scholarly journals Active nitrogen fixation by Crocosphaera expands their niche despite the presence of ammonium – A case study

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Keisuke Inomura ◽  
Takako Masuda ◽  
Julia M. Gauglitz
Keyword(s):  
Nitrogen Fixation ◽  
Mechanistic Model ◽  
Energy Costs ◽  
High Electron ◽  
Nitrogen Fixing ◽  
Active Nitrogen ◽  
State Culture ◽  
Nitrogen Fixers ◽  
Efficient Alternative

Abstract Unicellular nitrogen fixer Crocosphaera contributes substantially to nitrogen fixation in oligotrophic subtropical gyres. They fix nitrogen even when significant amounts of ammonium are available. This has been puzzling since fixing nitrogen is energetically inefficient compared with using available ammonium. Here we show that by fixing nitrogen, Crocosphaera can increase their population and expand their niche despite the presence of ammonium. We have developed a simple but mechanistic model of Crocosphaera based on their growth in steady state culture. The model shows that the growth of Crocosphaera can become nitrogen limited despite their capability to fix nitrogen. When they fix nitrogen, the population increases by up to 78% relative to the case without nitrogen fixation. When we simulate a simple ecological situation where Crocosphaera exists with non-nitrogen-fixing phytoplankton, the relative abundance of Crocosphaera increases with nitrogen fixation, while the population of non-nitrogen-fixing phytoplankton decreases since a larger fraction of fixed nitrogen is consumed by Crocosphaera. Our study quantitatively supports the benefit of nitrogen fixation despite the high electron/energy costs, even when an energetically efficient alternative is available. It demonstrates a competitive aspect of Crocosphaera, permitting them to be regionally significant nitrogen fixers.

scholarly journals The Nodule Microbiome: N2-Fixing Rhizobia Do Not Live Alone

2017 ◽  
Vol 1 (2) ◽  
pp. 70-82 ◽  
Author(s):  
Pilar Martínez-Hidalgo ◽  
Ann M. Hirsch
Keyword(s):  
Nitrogen Fixation ◽  
Environmental Stress ◽  
Host Plant ◽  
Diverse Population ◽  
Nitrogen Fixing ◽  
Chemical Fertilizers ◽  
Associated Bacteria ◽  
Culture Techniques ◽  
Nitrogen Fixers

For decades, rhizobia were thought to be the only nitrogen-fixing inhabitants of legume nodules, and biases in culture techniques prolonged this belief. However, other bacteria, which are not typical rhizobia, are often detected within nodules obtained from soil, thus revealing the existence of a phytomicrobiome where the interaction among the individuals is not only complex, but also likely to affect the behavior and fitness of the host plant. Many of these nonrhizobial bacteria are nitrogen fixers, and some also induce nitrogen-fixing nodules on legume roots. Even more striking is the incredibly diverse population of bacteria residing within nodules that elicit neither nodulation nor nitrogen fixation. Yet, this community exists within the nodule, albeit clearly out-numbered by nitrogen-fixing rhizobia. Few studies of the function of these nodule-associated bacteria in nodules have been performed, and to date, it is not known whether their presence in nodules is biologically important or not. Do they confer any benefits to the Rhizobium-legume nitrogen-fixing symbiosis, or are they parasites/saprophytes, contaminants, or commensals? In this review, we highlight the lesser-known bacteria that dwell within nitrogen-fixing nodules and discuss their possible role in this enclosed community as well as any likely benefits to the host plant or to the rhizobial inhabitants of the nodule. Although many of these nodule inhabitants are not capable of nitrogen fixation, they have the potential to enhance legume survival especially under conditions of environmental stress. This knowledge will be useful in defining strategies to employ these bacteria as bioinoculants by themselves or combined with rhizobia. Such an approach will enhance rhizobial performance or persistence as well as decrease the usage of chemical fertilizers and pesticides.

