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

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.

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

Peanut Science ◽

10.3146/i0095-3679-21-1-13 ◽

1994 ◽

Vol 21 (1) ◽

pp. 55-60 ◽

Cited By ~ 5

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.

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Direct Raman Spectroscopic Measurements of Biological Nitrogen Fixation under Natural Conditions: An Analytical Approach for Studying Nitrogenase Activity

Analytical Chemistry ◽

10.1021/acs.analchem.6b03101 ◽

2016 ◽

Vol 89 (2) ◽

pp. 1117-1122 ◽

Cited By ~ 27

Author(s):

Tobias Jochum ◽

Agnes Fastnacht ◽

Susan E. Trumbore ◽

Jürgen Popp ◽

Torsten Frosch

Keyword(s):

Nitrogen Fixation ◽

Biological Nitrogen Fixation ◽

Analytical Approach ◽

Nitrogenase Activity ◽

Natural Conditions ◽

Spectroscopic Measurements ◽

Raman Spectroscopic ◽

Biological Nitrogen

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Early response of biological nitrogen fixation in a mature oak dominated forest to elevated atmospheric CO2 fumigation at BIFoR-FACE

10.5194/egusphere-egu2020-8678 ◽

2020 ◽

Author(s):

Sami Ullah ◽

Ernesto Saiz Val ◽

Fotis Sgouridis ◽

Falko Drijfhout

Keyword(s):

Carbon Dioxide ◽

Nitrogen Fixation ◽

Biological Nitrogen Fixation ◽

Early Years ◽

Available Nitrogen ◽

Preliminary Results ◽

Hypnum Cupressiforme ◽

Feather Moss ◽

Feather Mosses ◽

Biological Nitrogen

Elevated atmospheric carbon dioxide concentrations are stimulating photosynthesis and carbon sequestration. However, the extent of photosynthetic stimulation in forests under future climates is highly uncertain given that nutrient limitation in soils may constrain the CO2 fertilization effect. The Birmingham Institute of Forest Research (BIFoR), University of Birmingham established the only global mature temperate deciduous forests Free Air Carbon Dioxide Enrichment (FACE) experiment to study the response of forests to future climates. Fumigation of the forest with ~550 ppm CO2 started in 2017 and will continue until at least 2026. Soil nutrients cycling including nitrogen transformation in response to elevated atmospheric CO2 (eCO2) fumigation is currently investigated to determine the role of nutrient availability in carbon capture by forests. In this paper, we show preliminary results of the response of asymbiotic biological nitrogen fixation (BNF) in soils and epiphytic bryophytes at BIFoR-FACE following a year of eCO2 fumigation. It is hypothesized that the demand for available nitrogen by trees will increase under eCO2 and that competition of roots and soil microbes for available nitrogen will enhance asymbiotic BNF to at least meet microbial metabolic nitrogen demands in the long run. Surface soils (0-5 cm) and epiphytic feather moss (Hypnum cupressiforme) growing on oak tree stems in the FACE site were &#160;collected during the second year of eCO2 fumigation for the quantification of BNF activity using the 15N2 assimilation methods (Saiz et al. 2019). Samples were incubated in 50 mL serum bottles under in situ conditions, followed by the analysis of soil and tissue samples for 15N signature on an Isotope Ratio Mass Spectrometer for the quantification of BNF activity.The BNF activity under eCO2 were 369% higher than in soils under ambient atmospheric CO2. BNF rates associated with feather mosses (Hypnum cupressiforme) did not differ between the eCO2 and control plots; however, rates under eCO2 on average were 60% lower than in the control plots. Unlike soils, the moisture of feather mosses correlated significantly (R2 = 51%) with BNF activity. Among nutrients in soil with implications for BNF activity, the concentrations of Mg, K, Co and Ni were significantly lower in soils under eCO2 than in the control plots, while in feather moss tissues no differences were observed. &#160;Our preliminary results show that eCO2 fumigation primed asymbiotic BNF activity in soils. An enhancement of BNF together with the observation of a relatively low nutrient content under eCO2 points to important changes in nitrogen cycling processes in the early years of CO2 fumigation. Further detailed studies are underway to fully disentangle controls on nitrogen availability to trees under future climates.&#160;ReferenceSaiz, E, Sgouridis, F, Drifjhout, F & Ullah, S. 2019. Biological nitrogen fixation in peatlands: comparison between acetylene reduction assay and 15N2 assimilation methods. Soil Biol. Biochem:131:157-165

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

Journal of Bacteriology ◽

10.1128/jb.00750-15 ◽

2015 ◽

Vol 198 (4) ◽

pp. 633-643 ◽

Cited By ~ 8

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.

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Elucidating the Potential of Native Rhizobial Isolates to Improve Biological Nitrogen Fixation and Growth of Common Bean and Soybean in Smallholder Farming Systems of Kenya

International Journal of Agronomy ◽

10.1155/2016/4569241 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 13

Author(s):

Ernest Wandera Ouma ◽

Anne Mercy Asango ◽

John Maingi ◽

Ezekiel Mugendi Njeru

Keyword(s):

Nitrogen Fixation ◽

Common Bean ◽

Farming Systems ◽

Dry Weight ◽

Field Studies ◽

Smallholder Farming ◽

Shoot Dry Weight ◽

Smallholder Farming Systems ◽

Commercial Inoculant ◽

Biological Nitrogen

Identification of effective indigenous rhizobia isolates would lead to development of efficient and affordable rhizobia inoculants. These can promote nitrogen fixation in smallholder farming systems of Kenya. To realize this purpose, two experiments were conducted under greenhouse conditions using two common bean cultivars; Mwezi moja (bush type) and Mwitemania (climbing type) along with soybean cultivar SB 8. In the first experiment, the common bean cultivars were treated with rhizobia inoculants including a consortium of native isolates, commercial isolate (CIAT 899), a mixture of native isolates and CIAT 899, and a control with no inoculation. After 30 days, the crop was assessed for nodulation, shoot and root dry weights, and morphological features. In the second experiment, soybean was inoculated with a consortium of native isolates, commercial inoculant (USDA 110), and a mixture of commercial and native isolates. Remarkably, the native isolates significantly (p<0.001) increased nodulation and shoot dry weight across the two common bean varieties compared to the commercial inoculant, CIAT 899. Mixing of the native rhizobia species and commercial inoculant did not show any further increase in nodulation and shoot performance in both crops. Further field studies will ascertain the effectiveness and efficiency of the tested indigenous isolates.

