Nitrogen fixation in the muskeg ecosystem of the James Bay Lowlands, Northern Ontario

1976 ◽  
Vol 22 (7) ◽  
pp. 897-907 ◽  
Author(s):  
Judith A. Blasco ◽  
D. C. Jordan
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
James Bay ◽  
Laboratory Assessment ◽  
Northern Ontario ◽  
Organic Layers ◽  
Bay Area ◽  
Subsurface Layers ◽  
Biological Nitrogen

The acetylene-reduction assay was used for in situ and laboratory assessment of biological nitrogen fixation in the acidic, waterlogged, muskeg ecosystem of the southern James Bay area, in the region of Moosonee, Ontario. In situ assays and subsequent laboratory experimentation revealed that nitrogenase activity was predominately a function of the activities of heterocystic blue-green bacteria associated with surface water, with the phyllosphere of mosses, and with at least one lichen, a species of Peltigera. No such in situ activity was detected in the subsurface organic material, even when such material was amended with glucose. However, under laboratory conditions at 20 °C, nitrogenase activity was evident in the subsurface layers after an extended lag and was shown to be higher under anaerobic than under aerobic conditions, to have an optimum temperature range extending about a mean of 20 °C, and to be stimulated by glucose. This potential for subsurface nitrogen fixation proved to be related to the presence of microorganisms existing in anaerobic microsites within the organic layers and no microorganisms capable of fixation could be detected under aerobic incubation.

scholarly journals Potential of Phototrophic Purple Nonsulfur Bacteria to Fix Nitrogen in Rice Fields

2021 ◽  
Vol 10 (1) ◽  
pp. 28
Author(s):  
Isamu Maeda
Keyword(s):  
Nitrogen Fixation ◽  
Regulatory Networks ◽  
Nitrogenase Activity ◽  
Field Studies ◽  
Rice Fields ◽  
Purple Nonsulfur Bacteria ◽  
Available Nitrogen ◽  
Nitrogenase Activities ◽  
Plant Available Nitrogen ◽  
Biological Nitrogen

Biological nitrogen fixation catalyzed by Mo-nitrogenase of symbiotic diazotrophs has attracted interest because its potential to supply plant-available nitrogen offers an alternative way of using chemical fertilizers for sustainable agriculture. Phototrophic purple nonsulfur bacteria (PNSB) diazotrophically grow under light anaerobic conditions and can be isolated from photic and microaerobic zones of rice fields. Therefore, PNSB as asymbiotic diazotrophs contribute to nitrogen fixation in rice fields. An attempt to measure nitrogen in the oxidized surface layer of paddy soil estimates that approximately 6–8 kg N/ha/year might be accumulated by phototrophic microorganisms. Species of PNSB possess one of or both alternative nitrogenases, V-nitrogenase and Fe-nitrogenase, which are found in asymbiotic diazotrophs, in addition to Mo-nitrogenase. The regulatory networks control nitrogenase activity in response to ammonium, molecular oxygen, and light irradiation. Laboratory and field studies have revealed effectiveness of PNSB inoculation to rice cultures on increases of nitrogen gain, plant growth, and/or grain yield. In this review, properties of the nitrogenase isozymes and regulation of nitrogenase activities in PNSB are described, and research challenges and potential of PNSB inoculation to rice cultures are discussed from a viewpoint of their applications as nitrogen biofertilizer.

Evaluation of Biological Nitrogen Fixation Capacity in Arachis Species and the Possible Role of Polyploidy1

1994 ◽  
Vol 21 (1) ◽  
pp. 55-60 ◽  
Author(s):  
H. T. Stalker ◽  
M. L. Nickum ◽  
J. C. Wynne ◽  
G. H. Elkan ◽  
T. J. Schneeweis
Keyword(s):  
Nitrogen Fixation ◽  
Arachis Hypogaea ◽  
Cover Crops ◽  
Biological Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Diploid Species ◽  
Dry Matter Accumulation ◽  
Arachis Species ◽  
Fixation Capacity ◽  
Biological Nitrogen