NON-SYMBIOTIC NITROGEN FIXATION IN SOME QUEBEC SOILS

1965 ◽  
Vol 11 (1) ◽  
pp. 29-38 ◽  
Author(s):  
P-C. Chang ◽  
R. Knowles
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Soil Types ◽  
Anaerobic Incubation ◽  
Nitrogen Fixing ◽  
Free Living ◽  
Aerobic Conditions ◽  
Bacterial Counts ◽  
Facultatively Anaerobic ◽  
Nitrogen Fixers

The occurrence of free-living nitrogen fixers, the potential for nitrogen fixation, and the correlation between the nitrogen-fixing capacities of the soils and bacterial counts were studied using representative Quebec soils.Clostridium occurred more frequently than did Azotobacter. Studies with N15showed that nitrogen fixation was more frequent under anaerobic than under aerobic conditions in all the soil types studied in their unamended state. The addition of glucose stimulated nitrogen fixation. During anaerobic incubation, nitrogen fixation was found to be correlated significantly with the increase in numbers of both total aerobes and Clostridia. The results suggested that facultatively anaerobic nitrogen fixers, and aerobic nitrogen fixers other than Azotobacter, were present.

scholarly journals TECHNOLOGY PECULIARITIES OF NEW BIOLOGICAL PREPARATION MICROHUMIN

2008 ◽  
Vol 7 ◽  
pp. 57-68
Author(s):  
V.V. Volkogon ◽  
O.M. Berdnikov ◽  
E.I. Volkogon ◽  
N.P. Shtan’ko
Keyword(s):  
Nitrogen Fixation ◽  
Growth And Development ◽  
Spring Barley ◽  
Research Data ◽  
Biologically Active ◽  
Nitrogen Fixing ◽  
Active Nitrogen ◽  
Associative Nitrogen Fixation ◽  
Biological Preparation ◽  
Effect On Growth

The paper covers research data on technology elaboration of new biological preparation Microhumin. It was shown that combination of biologically active biohumus extract with the suspension of active nitrogen fixing strain of azospirills in certain ratio results in creation of preparation performing additive stimulatory effect on growth and development of spring barley plants and activity of associative nitrogen fixation.

scholarly journals Ancient CO2 levels favor nitrogen fixing plants over a broader range of soil N compared to present

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haoran Chen ◽  
John Markham
Keyword(s):  
Nitrogen Fixation ◽  
Plant Biomass ◽  
Betula Papyrifera ◽  
Soil N ◽  
Nitrogen Fixing ◽  
N Level ◽  
Nitrogen Fixers ◽  
Alnus Viridis ◽  
Nitrogen Concentrations ◽  
Different Levels

AbstractSmall inreases in CO2 stimulate nitrogen fixation and plant growth. Increasing soil N can inhibit nitrogen fixation. However, no studies to date have tested how nitrogen fixing plants perform under ancient CO2 levels (100 MYA), when nitrogen fixing plants evolved, with different levels of N additions. The aim of this study was to assess if ancient CO2, compared to present, favors nitrogen fixers over a range of soil nitrogen concentrations. Nitrogen fixers (Alnus incana ssp. rugosa, Alnus viridis ssp. crispa, and Alnus rubra) and their close non-nitrogen fixing relatives (Betula pumila, Betula papyrifera, Betula glandulosa) were grown at ancient (1600 ppm) or present (400 ppm) CO2 over a range of soil N levels, equivalent to 0, 10, 50, and 200 kg N ha−1 year−1. The growth of non-N fixing plants increased more than N fixing plants in response to the increasing N levels. When grown at an ancient CO2 level, the N level at which non-nitrogen fixing plant biomass exceeded nitrogen fixing plant biomass was twice as high (61 kg N ha−1 year−1) as the N level when plants were grown at the ambient CO2 level. Specific nodule activity was also reduced with an increasing level of soil N. Our results show there was a greater advantage in being a nitrogen fixer under ancient levels of CO2 compared with the present CO2 level.

