query: which bacteria helps nitrogen fixation in the soil

pos: Nitrogen fixation manufacture of all chemical compounds that contain nitrogen, which includes explosives, most pharmaceuticals, and dyes. Nitrogen fixation is carried out naturally in the soil by a wide range of nitrogen fixing Bacteria and Archaea, including "Azotobacter". Some nitrogen-fixing bacteria have symbiotic relationships with some plant groups, especially legumes. Looser relationships between nitrogen-fixing bacteria and plants are often referred to as associative or non-symbiotic, as seen in nitrogen fixation occurring on rice roots. It also occurs naturally in the air by means of NOx production by lightning. All biological nitrogen fixation is effected by enzymes called nitrogenases. These enzymes contain iron,

pos: Soil biology fixation constantly puts additional nitrogen into biological circulation. This is carried out by free-living nitrogen-fixing bacteria in the soil or water such as "Azotobacter", or by those that live in close symbiosis with leguminous plants, such as rhizobia. These bacteria form colonies in nodules they create on the roots of peas, beans, and related species. These are able to convert nitrogen from the atmosphere into nitrogen-containing organic substances. While nitrogen fixation converts nitrogen from the atmosphere into organic compounds, a series of processes called denitrification returns an approximately equal amount of nitrogen to the atmosphere. Denitrifying bacteria tend to be

pos: Azotobacter "Pseudomonas aeruginosa", and in 2007 it was suggested that the genera "Azotobacter", "Azomonas" and "Pseudomonas" are related and might be synonyms. Azotobacter Azotobacter is a genus of usually motile, oval or spherical bacteria that form thick-walled cysts and may produce large quantities of capsular slime. They are aerobic, free-living soil microbes which play an important role in the nitrogen cycle in nature, binding atmospheric nitrogen, which is inaccessible to plants, and releasing it in the form of ammonium ions into the soil (nitrogen fixation). In addition to being a model organism for studying diazotrophs, it is used by humans for

pos: Azotobacter Azotobacter Azotobacter is a genus of usually motile, oval or spherical bacteria that form thick-walled cysts and may produce large quantities of capsular slime. They are aerobic, free-living soil microbes which play an important role in the nitrogen cycle in nature, binding atmospheric nitrogen, which is inaccessible to plants, and releasing it in the form of ammonium ions into the soil (nitrogen fixation). In addition to being a model organism for studying diazotrophs, it is used by humans for the production of biofertilizers, food additives, and some biopolymers. The first representative of the genus, "Azotobacter chroococcum", was discovered and described

pos: Sergei Winogradsky Moscow Society of Naturalists and, in 1902, corresponding member of the French Academy of Sciences. He retired from active scientific work in 1905, dividing his time between his private estate and Switzerland. In 1922, he accepted an invitation to head the division of agricultural bacteriology at the Pasteur Institute at an experimental station at Brie-Comte-Robert, France, about 30 km from Paris. During this period, he worked on a number of topics, among them iron bacteria, nitrifying bacteria, nitrogen fixation by "Azotobacter", cellulose-decomposing bacteria, and culture methods for soil microorganisms. Winogradsky retired from active life in 1940 and died in Brie-Comte-Robert

neg: Mycorrhiza helper bacteria in the soil, and create pools of available nitrogen. However, MHB do not cause plant modifications as legumes do, to help with nitrogen-fixation. Nitrogen-fixation is done only in the surrounding soil in relation to the mycorrhiza. In one study, researchers reported that a "Bacillius" MHB contributed to the nitrogen-fixation, and among other factors helped the plant grow when inoculated with a fungus. It has been proposed by Kaska, Myllylä, and Cooper that MHB induce growth hormones in a plant, which helps the mycorrhiza interact with the lateral roots in soil. An increase of root formation was also observed when "Pseudomonas

neg: Nitrogen fixation on such a scale that it accounts for almost half of the nitrogen fixation in marine systems globally. Plants that contribute to nitrogen fixation include those of the legume family – Fabaceae – with taxa such as kudzu, clovers, soybeans, alfalfa, lupines, peanuts, and rooibos. They contain symbiotic bacteria called rhizobia within nodules in their root systems, producing nitrogen compounds that help 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,

neg: Soil microbiology species of "Pseudomonas", such as "Pseudomonas aeruginosa" are able to respire both aerobically and anaerobically, using nitrate as the terminal electron acceptor". Bacteria are responsible for the process of nitrogen fixation, which is the conversion of atmospheric nitrogen into nitrogen-containing compounds (such as ammonia) that can be used by plants. Autotrophic bacteria derive their energy by making their own food through oxidation, like the "Nitrobacters" species, rather than feeding on plants or other organisms. These bacteria are responsible for nitrogen fixation. The amount of autotrophic bacteria is small compared to heterotrophic bacteria (the opposite of autotrophic bacteria, heterotrophic bacteria acquire

neg: Cover crop cover crops is that they form symbiotic relationships with the rhizobial bacteria that reside in legume root nodules. Lupins is nodulated by the soil microorganism "Bradyrhizobium" sp. (Lupinus). Bradyrhizobia are encountered as microsymbionts in other leguminous crops ("Argyrolobium", "Lotus", "Ornithopus", "Acacia", "Lupinus") of Mediterranean origin. These bacteria convert biologically unavailable atmospheric nitrogen gas () to biologically available ammonium () through the process of biological nitrogen fixation. Prior to the advent of the Haber-Bosch process, an energy-intensive method developed to carry out industrial nitrogen fixation and create chemical nitrogen fertilizer, most nitrogen introduced to ecosystems arose through biological nitrogen fixation (Galloway

neg: Nitrogen fixation package Nitrogen fixation packages must be used in a laboratory-type environment. This can be a temporary laboratory set up in the field, as long as it is under stable, uncontaminated conditions. The product must be supplied with many potted samples of the plants and of the neighbouring soil, taken from separate areas on the farm or field under study. The tests rely on the availability of the Herbaspirillum bacteria in the soil. This bacterium is found at the root of most legumes, which is where they produce nitrogen. To test soil properly, it must be free of added nitrogen fertilizers, which

neg: Ecosystem plant growth. Ecosystems continually exchange energy and carbon with the wider environment. Mineral nutrients, on the other hand, are mostly cycled back and forth between plants, animals, microbes and the soil. Most nitrogen enters ecosystems through biological nitrogen fixation, is deposited through precipitation, dust, gases or is applied as fertilizer. Since most terrestrial ecosystems are nitrogen-limited, nitrogen cycling is an important control on ecosystem production. Until modern times, nitrogen fixation was the major source of nitrogen for ecosystems. Nitrogen-fixing bacteria either live symbiotically with plants or live freely in the soil. The energetic cost is high for plants which support

neg: Soil and fix it to the soil but it took the development of bacteriology towards the end of the 19th century to lead to an understanding of the role played in nitrogen fixation by bacteria. The symbiosis of bacteria and leguminous roots, and the fixation of nitrogen by the bacteria, were simultaneously discovered by the German agronomist Hermann Hellriegel and the Dutch microbiologist Martinus Beijerinck. Crop rotation, mechanisation, chemical and natural fertilisers led to a doubling of wheat yields in western Europe between 1800 and 1900. The scientists who studied the soil in connection with agricultural practices had considered it mainly