Abstract Arachis species have potential for enhancing cultivated peanut (Arachis hypogaea L.) germplasm as forages and cover crops. This study's objective was to evaluate a range of Arachis species for biological nitrogen fixation capacity. Several Arachis species are tetraploids, and it has been shown that tetraploidy may play an important role in nodule initiation. Species were first tested under natural field conditions and then in the greenhouse using three Bradyrhizobium strains that had been previously shown to be effective on peanut. Nodule number, nodule weight, nitrogenase activity determined by acetylene reduction, and shoot dry weight were measured as indicators of nitrogen fixation capacity. In the field, tetraploid species produced significantly more nodules than the diploids, but total dry matter accumulation was independent of the number of nodules or rate of fixation. In the greenhouse, no significant differences were observed among the bradyrhizobial strains. Arachis hypogaea and A. monticola showed significantly higher measures of nitrogen fixation capacity for all measured traits than the diploid species. However, autotetraploid plants of A. villosa did not have significantly more nodules than diploids of the same accession; the autotetraploids consistently had higher nitrogenase activity. Arachis pusilla never formed a symbiotic relationship with the bradyrhizobial strains used.

scholarly journals OPTIMIZATION OF NITROGEN MINERAL FERTILIZATION OF AGRICULTURAL CULTURES BY THE PARAMETERS OF THE INTENSITY OF THE NITROGEN FIXATION AND DENITRIFICATION PROCESSES

2019 ◽  
Vol 30 ◽  
pp. 3-12
Author(s):  
V. V. Volkohon ◽  
S. B. Dimova ◽  
К. І. Volkohon ◽  
V. P. Gorban ◽  
N. P. Shtanko ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
N2o Emission ◽  
Mineral Nitrogen ◽  
Mineral Fertilizers ◽  
Nitrogen Compounds ◽  
Mineral Fertilization ◽  
Nitrogen Fixation Activity ◽  
Nitrogen Fertilizer Rate ◽  
Biological Nitrogen

Objective. Investigate the performance of the nitrogen fixation and process of N-N2O loss un-der the cultivation of potatoes and peas on the leached chornozem under various mineral agrarian backgrounds and the use of microbial preparations and to determine the ecological compromise normal rate of mineral nitrogen, under which the emission losses of nitrogen compounds will not exceed the intake of “biological” nitrogen in agrocenoses. Methods. Field experiment, gas chroma-tographic. Results. Studies of the activity of nitrogen fixation and N2O emission in situ in potato and pea agrocenoses using different rates of mineral fertilizers and microbial preparations, with subsequent calculations of the parameters of intake of the “biological” nitrogen and emission loss-es of the element indicate the possibility of determining the conditions (doses of mineral nitrogen) for which equality between profit and non-productive expenditure of the nitrogen balance is achieved. This amount of mineral nitrogen can be considered environmentally permissible, its ex-cess is undesirable due to a decrease in the intake of “biological” nitrogen and increased activity of the denitrification process. For potatoes grown on leached chornozem, environmentally permis-sible nitrogen fertilizer rate should be considered as 80 kg/ha, for peas — 60 kg/ha. The use of mi-crobial preparations in the cultivation of crops promotes an increase in the range of environmen-tally permissible normal rates of mineral nitrogen due to the formation of conditions under which the bacterization of plants require more nitrogen compounds to ensure a constructive metabolism, which additionally to increased nitrogen fixation activity is accompanied by an increase in the level of consumption of mineral nitrogen in the soil. At the same time, the activity of biological denitrifi-cation becomes reduced. Based on the obtained parameters, a model of optimization of nitrogen mineral fertilization of agricultural cultures was developed. Conclusion. It is advisable to deter-mine the ecologically permissible normal rates of mineral nitrogen fertilization of crops by the per-formance indices of the nitrogen fixation process and N-N2O losses. In this case, the emission losses of nitrogen compounds should not exceed the levels of intake of biologically bound nitrogen in ag-rocenoses.

scholarly journals Proteome Profiling of the Rhodobacter capsulatus Molybdenum Response Reveals a Role of IscN in Nitrogen Fixation by Fe-Nitrogenase

