Global distribution patterns of marine nitrogen-fixers by imaging and molecular methods
Pierella Karlusich, J.J.; Pelletier, E.; Lombard, F.; Carsique, M.; Dvorak, E.; Colin, S.; Picheral, M.; Cornejo-Castillo, F.M.; Acinas, S.G.; Pepperkok, R.; Karsenti, E.; de Vargas, C.; Wincker, P.; Bowler, C.; Foster, R.A. (2021). Global distribution patterns of marine nitrogen-fixers by imaging and molecular methods. Nature Comm. 12(1): 4160. https://dx.doi.org/10.1038/s41467-021-24299-y
In: Nature Communications. Nature Publishing Group: London. ISSN 2041-1723; e-ISSN 2041-1723, more
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| Authors | | Top |
- Pierella Karlusich, J.J.
- Pelletier, E.
- Lombard, F.
- Carsique, M.
- Dvorak, E.
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- Colin, S.
- Picheral, M.
- Cornejo-Castillo, F.M.
- Acinas, S.G.
- Pepperkok, R.
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- Karsenti, E.
- de Vargas, C.
- Wincker, P.
- Bowler, C.
- Foster, R.A.
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| Abstract |
Nitrogen fixation has a critical role in marine primary production, yet our understanding of marine nitrogen-fixers (diazotrophs) is hindered by limited observations. Here, we report a quantitative image analysis pipeline combined with mapping of molecular markers for mining >2,000,000 images and >1300 metagenomes from surface, deep chlorophyll maximum and mesopelagic seawater samples across 6 size fractions (<0.2–2000 μm). We use this approach to characterise the diversity, abundance, biovolume and distribution of symbiotic, colony-forming and particle-associated diazotrophs at a global scale. We show that imaging and PCR-free molecular data are congruent. Sequence reads indicate diazotrophs are detected from the ultrasmall bacterioplankton (<0.2 μm) to mesoplankton (180–2000 μm) communities, while images predict numerous symbiotic and colony-forming diazotrophs (>20 µm). Using imaging and molecular data, we estimate that polyploidy can substantially affect gene abundances of symbiotic versus colony-forming diazotrophs. Our results support the canonical view that larger diazotrophs (>10 μm) dominate the tropical belts, while unicellular cyanobacterial and non-cyanobacterial diazotrophs are globally distributed in surface and mesopelagic layers. We describe co-occurring diazotrophic lineages of different lifestyles and identify high-density regions of diazotrophs in the global ocean. Overall, we provide an update of marine diazotroph biogeographical diversity and present a new bioimaging-bioinformatic workflow. |
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