neg: Biological soil crust on successional state. Estimates of total net carbon uptake by crusts globally are ~3.9 pg/year (2.1-7.4 pg/year). Nitrogen cycling Biological soil crust contributions to the nitrogen cycle varies by crust composition because only cyanobacteria and cyanolichens fix nitrogen. Nitrogen fixation requires energy from photosynthesis products, and thus increase with temperature given sufficient moisture. Nitrogen fixed by crusts has been shown to leak into surrounding substrate and can be taken up by plants, bacteria, and fungi. Nitrogen fixation has been recorded at rates of 0.7–100 kg/ha*year, from hot deserts in Australia to cold deserts. Estimates of total biological nitrogen fixation are

neg: Soil matter overall, would release of nitrogen as ammonium per acre. In nitrogen fixation, rhizobium bacteria convert N to ammonia (NH). Rhizobia share a symbiotic relationship with host plants, since rhizobia supply the host with nitrogen and the host provides rhizobia with nutrients and a safe environment. It is estimated that such symbiotic bacteria in the root nodules of legumes add 45 to 250 pounds of nitrogen per acre per year, which may be sufficient for the crop. Other, free-living nitrogen-fixing bacteria and blue-green algae live independently in the soil and release nitrate when their dead bodies are converted by way

neg: Soil mesofauna recognizable plant material. Animal residues are higher in nitrogen than plant residues with respect to the total carbon in the residue. Some Nitrogen fixation is caused by bacteria which consume the amino acids and sugar that are exuded by the plant roots. However, approximately 30% of nitrogen re-mineralization is contributed by soil fauna in agriculture and natural ecosystems. Macro- and mesofauna break down plant residues to release Nitrogen as part of nutrient cycling. Soil mesofauna Soil Mesofauna are invertebrates between 0.1mm and 2mm in size, which live in the soil or in a leaf litter layer on the soil surface.

neg: Root nodule oxygen sensitive. Legume nodules harbor an iron containing protein called leghaemoglobin, closely related to animal myoglobin, to facilitate the diffusion of oxygen gas used in respiration. Plants that contribute to nitrogen fixation include the legume family – Fabaceae – with taxa such as kudzu, clovers, soybeans, alfalfa, lupines, peanuts, and rooibos. They contain symbiotic bacteria called rhizobia within the nodules, producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants and this helps to fertilize the soil. The great majority of

neg: Mimosa pudica This trait is common among plants in the family Fabaceae. Nitrogen is a vital element for both plant growth and reproduction. Nitrogen is also essential for plant photosynthesis because it is a component of chlorophyll. Nitrogen fixation contributes nitrogen to the plant and to the soil surrounding the plant's roots. "Mimosa pudica"’s ability to fix nitrogen may have arisen in conjunction with the evolution of nitrogen-fixing bacteria. Nitrogen fixation is an adaptive trait that has transformed the parasitic relationship between the bacteria and plants into a mutualistic relationship. The shifting dynamics of this relationship are demonstrated by the corresponding improvement

neg: Soil sequestered in clay by "fixation". A small amount of nitrogen is added to soil by rainfall. In the process of mineralisation, microbes feed on organic matter, releasing ammonia (NH), ammonium (NH) and other nutrients. As long as the carbon to nitrogen ratio (C/N) of fresh residues in the soil is above 30:1, nitrogen will be in short supply and other bacteria will feed on the ammonium and incorporate its nitrogen into their cells in the immobilization process. In that form the nitrogen is said to be "immobilised". Later, when such bacteria die, they too are "mineralised" and some of the

neg: Nitrogen fixation package Nitrogen fixation package A nitrogen fixation package is a piece of research equipment for studying nitrogen fixation in plants. One product of this kind, the Q-Box NF1LP made by Qubit Systems, operates by measuring the hydrogen (H) given off in the nitrogen-fixing chemical reaction enabled by nitrogenase enzymes. Nitrogen is produced by bacteria, which have an endo-symbiotic relationship with the legume host. In this relationship, the plant shares its carbohydrates with the bacteria so that the bacteria can thrive, and the plant benefits by having excess nitrogen made available. The bacteria's creation of nitrogen also creates hydrogen, which is what

neg: Soil management. Soil nitrogen typically decreases by 0.2 to 0.3% for every temperature increase by 10 °C. Usually, grassland soils contain more soil nitrogen than forest soils. Cultivation decreases soil nitrogen by exposing soil organic matter to decomposition by microorganisms, and soils under no-tillage maintain more soil nitrogen than tilled soils. Some micro-organisms are able to metabolise organic matter and release ammonium in a process called "mineralisation". Others take free ammonium and oxidise it to nitrate. Nitrogen-fixing bacteria are capable of metabolising N into the form of ammonia in a process called nitrogen fixation. Both ammonium and nitrate can be "immobilized"

neg: Bradyrhizobium Bradyrhizobium Bradyrhizobium is a genus of Gram-negative soil bacteria, many of which fix nitrogen. Nitrogen fixation is an important part of the nitrogen cycle. Plants cannot use atmospheric nitrogen (N); they must use nitrogen compounds such as nitrates. "Bradyrhizobium" species are Gram-negative bacilli (rod-shaped) with a single subpolar or polar flagellum. They are common soil-dwelling micro-organisms that can form symbiotic relationships with leguminous plant species where they fix nitrogen in exchange for carbohydrates from the plant. Like other rhizobia, many members of this genus have the ability to fix atmospheric nitrogen into forms readily available for other organisms to use.

neg: Martinus Beijerinck calling it ""contagium vivum fluidum"" (contagious living fluid). It was not until the first crystals of the tobacco mosaic virus (TMV) obtained by Wendell Stanley in 1935, the first electron micrographs of TMV produced in 1939 and the first X-ray crystallographic analysis of TMV performed in 1941 proved that the virus was particulate. Beijerinck also discovered nitrogen fixation, the process by which diatomic nitrogen gas is converted to ammonium ions and becomes available to plants. Bacteria perform nitrogen fixation, dwelling inside root nodules of certain plants (legumes). In addition to having discovered a biochemical reaction vital to soil fertility and

neg: Bacteria as butyric acid or propionic acid, and produce hydrogen, and methanogenic Archaea that consume hydrogen. The bacteria in this association are unable to consume the organic acids as this reaction produces hydrogen that accumulates in their surroundings. Only the intimate association with the hydrogen-consuming Archaea keeps the hydrogen concentration low enough to allow the bacteria to grow. In soil, microorganisms that reside in the rhizosphere (a zone that includes the root surface and the soil that adheres to the root after gentle shaking) carry out nitrogen fixation, converting nitrogen gas to nitrogenous compounds. This serves to provide an easily absorbable

neg: Host (biology) soil. Over 95% of plant families have been shown to have mycorrhizal associations. Another such relationship is between leguminous plants and certain nitrogen-fixing bacteria called rhizobia that form nodules on the roots of the plant. The host supplies the bacteria with the energy needed for nitrogen fixation and the bacteria provide much of the nitrogen needed by the host. Such crops as beans, peas, chickpeas and alfalfa are able to fix nitrogen in this way, and mixing clover with grasses increases the yield of pastures. Hosts of many species are involved in cleaning symbiosis, both in the sea and on