2015 ◽  
Vol 198 (4) ◽  
pp. 633-643 ◽  
Author(s):  
Marie-Christine Hoffmann ◽  
Eva Wagner ◽  
Sina Langklotz ◽  
Yvonne Pfänder ◽  
Sina Hött ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Rhodobacter Capsulatus ◽  
Nitrogenase Activity ◽  
Central Process ◽  
Content Type ◽  
Proteome Profiling ◽  
Biological Nitrogen ◽  
Diazotrophic Growth

ABSTRACTRhodobacter capsulatusis capable of synthesizing two nitrogenases, a molybdenum-dependent nitrogenase and an alternative Mo-free iron-only nitrogenase, enabling this diazotroph to grow with molecular dinitrogen (N2) as the sole nitrogen source. Here, the Mo responses of the wild type and of a mutant lacking ModABC, the high-affinity molybdate transporter, were examined by proteome profiling, Western analysis, epitope tagging, andlacZreporter fusions. Many Mo-controlled proteins identified in this study have documented or presumed roles in nitrogen fixation, demonstrating the relevance of Mo control in this highly ATP-demanding process. The levels of Mo-nitrogenase, NifHDK, and the Mo storage protein, Mop, increased with increasing Mo concentrations. In contrast, Fe-nitrogenase, AnfHDGK, and ModABC, the Mo transporter, were expressed only under Mo-limiting conditions. IscN was identified as a novel Mo-repressed protein. Mo control of Mop, AnfHDGK, and ModABC corresponded to transcriptional regulation of their genes by the Mo-responsive regulators MopA and MopB. Mo control of NifHDK and IscN appeared to be more complex, involving different posttranscriptional mechanisms. In line with the simultaneous control of IscN and Fe-nitrogenase by Mo, IscN was found to be important for Fe-nitrogenase-dependent diazotrophic growth. The possible role of IscN as an A-type carrier providing Fe-nitrogenase with Fe-S clusters is discussed.IMPORTANCEBiological nitrogen fixation is a central process in the global nitrogen cycle by which the abundant but chemically inert dinitrogen (N2) is reduced to ammonia (NH3), a bioavailable form of nitrogen. Nitrogen reduction is catalyzed by nitrogenases found in diazotrophic bacteria and archaea but not in eukaryotes. All diazotrophs synthesize molybdenum-dependent nitrogenases. In addition, some diazotrophs, includingRhodobacter capsulatus, possess catalytically less efficient alternative Mo-free nitrogenases, whose expression is repressed by Mo. Despite the importance of Mo in biological nitrogen fixation, this is the first study analyzing the proteome-wide Mo response in a diazotroph. IscN was recognized as a novel member of the molybdoproteome inR. capsulatus. It was dispensable for Mo-nitrogenase activity but supported diazotrophic growth under Mo-limiting conditions.

scholarly journals Phosphate solubilizing bacteria stimulate wheat rhizosphere and endosphere biological nitrogen fixation by improving phosphorus content

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9062
Author(s):  
Yongbin Li ◽  
Qin Li ◽  
Guohua Guan ◽  
Sanfeng Chen
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Available P ◽  
Plant Tissues ◽  
Diazotrophic Bacteria ◽  
Total N ◽  
P Content ◽  
Soil Available P ◽  
Biological Nitrogen ◽  
Total P

Phosphate (P) availability often limits biological nitrogen fixation (BNF) by diazotrophic bacteria. In soil, only 0.1% of the total P is available for plant uptake. P solubilizing bacteria can convert insoluble P to plant-available soluble P (ionic P and low molecular-weight organic P). However, limited information is available about the effects of synergistic application of diazotrophic bacteria and P solubilizing bacteria on the nitrogenase activity of rhizosphere and nifH expression of endosphere. In this study, we investigated the effects of co-inoculation with a diazotrophic bacterium (Paenibacillus beijingensis BJ-18) and a P-solubilizing bacterium (Paenibacillus sp. B1) on wheat growth, plant and soil total N, plant total P, soil available P, soil nitrogenase activity and the relative expression of nifH in plant tissues. Co-inoculation significantly increased plant biomass (length, fresh and dry weight) and plant N content (root: 27%, shoot: 30%) and P content (root: 63%, shoot: 30%). Co-inoculation also significantly increased soil total N (12%), available P (9%) and nitrogenase activity (69%) compared to P. beijingensis BJ-18 inoculation alone. Quantitative real-time PCR analysis showed co-inoculation doubled expression of nifH genes in shoots and roots. Soil nitrogenase activity and nifH expression within plant tissues correlated with P content of soil and plant tissues, which suggests solubilization of P by Paenibacillus sp. B1 increased N fixation in soils and the endosphere. In conclusion, P solubilizing bacteria generally improved soil available P and plant P uptake, and considerably stimulated BNF in the rhizosphere and endosphere of wheat seedlings.

