Nitrogenase

Nitrogenase

How life learned to break one of the strongest bonds in nature and pull nitrogen out of thin air: a 4.5-billion-year story, from lightning on the young Earth to root nodules and the fertilizer that feeds half of humanity.

Start 4.5 billion years agoGo to NFixDB

Before life

The early Earth: a volcanic coast under a violet sky, lightning striking the sea, nitrogen molecules drifting in the air and a few turned into nitrogen oxides by the strike N2 fills the air Lightning makes nitrogen oxides Vents and volcanoes

The young Earth was wrapped in nitrogen gas, and almost none of it was usable. Two atoms locked by a triple bond make N2 one of the most stubborn molecules in nature.

Only violent energy could split it. Lightning, hydrothermal vents and sunlight-driven chemistry each turned a trickle of N2 into usable forms such as ammonium and nitrogen oxides (Stüeken et al. 2015). Spark experiments suggest lightning in an early atmosphere of nitrogen and carbon dioxide fixed nitrogen about as efficiently as it does today, and some 3.7-billion-year-old rocks may still carry its isotopic fingerprint (2023 study).

An influential idea held that lightning’s output collapsed as carbon dioxide fell, setting off a “nitrogen crisis” that pushed life to make its own (Navarro-González et al. 2001). The rocks suggest life had already solved the problem.

Life breaks the bond

A shallow Archean sea with stromatolites built by microbial mats; a magnified microbe holds the nitrogenase active site, taking in N2 and releasing ammonia Nitrogenase N2 in NH3 out Microbial mats build stromatolites

By 3.2 billion years ago, microbes had evolved nitrogenase, an enzyme that does at seawater temperature what lightning does with a bolt of plasma.

The proof is written in rock. Fifty-two samples of 3.2- to 2.75-billion-year-old sediment from South Africa and Australia hold nitrogen isotope ratios averaging 0.0 ± 1.2‰, a signal that abiotic chemistry cannot readily explain but molybdenum nitrogenase can (Stüeken et al. 2015). The vanadium and iron-only versions of the enzyme leave a lighter fingerprint, around −6 to −7‰ (Zhang et al. 2014).

Those first fixers lived on their own, in seawater, sediments and the layered microbial mats that built stromatolites. The chemistry they invented has barely changed since, and it is not cheap:

N2from the air 8 H+protons 8 e−one at a time 16 ATPtwo per electron 2 NH3ammonia H2unavoidable by-product

Best-case accounting for molybdenum nitrogenase, with each ATP bound to magnesium. Every N2 costs at least 16 ATP and eight electrons.

Oxygen arrives

Banded iron rock in rust and grey stripes behind a cyanobacterial filament: green cells release oxygen while one thick-walled heterocyst fixes nitrogen Heterocyst fixes N2, makes no O2 Neighbors make O2 Banded iron formation

Cyanobacteria filled the air with oxygen. For nitrogenase, built around iron–sulfur clusters that oxygen destroys, it was a catastrophe.

About 2.4 billion years ago, oxygen released by photosynthesis began to build up in the atmosphere, an event called the Great Oxidation. Iron dissolved in seawater rusted out into striped rocks known as banded iron formations. Ever since, nitrogen fixers have had to hide their enzyme from the air.

Heterocysts
Filamentous cyanobacteria such as Anabaena and Nostoc fix nitrogen in thick-walled cells that lack oxygen-producing photosystem II.
Night shifts
Some single-celled cyanobacteria photosynthesize by day and fix nitrogen at night.
Fast breathing
Azotobacter respires so quickly that oxygen is used up before it reaches the enzyme.
A protective clamp
Azotobacter’s FeSII protein locks nitrogenase into an inactive but protected complex when oxygen spikes.

The one reported exception, an oxygen-insensitive nitrogenase in Streptomyces thermoautotrophicus, did not hold up when a team including the Friesen lab retested it: the strains scavenge combined nitrogen rather than fixing N2 (MacKellar et al. 2016).