neg: Bradyrhizobium or later crops. Intercropping with a legume has the potential to decrease the need for applied fertilizer. Commercial inoculants of "Bradyrhizobium" are available. These can be applied as a peat or liquid directly to the seed before planting. Bradyrhizobium Bradyrhizobium is a genus of Gram-negative soil bacteria, many of which fix nitrogen. Nitrogen fixation is an important part of the nitrogen cycle. Plants cannot use atmospheric nitrogen (N); they must use nitrogen compounds such as nitrates. "Bradyrhizobium" species are Gram-negative bacilli (rod-shaped) with a single subpolar or polar flagellum. They are common soil-dwelling micro-organisms that can form symbiotic relationships with

neg: Honey locust is disputed. Many scientific sources state that "Gleditsia" does not fix nitrogen. Some support this statement with the fact that "Gleditsia" does not form root nodules with symbiotic bacteria, the assumption being that without nodulation, no nitrogen fixation can occur. In contrast, many popular sources, permaculture publications in particular, claim that "Gleditsia" does fix nitrogen but by some other mechanism. There are anatomical, ecological, and taxonomic indications of nitrogen fixation in non-nodulating legumes. Both nodulating and non-nodulating species have been observed to grow well in nitrogen-poor soil with non-nodulating legumes even dominating some sites. The litter and seeds of non-nodulating

neg: Biological soil crust costs of disturbance. Today, direct inoculation of soil native microorganisms, bacteria and cyanobacteria, supposed as a new step, biologic, sustainable, eco-friendly and economically-effective technique to rehabilitate biological soil crust. Biological soil crust Biological soil crusts are communities of living organisms on the soil surface in arid and semi-arid ecosystems. They are found throughout the world with varying species composition and cover depending on topography, soil characteristics, climate, plant community, microhabitats, and disturbance regimes. Biological soil crusts perform important ecological roles including carbon fixation, nitrogen fixation, soil stabilization, alter soil albedo and water relations, and affect germination and nutrient levels in

neg: Nutrition require nitrogen compounds to be present in the soil in which they grow. This is made possible by the fact that largely inert atmospheric nitrogen is changed in a nitrogen fixation process to biologically usable forms in the soil by bacteria. Plant nutrition is a difficult subject to understand completely, partially because of the variation between different plants and even between different species or individuals of a given clone. Elements present at low levels may cause deficiency symptoms, and toxicity is possible at levels that are too high. Furthermore, deficiency of one element may present as symptoms of toxicity from

neg: Nitrogen fixation often with a second metal, usually molybdenum but sometimes vanadium. Microorganisms that can fix nitrogen are prokaryotes (both bacteria and archaea, distributed throughout their respective domains) called diazotrophs. Some higher plants, and some animals (termites), have formed associations (symbiosis) with diazotrophs. Nitrogen can be fixed by lightning converting nitrogen and oxygen into (nitrogen oxides). may react with water to make nitrous acid or nitric acid, which seeps into the soil, where it makes nitrate, which is of use to growing plants. Nitrogen in the atmosphere is highly stable and nonreactive due to there being a triple bond between atoms in

neg: Soil acid and ammonia, but most of the nitrogen is available in soils as a result of nitrogen fixation by bacteria. Once in the soil-plant system, most nutrients are recycled through living organisms, plant and microbial residues (soil organic matter), mineral-bound forms, and the soil solution. Both living microorganisms and soil organic matter are of critical importance to this recycling, and thereby to soil formation and soil fertility. Microbial activity in soils may release nutrients from minerals or organic matter for use by plants and other microorganisms, sequester (incorporate) them into living cells, or cause their loss from the soil by

neg: Nitrogen fixation 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 the oxygen with a protein such as leghemoglobin. Diazotrophs are widespread within domain Bacteria including cyanobacteria (e.g. the highly significant "Trichodesmium" and "Cyanothece"), as well as green sulfur bacteria, Azotobacteraceae, rhizobia and "Frankia". Several obligately anaerobic bacteria fix nitrogen including many (but not all) Clostridium spp. Some Archaea also fix nitrogen, including several methanogenic taxa, which are significant contributors to nitrogen fixation in anoxic soils. Cyanobacteria inhabit nearly all illuminated environments on

neg: Plant nutrition has proven to be beneficial to at least some plants although it does not appear to be essential for most species. It has, however, been shown to be essential for nitrogen fixation by the nitrogen-fixing bacteria associated with legumes and other plants. Aluminum is one of the few elements capable of making soil more acidic. This is achieved by aluminum taking hydroxide ions out of water, leaving hydrogen ions behind. As a result, the soil is more acidic, which makes it unlivable for many plants. Another consequence of aluminum in soils is aluminum toxicity, which inhibits root growth. Silicon is

neg: Bacteria bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×10 bacteria on Earth, forming a biomass which exceeds that of all plants and animals. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the

neg: Paenibacillus macerans the absence of oxygen it is able to convert nitrogen gas to ammonia which is more easily used by plant. "P. macerans" is usually found in soil and plant materials but has also been identified in blood cultures of infants with infection. The bacterium is not normally pathogenic in humans but could cause allergies as a result of its histamine producing properties. Paenibacillus macerans Paenibacillus macerans is a diazotroph bacterium found in soil and plants capable of nitrogen fixation and fermentation. This bacteria was originally discovered in 1905 by an Austrian biologist named Schardinger and thought to be a bacillus.

neg: Nitrogen cycle into a usable form to be taken up by plants. Between 5x10 and 10x10 g per year are fixed by lightning strikes, but most fixation is done by free-living or symbiotic bacteria known as diazotrophs. These bacteria have the nitrogenase enzyme that combines gaseous nitrogen is the with hydrogen to produce ammonia, which is converted by the bacteria into other organic compounds. Most biological nitrogen fixation occurs by the activity of Mo-nitrogenase, found in a wide variety of bacteria and some Archaea. Mo-nitrogenase is a complex two-component enzyme that has multiple metal-containing prosthetic groups. An example of free-living bacteria is

neg: Soil microbiology very simple cell structure with no internal organelles. Bacteria and archaea are the most abundant microorganisms in the soil, and serve many important purposes, including nitrogen fixation. One of the most distinguished features of bacteria is their biochemical versatility. A bacterial genus called "Pseudomonas" can metabolize a wide range of chemicals and fertilizers. In contrast, another genus known as "Nitrobacter" can only derive its energy by turning nitrite into nitrate, which is also known as oxidation. The genus "Clostridium" is an example of bacterial versatility because it, unlike most species, can grow in the absence of oxygen, respiring anaerobically. Several

neg: Nif gene host. Nif gene The "nif" genes are genes encoding enzymes involved in the fixation of atmospheric nitrogen into a form of nitrogen available to living organisms. The primary enzyme encoded by the "nif" genes is the nitrogenase complex which is in charge of converting atmospheric nitrogen (N) to other nitrogen forms such as ammonia which the organism can use for various purposes. Besides the nitrogenase enzyme, the "nif" genes also encode a number of regulatory proteins involved in nitrogen fixation. The "nif" genes are found in both free-living nitrogen-fixing bacteria and in symbiotic bacteria associated with various plants. The expression

neg: Nif gene Nif gene The "nif" genes are genes encoding enzymes involved in the fixation of atmospheric nitrogen into a form of nitrogen available to living organisms. The primary enzyme encoded by the "nif" genes is the nitrogenase complex which is in charge of converting atmospheric nitrogen (N) to other nitrogen forms such as ammonia which the organism can use for various purposes. Besides the nitrogenase enzyme, the "nif" genes also encode a number of regulatory proteins involved in nitrogen fixation. The "nif" genes are found in both free-living nitrogen-fixing bacteria and in symbiotic bacteria associated with various plants. The expression of

