39-527: See text Frankia is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants , similar to the Rhizobium bacteria found in the root nodules of legumes in the family Fabaceae . Frankia also initiate the forming of root nodules . This genus was originally named by Jørgen Brunchorst , in 1886 to honor the German biologist Albert Bernhard Frank . Brunchorst considered
78-460: A cyanobiont (cyanobacteria such as Nostoc ) which fix nitrogen for them: Some symbiotic relationships involving agriculturally-important plants are: A method for nitrogen fixation was first described by Henry Cavendish in 1784 using electric arcs reacting nitrogen and oxygen in air. This method was implemented in the Birkeland–Eyde process of 1903. The fixation of nitrogen by lightning
117-399: A nitrogenase enzyme. The overall reaction for BNF is: N 2 + 16ATP + 16H 2 O + 8e + 8H → 2NH 3 +H 2 + 16ADP + 16P i The process is coupled to the hydrolysis of 16 equivalents of ATP and is accompanied by the co-formation of one equivalent of H 2 . The conversion of N 2 into ammonia occurs at a metal cluster called FeMoco , an abbreviation for
156-1659: A Nodule primordium is created similarly to the intracellular mode of formation and the nodule matures. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) F. coriariae Nouioui et al. 2017 F. casuarinae Nouioui et al. 2016 F. canadensis Normand et al. 2018 F. umida Normand et al. 2023 F. torreyi Nouioui et al. 2019 F. alni (Woronin 1866) Von Tubeuf 1895 " F. gtarii " Nouioui et al. 2023 " F. tisai " Nouioui et al. 2023 F. inefficax Nouioui et al. 2017 F. asymbiotica Nouioui et al. 2017 F. saprophytica Nouioui et al. 2018 F. discariae Nouioui et al. 2017 F. soli Gtari et al. 2020 F. irregularis Nouioui et al. 2018 F. colletiae Nouioui et al. 2023 F. elaeagni (Schroeter 1886) Becking 1970 ex Nouioui et al. 2016 " Ca. F. meridionalis" Nguyen et al. 2019 " Ca. F. californiensis" Normand et al. 2017 F. coriariae [incl. " Ca. F. datiscae" Persson et al. 2011 ] F. inefficax F. asymbiotica F. saprophytica F. discariae F. soli F. elaeagni F. irregularis F. casuarinae F. canadensis " Ca. F. nodulisporulans" Herrera-Belaroussi et al. 2020 " Ca. F. alpina" Pozzi et al. 2020 [incl. " F. subtilis " Brunchorst 1886 ] F. alni F. torreyi Species incertae sedis: Nitrogen fixation Nitrogen fixation
195-543: A critical threshold. The specialized heterocyst cell is necessary for the performance of nitrogenase as a result of its sensitivity to ambient oxygen. Nitrogenase consist of two proteins, a catalytic iron-dependent protein, commonly referred to as MoFe protein and a reducing iron-only protein (Fe protein). There are three different iron dependent proteins, molybdenum -dependent, vanadium -dependent, and iron -only, with all three nitrogenase protein variations containing an iron protein component. Molybdenum-dependent nitrogenase
234-447: A low nitrogen content, has been shown to host a diazotrophic community. The bacteria enrich the wood substrate with nitrogen through fixation, thus enabling deadwood decomposition by fungi. Nitrogenases are rapidly degraded by oxygen. For this reason, many bacteria cease production of the enzyme in the presence of oxygen. Many nitrogen-fixing organisms exist only in anaerobic conditions, respiring to draw down oxygen levels, or binding
273-424: A new era of soil science ." In 1901, Beijerinck showed that Azotobacter chroococcum was able to fix atmospheric nitrogen. This was the first species of the azotobacter genus, so-named by him. It is also the first known diazotroph , species that use diatomic nitrogen as a step in the complete nitrogen cycle . Biological nitrogen fixation (BNF) occurs when atmospheric nitrogen is converted to ammonia by
312-451: A second metal (usually molybdenum , but sometimes vanadium ). Some nitrogen-fixing bacteria have symbiotic relationships with plants , especially legumes , mosses and aquatic ferns such as Azolla . Looser non-symbiotic relationships between diazotrophs and plants are often referred to as associative, as seen in nitrogen fixation on rice roots. Nitrogen fixation occurs between some termites and fungi . It occurs naturally in
351-446: Is a chemical process by which molecular dinitrogen ( N 2 ) is converted into ammonia ( NH 3 ). It occurs both biologically and abiologically in chemical industries . Biological nitrogen fixation or diazotrophy is catalyzed by enzymes called nitrogenases . These enzyme complexes are encoded by the Nif genes (or Nif homologs ) and contain iron , often with