scholarly journals BIOLOGICAL NITROGEN TRANSFORMATION IN AGROCENOSES OF POTATO AND PRODUCTIVITY OF CULTURE IN ORGANIC AGRICULTURE

2016 ◽  
Vol 24 ◽  
pp. 3-8
Author(s):  
V. V. Volkohon ◽  
S. B. Dimova ◽  
K. I. Volkohon ◽  
V. P. Horban ◽  
M. A. Zhurba ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Green Manure ◽  
Nitrogenase Activity ◽  
Significant Loss ◽  
Organic Fertilizers ◽  
Gaseous Nitrogen ◽  
Potato Plants ◽  
Biological Nitrogen ◽  
Productivity Gains

The effect of organic fertilizers (cattle manure and lupine green manure), as well asmicrobial preparation Biohran on the dynamics of the activity process of nitrogen fixation andN2O emissions in the rhizosphere soil of potato plants, crop yield, and product quality have beeninvestigated. The use of manures stimulates activity of nitrogen fixation, but at the same time,accompanied by a significant loss of gaseous nitrogen compounds. The efficiency of Biohran bythis agrobackground is largely levelled. Lupine green manure stimulates nitrogenase activity,especially in combination with biopreparation. At the same time, there is a tendency to reducenitrous oxide emission. Organic fertilizers contributed to a reliable raise of potato yield. Biohranprovide productivity gains only on the background of green manure. Microbial preparationcontributed to the improvement of quality of production parameters by all studiedagrobackgrounds.

The fixed nitrogen sensitivity of biological nitrogen fixation in salt marshes sediments from the northeastern United States

2020 ◽  
Author(s):  
Romain Darnajoux ◽  
Rei Zhang ◽  
Katja Luxem ◽  
Xinning Zhang
Keyword(s):  
Nitrogen Fixation ◽  
Salt Marshes ◽  
Biological Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Inorganic Nitrogen ◽  
Ammonium Concentration ◽  
Desulfovibrio Vulgaris ◽  
Fixed Nitrogen ◽  
Sulfate Reducing ◽  
Biological Nitrogen

<p>Biological nitrogen fixation, the main input of fixed N into ecosystems, converts inert N<sub>2</sub> gas into bioavailable ammonium in an energetically costly reaction catalyzed by the prokaryotic metalloenzyme nitrogenase.  The high ATP and reductant requirements of N<sub>2</sub> fixation explain why this process is highly regulated in diazotrophs, with the presence of ammonium inhibiting nitrogenase expression and activity. Yet, several reports of N<sub>2</sub> fixation in ammonium- and nitrate-rich (10 to 300 µM) benthic environments challenge our understanding of a key environmental sensitivity of N<sub>2</sub> fixation. Field studies point to heterotrophic sulfate reducers as the likely diazotrophs in these benthic settings, but the fixed N sensitivity of sulfate-reducing diazotrophs is not well understood due to a dearth of culture studies. Additionally, assays of N<sub>2</sub> fixation in incubations rarely involve parallel measurements of dissolved inorganic nitrogen, possibly leading to experimental bias in favor of detecting activity under ammonium-replete initial conditions.</p><p>To help reconcile the environmental results, we investigate the ammonium sensitivity of N<sub>2</sub> fixation using the acetylene reduction assay and <sup>15</sup>N<sub>2</sub> tracer methods in i) the model sulfate-reducing diazotroph, <em>Desulfovibrio vulgaris</em> str. Hildenborough (DvH), ii) four enrichment cultures from salt marsh sediments of New Jersey, and iii) slurry incubations of sediments collected from three northeastern salt marshes. In all instances, we found that ammonium strongly inhibits biological nitrogen fixation, with nitrogenase activity only detectable when ammonium concentration is below a threshold of 10 µM (slurry incubation) or 2 µM (pure cultures, enrichments). Amendment of ammonium quickly inhibits nitrogen fixation and nitrogenase activity only resumes  once ammonium is depleted to the threshold level. Ammonium additions to actively fixing samples show complete inhibition of N<sub>2</sub> fixation within several hours post-addition. </p><p>Our measurements of the ammonium sensitivity of benthic N<sub>2</sub> fixation are consistent with the traditional understanding of nitrogen fixer metabolism and with early findings of Postgate et al. (1984) demonstrating that N<sub>2</sub> fixation by the sulfate reducer <em>Desulfovibrio gigas</em> is inhibited by ammonium levels that exceed 10 µM. These results help clarify a long-standing paradox in benthic nitrogen cycling. We suggest that prior observations of N<sub>2</sub> fixation at elevated ammonium levels could reflect methodological artifacts due to very fast depletion of ammonium during activity assays, legacy N<sub>2</sub> fixation activity associated with incomplete inhibition by ammonium, or spatial heterogeneity. Further work to standardize fixed N sensitivity assays could help with cross-study comparisons and with clarifying inconsistencies in our understanding of how environmental fixed nitrogen levels control nitrogen fixation.</p>