neg: Nitrogen fixation package have harmful effects on the Herbaspirillum bacteria needed for fixation. Different aspects of nitrogen fixation can be examined with these products, such as effects of temperature on the fixation process, the regulation of the process by oxygen, and the inhibition of nitrogen fixation by an over-abundance of fertilizers. Nitrogen fixation package A nitrogen fixation package is a piece of research equipment for studying nitrogen fixation in plants. One product of this kind, the Q-Box NF1LP made by Qubit Systems, operates by measuring the hydrogen (H) given off in the nitrogen-fixing chemical reaction enabled by nitrogenase enzymes. Nitrogen is produced by

neg: Mycorrhizosphere that are inaccessible to roots. In some cases, mycorrhizal fungi in the mycorrhizosphere may ward off fungal plant pathogens. For example, the arbuscular mycorrhizal fungus "Glomus intraradices" reduces germination of the pathogen "Fusarium oxysporum", but stimulates germination of a non-pathogenic fungus "Trichoderma harzianum". Soil bacteria in the mycorrhizosphere influence plant growth in several ways: by affecting the uptake of nutrients, providing protection against pathogens, contributing to nitrogen fixation, and contributing to mineral weathering. Archaea are also known to exist in mycorrhizosphere. They may contribute to nitrogen fixation and produce antibiotic compounds, but the extent of their interactions with other organisms

neg: Nitrogen cycle is to transform nitrogen from one form to another. Many of those processes are carried out by microbes, either in their effort to harvest energy or to accumulate nitrogen in a form needed for their growth. For example, the nitrogenous wastes in animal urine are broken down by nitrifying bacteria in the soil to be used as new. The diagram {besides} alongside shows how these processes fit together to form the nitrogen cycle. The conversion of nitrogen gas (N) into nitrates and nitrites through atmospheric, industrial and biological processes is called nitrogen fixation. Atmospheric nitrogen must be processed, or "fixed",

neg: Paenibacillus fields ranging from cosmetics to biofuel production. Various "Paenibacillus" spp. also produce antimicrobial substances that affect a wide spectrum of micro-organisms such as fungi, soil bacteria, plant pathogenic bacteria, and even important anaerobic pathogens such as "Clostridium botulinum". More specifically, several "Paenibacillus "species serve as efficient plant growth-promoting rhizobacteria (PGPR), which competitively colonize plant roots and can simultaneously act as biofertilizers and as antagonists (biopesticides) of recognized root pathogens, such as bacteria, fungi, and nematodes. They enhance plant growth by several direct and indirect mechanisms. Direct mechanisms include phosphate solubilization, nitrogen fixation, degradation of environmental pollutants, and hormone production. Indirect

neg: Mucuna bracteata Mucuna bracteata Mucuna bracteata is a leguminous plant. It is a nitrogen-regulating plant that is used in agroecosystems operating around certain types of agricultural plant systems including: rubber trees, oil palm, citrus and coconut. "M. bracteate" is a cover crop which helps to cover and shield the soil from weeds or plants, as well as providing rapid growth for existing agricultural crops, preventing soil erosion, and providing nitrogen fixation. The "Mucuna bracteata" crop grows about 10–15 cm/day in conditions similar to those that rubber and palm oil plants thrive in. "Mucuna bracteata" grows in a warm and humid ecosystem, at

neg: Lespedeza plant was derived. Some species are grown as garden or ornamental plants, and are used as a forage crops, notably in the southern United States, and as a means of soil enrichment and for prevention of erosion. In some areas, certain species are invasive. "Lespedeza", like other legumes, have root nodules that harbor bacteria capable of nitrogen fixation from the air into a soil-bound form that can be taken up by other plants. Growers can take advantage of this process by putting the plants in their fields to release nitrogen, so they can use less fertilizer. "L. bicolor" leaves and

neg: Nitrogen assimilation case as ammonia can predominate in grasslands and in flooded, anaerobic soils like rice paddies. Plant roots themselves can affect the abundance of various forms of nitrogen by changing the pH and secreting organic compounds or oxygen. This influences microbial activities like the inter-conversion of various nitrogen species, the release of ammonia from organic matter in the soil and the fixation of nitrogen by non-nodule-forming bacteria. Ammonium ions are absorbed by the plant via ammonia transporters. Nitrate is taken up by several nitrate transporters that use a proton gradient to power the transport. Nitrogen is transported from the root to

neg: Nitrogen fixation but a few genera (e.g., "Styphnolobium") do not. In many traditional and organic farming practices, fields are rotated through various types of crops, which usually include one consisting mainly or entirely of clover or buckwheat (non-legume family Polygonaceae), often referred to as "green manure". The efficiency of nitrogen fixation in soil is dependent on many factors, including the legume as well as air and soil conditions. For example, nitrogen fixation by red clover can range from 50 - 200 lb./acre depending on these variables. Inga alley farming relies on the leguminous genus "Inga", a small tropical, tough-leaved, nitrogen-fixing tree. Although

neg: Roystonea regia are green when immature, turning red and eventually purplish-black as they mature. Root nodules containing "Rhizobium" bacteria have been found on "R. regia" trees in India. The presence of rhizobia-containing root nodules is usually associated with nitrogen fixation in legumes; this was the first record of root nodules in a monocotyledonous tree. Further evidence of nitrogen fixation was provided by the presence of nitrogenase (an enzyme used in nitrogen fixation) and leghaemoglobin, a compound which allows nitrogenase to function by reducing the oxygen concentration in the root nodule. In addition to evidence of nitrogen fixation, the nodules were also found

neg: Lupinus albus factor for nitrogen fixation. Thanks to the symbiosis with nitrogen fixing bacteria, white lupin doesn't need a nitrogen fertilisation, while it requires about 40 kg P2O5/ha and 60 kg K2O/ha. Fertilisations based on compost or composted manure are better than fresh manure. Thanks to its long tap root, white lupin can exploit well phosphorus reserves in the soil. The crop rotation for white lupin ideally lasts at least four, ideally five years and often lupin is grown after a cereal crop. Lupin is a good preculture, since it let in the field about 50 kg nitrogen/ha. The lupin doesn't compete

neg: Crocosphaera watsonii separation entails temporal regulation of many enzymes and processes in these bacteria. Consistent with this, many genes involved in nitrogen fixation and photosynthesis show variation in transcription between day and night. This difference in gene expression between light and dark periods for genes involved in nitrogen fixation was about ten times bigger than for genes involved in photosynthesis, suggesting more stable photosystems compared to nitrogenase in these bacteria. The expression of many genes involved in nitrogen fixation and photosynthesis have been individually monitored. These include genes encoding the proteins nifH, nifX, glutamate synthetase, ntcA, glnB-like proteins and glgP, all of

neg: Crocosphaera watsonii both photosynthesis and nitrogen fixation also helps enforce the diel cycle of photosynthesis and nitrogen fixation. "Crocosphaera watsonii," which contributes significantly to oceanic nitrogen fixation, is limited by iron as is also the case for other marine diazotrophs. The reason for this is that the enzyme responsible for nitrogen fixation in diazotrophs, nitrogenase, uses iron as a cofactor. To overcome the challenge of iron scarcity, "Crocosphaera watsonii" has come up with a unique mechanism that involves reduction of metalloenzyme inventories. In this mechanism, the metalloenzyme will be synthesized only when needed and will be degraded as soon as they are