390-408: Is a required precursor to fertilizers , explosives , and other products. The Haber process requires high pressures (around 200 atm) and high temperatures (at least 400 °C), which are routine conditions for industrial catalysis. This process uses natural gas as a hydrogen source and air as a nitrogen source. The ammonia product has resulted in an intensification of nitrogen fertilizer globally and
429-532: Is a very similar natural occurring process. The possibility that atmospheric nitrogen reacts with certain chemicals was first observed by Desfosses in 1828. He observed that mixtures of alkali metal oxides and carbon react with nitrogen at high temperatures. With the use of barium carbonate as starting material, the first commercial process became available in the 1860s, developed by Margueritte and Sourdeval. The resulting barium cyanide reacts with steam, yielding ammonia. In 1898 Frank and Caro developed what
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#1732772295411468-526: Is able to resist heavy metals. Frankia is a gram-positive Bacteria that is found on the roots of plants. The fact that Frankia is gram-positive means that the bacteria is made up of thick cell walls made out of protein called peptidologlycan. This helps with the resistance of the heavy metals that may be in the degraded soil. Frankia tolerates a narrow range of temperatures and soil pH levels. It grows best at around 30 degrees Celsius with an environment pH between 6.5 and 7. These facts shows that Frankia
507-566: Is credited with supporting the expansion of the human population from around 2 billion in the early 20th century to roughly 8 billion people now. Much research has been conducted on the discovery of catalysts for nitrogen fixation, often with the goal of lowering energy requirements. However, such research has thus far failed to approach the efficiency and ease of the Haber process. Many compounds react with atmospheric nitrogen to give dinitrogen complexes . The first dinitrogen complex to be reported
546-442: Is dependent on many factors, including the legume and air and soil conditions. For example, nitrogen fixation by red clover can range from 50 to 200 lb/acre (56 to 224 kg/ha). The ability to fix nitrogen in nodules is present in actinorhizal plants such as alder and bayberry , with the help of Frankia bacteria. They are found in 25 genera in the orders Cucurbitales , Fagales and Rosales , which together with
585-408: Is genetically regulated, and the activity of the protein complex is dependent on ambient oxygen concentrations, and intra- and extracellular concentrations of ammonia and oxidized nitrogen species (nitrate and nitrite). Additionally, the combined concentrations of both ammonium and nitrate are thought to inhibit N Fix , specifically when intracellular concentrations of 2- oxoglutarate (2-OG) exceed
624-571: Is known as the Frank–Caro process to fix nitrogen in the form of calcium cyanamide . The process was eclipsed by the Haber process , which was discovered in 1909. The dominant industrial method for producing ammonia is the Haber process also known as the Haber-Bosch process. Fertilizer production is now the largest source of human-produced fixed nitrogen in the terrestrial ecosystem . Ammonia
663-796: Is no conclusive agreement on which form of nitrogenase arose first. Diazotrophs are widespread within domain Bacteria including cyanobacteria (e.g. the highly significant Trichodesmium and Cyanothece ), green sulfur bacteria , purple sulfur bacteria , Azotobacteraceae , rhizobia and Frankia . Several obligately anaerobic bacteria fix nitrogen including many (but not all) Clostridium spp. Some archaea such as Methanosarcina acetivorans also fix nitrogen, and several other methanogenic taxa , are significant contributors to nitrogen fixation in oxygen-deficient soils. Cyanobacteria , commonly known as blue-green algae, inhabit nearly all illuminated environments on Earth and play key roles in
702-590: Is the most commonly present nitrogenase. The different types of nitrogenase can be determined by the specific iron protein component. Nitrogenase is highly conserved. Gene expression through DNA sequencing can distinguish which protein complex is present in the microorganism and potentially being expressed. Most frequently, the nif H gene is used to identify the presence of molybdenum-dependent nitrogenase, followed by closely related nitrogenase reductases (component II) vnf H and anf H representing vanadium-dependent and iron-only nitrogenase, respectively. In studying
741-449: Is very sensitive to its environment. Though Frankia would not be suitable for all agriculture it does demonstrate possibilities in select areas, or in temperature controlled environments. Frankia forms nodules via two methods of root infection, intercellularly and intracellularly. Intracellular infection is characterized by initial root-hair deformation which is then infected by the filamentous Frankia . The Frankia then moves within
