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Unusual marine cyanobacteria/haptophyte symbiosis relies on N2 fixation even in N-rich environments
- Source :
- The ISME journal, vol 14, iss 10, The ISME Journal
- Publication Year :
- 2020
- Publisher :
- eScholarship, University of California, 2020.
-
Abstract
- The microbial fixation of N2is the largest source of biologically available nitrogen (N) to the oceans. However, it is the most energetically expensive N-acquisition process and is believed inhibited when less energetically expensive forms, like dissolved inorganic N (DIN), are available. Curiously, the cosmopolitan N2-fixing UCYN-A/haptophyte symbiosis grows in DIN-replete waters, but the sensitivity of their N2fixation to DIN is unknown. We used stable isotope incubations, catalyzed reporter deposition fluorescence in-situ hybridization (CARD-FISH), and nanoscale secondary ion mass spectrometry (nanoSIMS), to investigate the N source used by the haptophyte host and sensitivity of UCYN-A N2fixation in DIN-replete waters. We demonstrate that under our experimental conditions, the haptophyte hosts of two UCYN-A sublineages do not assimilate nitrate (NO3−) and meet little of their N demands via ammonium (NH4+) uptake. Instead the UCYN-A/haptophyte symbiosis relies on UCYN-A N2fixation to supply large portions of the haptophyte’s N requirements, even under DIN-replete conditions. Furthermore, UCYN-A N2fixation rates, and haptophyte host carbon fixation rates, were at times stimulated by NO3−additions in N-limited waters suggesting a link between the activities of the bulk phytoplankton assemblage and the UCYN-A/haptophyte symbiosis. The results suggest N2fixation may be an evolutionarily viable strategy for diazotroph–eukaryote symbioses, even in N-rich coastal or high latitude waters.
- Subjects :
- Cyanobacteria
Technology
010504 meteorology & atmospheric sciences
Oceans and Seas
01 natural sciences
Microbiology
Article
Haptophyte
03 medical and health sciences
chemistry.chemical_compound
Symbiosis
Nitrate
Nitrogen Fixation
Phytoplankton
Ammonium
Seawater
Ecology, Evolution, Behavior and Systematics
Microbial biooceanography
030304 developmental biology
0105 earth and related environmental sciences
0303 health sciences
biology
Stable isotope ratio
Carbon fixation
Haptophyta
Biogeochemistry
Biological Sciences
biology.organism_classification
chemistry
Environmental chemistry
Environmental Sciences
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- The ISME journal, vol 14, iss 10, The ISME Journal
- Accession number :
- edsair.doi.dedup.....0562d56329ff855550d6c3273e91f185