Modeling the Dynamic Regulation of Nitrogen Fixation in the Cyanobacterium
            <i>Trichodesmium</i>
            sp

Rabouille, Sophie; Staal, Marc; Stal, Lucas J.; Soetaert, Karline

doi:10.1128/aem.72.5.3217-3227.2006

Cited by 58 publications

(68 citation statements)

References 53 publications

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“…Diel patterns of N 2 fixation activity in the marine cyanobacteria Trichodesmium, UCYN-A, and Crocosphaera watsonii have been reported, and while probably partially regulated by circadian rhythms (Chen et al, 1996), the cycles of nitrogenase activity are directly linked with access to energy supporting the enzyme and strategies for protection against inhibition by O 2 (Postgate, 1990;Rabouille et al, 2006). The diel cycle in the marine filamentous cyanobacterium Trichodesmium is well characterized, with the majority of the N 2 fixation occurring during the day (Staal et al, 2007b).…”

Section: Introductionmentioning

confidence: 99%

Gammaproteobacterial diazotrophs and nifH gene expression in surface waters of the South Pacific Ocean

et al. 2014

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In addition to the cyanobacterial N2-fixers (diazotrophs), there is a high nifH gene diversity of non-cyanobacterial groups present in marine environments, yet quantitative information about these groups is scarce. N2 fixation potential (nifH gene expression), diversity and distributions of the uncultivated diazotroph phylotype γ-24774A11, a putative gammaproteobacterium, were investigated in the western South Pacific Ocean. γ-24774A11 gene copies correlated positively with diazotrophic cyanobacteria, temperature, dissolved organic carbon and ambient O2 saturation, and negatively with depth, chlorophyll a and nutrients, suggesting that carbon supply, access to light or inhibitory effects of DIN may control γ-24774A11 abundances. Maximum nifH gene-copy abundance was 2 × 104 l−1, two orders of magnitude less than that for diazotrophic cyanobacteria, while the median γ-24774A11 abundance, 8 × 102 l−1, was greater than that for the UCYN-A cyanobacteria, suggesting a more homogeneous distribution in surface waters. The abundance of nifH transcripts by γ-24774A11 was greater during the night than during the day, and the transcripts generally ranged from 0–7%, but were up to 26% of all nifH transcripts at each station. The ubiquitous presence and low variability of γ-24774A11 abundances across tropical and subtropical oceans, combined with the consistent nifH expression reported in this study, suggest that γ-24774A11 could be one of the most important heterotrophic (or photoheterotrophic) diazotrophs and may need to be considered in future N budget estimates and models.

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Section: Introductionmentioning

confidence: 99%

Gammaproteobacterial diazotrophs and nifH gene expression in surface waters of the South Pacific Ocean

et al. 2014

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“…9), the N excess exuded being equally distributed into the DON and NH + 4 pools. As in Rabouille et al (2006), the nitrogenase activity (Nase, in mol N cell −1 s −2 ) is a state variable, the dynamics of which are described in Eq. (5).…”

Section: Modeling N 2 Fixationmentioning

confidence: 99%

“…4) used to represent N 2 fixation was adapted from Rabouille et al (2006) in order to be compatible with the formal features of the present model. It describes the N 2 fixation flux as a function of the nitrogenase (i.e., the enzyme catalyzing N 2 fixation) activity (Nase) and the diazotroph abundance (DIAZO cell , where DIAZO either refers to TRI or UCYN-C).…”

Section: Modeling N 2 Fixationmentioning

confidence: 99%

“…In these models, Trichodesmium is the most frequently represented organism since it is the most studied diazotroph and its physiology is well documented in the literature (Moore et al, 2001b;Fennel et al, 2001;Moore et al, 2004;Rabouille et al, 2006). In recent studies, other diazotrophs such as unicellular Cyanobacteria (termed UCYN) or diatom-diazotroph associations (termed DDAs) have been implemented in biogeochemical models.…”

Section: Introductionmentioning

confidence: 99%

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Biogeochemical fluxes and fate of diazotroph-derived nitrogen in the food web after a phosphate enrichment: modeling of the VAHINE mesocosms experiment