780-485: The Fabales form a nitrogen-fixing clade of eurosids . The ability to fix nitrogen is not universally present in these families. For example, of 122 Rosaceae genera, only four fix nitrogen. Fabales were the first lineage to branch off this nitrogen-fixing clade; thus, the ability to fix nitrogen may be plesiomorphic and subsequently lost in most descendants of the original nitrogen-fixing plant; however, it may be that
819-449: The enzyme nitrogenase , a process known as nitrogen fixation . They do this while living in root nodules on actinorhizal plants. The bacteria can supply most or all of the nitrogen requirements of the host plant. As a result, actinorhizal plants colonise and often thrive in soils that are low in plant nutrients. Several Frankia genomes are now available which may help clarify how the symbiosis between prokaryote and plant evolved, how
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#1732772295411858-414: The air by means of NO x production by lightning . Nitrogen fixation is essential to life on Earth because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing organic compounds such as amino acids , polypeptides and proteins , nucleoside triphosphates and nucleic acids . As part of the nitrogen cycle , it is essential for soil fertility and
897-697: The amount of nitrogen fixed in the ocean is at least as much as that on land. The colonial marine cyanobacterium Trichodesmium is thought to fix nitrogen on such a scale that it accounts for almost half of the nitrogen fixation in marine systems globally. Marine surface lichens and non-photosynthetic bacteria belonging in Proteobacteria and Planctomycetes fixate significant atmospheric nitrogen. Species of nitrogen fixing cyanobacteria in fresh waters include: Aphanizomenon and Dolichospermum (previously Anabaena). Such species have specialized cells called heterocytes , in which nitrogen fixation occurs via
936-409: The basic genetic and physiological requirements were present in an incipient state in the most recent common ancestors of all these plants, but only evolved to full function in some of them. In addition, Trema ( Parasponia ), a tropical genus in the family Cannabaceae , is unusually able to interact with rhizobia and form nitrogen-fixing nodules. Some other plants live in association with
975-561: The carbon and nitrogen cycle of the biosphere . In general, cyanobacteria can use various inorganic and organic sources of combined nitrogen, such as nitrate , nitrite , ammonium , urea , or some amino acids . Several cyanobacteria strains are also capable of diazotrophic growth, an ability that may have been present in their last common ancestor in the Archean eon. Nitrogen fixation not only naturally occurs in soils but also aquatic systems, including both freshwater and marine. Indeed,
1014-498: The ecology and evolution of nitrogen-fixing bacteria , the nifH gene is the biomarker most widely used. nif H has two similar genes anf H and vnfH that also encode for the nitrogenase reductase component of the nitrogenase complex. Nitrogenase is thought to have evolved sometime between 1.5-2.2 billion years ago (Ga), although some isotopic support showing nitrogenase evolution as early as around 3.2 Ga. Nitrogenase appears to have evolved from maturase -like proteins, although
1053-429: The environmental and geographical adaptations occurred, the metabolic diversity, and the horizontal gene flow among the symbiotic prokaryotes. Frankia can resist low concentration of heavy metals such as, Cu, Co, and Zn. Frankia may be an advantage for degraded soil. Degraded soil is known as soil that is heavy metal rich or nutrient depleted due to a drought. Frankia is a nitrogen-fixed organism, explaining why it
1092-410: The function of the preceding protein is currently unknown. Nitrogenase has three different forms ( Nif, Anf, and Vnf ) that correspond with the metal found in the active site of the protein (Molybdenum, Iron, and Vanadium respectively). Marine metal abundances over Earth’s geologic timeline are thought to have driven the relative abundance of which form of nitrogenase was most common. Currently, there
1131-406: The growth of terrestrial and semiaquatic vegetations , upon which all consumers of those ecosystems rely for biomass . Nitrogen fixation is thus crucial to the food security of human societies in sustaining agricultural yields (especially staple crops ), livestock feeds ( forage or fodder ) and fishery (both wild and farmed ) harvests . It is also indirectly relevant to
