scholarly journals Microbially facilitated nitrogen cycling in tropical corals

2021 ◽  
Author(s):  
Thomas D. Glaze ◽  
Dirk V. Erler ◽  
Henri. M. P. Siljanen
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Cycling ◽  
Scleractinian Corals ◽  
N Cycling ◽  
N Transformations ◽  
Nitrification Activity ◽  
Nitrogen Fixation Activity ◽  
N Removal ◽  
Denitrification Activity ◽  
Microbial Symbionts

AbstractTropical scleractinian corals support a diverse assemblage of microbial symbionts. This ‘microbiome’ possesses the requisite functional diversity to conduct a range of nitrogen (N) transformations including denitrification, nitrification, nitrogen fixation and dissimilatory nitrate reduction to ammonium (DNRA). Very little direct evidence has been presented to date verifying that these processes are active within tropical corals. Here we use a combination of stable isotope techniques, nutrient uptake calculations and captured metagenomics to quantify rates of nitrogen cycling processes in a selection of tropical scleractinian corals. Denitrification activity was detected in all species, albeit with very low rates, signifying limited importance in holobiont N removal. Relatively greater nitrogen fixation activity confirms that corals are net N importers to reef systems. Low net nitrification activity suggests limited N regeneration capacity; however substantial gross nitrification activity may be concealed through nitrate consumption. Based on nrfA gene abundance and measured inorganic N fluxes, we calculated significant DNRA activity in the studied corals, which has important implications for coral reef N cycling and warrants more targeted investigation. Through the quantification and characterisation of all relevant N-cycling processes, this study provides clarity on the subject of tropical coral-associated biogeochemical N-cycling.

scholarly journals An Overview of Key Soil Nitrogen Cycling Transformations

EDIS ◽  
2020 ◽  
Vol 2020 (3) ◽  
Author(s):  
Clayton J Nevins ◽  
Sarah L Strauss ◽  
Patrick Inglett
Keyword(s):  
Side Effects ◽  
Plant Growth ◽  
Nitrogen Cycling ◽  
Soil Nitrogen ◽  
Crop Production ◽  
N Cycling ◽  
N Transformations ◽  
N Cycle ◽  
Soil Nitrogen Cycling ◽  
Soil And Water

Although nitrogen (N) is one of the most abundant elements in the biosphere, it is generally at levels that are limiting for optimum plant growth and crop production in Florida soils. To maintain adequate N levels in Florida soils without having detrimental environmental side effects, one must understand and manage N cycling transformations and processes. This new 5-page article, published by the UF/IFAS Department of Soil and Water Sciences, provides an overview of the N cycle by describing key N transformations that result in soils gaining or losing N. The biotic and abiotic processes that govern these transformations are described, as well as practical examples of these transformations in Florida soils. Written by Clayton J. Nevins, Sarah L. Strauss, and Patrick Inglett.https://edis.ifas.ufl.edu/ss684

scholarly journals Nitrogen removal processes in lakes of different trophic states from on-site measurements and historic data

2021 ◽  
Vol 83 (2) ◽  
Author(s):  
Beat Müller ◽  
Raoul Thoma ◽  
Kathrin B. L. Baumann ◽  
Cameron M. Callbeck ◽  
Carsten J. Schubert
Keyword(s):  
Eutrophic Lake ◽  
Oligotrophic Lake ◽  
Removal Rates ◽  
N Removal ◽  
Central Switzerland ◽  
Denitrification Activity ◽  
Historic Data ◽  
Anthropogenic Nitrogen ◽  
Removal Processes ◽  
Sediment Interface

AbstractFreshwater lakes are essential hotspots for the removal of excessive anthropogenic nitrogen (N) loads transported from the land to coastal oceans. The biogeochemical processes responsible for N removal, the corresponding transformation rates and overall removal efficiencies differ between lakes, however, it is unclear what the main controlling factors are. Here, we investigated the factors that moderate the rates of N removal under contrasting trophic states in two lakes located in central Switzerland. In the eutrophic Lake Baldegg and the oligotrophic Lake Sarnen, we specifically examined seasonal sediment porewater chemistry, organic matter sedimentation rates, as well as 33-year of historic water column data. We find that the eutrophic Lake Baldegg, which contributed to the removal of 20 ± 6.6 gN m−2 year−1, effectively removed two-thirds of the total areal N load. In stark contrast, the more oligotrophic Lake Sarnen contributed to 3.2 ± 4.2 gN m−2 year−1, and had removed only one-third of the areal N load. The historic dataset of the eutrophic lake revealed a close linkage between annual loads of dissolved N (DN) and removal rates (NRR = 0.63 × DN load) and a significant correlation of the concentration of bottom water nitrate and removal rates. We further show that the seasonal increase in N removal rates of the eutrophic lake correlated significantly with seasonal oxygen fluxes measured across the water–sediment interface (R2 = 0.75). We suggest that increasing oxygen enhances sediment mineralization and stimulates nitrification, indirectly enhancing denitrification activity.