scholarly journals Engineering Nitrogen Fixation Activity in an Oxygenic Phototroph

2018 ◽  
Author(s):  
Deng Liu ◽  
Michelle Liberton ◽  
Jingjie Yu ◽  
Himadri B. Pakrasi ◽  
Maitrayee Bhattacharyya-Pakrasi
Keyword(s):  
Nitrogen Fixation ◽  
Energy Demand ◽  
Nitrogenase Activity ◽  
Crop Plants ◽  
Nitrogen Fertilizers ◽  
Nitrogen Fixation Activity ◽  
Fixation Activity ◽  
Photosynthetic Organism ◽  
Biological Nitrogen ◽  
Oxygenic Phototroph

ABSTRACTBiological nitrogen fixation is catalyzed by nitrogenase, a complex metalloenzyme found only in prokaryotes. N2fixation is energetically highly expensive, and an energy generating process such as photosynthesis can meet the energy demand of N2fixation. However, synthesis and expression of nitrogenase is exquisitely sensitive to oxygen. Thus, engineering nitrogen fixation activity in photosynthetic organisms that produce oxygen is challenging. Cyanobacteria are oxygenic photosynthetic prokaryotes, and some of them also fix N2. Here, we demonstrate a feasible way to engineer nitrogenase activity in the non-diazotrophic cyanobacteriumSynechocystissp. PCC 6803 through the transfer of 35 nitrogen fixation (nif) genes from the diazotrophic cyanobacteriumCyanothecesp. ATCC 51142. In addition, we have identified the minimalnifcluster required for such activity inSynechocystis6803. Moreover, nitrogenase activity was significantly improved by increasing the expression levels ofnifgenes. Importantly, the O2tolerance of nitrogenase was enhanced by introduction of uptake hydrogenase genes, showing this to be a functional way to improve nitrogenase enzyme activity under micro-oxic conditions. To date, our efforts have resulted in engineeredSynechocystis6803 strains that remarkably have more than 30% N2-fixation activity compared to that inCyanothece51142, the highest such activity established in any non-diazotrophic oxygenic photosynthetic organism. This study establishes a baseline towards the ultimate goal of engineering nitrogen fixation ability in crop plants.IMPORTANCEApplication of chemically synthesized nitrogen fertilizers has revolutionized agriculture. However, the energetic costs of such production processes as well as the wide spread application of fertilizers have raised serious environmental issues. A sustainable alternative is to endow crop plants the ability to fix atmospheric N2in situ. One long-term approach is to transfer allnifgenes from a prokaryote to plant cells, and express nitrogenase in an energy-producing organelle, chloroplast or mitochondrion. In this context,Synechocystis6803, the non-diazotrophic cyanobacterium utilized in this study, provides a model chassis for rapid investigation of the necessary requirements to establish diazotrophy in an oxygenic phototroph.

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