Global distribution patterns of marine nitrogen-fixers by imaging and molecular methods.
Nat Commun
; 12(1): 4160, 2021 07 06.
Article
in En
| MEDLINE
| ID: mdl-34230473
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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Seawater
/
Molecular Imprinting
/
Nitrogen
/
Nitrogen Fixation
Language:
En
Journal:
Nat Commun
Journal subject:
BIOLOGIA
/
CIENCIA
Year:
2021
Type:
Article
Affiliation country:
France