neg: Paenibacillus macerans Paenibacillus macerans Paenibacillus macerans is a diazotroph bacterium found in soil and plants capable of nitrogen fixation and fermentation. This bacteria was originally discovered in 1905 by an Austrian biologist named Schardinger and thought to be a bacillus. "Paenibacillus macerans" is a part of the Paenibacillaceae family which are facultative anaerobes. It is gram-variable, being gram-positive or gram-negative rods. Does not have a capsule and has peritrichous flagella for movement. It does form ellipsoidal, terminal, or subterminal spores which may last in the soil for many years. "P. macerans" can be grown in the lab on a nurtient agar with

neg: Nitrosomonas Nitrosomonas "Nitrosomonas" is a genus of Gram-negative rod-shaped chemoautotrophic bacteria. This organism oxidizes ammonia into nitrite as a metabolic process. "Nitrosomonas" are useful in bioremediation. They are important in the nitrogen cycle by increasing the availability of nitrogen to plants while limiting carbon dioxide fixation. The genus is found in soil, freshwater, and on building surfaces, especially in areas that contains high levels of nitrogen compounds. "Nitrosomonas" prefers an optimum pH of 6.0-9.0 and a temperature range of 20 to 30 °C. Most species are motile with a flagellum located in the polar regions. The organism has power generating membranes,

neg: Symbiotic bacteria are endosymbiont. Certain plants establish a symbiotic relationship with bacteria, enabling them to produce nodules that facilitate the conversion of atmospheric nitrogen to ammonia. In this connection, cytokinins have been found to play a role in the development of root fixing nodules. It appears that not only must the plant have a need for nitrogen fixing bacteria, but they must also be able to synthesize cytokinins which promote the production of root nodules, required for nitrogen fixation. Symbiotic bacteria are able to live in or on plant or animal tissue. In digestive systems, symbiotic bacteria help break down foods that

neg: William Albrecht He presented his doctoral research in 1919, and it was published in the journal "Soil Science" in 1920 titled 'Symbiotic nitrogen fixation as influenced by nitrogen in the soil' His paper concluded that the nitrogen level in soil had no significant effect on fixation by legumes. Albrecht was a devout agronomist, the foremost authority on the relation of soil fertility to human health and earned four degrees from the University of Illinois. He became emeritus professor of soils at the University of Missouri. Dr. Albrecht saw a direct link between soil quality and food quality, drawing direct connection between poor

neg: Root hair curling Root hair curling Root hair curling is the process by which the root hairs of legume plants curl around bacteria to allow an infection into the cortical cells of the roots to form a nitrogen fixing nodule. Legume plants, just like all plants, need nitrogen in order to grow. Legumes include plants such as alfalfa, beans, peanuts, and lentils. Nitrogen is available in excess in the air, but it that form is not actually usable by plants. The gaseous form (N) must be reduced to ammonia (NH) in a process known as nitrogen fixation. This nitrogen fixation can occur in

neg: Nitrogenase Nitrogenase Nitrogenases are enzymes () that are produced by certain bacteria, such as cyanobacteria (blue-green algae). These enzymes are responsible for the reduction of nitrogen (N) to ammonia (NH). Nitrogenases are the only family of enzymes known to catalyze this reaction, which is a key step in the process of nitrogen fixation. Nitrogen fixation is required for all forms of life, with nitrogen being essential for the biosynthesis of molecules (nucleotides, amino acids) that create plants, animals and other organisms. The equilibrium formation of ammonia from molecular hydrogen and nitrogen has an overall negative enthalpy of reaction (formula_1), the activation

neg: Nitrogenase Fe protein enter the MoFe protein at the P-clusters, which then transfer the electrons to the FeMo cofactors. Each FeMo cofactor then acts as a site for nitrogen fixation, with N binding in the central cavity of the cofactor. Nitrogenase is an enzyme responsible for catalyzing nitrogen fixation, which is the reduction of nitrogen (N) to ammonia (NH) and a process vital to sustaining life on Earth. There are three types of nitrogenase found in various nitrogen-fixing bacteria: molybdenum (Mo) nitrogenase, vanadium (V) nitrogenase, and iron-only (Fe) nitrogenase. Molybdenum nitrogenase, which can be found in diazotrophs and legumes, is the

neg: Nitrosomonas by oxidizing ammonia (the other product of urease) to nitrite. This feature may explain enhanced growth of AOB in the presence of urea in acidic environments. Some sources regard Nitrobacteraceae to be the family of the genus "Nicosomonas". Nitrosomonas "Nitrosomonas" is a genus of Gram-negative rod-shaped chemoautotrophic bacteria. This organism oxidizes ammonia into nitrite as a metabolic process. "Nitrosomonas" are useful in bioremediation. They are important in the nitrogen cycle by increasing the availability of nitrogen to plants while limiting carbon dioxide fixation. The genus is found in soil, freshwater, and on building surfaces, especially in areas that contains high

neg: Rhizobacteria due to the high energy required to break the triple bonds between the two atoms. Rhizobacteria, through nitrogen fixation, are able to convert gaseous nitrogen (N) to ammonia (NH) making it an available nutrient to the host plant which can support and enhance plant growth. The host plant provides the bacteria with amino acids so they do not need to assimilate ammonia. The amino acids are then shuttled back to the plant with newly fixed nitrogen. Nitrogenase is an enzyme involved in nitrogen fixation and requires anaerobic conditions. Membranes within root nodules are able to provide these conditions. The rhizobacteria

neg: Coarse woody debris is important actor contributing to soil nutrients cycles. CWD, while itself not particularly rich in nitrogen, contributes nitrogen to the ecosystem by acting as a host for nonsymbiotic free-living nitrogen-fixing bacteria. Scientific studies show that coarse woody debris can be a significant contributor to biological carbon sequestration. Trees store atmospheric carbon in their wood using photosynthesis. Once the trees die, fungi and other saprotrophs transfer some of that carbon from CWD into the soil. This sequestration can continue in old-growth forests for hundreds of years. By providing both food and microhabitats for many species, coarse woody debris helps to maintain

neg: Sustainable agriculture as not to compete with each other for natural resources. This system would result in increased resistance to diseases and decreased effects of erosion and loss of nutrients in soil. Nitrogen fixation from legumes, for example, used in conjunction with plants that rely on nitrate from soil for growth, helps to allow the land to be reused annually. Legumes will grow for a season and replenish the soil with ammonium and nitrate, and the next season other plants can be seeded and grown in the field in preparation for harvest. Monoculture, a method of growing only one crop at a

neg: Period 5 element medium, and the earliest laser designs used xenon flash lamps as pumps. Xenon is also being used to search for hypothetical weakly interacting massive particles and as the propellant for ion thrusters in spacecraft. Rubidium, strontium, yttrium, zirconium, and niobium have no biological role. Yttrium can cause lung disease in humans. Molybdenum-containing enzymes are used as catalysts by some bacteria to break the chemical bond in atmospheric molecular nitrogen, allowing biological nitrogen fixation. At least 50 molybdenum-containing enzymes are now known in bacteria and animals, though only the bacterial and cyanobacterial enzymes are involved in nitrogen fixation. Owing to the

