch cultivation as an example. (C) 1997 Elsevier Science B.V.