Ratiometric control of two microbial populations via a dual chamber bioreactor

Maintaining stable coexistence in microbial consortia, particularly when one species grows faster than another (i.e. the species are non-complementary), poses significant challenges. We introduce a novel control architecture that employs two bioreactors. In this system, the slower-growing species is cultivated separately before being introduced into the main mixing chamber. We analyze the open-loop dynamics of this setup and propose a switching feedback mechanism that controls the dilution rates to ensure robust regulation of population density and composition within the microbial consortium. Validated in silico using parameters from real experiments, our approach demonstrates effective and robust maintenance of microbial balance across various strains without requiring genetic modifications.