neg: Guar it lives in symbiosis with nitrogen-fixing bacteria. In fact, agriculturists in semi-arid regions of Rajasthan follow crop-rotation and use guar as a source to replenish the soil with essential fertilizers and nitrogen fixation, before the next crop. Guar as a plant has a multitude of different functions for human and animal nutrition but its gelling-agent-containing seeds (guar gum) are today the most important use. Demand is rising rapidly due to industrial use of guar gum in hydraulic fracturing (oil shale gas). About 80% of world production occurs in India and Pakistan, but due to strong demand, the plant is being

neg: Acacia cochlearis high winds it is utilised in mixed plantings with other species such as "Acacia rostellifera" and "Scaevola crassifolia". It is an indicator of good quality dunes as the species is vulnerable to disturbance once established. "A. cochlearis" can be grown from seed, the seeds should be soaked in hot water or lightly abraided with fine sandpaper prior to planting. Seeds should be sown in free draining soil and can benefit from the addition of disease free soil from existing plants to transfer the "Rhizobium" bacteria that are important in nitrogen fixation. Plants require a position in full sun. Acacia cochlearis

neg: Soil released as ammonium by the processes of mineralisation. Protein material is easily broken down, but the rate of its decomposition is slowed by its attachment to the crystalline structure of clay and when trapped between the clay layers. The layers are small enough that bacteria cannot enter. Some organisms can exude extracellular enzymes that can act on the sequestered proteins. However, those enzymes too may be trapped on the clay crystals. Ammonium fixation occurs when ammonium pushes potassium ions from between the layers of clay such as illite or montmorillonite. Only a small fraction of soil nitrogen is held this

neg: Soil nitrogen is released as ammonium and nitrate. If the C/N is less than 15, ammonia is freed to the soil, where it may be used by bacteria which oxidise it to nitrate (nitrification). Bacteria may on average add nitrogen per acre, and in an unfertilised field, this is the most important source of usable nitrogen. In a soil with 5% organic matter perhaps 2 to 5% of that is released to the soil by such decomposition. It occurs fastest in warm, moist, well aerated soil. The mineralisation of 3% of the organic material of a soil that is 4% organic

neg: Nitrogen the industrial synthesis of ammonia and nitric acid became common. Nitrogen compounds constantly interchange between the atmosphere and living organisms. Nitrogen must first be processed, or "fixed", into a plant-usable form, usually ammonia. Some nitrogen fixation is done by lightning strikes producing the nitrogen oxides, but most is done by diazotrophic bacteria through enzymes known as nitrogenases (although today industrial nitrogen fixation to ammonia is also significant). When the ammonia is taken up by plants, it is used to synthesise proteins. These plants are then digested by animals who use the nitrogen compounds to synthesise their own proteins and excrete

neg: Ammonia the soil by decaying matter. Others, such as nitrogen-fixing legumes, benefit from symbiotic relationships with rhizobia that create ammonia from atmospheric nitrogen. In certain organisms, ammonia is produced from atmospheric nitrogen by enzymes called nitrogenases. The overall process is called nitrogen fixation. Intense effort has been directed toward understanding the mechanism of biological nitrogen fixation; the scientific interest in this problem is motivated by the unusual structure of the active site of the enzyme, which consists of an FeMoS ensemble. Ammonia is also a metabolic product of amino acid deamination catalyzed by enzymes such as glutamate dehydrogenase 1. Ammonia excretion

neg: Mycorrhiza helper bacteria fact, the plant could grow with the presence of multiple bacteria. It has been hypothesized that rhizosphere helper bacteria, in the soil, have developed traits to aid them in competition for inoculating fungi in their environment. Thus, it is plausible that MHBs select for certain fungi and developed some specificity towards a fungus that favours the bacteria. MHB help mycorrhiza establish symbiotic associations in stressful environments such as those high in toxic metals. In harsh environments, the bacteria assist in acquiring more nutrients such as nitrogen and phosphorus. MHB helps to prevent the uptake of toxic metals including lead, zinc,

neg: Mammillaria fraileana of its summer height, will help the flowering process. Studies have shown that "Mammillaria fraileana" is a pioneer cactus in rock-colonizing. These cacti grow in rocky habitats, many including rhyodacite rocks. Evidence has shown that rhyodacite is weathered to greater extents while in the presence of these cacti which supports the argument that this species is directly associated with rock weathering and thus, the formation of soil. This small cactus does this through processes like nitrogen fixation that take place in the endophytic bacteria that lives in inside the cactus and on its roots. Studies have found large populations of

neg: Soil conservation the surrounding upper of soil. The weight of casts produced may be greater than 4.5 kg per worm per year. By burrowing, the earthworm improves soil porosity, creating channels that enhance the processes of aeration and drainage. Other important soil organisms include nematodes, mycorrizha and bacteria. Degraded soil requires synthetic fertilizer to produce high yields. Lacking structure increases erosion and carries nitrogen and other pollutants into rivers and streams. Each one percent increase in soil organic matter helps soil hold 20,000 gallons more water per acre. To allow plants full realization of their phytonutrient potential, active mineralization of the soil

neg: Alnus cordata for up to a year after. "Alnus cordata" has gained The Royal Horticultural Society's Award of Garden Merit. Like other alders, it is able to improve soil fertility through symbiotic nitrogen fixation with the bacteria Actinomyces alni (Frankia alni). It thrives on much drier soils than most other alders, and grows rapidly even under very unfavourable circumstances, which renders it extremely valuable for landscape planting on difficult sites such as mining spoil heaps and heavily compacted urban sites. It is commonly grown as a windbreak. The tree also produces valuable reddish-orange wood. It breaks down rapidly when exposed to air,

neg: Biofertilizer the use of phosphate-solubilizing bacteria or phosphate biofertilizers. Benefits of biofertilizers are: Some important groups of biofertilizers include: Biofertilizer A biofertilizer (also bio-fertilizer) is a substance which contains living microorganisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Biofertilizers add nutrients through the natural processes of nitrogen fixation, solubilizing phosphorus, and stimulating plant growth through the synthesis of growth-promoting substances. Biofertilizers can be expected to reduce the use of synthetic fertilizers and pesticides. The

neg: Lithotroph lithotrophs that have the ability to ferment, implying their ability to convert organic carbon into another usable form. Another example is the cycling of nitrogen. Many lithotrophic bacteria play a role in reducing inorganic nitrogen (nitrogen gas) to organic nitrogen (ammonium) in a process called nitrogen fixation. Likewise, there are many lithotrophic bacteria that also convert ammonium into nitrogen gas in a process called denitrification. Carbon and nitrogen are important nutrients, essential for metabolic processes, and can sometimes be the limiting factor that affects organismal growth and development. Thus, lithotrophs are key players in both providing and removing these important

neg: Bradyrhizobium Bradyrhizobia are also major components of forest soil microbial communities, where strains isolated from these soils are not typically capable of nitrogen fixation or nodulation. They are slow-growing in contrast to "Rhizobium" species, which are considered fast-growing rhizobia. In a liquid medium, "Bradyrhizobium" species take 3–5 days to create a moderate turbidity and 6–8 hours to double in population size. They tend to grow best with pentoses as carbon sources. Some strains (for example, USDA 6 and CPP) are capable of oxidizing carbon monoxide aerobically. Nodules are growths on the roots of leguminous plants where the bacteria reside. The plant

