CONSUMALG · Coupling multi-Omics and Nano-sims approaches to Study the microbial Uptake of Macro-ALGal biomass from marine environments

Macroalgae play essential roles within their ecosystems, as they provide food and habitats for a large diversity of marine organisms. They are also important primary producers, fixing atmospheric CO2 via photosynthesis, thus acting as one of the most important carbon reservoirs in coastal habitats. The degradation of this organic matter is controlled by microbial interactions shaping the global carbon flow within the ocean. By releasing degradation products from algal biomass, heterotrophic marine bacteria provide an important source of nutrients for the whole trophic chain. Additionally, future global changes, especially warming temperatures, are predicted to highly impact macroalgae. These observations raise the importance of better understanding mechanisms associated with the microbial degradation of the algal biomass. However, the different bacterial groups able to initiate algal biomass breakdown or uptake the released degradation products are largely unknown. More importantly, their metabolic activities and their quantitative contributions to carbon fluxes remain a black box, hindering an accurate vision of the marine carbon cycle, and the health of marine ecosystems under global warming. In this context, the CONSUMALG project aims to study the degradation mechanisms associated with the algal model Saccharina latissima, a kelp species known to provide important ecosystem services, but also industrial applications. With this project, a multidisciplinary approach will be developed to trace the carbon flow during the degradation, to obtain a detailed qualitative and quantitative description of the bacterial degraders and associated functions. Following the first objective associated with the development of optimized protocols (WP1), a second one will be dedicated to the early degradation steps during the algal breakdown (WP2), while a third will be dedicated to the algal dissolved organic matter (DOM) uptake from secondary degraders (WP3).