Nonlinear model predictive control of fed-batch cultures of micro-organisms exhibiting overflow metabolism

Overflow metabolism characterizes cells strains that are likely to produce inhibiting metabolites resulting from an excess of substrate feeding and a saturated respiratory capacity. The critical substrate level separating the two different metabolic pathways is generally not well defined. This occurs for instance in Escherichia coli cultures with aerobic acetate formation. This paper considers the control problem of a lab-scale E. coli biomass production. A preliminary study is presented to access the application of a multivariable nonlinear model predictive control approach to maximize the biomass production. This strategy is tested by simulation and its performance to control the bioreactor system is evaluated with various objective cost functions, and in the presence of noise and dead-time on the acetate concentration measurement.