neg: Clostridium indolis believed to be beneficial in carbohydrate limited environments. "C. indolis" also contains 261 genes related to energy production and conversion. Amongst these, there are genes for citrate utilization, lactate utilization, and nitrogen fixation. "C. indolis" is commonly isolated from soil as well as human and bird feces. It is associated with infections of the intestinal tract. Clostridium indolis Clostridium indolis is a Gram-positive, motile, anaerobic, rod-shaped bacteria that produces terminal spores. "Clostridium indolis" was originally named for its ability to hydrolyze tryptophan to indole, pyruvate, and ammonia in the classic indole test which is used to distinguish bacterial species. It

neg: Frankia the only named species in this genus, but a great many strains are specific to different plant species. The bacteria are filamentous and convert atmospheric nitrogen into ammonia via 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

neg: Bioturbation nitrogen. This increased removal of biologically available nitrogen has been suggested to be linked to increased rates of nitrogen fixation in microenvironments within burrows, as indicated by evidence of nitrogen fixation by sulfate-reducing bacteria via the presence of "nif"H (nitrogenase) genes. Bioturbation by walrus feeding is a significant source of sediment and biological community structure and nutrient flux in the Bering Sea. Walruses feed by digging their muzzles into the sediment and extracting clams through powerful suction. By digging through the sediment, walruses rapidly release large amounts of organic material and nutrients, especially ammonium, from the sediment to the water

neg: Urea as a nitrogen-release fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use. Therefore, it has the lowest transportation costs per unit of nitrogen nutrient. Many soil bacteria possess the enzyme urease, which catalyzes conversion of urea to ammonia (NH) or ammonium ion (NH) and bicarbonate ion (HCO). Thus urea fertilizers rapidly transform to the ammonium form in soils. Among the soil bacteria known to carry urease, some ammonia-oxidizing bacteria (AOB), such as species of "Nitrosomonas", can also assimilate the carbon dioxide the reaction releases to make biomass via the Calvin cycle, and harvest energy

neg: Ecosystem nitrogen-fixing symbionts—as much as 25% of gross primary production when measured in controlled conditions. Many members of the legume plant family support nitrogen-fixing symbionts. Some cyanobacteria are also capable of nitrogen fixation. These are phototrophs, which carry out photosynthesis. Like other nitrogen-fixing bacteria, they can either be free-living or have symbiotic relationships with plants. Other sources of nitrogen include acid deposition produced through the combustion of fossil fuels, ammonia gas which evaporates from agricultural fields which have had fertilizers applied to them, and dust. Anthropogenic nitrogen inputs account for about 80% of all nitrogen fluxes in ecosystems. When plant tissues

neg: Plant nutrition to total N might be a useful ratio in this regard. Nitrogen availability in the rooting medium also affects the size and structure of tracheids formed in the long lateral roots of white spruce (Krasowski and Owens 1999). Microorganisms have a central role in almost all aspects of nitrogen availability, and therefore for life support on earth. Some bacteria can convert N into ammonia by the process termed "nitrogen fixation"; these bacteria are either free-living or form symbiotic associations with plants or other organisms (e.g., termites, protozoa), while other bacteria bring about transformations of ammonia to nitrate, and of nitrate

neg: Rhizobia "Nostoc" are associated with aquatic ferns, "Cycas" and "Gunneras," although they do not form nodules. Additionally, loosely associated plant bacteria, termed endophytes, have been reported to fix nitrogen "in planta". These bacteria colonize the intercellular spaces of leaves, stems and roots in plants but do not form specialized structures unlike rhizobia and "Frankia." Diazotrophic bacterial endophytes have very broad host ranges, in some cases colonizing both monocots and dicots. Rhizobia Rhizobia are bacteria that fix nitrogen (diazotrophs) after becoming established inside root nodules of legumes (Fabaceae). To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently

neg: Ecosystem are shed or are eaten, the nitrogen in those tissues becomes available to animals and microbes. Microbial decomposition releases nitrogen compounds from dead organic matter in the soil, where plants, fungi, and bacteria compete for it. Some soil bacteria use organic nitrogen-containing compounds as a source of carbon, and release ammonium ions into the soil. This process is known as nitrogen mineralization. Others convert ammonium to nitrite and nitrate ions, a process known as nitrification. Nitric oxide and nitrous oxide are also produced during nitrification. Under nitrogen-rich and oxygen-poor conditions, nitrates and nitrites are converted to nitrogen gas, a process

neg: Plant nutrition one element may present as symptoms of toxicity from another element, and vice versa. An abundance of one nutrient may cause a deficiency of another nutrient. For example, K uptake can be influenced by the amount of NH available. Although nitrogen is plentiful in the Earth's atmosphere, relatively few plants engage in nitrogen fixation (conversion of atmospheric nitrogen to a biologically useful form). Most plants, therefore, require nitrogen compounds to be present in the soil in which they grow. Carbon and oxygen are absorbed from the air while other nutrients are absorbed from the soil. Green plants obtain their carbohydrate

neg: Environmental impact of pesticides resistant to degradation and extraction as they lose biological activity. Nitrogen fixation, which is required for the growth of higher plants, is hindered by pesticides in soil. The insecticides DDT, methyl parathion, and especially pentachlorophenol have been shown to interfere with legume-rhizobium chemical signaling. Reduction of this symbiotic chemical signaling results in reduced nitrogen fixation and thus reduced crop yields. Root nodule formation in these plants saves the world economy $10 billion in synthetic nitrogen fertilizer every year. Pesticides can kill bees and are strongly implicated in pollinator decline, the loss of species that pollinate plants, including through the mechanism

neg: Nif gene "nifA" in the same manner described before, but it uses a different "nifA" activator which initiates the NtrC. NtrC activates a different expression of "nifA" and the other "nif" genes. "Rhizobium" spp.—Gram-negative, symbiotic nitrogen fixing bacteria that usually form a symbiotic relationship with legume species. In some rhizobia, the "nif" genes are located on plasmids called 'sym plasmids' (sym = symbiosis) which contain genes related to nitrogen fixation and metabolism, while the chromosomes contain most of the housekeeping genes of the bacteria. Regulation of the "nif" genes is at the transcriptional level and is dependent on colonization of the plant

neg: Soil respiration for a spike in resources for many other bacteria. This rapid increase in available labile substrates causes short-term enhanced soil respiration. Root respiration will increase with increasing soil moisture, especially in dry ecosystems; however, individual species root respiration response to soil moisture will vary widely from species to species depending on life history traits. Upper levels of soil moisture will depress root respiration with the exception of wetland plants, which have developed specific mechanisms for root aeration. Soil moisture levels regulate root respiration, which is essential for nitrogen uptake. Nitrogen directly affects soil respiration in several ways. Nitrogen must be

neg: Soil mesofauna of total pore spaces. Clay soils have much smaller particles which reduce pore space. Organic material can fill small pores. Grazing of bacteria by bacterivorous nematodes and flagellates, soil mesofauna living in the pores, may considerably increase Nitrogen mineralization because the bacteria are broken down and the nitrogen is released. In agricultural soils, most of the biological activity occurs in the top , the soil biomantle or plow layer, while in non-cultivated soils, the most biological activity occurs in top of soil. The top layer is the organic horizon or O horizon, the area of accumulation of animal residues and