1170-548: The iron- molybdenum cofactor. The mechanism proceeds via a series of protonation and reduction steps wherein the FeMoco active site hydrogenates the N 2 substrate. In free-living diazotrophs , nitrogenase-generated ammonia is assimilated into glutamate through the glutamine synthetase /glutamate synthase pathway. The microbial nif genes required for nitrogen fixation are widely distributed in diverse environments. For example, decomposing wood, which generally has
1209-492: The manufacture of all nitrogenous industrial products , which include fertilizers , pharmaceuticals , textiles , dyes and explosives . Biological nitrogen fixation was discovered by Jean-Baptiste Boussingault in 1838. Later, in 1880, the process by which it happens was discovered by German agronomist Hermann Hellriegel and Hermann Wilfarth [ de ] and was fully described by Dutch microbiologist Martinus Beijerinck . "The protracted investigations of
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1248-473: The nitrogenase enzyme. One type of organelle can turn nitrogen gas into a biologically available form. This nitroplast was discovered in algae . Plants that contribute to nitrogen fixation include those of the legume family — Fabaceae — with taxa such as kudzu , clover , soybean , alfalfa , lupin , peanut and rooibos . They contain symbiotic rhizobia bacteria within nodules in their root systems , producing nitrogen compounds that help
1287-504: The organism he had identified to be a filamentous fungus. Becking [ de ; nl ] redefined the genus in 1970 as containing prokaryotic actinomycetes and created the family Frankiaceae within the Actinomycetales . He retained the original name of Frankia for the genus. Most Frankia strains are specific to different plant species. The bacteria are filamentous and convert atmospheric nitrogen into ammonia via
1326-409: The oxygen with a protein such as leghemoglobin . Atmospheric nitrogen is inaccessible to most organisms, because its triple covalent bond is very strong. Most take up fixed nitrogen from various sources. For every 100 atoms of carbon, roughly 2 to 20 atoms of nitrogen are assimilated. The atomic ratio of carbon (C) : nitrogen (N) : phosphorus (P) observed on average in planktonic biomass
1365-475: The plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants; this helps to fertilize the soil . The great majority of legumes have this association, but a few genera (e.g., Styphnolobium ) do not. In many traditional farming practices, fields are rotated through various types of crops, which usually include one consisting mainly or entirely of clover . Fixation efficiency in soil
1404-462: The relation of plants to the acquisition of nitrogen begun by de Saussure , Ville , Lawes , Gilbert and others, and culminated in the discovery of symbiotic fixation by Hellriegel and Wilfarth in 1887." "Experiments by Bossingault in 1855 and Pugh, Gilbert & Lawes in 1887 had shown that nitrogen did not enter the plant directly. The discovery of the role of nitrogen fixing bacteria by Herman Hellriegel and Herman Wilfarth in 1886-1888 would open
1443-412: The root cells and forms a pre-nodule which is characterized by a bump on the root. This then gives rise to a Nodule primordium which feeds the bacteria via the vascular tissue of the plant allowing the nodule to mature. In contrast the intercellular infection does not have root hair deformation. Instead, the filamentous Frankia invades the roots in the space between cells on the root. After this invasion
1482-767: Was Ru(NH 3 ) 5 ( N 2 ) . Some soluble complexes do catalyze nitrogen fixation. Nitrogen can be fixed by lightning converting nitrogen gas ( N 2 ) and oxygen gas ( O 2 ) in the atmosphere into NO x ( nitrogen oxides ). The N 2 molecule is highly stable and nonreactive due to the triple bond between the nitrogen atoms. Lightning produces enough energy and heat to break this bond allowing nitrogen atoms to react with oxygen, forming NO x . These compounds cannot be used by plants, but as this molecule cools, it reacts with oxygen to form NO 2 , which in turn reacts with water to produce HNO 2 ( nitrous acid ) or HNO 3 ( nitric acid ). When these acids seep into
1521-422: Was originally described by Alfred Redfield, who determined the stoichiometric relationship between C:N:P atoms, The Redfield Ratio, to be 106:16:1. The protein complex nitrogenase is responsible for catalyzing the reduction of nitrogen gas (N 2 ) to ammonia (NH 3 ). In cyanobacteria , this enzyme system is housed in a specialized cell called the heterocyst . The production of the nitrogenase complex
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