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Nitrogen fixation (C2H2reduction) in the rice rhizosphere soil as influenced by pesticides and methods of their application

The Journal of Agricultural Science ◽

10.1017/s0021859600035401 ◽

1983 ◽

Vol 100 (3) ◽

pp. 637-642 ◽

Cited By ~ 18

Author(s):

J. L. N. Rao ◽

I. C. Pasalu ◽

V. Rajaramamohan Rao

Keyword(s):

Nitrogen Fixation ◽

Rhizosphere Soil ◽

Nitrogenase Activity ◽

Differential Response ◽

Field Application ◽

Rice Fields ◽

Variable Effect ◽

Seedling Root ◽

Rice Rhizosphere ◽

Micro Organisms

SUMMARYThe effect of pesticides on nitrogenase activity in rhizosphere soil from rice fields was investigated. The differential response of insecticides on nitrogenase depended on the method of field application. Results also showed that the differential response to the pesticides of. specific groups of nitrogen-fixing micro-organisms depended upon the method of application.Soil incorporation of carbofuran stimulated the rhizosphere nitrogenase, while endosulfan and hexachlorocyclohexane inhibited it. Carbofuran and hexachlorocyclohexane stimulated nitrogenase when applied to the standing water. Seedling root dips of isofenphos stimulated nitrogenase, while endosulfan, BPMC and carbaryl showed a variable effect. Quinalphos inhibited nitrogenase irrespective of method of application.

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Nitrogen Fixation (Acetylene Reduction) Associated with Sea Urchins (Strongylocentrotus droebachiensis) Feeding on Seaweeds and Eelgrass

Journal of the Fisheries Research Board of Canada ◽

10.1139/f77-067 ◽

1977 ◽

Vol 34 (3) ◽

pp. 416-420 ◽

Cited By ~ 24

Author(s):

M. L. Guerinot ◽

W. Fong ◽

D. G. Patriquin

Keyword(s):

Nitrogen Fixation ◽

Acetylene Reduction ◽

Sea Urchins ◽

Nitrogenase Activity ◽

Average Rate ◽

Strongylocentrotus Droebachiensis ◽

Molar Ratio ◽

Laminaria Digitata ◽

Bare Rock ◽

Nitrogenase Activities

Sea urchins feeding in different macrophyte zones in St. Margaret's Bay, Nova Scotia, in November and December 1975 were examined for nitrogenase activity using the acetylene reduction technique. For sea urchins feeding on Laminaria digitata and L. longicruris, the average rate of acetylene reduction was equivalent to N2 fixation of 55 μg N2 per sea urchin per day assuming a 3:1 molar ratio of C2H2 reduction to N2 fixation. Lower nitrogenase activities were observed for sea urchins feeding on Agarum cribrosum and Zostera marina, and no nitrogenase activity was observed for sea urchins taken from bare rock substrate on which kelp had been absent for 4 yr. Samples of separated digestive tracts but not the degutted bodies of sea urchins exhibited nitrogenase activity, suggesting that the digestive tract is the site of nitrogen fixation in whole sea urchins.

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

PeerJ ◽

10.7717/peerj.9062 ◽

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.

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

Agriciltural microbiology ◽

10.35868/1997-3004.24.3-8 ◽

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.

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

10.5194/egusphere-egu2020-11857 ◽

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

Biological nitrogen fixation, the main input of fixed N into ecosystems, converts inert N2 gas into bioavailable ammonium in an energetically costly reaction catalyzed by the prokaryotic metalloenzyme nitrogenase. &#160;The high ATP and reductant requirements of N2 fixation explain why this process is highly regulated in diazotrophs, with the presence of ammonium inhibiting nitrogenase expression and activity. Yet, several reports of N2 fixation in ammonium- and nitrate-rich (10 to 300 &#181;M) benthic environments challenge our understanding of a key environmental sensitivity of N2 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 N2 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.To help reconcile the environmental results, we investigate the ammonium sensitivity of N2 fixation using the acetylene reduction assay and 15N2 tracer methods in i) the model sulfate-reducing diazotroph, Desulfovibrio vulgaris 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 &#181;M (slurry incubation) or 2 &#181;M (pure cultures, enrichments). Amendment of ammonium quickly inhibits nitrogen fixation and nitrogenase activity only resumes &#160;once ammonium is depleted to the threshold level. Ammonium additions to actively fixing samples show complete inhibition of N2 fixation within several hours post-addition.&#160;Our measurements of the ammonium sensitivity of benthic N2 fixation are consistent with the traditional understanding of nitrogen fixer metabolism and with early findings of Postgate et al. (1984) demonstrating that N2 fixation by the sulfate reducer Desulfovibrio gigas is inhibited by ammonium levels that exceed 10 &#181;M. These results help clarify a long-standing paradox in benthic nitrogen cycling. We suggest that prior observations of N2 fixation at elevated ammonium levels could reflect methodological artifacts due to very fast depletion of ammonium during activity assays, legacy N2 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.

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