16S rRNA Metabarcoding of Microcystis microbiome along a salinity gradient

Due to climate changes and eutrophication, blooms of predominantly toxic freshwater cyanobacteria are intensifying and are likely to colonize estuaries, thus impacting benthic organisms and shellfish farming representing a major ecological, health and economic risk. However, little is known about the fate of natural colonies of Microcystis by salinity increase. In natural environment, Microcystis form large mucilaginous colonies with numerous heterotrophic bacteria embedded in the mucilage. This micro-environment, known as phycosphere, is the place of numerous biotic interactions that influence the development of both cyanobacterial and bacterial communities, as well as the production and fate of toxins. The aim of this project is to study the impact of a salinity increase on the cyanobacterial genotypic composition, the physicochemical characteristics of the mucilage and the production of specific metabolites (toxins and compatible solutes) along a French freshwater-marine gradient at different phases of a bloom. We will also determine how these changes influence the structure and the composition of the bacterial community associated with Microcystis and their function in toxins degradation.