The free-livers

Free-living nitrogen fixers: in the ocean, golden Trichodesmium colonies and algae carrying UCYN-A; in the soil, bacteria clustered around a plant root, including Azotobacter Trichodesmium UCYN-A Azotobacter Root exudates feed rhizosphere fixers Ocean microbes: about 140 million tonnes of nitrogen a year

The original nitrogen fixers never needed a host, and they still do a huge share of the world’s work.

In the open ocean, the colonial cyanobacterium Trichodesmium and the tiny UCYN-A fix nitrogen in waters starved of it. With other marine microbes they add about 140 million tonnes of nitrogen a year, more than the world’s ammonia plants produce (Fowler et al. 2013).

On land, Azotobacter and the oxygen-shy Clostridium fix nitrogen without partners, and many rhizosphere bacteria fix it around roots, fed by the sugars and acids that roots leak. Free-living fixation runs on its own rules and is carried out by different microbes than symbiotic fixation (Smercina et al. 2019).

It can matter a great deal. In switchgrass on marginal land, free-living fixation could potentially meet up to 80% of the crop’s nitrogen demand (Smercina et al. 2021). Metagenomes from that rhizosphere point to Janthinobacterium as a candidate partner (White et al. 2023), and a soil fixer’s ability to break down organic nitrogen with secreted enzymes shapes how much N2 it fixes (Norman and Friesen 2017).

Plants strike a deal

A pea plant's roots dotted with pink nodules; one nodule is shown cut open, its pink center packed with nitrogen-fixing cells, with sugars flowing in and ammonia flowing out A nodule, cut open Leghemoglobin makes it pink Flavonoids out Nod factors back sugars in ammonia out

Plants cannot make nitrogenase. Some evolved a new organ, the root nodule, to house bacteria that can.

More than 100 million years ago, the ancestor of one group of flowering plants gained a still-mysterious innovation that set its descendants up for nodulation (Werner et al. 2014). Every plant with nitrogen-fixing root nodules, from peas and soybeans to alders, belongs to that one clade, and many of its members have since lost the trait (Griesmann et al. 2018).

  1. Invitation. Roots release flavonoids into the soil.
  2. Reply. Compatible rhizobia answer with Nod factors (lipochitooligosaccharides).
  3. Entry. A root hair curls around the bacteria and an infection thread carries them inward; some legumes let them in between cells instead.
  4. Organ building. Root cells divide to form a nodule, and the rhizobia become nitrogen-fixing bacteroids inside host-membrane compartments.
  5. Oxygen control. Leghemoglobin keeps free oxygen low enough for nitrogenase while feeding bacterial respiration, and turns working nodules pink.
  6. Trade. The plant pays in carbon, as malate and succinate; the bacteroids pay in ammonia.
  7. Enforcement. Hosts can cut support to nodules that fix little nitrogen (Kiers et al. 2003) and invest more in nodules when light is plentiful and soil nitrogen is scarce (Friel and Friesen 2019).

Beyond legumes

More than 200 species of trees and shrubs, including alders and Casuarina, host Frankia bacteria in root nodules. Cyanobacteria such as Nostoc live in the water fern Azolla, in Gunnera stems, in cycad roots and in many lichens.

Keeping partners honest

Rhizobia range from excellent partners to near-freeloaders, and one root meets many strains. Friesen-lab work asks why ineffective rhizobia persist (Friesen and Mathias 2010), how closely plant and rhizobium fitness line up (Friesen 2012), how “cheaters” fit theories of mutualism (Jones et al. 2015) and which genomic changes underlie cooperation in wild Mesorhizobium (Porter et al. 2019). See all symbiosis papers.

People take notice

A botanical ink drawing of a pea plant with pods, tendrils and nodules on its roots Fig. 1. Pisum sativum, with root nodules

Farmers had long known that beans and clover leave soil richer. In the 1880s, scientists found out why.

  1. 1886Hermann Hellriegel and Hermann Wilfarth show that legumes take nitrogen from the air only when their roots carry nodules.
  2. 1888Martinus Beijerinck grows the nodule bacteria, now called rhizobia, in pure culture.
  3. 1890sSergei Winogradsky isolates Clostridium pasteurianum, the first known free-living nitrogen fixer.
  4. 1898William Crookes warns that the world’s wheat will run short of nitrogen fertilizer unless chemists learn to fix it from the air.
  5. 1901Beijerinck isolates Azotobacter, an oxygen-breathing free-living fixer.

