Driving Species Competition in a Light-limited Chemostat

In this paper, we tackle the problem of microalgae selection in a continuous photobioreactor where microalgae growth is limited by light. We propose a closed-loop control for selecting, for a given range of light intensity, the strain with the maximum growth rate from the microalgae population. In particular, we are interested in strains with high growth rate for high light intensity, i.e., strains with high resistance to photoinhibition. Firstly, we recall the framework of the light-limited chemostat. Then, we propose a nonlinear adaptive control which regulates the light intensity at the bottom of the photobioreactor in monoculture. This light is of particular interest as it defines the winner of the competition in a multispecies culture operated in open-loop mode. Finally, we show that the proposed controller allows the selection of a strain of interest in the case of a culture with η species.