Ecosystem scale evidence for the contribution of vanadium-based nitrogenase to biological nitrogen fixation

2020 ◽  
Author(s):  
Jean-Philippe Bellenger ◽  
Romain Darnajoux ◽  
Nicolas Magain ◽  
Marie Renaudin ◽  
Francois Lutzoni ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
High Latitude ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Growing Season ◽  
The Arctic ◽  
Field Evidence ◽  
N Input ◽  
Vanadium Nitrogenase ◽  
Biological Nitrogen

<p>Nitrogen is the primary limiting nutrient in high latitude ecosystems. Biological nitrogen fixation (BNF) by microorganisms associated with cryptogamic covers, such as cyanolichens and bryophytes, is an important source of new reactive nitrogen in pristine, high-latitude ecosystems. BNF is catalyzed by the enzyme nitrogenase, for which three isoforms have been described; the canonical molybdenum (Mo) nitrogenase which requires Mo in its active site and two alternative nitrogenases, the vanadium and iron-only nitrogenases. The low availability of Mo on land has been shown to limit BNF in many ecosystems from the tropical forest to the arctic tundra. Alternative nitrogenases have been suggested as viable alternatives to cope with Mo limitation of BNF, however, field data supporting this long-standing hypothesis have been lacking.</p><p>Here, we elucidated the contribution of the vanadium nitrogenase to BNF by cyanolichens across a 600 km latitudinal transect in eastern Canadian boreal forests. We report a widespread activity of the vanadium nitrogenase which contributed between 15 to 50% of total BNF rates on all sites. Vanadium nitrogenase contribution to BNF was more robust in the northern part of the transect. Vanadium nitrogenase contribution to BNF also changed during the growing season, with a three-fold increase between the early (May) and late (September) growing season. By including the contribution of the vanadium nitrogenase to BNF, estimates of new N input by cyanolichens increase by up to 30%, a significant change in these low N input ecosystems. Finally, we found that Mo availability was the primary driver for the contribution of the vanadium nitrogenase to BNF with a Mo threshold of ~ 250 ng.g<sub>lichen</sub><sup>-1</sup> for the onset of vanadium based BNF.</p><p>This study on N<sub>2</sub>-fixing cyanolichens provides extensive field evidence, at an ecosystem scale, that vanadium-based nitrogenase greatly contributes to BNF when Mo availability is limited. The results showcase the resilience of BNF to micronutrient limitation and reveal a strong link between the biogeochemical cycle of macro- and micronutrients in terrestrial ecosystems. Given widespread findings of Mo limitation of BNF in terrestrial ecosystems, additional consideration of vanadium-based BNF is required in experimental and modeling studies of terrestrial biogeochemistry.</p>

Ecosystem scale evidence for the contribution of vanadium-based nitrogenase to biological nitrogen fixation. 

2021 ◽  
Author(s):  
Jean-Philippe Bellenger ◽  
Romain Darnajoux ◽  
Nicolas Magain ◽  
Marie Renaudin ◽  
Francois Lutzoni ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
High Latitude ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Growing Season ◽  
The Arctic ◽  
Field Evidence ◽  
N Input ◽  
Vanadium Nitrogenase ◽  
Biological Nitrogen

<p>Nitrogen is the primary limiting nutrient in high latitude ecosystems. Biological nitrogen fixation (BNF) by microorganisms associated with cryptogamic covers, such as cyanolichens and bryophytes, is an important source of new reactive nitrogen in pristine, high-latitude ecosystems. BNF is catalyzed by the enzyme nitrogenase, for which three isoforms have been described; the canonical molybdenum (Mo) nitrogenase which requires Mo in its active site and two alternative nitrogenases, the vanadium and iron-only nitrogenases. The low availability of Mo on land has been shown to limit BNF in many ecosystems from the tropical forest to the arctic tundra. Alternative nitrogenases have been suggested as viable alternatives to cope with Mo limitation of BNF, however, field data supporting this long-standing hypothesis have been lacking.</p><p>Here, we elucidated the contribution of the vanadium nitrogenase to BNF by cyanolichens across a 600 km latitudinal transect in eastern Canadian boreal forests. We report a widespread activity of the vanadium nitrogenase which contributed between 15 to 50% of total BNF rates on all sites. Vanadium nitrogenase contribution to BNF was more robust in the northern part of the transect. Vanadium nitrogenase contribution to BNF also changed during the growing season, with a three-fold increase between the early (May) and late (September) growing season. By including the contribution of the vanadium nitrogenase to BNF, estimates of new N input by cyanolichens increase by up to 30%, a significant change in these low N input ecosystems. Finally, we found that Mo availability was the primary driver for the contribution of the vanadium nitrogenase to BNF with a Mo threshold of ~ 250 ng.g<sub>lichen</sub><sup>-1</sup> for the onset of vanadium based BNF.</p><p>This study on N<sub>2</sub>-fixing cyanolichens provides extensive field evidence, at an ecosystem scale, that vanadium-based nitrogenase greatly contributes to BNF when Mo availability is limited. The results showcase the resilience of BNF to micronutrient limitation and reveal a strong link between the biogeochemical cycle of macro- and micronutrients in terrestrial ecosystems. Given widespread findings of Mo limitation of BNF in terrestrial ecosystems, additional consideration of vanadium-based BNF is required in experimental and modeling studies of terrestrial biogeochemistry.</p>

scholarly journals Fixação biológica de nitrogênio no Semiárido Brasileiro (Biological nitrogen fixation in the Brazilian Semiarid)