Bread from air

A Haber–Bosch ammonia reactor: a tall steel vessel glowing with heat, fed with nitrogen from the air and hydrogen from natural gas, with gauges reading about 450 degrees Celsius and 200 bar, and ammonia flowing out to a field N2 + 3 H2 → 2 NH3 N2 from the air H2 from natural gas ≈200 bar ≈450 °C ammonia to the fields

Fritz Haber found a way to fix nitrogen in a reactor; Carl Bosch scaled it into an industry. The world has not been the same since.

Haber filed his patent for making ammonia from its elements in October 1908 (Erisman et al. 2008), and BASF opened the first industrial plant, at Oppau, in 1913. The process drives N2 and hydrogen together over an iron catalyst at roughly 400–500 °C and 150–300 bar. Haber won the 1918 Nobel Prize in Chemistry; Bosch shared the 1931 prize for high-pressure chemistry.

The chemistry cut both ways. During the First World War it supplied Germany with nitrates for explosives after imports of Chilean saltpeter were cut off.

of the world’s people in 2008 were sustained by food grown with Haber–Bosch nitrogen (Erisman et al. 2008).

Where Earth’s new nitrogen comes from

Millions of tonnes of nitrogen fixed per year, around 2010

NitrogenaseIndustry, fire and lightning

Ocean microbes
140
Haber–Bosch
120
Crops and their partners
60
Wild land ecosystems
58
Fuel combustion
30
Lightning
5
Of about 413 million tonnes a year, nitrogenase still supplies roughly 258, about three-fifths. Data: Fowler et al. 2013.

Same reaction, two routes

Haber–BoschNitrogenase
Conditionsabout 400–500 °C, 150–300 barsoil, sea or nodule temperature, about 1 atmosphere
Catalystpromoted ironiron–sulfur clusters with molybdenum, vanadium or iron
Hydrogen fromH2 made mostly from natural gas or coalprotons and electrons from metabolism
Energycommonly estimated at 1–2% of world energy useat least 16 ATP per N2
By-productCO2 from making the hydrogenat least one H2 per N2

The bill comes later

Fertilizer that crops do not take up leaks away as nitrate, feeding algal blooms and coastal dead zones, and as nitrous oxide, a greenhouse gas far more potent than CO2. Leaching and rivers carry 40–70 million tonnes of nitrogen a year to coastal waters (Fowler et al. 2013). Getting more from biological fixation, in legumes, free-living partners and perhaps one day in cereals, is one of agriculture’s great open problems.

Reading the machine

The FeMo-cofactor drawn as glowing spheres: seven iron atoms and nine sulfur atoms around a central carbon, capped by molybdenum Fe S central carbon Mo homocitrate binds here MoFe7S9C, drawn schematically

A century after Haber, scientists are still working out how nitrogenase does at room temperature what industry needs a furnace for.

The answer sits in a cluster of seven iron atoms, nine sulfurs, a molybdenum and a single carbon at the center, the FeMo-cofactor. Electrons arrive one at a time, and the cluster stores them until it can bind N2 and break it apart.

Look inside the enzymeExplore NFixDB

  1. 1960Nitrogen is fixed in cell-free extracts of Clostridium pasteurianum, opening the enzyme to biochemistry.
  2. 1992The first crystal structures of the nitrogenase proteins are solved.
  3. 2011The FeMo-cofactor’s central carbon atom is identified.
  4. 2024A marine alga’s partner UCYN-A is shown to be an organelle: the nitroplast (Coale et al. 2024).
  5. 2024NFixDB maps every nitrogenase family across sequenced genomes (Bellanger et al. 2024).

Inside the enzyme

Nitrogenase is a two-part metalloenzyme. A small protein loads electrons with the help of ATP, and a large one holds the active site where N2 is reduced. Only bacteria and archaea carry the genes for it.