scholarly journals NITROGEN FIXING BACTERIA OF SPRING WHEAT ROOT ZONE

2013 ◽  
Vol 17 ◽  
pp. 7-20
Author(s):  
O. V. Nadkernychna ◽  
E. P. Kopylov
Keyword(s):  
Nitrogen Fixation ◽  
Spring Wheat ◽  
Root Zone ◽  
Molecular Nitrogen ◽  
Wheat Root ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Active Nitrogen ◽  
Nitrogen Fixation Activity ◽  
Fixation Activity

The paper presents the study of active nitrogen fixation bacteria of genera Azotobacter, Azospirillum, Bacillus, Flavobacterium, Enterobacter and Pseudomonas isolated from root zone of spring wheat plants. The ability of selected diazotrophs to form associative systems with spring wheat was investigated. The most significant increase of molecular nitrogen fixation activity in root zone of plants was observed under the Azospirillum species background.

scholarly journals Ancient CO2 Levels Favor Nitrogen Fixing Plants Over a Broader Range of Soil N Compared to Present

2020 ◽  
Author(s):  
Haoran Chen ◽  
John Markham
Keyword(s):  
Nitrogen Fixation ◽  
Plant Biomass ◽  
Betula Papyrifera ◽  
Soil N ◽  
Nitrogen Fixing ◽  
N Level ◽  
Nitrogen Fixers ◽  
Alnus Viridis ◽  
Nitrogen Concentrations ◽  
Different Levels

Abstract Small inreases in CO2 stimulate nitrogen fixation and plant growth. Increasing soil N can inhibit nitrogen fixation. However, no studies to date have tested how nitrogen fixing plants perform under ancient CO2 levels (100 MYA) when nitrogen fixers evolved, with different levels of N additions. The aim of this study was to assess if ancient CO2, compared to present, favors nitrogen fixers over a range of soil nitrogen concentrations. Nitrogen fixers (Alnus incana ssp. rugosa, Alnus viridis ssp. crispa, and Alnus rubra) and their close non-nitrogen fixing relatives (Betula pumila, Betula papyrifera, Betula glandulosa) were grown at ancient CO2 (1600 ppm) or present CO2 (400 ppm) over a range of soil N levels, equivalent to 0, 10, 50, and 200 kg N ha-1 year-1. The growth of non-N fixing plants increased more than N fixing plants in response to the increasing N levels. When grown at an ancient CO2 level, the N level at which non-nitrogen fixing plant biomass exceeded nitrogen fixing plant biomass was twice as high (61 kg N ha-1 y-1) as the N level when plants were grown at an ambient CO2 level. Specific nodule activity was also reduced with an increasing level of soil N. Our results showed there was a greater advantage in being a nitrogen fixer under ancient levels of CO2 compared with the present CO2 level.

Nitrogen fixation by soil microorganisms

1928 ◽  
Vol 18 (3) ◽  
pp. 432-438 ◽  
Author(s):  
P. G. Krishna
Keyword(s):  
Nitrogen Fixation ◽  
Organic Acids ◽  
Soil Microorganisms ◽  
Limited Extent ◽  
Nitrogen Fixing ◽  
Optimum Range ◽  
Nitrogen Fixers ◽  
The Media

From the results presented it may be permissible to point out the following:Fungi are responsible for the fixation of very small quantities of nitrogen, while the Azotobacter and B. amylobacter groups are the important nitrogen fixers in the soil.B. amylobacter is able to fix from 4 to 5 mg. of nitrogen per gm. of dextrose consumed.B. amylobacter has an optimum range of pH. between 6·0 and 7·0, and Azotobacter between 7·0 and 8·4.Azotobacter utilises the organic acids produced during the fermentation of dextrose as sources of energy for nitrogen fixation in the absence of dextrose. B. amylobacler does not, or does only to a limited extent, utilise such products.Large quantities of dextrose do not favour an efficient nitrogen fixation, as large quantities of the organic acids produced effect the reaction of the media rendering the organisms inactive.The nitrogen fixing organisms seem to be equally well represented in the heavy and light soils.

