Sinking Trichodesmium fixes nitrogen in the dark ocean
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Sinking Trichodesmium fixes nitrogen in the dark ocean. / Benavides, Mar; Bonnet, Sophie; Le Moigne, Frédéric A. C.; Armin, Gabrielle; Inomura, Keisuke; Hallstrøm, Søren; Riemann, Lasse; Berman-Frank, Ilana; Poletti, Emilie; Garel, Marc; Grosso, Olivier; Leblanc, Karine; Guigue, Catherine; Tedetti, Marc; Dupouy, Cécile.
In: The ISME Journal, Vol. 16, No. 10, 2022, p. 2398-2405.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Sinking Trichodesmium fixes nitrogen in the dark ocean
AU - Benavides, Mar
AU - Bonnet, Sophie
AU - Le Moigne, Frédéric A. C.
AU - Armin, Gabrielle
AU - Inomura, Keisuke
AU - Hallstrøm, Søren
AU - Riemann, Lasse
AU - Berman-Frank, Ilana
AU - Poletti, Emilie
AU - Garel, Marc
AU - Grosso, Olivier
AU - Leblanc, Karine
AU - Guigue, Catherine
AU - Tedetti, Marc
AU - Dupouy, Cécile
PY - 2022
Y1 - 2022
N2 - The photosynthetic cyanobacterium Trichodesmium is widely distributed in the surface low latitude ocean where it contributes significantly to N2 fixation and primary productivity. Previous studies found nifH genes and intact Trichodesmium colonies in the sunlight-deprived meso- and bathypelagic layers of the ocean (200–4000 m depth). Yet, the ability of Trichodesmium to fix N2 in the dark ocean has not been explored. We performed 15N2 incubations in sediment traps at 170, 270 and 1000 m at two locations in the South Pacific. Sinking Trichodesmium colonies fixed N2 at similar rates than previously observed in the surface ocean (36–214 fmol N cell−1 d−1). This activity accounted for 40 ± 28% of the bulk N2 fixation rates measured in the traps, indicating that other diazotrophs were also active in the mesopelagic zone. Accordingly, cDNA nifH amplicon sequencing revealed that while Trichodesmium accounted for most of the expressed nifH genes in the traps, other diazotrophs such as Chlorobium and Deltaproteobacteria were also active. Laboratory experiments simulating mesopelagic conditions confirmed that increasing hydrostatic pressure and decreasing temperature reduced but did not completely inhibit N2 fixation in Trichodesmium. Finally, using a cell metabolism model we predict that Trichodesmium uses photosynthesis-derived stored carbon to sustain N2 fixation while sinking into the mesopelagic. We conclude that sinking Trichodesmium provides ammonium, dissolved organic matter and biomass to mesopelagic prokaryotes.
AB - The photosynthetic cyanobacterium Trichodesmium is widely distributed in the surface low latitude ocean where it contributes significantly to N2 fixation and primary productivity. Previous studies found nifH genes and intact Trichodesmium colonies in the sunlight-deprived meso- and bathypelagic layers of the ocean (200–4000 m depth). Yet, the ability of Trichodesmium to fix N2 in the dark ocean has not been explored. We performed 15N2 incubations in sediment traps at 170, 270 and 1000 m at two locations in the South Pacific. Sinking Trichodesmium colonies fixed N2 at similar rates than previously observed in the surface ocean (36–214 fmol N cell−1 d−1). This activity accounted for 40 ± 28% of the bulk N2 fixation rates measured in the traps, indicating that other diazotrophs were also active in the mesopelagic zone. Accordingly, cDNA nifH amplicon sequencing revealed that while Trichodesmium accounted for most of the expressed nifH genes in the traps, other diazotrophs such as Chlorobium and Deltaproteobacteria were also active. Laboratory experiments simulating mesopelagic conditions confirmed that increasing hydrostatic pressure and decreasing temperature reduced but did not completely inhibit N2 fixation in Trichodesmium. Finally, using a cell metabolism model we predict that Trichodesmium uses photosynthesis-derived stored carbon to sustain N2 fixation while sinking into the mesopelagic. We conclude that sinking Trichodesmium provides ammonium, dissolved organic matter and biomass to mesopelagic prokaryotes.
U2 - 10.1038/s41396-022-01289-6
DO - 10.1038/s41396-022-01289-6
M3 - Journal article
C2 - 35835942
VL - 16
SP - 2398
EP - 2405
JO - I S M E Journal
JF - I S M E Journal
SN - 1751-7362
IS - 10
ER -
ID: 314070109