2016

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Abstract. The VAHINE mesocosm experiment in the oligotrophic waters of the Nouméa lagoon (New Caledonia), where high N 2 fixation rates and abundant diazotroph organisms were observed, aimed to assess the role of the nitrogen input through N 2 fixation in carbon production and export and to study the fate of diazotroph-derived nitrogen (DDN) throughout the planktonic food web. A 1-D vertical biogeochemical mechanistic model was used in addition to the in situ experiment to enrich our understanding of the dynamics of the planktonic ecosystem and the main biogeochemical carbon (C), nitrogen (N) and phosphate (P) fluxes. The mesocosms were intentionally enriched with ∼ 0.8 µmol L −1 of inorganic P to trigger the development of diazotrophs and amplify biogeochemical fluxes. Two simulations were run, one with and the other without the phosphate enrichment. In the P-enriched simulation, N 2 fixation, primary production (PP) and C export increased by 201, 208 and 87 %, respectively, consistent with the trends observed in the mesocosms (+124, +141 and +261 % for N 2 fixation, PP and C export, respectively). In total, 5-10 days were necessary to obtain an increase in primary and export productions after the dissolved inorganic phosphate (DIP) enrichment, thereby suggesting that classical methods (short-term microcosms experiments) used to quantify nutrient limitations of primary production may not be relevant. The model enabled us to monitor the fate of fixed N 2 by providing the proportion of DDN in each compartment (inorganic and organic) of the model over time. At the end of the simulation (25 days), 43 % of the DDN was found in the non-diazotroph organisms, 33 % in diazotrophs, 16 % in the dissolved organic nitrogen pool, 3 % in the particulate detrital organic pool and 5 % in traps, indicating that N 2 fixation was of benefit to non-diazotrophic organisms and contributed to C export.

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“…was in 1969 by Wyatt and Silvey 17 , and followed by work of Singh 18 , Ni et al 19 , Gallon and Stal 20 , and Fay 21 . Other studies relate to interactions between nitrogen fixation and O -2 and other diazotrophs 21,22 and the more specialized reviews of Huang and Grobbelaar 23 on Synechococcus RF-1, Trichodesmium 24 , and cyanobacterial mats [25][26][27][28][29] all point to the fact that nonheterocystous filamentous and unicellular cyanobacteria are capable of N 2 fixation.…”

Section: Introductionmentioning

confidence: 99%

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Banerjee¹,

Verma²

2009

ScienceAsia

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Nitrogen is scarce in the sandstones of McMurdo Dry Valley, Antarctica, and the possibility for the input from precipitation is minimal. In endolithic communities dominated by phototrophs, nitrogen availability by nitrogen fixation may therefore be very important. To investigate this, nitrogenase activity of the whole communities (rock plus microorganisms) of Linneus Terrace, McMurdo Dry Valley, was measured by acetylene reduction assay and environmental factors affecting the enzyme activity were studied. The activity obtained from these studies presumably came from the dominant phototroph identified, the ancient unicellular cyanobacterium Chroococcidiopsis. We describe a comparative study of nitrogen fixation where one set of experiments was conducted under conditions likely to be present in the Antarctic from where the samples were obtained i.e., 275 lux and 5°C, and the other under laboratory conditions with 2500 lux and 20°C. Our studies revealed that there was a distinct diurnal pattern of nitrogenase activity in these endoliths. Nitrogen fixation thus seems to be a very important activity in the Antarctic endoliths where there is a permanently immobilized layer of phototrophic cells exposed to extreme environmental conditions. It is probable that, although there is a drastic reduction in the photosynthesis active radiation of about 1-3% photons reaching the phototrophic region of the endolith for photosynthesis during the day, it is this that provides the energy for nitrogen fixation during the night. Also a heterotrophic mechanism involved in the nitrogen fixation process cannot be ruled out, as osmolytes are abundant in these environments to protect the cells from desiccation.

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Modeling the Dynamic Regulation of Nitrogen Fixation in the Cyanobacterium Trichodesmium sp

Cited by 58 publications

References 53 publications

Gammaproteobacterial diazotrophs and nifH gene expression in surface waters of the South Pacific Ocean

Gammaproteobacterial diazotrophs and nifH gene expression in surface waters of the South Pacific Ocean

Biogeochemical fluxes and fate of diazotroph-derived nitrogen in the food web after a phosphate enrichment: modeling of the VAHINE mesocosms experiment

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