Detecting modes in fed-batch fermented process. Application to Escherichia Coli Cultivation

This paper presents a strategy based on residual generation to detect acetate formation during a culture of Escherichia coli as producer of recombinant proteins. Indeed protein productivity is both affected by acetate concentration that inhibits cell growth and by acetate production that reduces protein production. Formation of acetate occurs when the specific glucose uptake exceeds a critical value. This situation must consequently be avoided. The proposed approach deeply uses a model that gathers the knowledge about the process. It aims to study the possibility to identify the current biological behaviour from this model and from a reduced instrumentation. Depending on the instrumentation, specialized residuals are generated for the different biological modes. These residuals, calculated from the available measurement, have to be close to zero when the mode they have been design for is active. According to the residuals that trigger a deviation from zero test, it is then possible to recognize the current mode and, that way, to determine the strain biological activity