Cyanobacteria are a prolific source of diverse bioactive secondary metabolites. However, some of them are toxic and have a deleterious impact on human health and ecosystem sustainability. But others with potent biological activities have gathered considerable attention due to their potential therapeutic and agrochemical applications. Unfortunately, the biotic factors governing the production of these cyanobacterial secondary metabolites are poorly understood and their ecological roles have largely remained elusive.To advance knowledge on these topics, we propose to combine innovative ecophysiological experiments with cutting-edge metabolomic and modeling approaches. The CYANOMIC project will focus on Microcystis aeruginosa, which has a worldwide distribution and has been implicated in numerous intoxications due to its capacity to produce microcystins (MC), the most widely encountered toxin in freshwater ecosystems. The metabolomes of the MC-producing M. aeruginosa strain and its non-MC-producing mutant will be compared in the presence and absence of their associated bacteria. The isolation and characterization of their metabolites will allow us to study the dynamics of their production with the aim to provide the data necessary to produce a model that predicts the potential toxicity of a Microcystis bloom and the cellular communication between cyanobacterial strains as well as with bacteria and with surrounding microorganisms.The CYANOMIC project aims to help a researcher broaden her knowledge and skills through the study of cyanobacterial secondary metabolites production. The tailored workpackage will produce a young scientist able to help lead European research in this important area. In addition to being a stepping-stone to a future career in science, it will provide an invaluable opportunity to help share the knowledge between experts in cyanobacterial ecology and to strengthen the link between Europe and USA in this timely and significant scientific area.