Ferredoxin or flavodoxin

the cell’s electron donors

Fe protein

(NifH)2 with one [4Fe-4S] cluster; binds 2 MgATP

P-cluster

[8Fe-7S], inside the MoFe protein (NifDK)

FeMo-cofactor

MoFe7S9C with homocitrate; the active site

N2 becomes 2 NH3

plus at least one H2

Electrons travel one at a time from the cell’s reductants through three metal clusters to the active site. Cluster drawings are schematic: iron, sulfur, molybdenum and the central carbon.

The Fe protein

Also called dinitrogenase reductase, it is a homodimer of NifH with a single [4Fe-4S] cluster bridging its two halves. Binding two MgATP readies it to dock onto the MoFe protein and hand over one electron. In living cells it is the MoFe protein’s only electron donor.

The MoFe protein

Also called dinitrogenase, it is an α2β2 tetramer of NifD and NifK. Each αβ half carries a P-cluster, which relays electrons, and an FeMo-cofactor, where substrates bind and are reduced.

The FeMo-cofactor

The active site is a MoFe7S9C cluster with an organic homocitrate bound to the molybdenum. Its central carbon atom was identified only in 2011. Building it takes a dedicated set of genes, including nifB, nifEN and nifV.

Three nitrogenases

Many nitrogen fixers carry backup enzymes that use vanadium or iron in place of molybdenum. Each is encoded by its own gene set and switched on when molybdenum runs short.

MolybdenumVanadiumIron-only
Structural genesnifHDKvnfHDGKanfHDGK
Active-site cofactorFeMo-cofactorFeV-cofactorFeFe-cofactor
Extra subunitnoneδ (VnfG)δ (AnfG)
Typically used whenmolybdenum is availableMo is scarce and V is presentboth Mo and V are scarce
Electrons lost to H2fewestmoremost

The alternative enzymes have extra chemistry of their own: vanadium nitrogenase can reduce carbon monoxide to short hydrocarbons, and both alternatives can turn CO2 into methane. Because nifH is conserved across nearly all nitrogen fixers, it is the standard marker gene for surveying them; NFixDB extends that toolkit to the H, D and K genes of every family.

How nitrogen gets fixed

Nitrogenase is slow and expensive. It moves electrons one at a time, spends two ATP on each, and needs eight of them for every N2 it reduces.

One turn of the Fe-protein cycle

  1. Charge. The Fe protein is reduced by ferredoxin or flavodoxin and binds two MgATP.
  2. Dock. It docks onto one αβ half of the MoFe protein.
  3. Transfer. An electron reaches the FeMo-cofactor through the P-cluster. In the current “deficit spending” model, the P-cluster gives up an electron first and is then refilled by the Fe protein’s [4Fe-4S] cluster.
  4. Pay. Both ATP are hydrolyzed to ADP and phosphate.
  5. Release. The Fe protein lets go of phosphate and dissociates. This is the slowest step of the cycle.
  6. Repeat. Eight cycles supply the eight electrons needed to turn one N2 into two NH3 and one H2.

Inside the active site: E0 to E8

The Lowe–Thorneley scheme names each state of the FeMo-cofactor by how many electrons and protons it has received (Hoffman et al. 2014).

  1. E0: resting state

    The cofactor holds no extra electrons. Each step that follows adds one electron from the Fe protein and one proton.

  2. E1: first electron

    One Fe-protein cycle has delivered one electron and spent two ATP.

  3. E2: two stored

    With two electrons and protons on board, the cofactor can simply release H2 and fall back to E0. That side path costs energy without fixing anything.

  4. E3: three stored

    The added electrons and protons accumulate on the cofactor as metal-bound hydrides.

  5. E4: the “Janus” state

    Four electrons and protons are stored as two iron-bridging hydrides. This is the state that can bind N2.

  6. E4 with N2: H2 leaves

    N2 binds as the two hydrides combine and depart as H2, a step called reductive elimination. This is why at least one H2 is made for every N2 fixed.

  7. E5 to E7: hydrogenation

    Three more electrons and protons add to the bound nitrogen, one at a time. Along the way the N–N bond breaks and the first NH3 is released.

  8. E8: back to rest

    The eighth electron frees the second NH3, and the cofactor returns to E0, ready for the next N2.

