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The missing majority: understanding global ocean ecology by revealing the unknown biology of the most abundant marine microbial eukaryotes

Project description

The unknown biology of the most abundant marine microbial eukaryotes

Which are the most abundant microbial eukaryote species in the world’s sunlit oceans, and what roles do they play in global ecology? The EU-funded GROWCEAN project will isolate abundant, unknown marine microbial eukaryotes and transform them into new model organisms to study ocean ecology and evolution. First, it will characterise their cell biology, behaviour, life history and interspecies interactions with time-lapse and fluorescence microscopy. Next, it will use single-cell techniques to sequence their genomes/transcriptomes to understand their metabolic potential. Finally, it will interrogate global sequence datasets to build hypotheses about their ecological characteristics, and then test these hypotheses in lab cultures, with the goal of revealing how these globally abundant protists influence oceanic ecosystems.


Which are the most abundant microbial eukaryotic species in the world’s sunlit oceans, and what roles do they play in global marine ecology? At present, the answers to both of these questions remain largely unknown. Recently, the Tara Oceans expedition conducted a global ribosomal barcode survey of the surface oceans, revealing that, of roughly 500,000 total Operational Taxonomic Units (OTUs), only 89, which were present in every station sampled by Tara, represent half of the total global OTU abundance. Yet, of these 89 OTUs, 81 do not match any known species.

The goal of this project is to characterize the biology, interspecies interactions, and ecosystem relevance of these 81 highly abundant, ubiquitous unknown microbial eukaryotes. We propose three research objectives. First, using a novel isolation approach, we will establish robust laboratory cultures and sequence their transcriptomes to produce gene catalogs. Second, we will apply time-lapse light and fluorescence microscopy to understand their life history and behavior and to build hypotheses about their individual and community metabolic potential. Third, we will characterize their ecosystem relevance by leveraging Tara Oceans metatranscriptomes to explore how their genetic toolkit is expressed across varying oceanic conditions on a global scale, and by performing laboratory manipulations to test hypotheses on a local scale.

Overall, we will provide the first glimpse of the morphological, life history, behavioral and transcriptional features of currently unknown globally abundant protists. Discoveries about their biology will have immediate implications for studies of the ecology and community structure of oceanic ecosystems. Finally, we anticipate that our efforts will lead to the establishment of ecologically relevant microbial eukaryotes as new model systems whose biology can be studied intensively in the laboratory.


Net EU contribution
€ 1 500 000,00
Calle serrano 117
28006 Madrid

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Comunidad de Madrid Comunidad de Madrid Madrid
Activity type
Research Organisations
Other funding
€ 0,00

Beneficiaries (1)