neg: Glyphosate These values make glyphosate "slightly toxic to practically non-toxic". The antimicrobial activity of glyphosate has been described in the microbiology literature since its discovery in 1970 and the description of glyphosate's mechanism of action in 1972. Efficacy was described for numerous bacteria and fungi. Glyphosate can control the growth of apicomplexan parasites, such as "Toxoplasma gondii", "Plasmodium falciparum" (malaria), and "Cryptosporidium parvum", and has been considered an antimicrobial agent in mammals. Inhibition can occur with some Rhizobium species important for soybean nitrogen fixation, especially under moisture stress. When glyphosate comes into contact with the soil, it can be bound to

neg: Fat sand rat winter, fat sand rats prefer the wadi habitat as a result of the vegetative growth during this time, but after a wet autumn more individuals will burrow in a terrace habitat even when population density is low, as opposed to after a dry autumn when individuals only burrow in terrace habitats when the population density is high. The burrowing activities of the rodents can impact their habitat, affecting the bacteria in the soil around their burrows such that nitrogen fixation and denitrification activity are decreased. The fat sand rat also disturbs vegetation cover while burrowing, further altering its environment. Mounds

neg: Lar1 nitrogen fixation (converting dinitrogen gas into a molecular form which is easily assimilated). Many lichens grow in extremely nutrient-poor environments and may rely on nitrogen-fixing bacteria to provide them with enough molecular nitrogen to survive. It has been documented by numerous researchers that microbes associated with green-algal lichens have the potential to fix nitrogen in abundance. However, nearly all of these studies have relied solely on culture-based methods, which may provide an inaccurate picture of what the most abundant or important nitrogen-fixers actually are. Independent studies on lichens have used culture-free techniques to detect the presence of the primary gene

neg: Soil of mineralisation. Some amount of usable nitrogen is fixed by lightning as nitric oxide (NO) and nitrogen dioxide (NO). Nitrogen dioxide is soluble in water to form nitric acid (HNO) solution of H and NO. Ammonia, NH, previously released from the soil or from combustion, may fall with precipitation as nitric acid at a rate of about five pounds nitrogen per acre per year. When bacteria feed on soluble forms of nitrogen (ammonium and nitrate), they temporarily sequester that nitrogen in their bodies in a process called "immobilisation". At a later time when those bacteria die, their nitrogen may be

neg: Gluconacetobacter diazotrophicus correct classification for "Gluconacetobacter diazotrophicus". In addition to sugarcane, "G. diazotrophicus" has been found in different plants like coffee tree and pineapple. "Gluconacetobacter diazotrophicus" is also known for nitrogen fixation. This feature allows the bacteria to work on nitrogen in the air in order for the correct amount of nitrogen can be received by plants."Gluconacetobacter diazotrophicus" is a notable microbe because studies have shown that the bacteria can help tomatoes and other crops grow. Besides to be a nitrogen-fixing bacterium, "G. diazotrophicus" synthezises Indole-3-acid acetic, that could contribute to promote the growth of the associated plant. This microbe fights off

neg: Mycorrhiza helper bacteria Bacilli, and is a rod-shaped organism that can be free-living or pathogenic. However, in the presence of mycorrhiza some species can be beneficial and are considered to be MHBs. Since they are common, they can form a relationship with ectomycorrhiza and arbuscular mycorrhiza, similar to the previous genera. "Bacillius" aids the establishment and growth of mycorrhiza, and helps with the fixation of nitrogen in the rhizosphere. MHB are known to have several functions when interacting with the roots and growth of fungi. In several studies it has been reported that MHB can help fungi by increasing growth and aid with

neg: Vanadium nitrogenase Vanadium nitrogenase Vanadium nitrogenase is a key enzyme for nitrogen fixation found in nitrogen-fixing bacteria, and is used as an alternative to molybdenum nitrogenase when molybdenum is unavailable. Vanadium nitrogenases are an important biological use of vanadium, which is uncommonly used by life. An important component of the nitrogen cycle, vanadium nitrogenase converts nitrogen gas to ammonia, thereby making otherwise inaccessible nitrogen available to plants. Unlike molybdenum nitrogenase, vanadium nitrogenase can also reduce carbon monoxide to ethylene, ethane and propane but both enzymes can reduce protons to hydrogen gas and acetylene to ethylene. Vanadium nitrogenases are found in members of

neg: Cyanobacteria of specialized cells called heterocysts. Heterocysts may also form under the appropriate environmental conditions (anoxic) when fixed nitrogen is scarce. Heterocyst-forming species are specialized for nitrogen fixation and are able to fix nitrogen gas into ammonia (), nitrites () or nitrates (), which can be absorbed by plants and converted to protein and nucleic acids (atmospheric nitrogen is not bioavailable to plants, except for those having endosymbiotic nitrogen-fixing bacteria, especially the Fabaceae family, among others). Free-living cyanobacteria are present in the water of rice paddies, and cyanobacteria can be found growing as epiphytes on the surfaces of the green alga,

neg: Korean natural farming of plant secretions. Mold constitutes 70-75%, bacteria 20-25% and small animals the rest. The microorganisms contain approximately 70 kg of carbon and 11 kg of nitrogen, similar to the amount of nitrogen typically applied as fertilizer. Nutrients are taken up and deposited in a natural cycle unless disrupted by human intervention. As plants decay,"detrital" nitrogen and phosphorus is returned to the soil. Soil fungus and bacteria absorb these nutrients. The fungus and bacteria are consumed by fungal and bacterial-feeding namatodes, respectively. These nematodes are in turn consumed by omnivorous predatory nematodes. At each stage, some inorganic nitrogen and phosphorus is

neg: Biological soil crust Biological soil crust Biological soil crusts are communities of living organisms on the soil surface in arid and semi-arid ecosystems. They are found throughout the world with varying species composition and cover depending on topography, soil characteristics, climate, plant community, microhabitats, and disturbance regimes. Biological soil crusts perform important ecological roles including carbon fixation, nitrogen fixation, soil stabilization, alter soil albedo and water relations, and affect germination and nutrient levels in vascular plants. They can be damaged by fire, recreational activity, grazing, and other disturbance and can require long time periods to recover composition and function. Biological soil crusts are

neg: Soil way. Usable nitrogen may be lost from soils when it is in the form of nitrate, as it is easily leached. Further losses of nitrogen occur by denitrification, the process whereby soil bacteria convert nitrate (NO) to nitrogen gas, N or NO. This occurs when poor soil aeration limits free oxygen, forcing bacteria to use the oxygen in nitrate for their respiratory process. Denitrification increases when oxidisable organic material is available and when soils are warm and slightly acidic. Denitrification may vary throughout a soil as the aeration varies from place to place. Denitrification may cause the loss of 10

neg: Soil crust plant community, microhabitats, and disturbance regimes. Biological soil crusts perform important ecological roles including carbon fixation, nitrogen fixation, soil stabilization, alter soil albedo and water relations, and affect germination and nutrient levels in vascular plants. They can be damaged by fire, recreational activity, grazing, and other disturbance and can require long time periods to recover composition and function. Biological soil crusts are also known as cryptogamic, microbiotic, microphytic, or cryptobiotic soils. Physical (as opposed to biological) soil crusts results from raindrop or trampling impacts. They are often hardened relative to uncrusted soil due to the accumulation of salts and silica.