Continuous Selection of the Fastest Growing Species in the Chemostat

This paper proposes control laws for the continuous culture of microorganisms, which make it possible to select species which maximize a criterion. In particular, by controlling the dilution rate and the input substrate concentration, the species with the fastest growth rate in chosen environmental conditions can be selected. In a first step a control is proposed for Monod and Droop models in order to achieve periodic substrate stresses, and a closed loop control is proposed to regulate the total biomass concentration. We show that this biomass regulation causes the selection of the fastest growing species if the system has a periodic behavior, and derive new selection criteria. Finally, the method is simulated using the Droop model for selecting species which maximize these criteria.