Nutritional limitation modelling for continuous control of lactic acid production by Lactobacillus casei

The design of a continuous-flow control strategy in lactic acid production by Lactobacillus casei is reported here. The main idea is to take advantage of recently modelled nutritional limitation effect in order to reduce production costs and improve productivity. The control objective was to maintain the production rate at a constant high value, or equivalently to regulate the glucose concentration at a constant low value according to a model-based preliminary steady-state analysis. Due to the practical importance of achieving applicable control, an adaptive predictive control law, where only the process output is needed and where the specific consumption rate is considered as a time-varying parameter, is proposed. Batch experimental data and evaluation by simulation show the feasibility of such a control system.