NFixDB

The Nitrogen Fixation DataBase: a whole-genome catalog of nitrogenases and the microbes that carry them.

NFixDB brings every nitrogenase family into one searchable resource: molybdenum (nifHDK), vanadium (vnfHDK) and iron-only (anfHDK) nitrogenases, plus nitrogenase-like enzymes such as nflHD. Each entry is linked to its genome’s ribosomal RNA operon and taxonomy, connecting the potential to fix nitrogen with the organism that carries it.

Built from
Hidden Markov models searched against every genome in the Genome Taxonomy Database, release 214
Contents
Reference HMMs, complete rRNA operons, GTDB and NCBI/RefSeq taxonomy, and an SQL database for queries
Scale
More than 4,000 verified nifHDK sequences from 50 phyla of bacteria and archaea; Proteobacteria make up more than half
Compared with
The Buckley, Zehr, Mise and FunGene nifH databases, which turned out to hold vnfH and nflH sequences as well as nifH
Built by
Madeline Bellanger, Jose L. Figueroa III, Lisa Tiemann, Maren L. Friesen and Richard Allen White III

Get NFixDB

How to cite

Bellanger M, Figueroa JL III, Tiemann L, Friesen ML, White RA III (2024). NFixDB (Nitrogen Fixation DataBase): a comprehensive integrated database for robust ‘omics analysis of diazotrophs. NAR Genomics and Bioinformatics 6(2): lqae063. https://doi.org/10.1093/nargab/lqae063

A December 2024 correction clarifies the hit-filtering thresholds: the paper’s results come from v2.1, which applied the E-value and bitscore cutoffs as alternatives, and the pipeline was updated in v3.1 to require all of them.

Papers

Research on nitrogenase, free-living nitrogen fixation and plant–microbe symbiosis from Richard Allen White III and Maren L. Friesen, with their students and collaborators. Both names are in bold.

23 papers

  1. 2024

    NFixDB (Nitrogen Fixation DataBase): a comprehensive integrated database for robust ‘omics analysis of diazotrophs Editor’s pick

    Bellanger M, Figueroa JL III, Tiemann L, Friesen ML, White RA III

    NAR Genomics and Bioinformatics 6(2): lqae063. doi:10.1093/nargab/lqae063

    All three nitrogenase families plus nitrogenase-like genes, mined from GTDB genomes with HMMs and linked to rRNA operons and taxonomy.

  2. 2024

    MerCat2: a versatile k-mer counter and diversity estimator for database-independent property analysis obtained from omics data

    Figueroa JL III, Redinbo A, Panyala A, Colby S, Friesen ML, Tiemann L, White RA III

    Bioinformatics Advances: vbae061. doi:10.1093/bioadv/vbae061

  3. 2023

    Genome-resolved metagenomics of nitrogen transformations in the switchgrass rhizosphere microbiome on marginal lands

    White RA III, Garoutte A, Mclachlan EE, Tiemann LK, Evans S, Friesen ML

    Agronomy 13(5): 1294. doi:10.3390/agronomy13051294

    Twenty-nine genomes resolved from the rhizosphere; points to Janthinobacterium as a possible associative nitrogen fixer for switchgrass.

  4. 2022

    Root exudates shift how N mineralization and N fixation contribute to the plant-available N supply in low fertility soils

    Liu Y, Evans SE, Friesen ML, Tiemann LK

    Soil Biology and Biochemistry 165: 108541. doi:10.1016/j.soilbio.2021.108541

  5. 2021

    Temporal dynamics of free-living nitrogen fixation in the switchgrass rhizosphere

    Smercina DN, Evans SE, Friesen ML, Tiemann LK

    GCB Bioenergy 13: 1814–1830. doi:10.1111/gcbb.12893

    Measured through two growing seasons, free-living fixation could potentially meet up to 80% of switchgrass nitrogen demand.