2015 ◽  
Vol 8 ◽  
pp. 585
Author(s):  
Ana Dolores Santiago de Freitas ◽  
Everardo Sampaio ◽  
Carolina Santos ◽  
Aleksandro Silva ◽  
Renata Carvalho
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Plant Density ◽  
Tree Cover ◽  
Semiarid Region ◽  
Legume Species ◽  
Natural Ecosystems ◽  
Brazilian Semiarid ◽  
N Input ◽  
Biological Nitrogen

A fixação biológica de nitrogênio (FBN) é a principal forma de entrada de N em ecossistemas naturais e em sistemas agrícolas de subsistência, como os praticados predominantemente no Semiárido brasileiro. Estimativas dos aportes de N na Caatinga e em cultivos de importância para a região ainda são escassas, em parte pela dificuldade de medir simultaneamente as proporções de N derivadas da atmosfera (%Ndda) e as produções de biomassa no mesmo sistema. Estudos pioneiros indicam que diversas espécies de leguminosas, herbáceas e arbóreas, nativas e/ou cultivadas, podem fixar elevadas proporções de seu N. Em Caatinga bem preservada, os aportes de N em leguminosas arbóreas foram estimados em 11 kg ha-1 ano-1, um valor relativamente baixo devido à baixa densidade de plantas fixadoras. Entretanto, a densidade de leguminosas fixadoras na vegetação não é o único fator definindo o aporte de N, pois há observações de ausência de FBN em áreas de Caatinga em regeneração, dominadas por espécies fixadoras. No estrato herbáceo, os aportes de N podem chegar a 6 kg ha-1 ano-1, nas áreas com menor cobertura de arbóreas. As quantidades de N fixadas nos diferentes sistemas de cultivo são pouco conhecidas. Para o feijão-caupi, a FBN pode se aproximar dos 30 kg ha-1, em cultivos consorciados com milho, chegando a 45 kg ha-1, em cultivos solteiros. Em cultivos irrigados, adubos verdes podem adicionar 185 kg ha-1, superando a quantidade exportada nas colheitas. Em sistemas agroflorestais, a adição anual de N pode chegar a 40 kg ha-1. Não existem estimativas do N fixado em gramíneas na região, mas algumas espécies apresentem potencial de FBN. Biological nitrogen fixation (BNF) is the main N input in natural ecosystems and in subsistence agricultural systems, such as those commonly practiced in the Brazilian semiarid region. Estimates of N inputs in Caatinga and the main regional crops are still scarce, partly due to the difficulty in measuring concomitantly the proportion of plant N derived from the atmosphere (%Ndfa) and the amount of biomass produced in the same system. Pioneer studies indicate that several legume species, herbs and trees, native and/or cultivated, can fix large proportions of their N. In mature Caatinga, N inputs in tree legumes were estimated at 11 kg ha-1 year-1, a relatively low value due to the low plant density of the legume species. However, plant density is not the only factor defining N input, since absence of fixation has been reported in regenerating Caatinga, even in those dominated by potentially fixing species. In the herb stratum, N input up to 6 kg ha-1 year-1 has been reported in areas with lower tree cover. Inputs in crop systems are largely unknown. Fixation in cowpea can reach 30 kg ha-1, in plants consortiated with corn, and 45 kg ha-1, in single crop. Under irrigation, green manure crops can add 185 kg ha-1 of fixed N, more than the amounts exported by the main crop. In agroforest systems, the annual input may reach 40 kg ha-1. There are no publish reports on N biologically fixed by Poaceae species growing in the semiarid region but it is known that some species have the potential to fix. Keywords: N-15 natural abundance, slash and burn agriculture, diazotrophic microorganism, rhizobia, symbiosis.   

scholarly journals A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems

2021 ◽  
Author(s):  
Fiona M Soper ◽  
Benton N Taylor ◽  
Joy B Winbourne ◽  
Michelle Y Wong ◽  
Katherine A Dynarski ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Biological Nitrogen

scholarly journals Impacts of biological nitrogen fixation on N<sub>2</sub>O emissions from global natural terrestrial ecosystem soils: An Analysis with a process-based biogeochemistry model

2019 ◽  
Author(s):  
Tong Yu ◽  
Qianlai Zhuang
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Climatic Conditions ◽  
N2o Emissions ◽  
Emission Model ◽  
Fixation Rate ◽  
Observational Site ◽  
Biological Nitrogen

