The objectives of the Ctrl-AB project are (i) to develop new control methods for the optimization of the productivity of a microbial community, and (ii) to demonstrate the effectiveness of these methods on a synthetic algal-bacterial consortium. We will focus on the green algae Chlorella vulgaris, which is ubiquitous in freshwater and occurs in communities with other microbial species, notably the model bacterium Escherichia coli. Interestingly, co-culturing of E. coli with Chlorella leads to higher biomass and lipid productivity by the algae. Improved growth of Chlorella occurs despite competition of E. coli for the same substrates. On top of its ability to produce molecules like vitamins, which are necessary for algal growth, the bacteria also produce carbon dioxide (CO2), which is the substrate of the photosynthesis of the algae. The algae can produce oxygen (O2) fueling bacterial growth, thus giving rise to a mutualistic pattern of interactions.