  6. 2021

    Switchgrass rhizosphere metabolite chemistry driven by nitrogen availability

    Smercina DN, Bowsher AW, Evans SE, Friesen ML, Eder EK, Hoyt DW, Tiemann LK

    Phytobiomes Journal 5(1): 88–96. doi:10.1094/PBIOMES-09-19-0055-FI

  7. 2020

    Impacts of nitrogen addition on switchgrass root-associated diazotrophic community structure and function

    Smercina DN, Evans SE, Friesen ML, Tiemann LK

    FEMS Microbiology Ecology 96(12): fiaa208. doi:10.1093/femsec/fiaa208

  8. 2020

    Interactive effects of microbes and nitrogen on Panicum virgatum root functional traits and patterns of phenotypic selection

    Petipas RH, McLachlan E, Bekkering C, Bowsher A, Jack C, White RA, Younginger B, Tiemann LK, Evans S, Friesen ML

    International Journal of Plant Sciences 181(1): 20–32. doi:10.1086/706198

  9. 2019

    To fix or not to fix: controls on free-living nitrogen fixation in the rhizosphere

    Smercina DN, Evans SE, Friesen ML, Tiemann LK

    Applied and Environmental Microbiology 85(6): e02546-18. doi:10.1128/AEM.02546-18

    Review of the environmental and biological controls on nitrogen fixation by free-living rhizosphere bacteria.

  10. 2019

    Optimization of the 15N2 incorporation and acetylene reduction methods for free-living nitrogen fixation

    Smercina DN, Evans SE, Friesen ML, Tiemann LK

    Plant and Soil 445: 595–611. doi:10.1007/s11104-019-04307-3

  11. 2019

    Legumes modulate allocation to rhizobial nitrogen fixation in response to factorial light and nitrogen manipulation

    Friel CA, Friesen ML

    Frontiers in Plant Science 10: 1316. doi:10.3389/fpls.2019.01316

    Medicago truncatula invests more in nodules when light is plentiful and soil nitrogen is low, keeping the partnership from turning parasitic.

  12. 2019

    Dynamic genomic architecture of mutualistic cooperation in a wild population of Mesorhizobium

    Porter SS, Faber-Hammond J, Montoya AP, Friesen ML, Sackos C

    The ISME Journal 13: 301–315. doi:10.1038/s41396-018-0266-y

  13. 2018

    Effect of nitrogen fertilization on the abundance of nitrogen cycling genes in agricultural soils: a meta-analysis of field studies

    Ouyang Y, Evans SE, Friesen ML, Tiemann LK

    Soil Biology and Biochemistry 127: 71–78. doi:10.1016/j.soilbio.2018.08.024

  14. 2018

    Effects of soil nitrogen availability on rhizodeposition in plants: a review

    Bowsher AW, Evans S, Tiemann LK, Friesen ML

    Plant and Soil 423: 59–85. doi:10.1007/s11104-017-3497-1

  15. 2017

    Complex N acquisition by soil diazotrophs: how the ability to release exoenzymes affects N fixation by terrestrial free-living diazotrophs

    Norman JS, Friesen ML

    The ISME Journal 11(2): 315–326. doi:10.1038/ismej.2016.127

  16. 2017

    Association mapping reveals novel serpentine adaptation gene clusters in a population of symbiotic Mesorhizobium

    Porter SS, Chang PL, Conow CA, Dunham JP, Friesen ML

    The ISME Journal 11: 248–262. doi:10.1038/ismej.2016.88

  17. 2016

    Streptomyces thermoautotrophicus does not fix nitrogen

    MacKellar D, Lieber L, Norman JS, … Friesen ML, Prell J

    Scientific Reports 6: 20086. doi:10.1038/srep20086

    Tested the claim of an oxygen-insensitive nitrogenase and found no evidence for it: the strains scavenge combined nitrogen instead of fixing N2.

  18. 2015

    Cheaters must prosper: reconciling theoretical and empirical perspectives on cheating in mutualism

    Jones EI, Afkhami ME, Akçay E, … Friesen ML

    Ecology Letters 18(11): 1270–1284. doi:10.1111/ele.12507

  19. 2013

    One hundred years of solitude: integrating single-strain inoculations with community perspectives in the legume–rhizobium symbiosis

    Friesen ML, Heath KD

    New Phytologist 198(1): 7–9. doi:10.1111/nph.12173

  20. 2012

    Widespread fitness alignment in the legume–rhizobium symbiosis

    Friesen ML

    New Phytologist 194(4): 1096–1111. doi:10.1111/j.1469-8137.2012.04099.x

  21. 2012

    Modelling the evolution of mutualistic symbioses

    Friesen ML, Jones EI

    In Bacterial Molecular Networks: Methods and Protocols, Methods in Molecular Biology 804: 481–499 (Springer).

