UNIT-FIX · Unifying meta-omics data and biogeochemical modelling to improve future predictions of marine nitrogen fixation

Marine microbes, while only representing 1% of the photosynthetic biomass on Earth, contribute nearly half of global net primary production. Nitrogen (N) is one of the most limiting nutrients in the ocean, controlling marine phytoplanktonic growth and carbon storage. The primary source of nitrogen in the ocean is nitrogen fixation, a process achieved by diazotrophs using the nitrogenase enzyme. Over the last 20 years, the biological knowledge on nitrogen fixation has significantly evolved with the advent of meta-omics data (i.e., high-throughput sequencing of full communities). It is now clear that diazotrophs are a diverse group with various lifestyles, growth strategies and metabolisms, allowing them to occupy a wide range of ecological niches. Yet, climate models models fail to capture diazotroph diversity, leading to uncertainty in predictions of future marine primary production. The advent of marine big data, including large scale environmental meta-omics datasets, offers a chance to bridge biological diversity observations with biogeochemical modelling to enhance marine ecosystem future predictions in a changing climate.In UNIT-FIX, I aim to take advantage of the wealth of public meta-omics data to achieve three overarching goals: (1) develop a holistic and data-driven description of diazotroph diversity, (2) implement diazotroph diversity into data-driven modelling frameworks, and (3) improve predictions of the future states of diazotrophs and associated impacts on marine productions in a changing climate. These goals will be reached by bridging genome-level omics data and state-of-the-art modelling methods, including niche modelling, metabolic modelling and biogeochemical modelling. Highlighting key actors from marine microbial ecosystems and paving the way for their integration in climate models, UNIT-FIX will contribute to Sustainable Development Goals 13 and 14 of the United Nations: Climate Action and Life Below Water.