Some aspects of the biology of nitrogen-fixing organisms

1987 ◽  
Vol 317 (1184) ◽  
pp. 111-129 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Root Hairs ◽  
Atp Synthesis ◽  
Host Cells ◽  
Diffusion Resistance ◽  
Nitrogen Fixing ◽  
Active Nitrogen ◽  
Rapid Responses ◽  
Infection Threads ◽  
Eukaryotic Organisms

Eukaryotic organisms do not fix nitrogen. Animals generally have no need to do so because of their complex food-acquisition and waste-disposal systems. Plants, by using carbon polymers for structural purposes, minimize their need for nitrogen. When very nitrogen-limited, to enter into symbiosis with nitrogen-fixing microorganisms may be the most controllable method for eukaryotes to obtain fixed nitrogen. Filamentous, heterocystous nitrogen-fixing cyanobacteria may be better adapted to a free-living than to a symbiotic existence, because of their complexity. In symbioses, their photosynthetic machinery becomes redundant and the need to differentiate heterocysts as well as derepress nif genes may be a disadvantage. This could in part account for the greater success of symbioses involving the structurally simpler genera Frankia , Rhizobium and Bradyrhizobium . Nitrogen fixation by legume nodules can be controlled by varying the oxygen supply. This control may be effected by a variable diffusion resistance, enabling oxygen required for ATP synthesis to be matched to available photosynthate. Such a resistance, which is probably located in the nodule cortex, may also be used to reduce nitrogen fixation in the presence of combined nitrogen and could also facilitate rapid responses to other forms of stress. Alternative resistances to gaseous diffusion may operate when water supplies are restricted. Rhizobium and Bradyrhizobium follow different patterns of differentiation into nitrogen-fixing bacteroids. These patterns are coupled with retention or loss of viability and with significant or no natural enrichment of the bacteroids with 15 N respectively. The basic patterns of each type are subject to host-modification. Recent studies on structures of primitive legume nodules show some parallels both with actinorhizas and with nodules on Parasponia induced by Bradyrhizobium . In particular, distribution of rhizobia in nodule tissues is intercellular and infection threads are formed only when bacteria ‘enter’ host cells; there is no intracellular ‘bacteroid’ stage. These threads are retained in the active nitrogen-fixing cells. Many legumes and some actinorhizas are not infected via root hairs. Therefore two of the stages often considered typical of the development of effective legume nodules, i.e. ‘release’ of bacteria into vesicles bounded by peribacteroid membrane and infection through root hairs, can be omitted; these omissions may be of use in attempts to transfer nodulating ability to new genera.

Herbivory by an invasive snail increases nitrogen fixation in a nitrogen-limited stream

2009 ◽  
Vol 66 (8) ◽  
pp. 1309-1317 ◽  
Author(s):  
Clay Porter Arango ◽  
Leslie Anne Riley ◽  
Jennifer Leah Tank ◽  
Robert Ogden Hall,
Keyword(s):  
Nitrogen Fixation ◽  
New Zealand ◽  
Nitrogen Cycling ◽  
Algal Biomass ◽  
Nitrogen Fixing ◽  
Nitrogen Flux ◽  
Future Studies ◽  
Nitrogen Fixers ◽  
Heavy Grazing ◽  
Anthropogenic Nitrogen