Abstract. Biological nitrogen fixation plays an important role in the global nitrogen cycle. However, the fixation rate has been usually measured or estimated at a particular observational site. To quantify the fixation amount at the global scale, a process-based model is needed. This study develops a biological nitrogen fixation model and couples it with an extant biogeochemistry model of N2O emissions to examine the fixation rate and its effects on N2O emissions. The revised N2O emission model better matches the observed data in comparison with our previous model that has not considered the fixation effects. The new model estimates that tropical forests have the highest fixation rate among all ecosystem types, and decrease from the equator to the polar region. The estimated nitrogen fixation in global terrestrial ecosystems is 61.5 Tg N yr−1 with a range of 19.8–107.9 Tg N yr−1 in the 1990s. Our estimates are relatively low compared to some early estimates using empirical approaches, but comparable to more recent estimates that involve more detailed processes in their modeling. Furthermore, we estimate that the fixation contributes to −5 % to 20 % changes in N2O emissions compared to our previous estimates, depending on ecosystem types and climatic conditions. This study highlights that there are relatively large effects of the biological nitrogen fixation on ecosystem nitrogen cycling and soil N2O emissions and calls for more comprehensive understanding of biological nitrogen fixation and more observational data for different ecosystems to improve future quantification of the fixation and its impacts.

Biological nitrogen fixation by alternative nitrogenases in terrestrial ecosystems: a review

2020 ◽  
Vol 149 (1) ◽  
pp. 53-73 ◽  
Author(s):  
J. P. Bellenger ◽  
R. Darnajoux ◽  
X. Zhang ◽  
A. M. L. Kraepiel
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Biological Nitrogen

scholarly journals Modeling biological nitrogen fixation in global natural terrestrial ecosystems

2020 ◽  
Vol 17 (13) ◽  
pp. 3643-3657
Author(s):  
Tong Yu ◽  
Qianlai Zhuang
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Cycle ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Climatic Conditions ◽  
Fixation Rate ◽  
Observational Site ◽  
Biological Nitrogen ◽  
Global Nitrogen Cycle

Abstract. Biological nitrogen fixation plays an important role in the global nitrogen cycle. However, the fixation rate has been usually measured or estimated at a particular observational site. To quantify the fixation amount at the global scale, process-based models are needed. This study develops a biological nitrogen fixation model to quantitatively estimate the nitrogen fixation rate by plants in a natural environment. The revised nitrogen module better simulates the nitrogen cycle in comparison with our previous model that has not considered the fixation effects. The new model estimates that tropical forests have the highest fixation rate among all ecosystem types, which decreases from the Equator to the polar region. The estimated nitrogen fixation in global terrestrial ecosystems is 61.5 Tg N yr−1 with a range of 19.8–107.9 Tg N yr−1 in the 1990s. Our estimates are relatively low compared to some early estimates using empirical approaches but comparable to more recent estimates that involve more detailed processes in their modeling. Furthermore, the contribution of nitrogen made by biological nitrogen fixation depends on ecosystem type and climatic conditions. This study highlights that there are relatively large effects of biological nitrogen fixation on ecosystem nitrogen cycling. and the large uncertainty of the estimation calls for more comprehensive understanding of biological nitrogen fixation. More direct observational data for different ecosystems are in need to improve future quantification of fixation and its impacts.

scholarly journals Biological nitrogen fixation: rates, patterns and ecological controls in terrestrial ecosystems

2013 ◽  
Vol 368 (1621) ◽  
pp. 20130119 ◽  
Author(s):  
Peter M. Vitousek ◽  
Duncan N. L. Menge ◽  
Sasha C. Reed ◽  
Cory C. Cleveland
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Global Environmental Change ◽  
Terrestrial Ecosystems ◽  
N Fixation ◽  
New Techniques ◽  
N Cycle ◽  
Global Environmental ◽  
Wide Range ◽  
Biological Nitrogen

New techniques have identified a wide range of organisms with the capacity to carry out biological nitrogen fixation (BNF)—greatly expanding our appreciation of the diversity and ubiquity of N fixers—but our understanding of the rates and controls of BNF at ecosystem and global scales has not advanced at the same pace. Nevertheless, determining rates and controls of BNF is crucial to placing anthropogenic changes to the N cycle in context, and to understanding, predicting and managing many aspects of global environmental change. Here, we estimate terrestrial BNF for a pre-industrial world by combining information on N fluxes with 15 N relative abundance data for terrestrial ecosystems. Our estimate is that pre-industrial N fixation was 58 (range of 40–100) Tg N fixed yr −1 ; adding conservative assumptions for geological N reduces our best estimate to 44 Tg N yr −1 . This approach yields substantially lower estimates than most recent calculations; it suggests that the magnitude of human alternation of the N cycle is substantially larger than has been assumed.

Sign in / Sign up

Export Citation Format

Share Document