  22. 2011

    Microbially mediated plant functional traits

    Friesen ML, et al.

    Annual Review of Ecology, Evolution, and Systematics 42: 23–46. doi:10.1146/annurev-ecolsys-102710-145039

  23. 2010

    Mixed infections may promote diversification of mutualistic symbionts: why are there ineffective rhizobia?

    Friesen ML, Mathias A

    Journal of Evolutionary Biology 23(2): 323–334. doi:10.1111/j.1420-9101.2009.01902.x

Labs

RAW Lab

Richard Allen White III, PhD

Associate Professor of Bioinformatics and Genomics, UNC Charlotte, at the North Carolina Research Campus in Kannapolis

Computational tools and multi-omics for microbes and their viruses. The lab built NFixDB with collaborators at Washington State and Michigan State.

Friesen Lab

Maren L. Friesen, PhD

Departments of Plant Pathology and Crop and Soil Sciences, Washington State University, Pullman

Evolutionary ecology and genomics of plant–microbe symbioses, from legume–rhizobium mutualism to free-living nitrogen fixation in the rhizosphere.

Frequent collaborator: Lisa K. Tiemann, Soil Biology and Ecology Lab, Michigan State University, co-author on NFixDB and the switchgrass nitrogen studies.

Sources for the story

  • Coale TH, et al. (2024) Nitrogen-fixing organelle in a marine alga. Science 384: 217–222. doi:10.1126/science.adk1075
  • Erisman JW, Sutton MA, Galloway J, Klimont Z, Winiwarter W (2008) How a century of ammonia synthesis changed the world. Nature Geoscience 1: 636–639. doi:10.1038/ngeo325
  • Fowler D, et al. (2013) The global nitrogen cycle in the twenty-first century. Philosophical Transactions of the Royal Society B 368: 20130164. doi:10.1098/rstb.2013.0164
  • Griesmann M, et al. (2018) Phylogenomics reveals multiple losses of nitrogen-fixing root nodule symbiosis. Science 361: eaat1743. doi:10.1126/science.aat1743
  • Hoffman BM, Lukoyanov D, Yang Z-Y, Dean DR, Seefeldt LC (2014) Mechanism of nitrogen fixation by nitrogenase: the next stage. Chemical Reviews 114: 4041–4062. doi:10.1021/cr400641x
  • Isotopic constraints on lightning as a source of fixed nitrogen in Earth’s early biosphere (2023). Nature Geoscience 16: 478–484. doi:10.1038/s41561-023-01187-2
  • Kiers ET, Rousseau RA, West SA, Denison RF (2003) Host sanctions and the legume–rhizobium mutualism. Nature 425: 78–81. doi:10.1038/nature01931
  • Navarro-González R, McKay CP, Mvondo DN (2001) A possible nitrogen crisis for Archaean life due to reduced nitrogen fixation by lightning. Nature 412: 61–64. doi:10.1038/35083537
  • Seefeldt LC, Yang Z-Y, Lukoyanov DA, Harris DF, Dean DR, Raugei S, Hoffman BM (2020) Reduction of substrates by nitrogenases. Chemical Reviews 120: 5082–5106. doi:10.1021/acs.chemrev.9b00556
  • Stüeken EE, Buick R, Guy BM, Koehler MC (2015) Isotopic evidence for biological nitrogen fixation by molybdenum-nitrogenase from 3.2 Gyr. Nature 520: 666–669. doi:10.1038/nature14180
  • Werner GDA, et al. (2014) A single evolutionary innovation drives the deep evolution of symbiotic N2-fixation in angiosperms. Nature Communications 5: 4087. doi:10.1038/ncomms5087
  • Zhang X, et al. (2014) Nitrogen isotope fractionation by alternative nitrogenases and past ocean anoxia. PNAS 111: 4782–4787. Find the article