Despite anthropogenic nitrogen contributions, nitrogen fixation contributes half of biosphere inputs but has rarely been quantified in streams. Herbivory controls algal biomass and productivity in streams, and we hypothesized that herbivory could also control nitrogen fixation. We released periphyton from herbivory in nitrogen-limited Polecat Creek, Wyoming, where heavy grazing by the invasive New Zealand mudsnail ( Potamopyrgus antipodarum ) dominates nitrogen cycling. One and two weeks after releasing periphyton, we found higher rates of nitrogen fixation on heavily grazed rocks (two-way analysis of variance (ANOVA), p = 0.012). Time elapsed after snail manipulation had no effect (two-way ANOVA, p = 0.24). Grazing changed periphyton composition by reducing the proportion of green algae and increasing the proportion of nitrogen-fixing diatoms (multivariate ANOVA, p = 0.001). Nitrogen fixation rates increased disproportionately to nitrogen-fixing algal cells, indicating that snails increased nitrogenase efficiency, probably by improving light and (or) nutrient availability to nitrogen fixers. We incorporated our nitrogen fixation rates into a published nitrogen budget for Polecat Creek and found that nitrogen flux into the periphyton was 50% higher when we included nitrogen fixation. Herbivory can increase nitrogen fixation in streams, and future studies should measure nitrogen fixation for a more thorough understanding of stream nitrogen cycling.

scholarly journals INCREASING SOIL FERTILITY AS A RESULT OF THE ACCUMULATION OF NITROGEN BY LEGUMINOUS CROPS

2020 ◽  
pp. 48-60
Author(s):  
Ihor Didur ◽  
Victoriia Shevchuk
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Soil Fertility ◽  
Growth Regulator ◽  
Plant Growth Regulator ◽  
Humus Content ◽  
Organic Fertilizers ◽  
Natural Fertility ◽  
Nitrogen Fixing ◽  
Active Nitrogen

Analysis of literary sources shows that legume-rhizobial systems annually fix nitrogen from the atmosphere in the amount of from 40 to 300 kg of per 1 ha of crop. Crops of legumes by Nitrogen fixation capabilities play an important role in saving and improvement of the natural soil fertility. It is known that in the process of the crop rotation with legumes the species composition of soil microorganisms is restored, as a result stable soil fertility rate is supported. Legumes plants are valuable siderata. Green legume fertilizer has a positive effect on increasing the productivity of plants, causes to the conservancy and increase of soil fertility. The plowing of the siderates leads to an increase in the humus content in the soil and the availability of phosphate treatment, a reduction in nitrogen gas losses from the soil. After decomposition and mineralization of leguminous siderata, the soil is replenished with nutritious macro- and microelements. Siderata is able to loosen heavy soils, improve their structure, and inhibit the growth of weeds that create water deficiency and reduce the content of minerals in the soil. Growing of peas leads to increased of the absorption efficiency of organic fertilizers by the following crops. The article approves the results of increasing the nitrogen-fixing ability of sowing pea with applying of the microbial preparation Bioinoculant and plant growth regulator Mars EL, and their role in increasing of biological nitrogen content for repair of soil fertility. It was established that the symbiotic activity of pea plants depends on the growth phase of the crop. The highest indexes of active nitrogen-fixing nodules on the roots of pea plants were found in the budding phase after pre-sowing seed complex treatment with Bioinoculant and growth regulator Mars EL. It was researched that he combined use of Bioinoculant and plant growth regulator Mars EL provided the increase of the mass of active nodules at the roots of the plant by 33% (phase of formation of 5-6 leaves), 38,8% (budding phase) and 22,8% (flowering phase) compared to the control. It was found that the use of inoculant and plant growth regulator with N30P30K30 fertilizer background leads to the greatest concentration of nodules on the main roots of the plants. The nodules had a pink color. In the technological process, the pre-sowing treatment of pea seeds with Bioinoculant and plant growth regulator Mars EL is an important perspective for improving the symbiotic activity of culture. This induces the reproduction of the soil's natural fertility. It is advisable to investigate the effect of inoculation and growth regulators with the different mechanism of action on the symbiotic activity of winter peas. Key words: soil fertility, legumes, siderata, symbiotic nitrogen fixation, inoculant, plant growth regulator

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