scholarly journals Transcriptomics differentiate two novel bioactive strains of Paenibacillus sp. isolated from the perennial ryegrass seed microbiome

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tongda Li ◽  
Ross Mann ◽  
Jatinder Kaur ◽  
German Spangenberg ◽  
Timothy Sawbridge
Keyword(s):  
Nitrogen Fixation ◽  
Secondary Metabolite ◽  
Perennial Ryegrass ◽  
Fusarium Verticillioides ◽  
In Vitro Assays ◽  
Colletotrichum Graminicola ◽  
Nitrogen Fixation Activity ◽  
Auxin Production ◽  
Paenibacillus Sp

AbstractPaenibacillus species are Gram-positive bacteria that have been isolated from a diverse array of plant species and soils, with some species exhibiting plant growth-promoting (PGP) activities. Here we report two strains (S02 and S25) of a novel Paenibacillus sp. that were isolated from perennial ryegrass (Lolium perenne) seeds. Comparative genomics analyses showed this novel species was closely related to P. polymyxa. Genomic analyses revealed that strains S02 and S25 possess PGP genes associated with biological nitrogen fixation, phosphate solubilisation and assimilation, as well as auxin production and transportation. Moreover, secondary metabolite gene cluster analyses identified 13 clusters that are shared by both strains and three clusters unique to S25. In vitro assays demonstrated strong bioprotection activity against phytopathogens (Colletotrichum graminicola and Fusarium verticillioides), particularly for strain S02. A transcriptomics analysis evaluating nitrogen fixation activity showed both strains carry an expressed nif operon, but strain S02 was more active than strain S25 in nitrogen-free media. Another transcriptomics analysis evaluating the interaction of strains with F. verticillioides showed strain S02 had increased expression of core genes of secondary metabolite clusters (fusaricidin, paenilan, tridecaptin and polymyxin) when F. verticillioides was present and absent, compared to S25. Such bioactivities make strain S02 a promising candidate to be developed as a combined biofertiliser/bioprotectant.

scholarly journals Microbiome of the Rhizosphere: from Structure to Functions

2021 ◽  
Author(s):  
Ning Ling ◽  
Tingting Wang ◽  
Yakov Kuzyakov
Keyword(s):  
Nitrogen Fixation ◽  
Microbial Ecology ◽  
16S Rdna ◽  
N Cycling ◽  
Microbial Interactions ◽  
Community Diversity ◽  
Organic Substances ◽  
Microbial Composition ◽  
Soil Function ◽  
Copiotrophic Bacteria

Abstract Microbial composition and functioning in the rhizosphere are among the most fascinating but hidden topics in microbial ecology. We generalized bacterial traits regarding community diversity, composition and functions using published 16s rDNA amplicon sequences of 584 pairs of bulk soils vs rhizosphere of crops. The lower bacterial diversity in the rhizosphere (-7% richness) compared to root-free soil reflects the excess of available organic substances near the root. The rhizosphere is enriched by Bacteroidetes, Proteobacteria and Cyanobacteria as well as other copiotrophic bacteria (r strategists). Complex but unstable bacterial networks in rhizosphere reflect tight microbial interactions and adaptations to fluctuating conditions common for r strategists. The dominant dormancy strategy in the rhizosphere is the toxin-antitoxin system, while sporulation is common in bulk soil. Function prediction analysis showed that the rhizosphere is strongly enriched (50–115%) in methanol oxidation, ureolysis, cellulolysis, chitinolysis and nitrogen fixation, but strongly depleted in functions related to N-cycling.

scholarly journals Root Distribution and Nitrogen Fixation Activity of Tropical Forage Legume American Jointvetch (Aeschynomene americanaL.) cv. Glenn under Waterlogging Conditions

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Manabu Tobisa ◽  
Masataka Shimojo ◽  
Yasuhisa Masuda
Keyword(s):  
Nitrogen Fixation ◽  
Root Distribution ◽  
Water Surface ◽  
Nitrogenase Activity ◽  
Soil Surface ◽  
Nodule Formation ◽  
Nitrogen Fixation Activity ◽  
Fixation Activity ◽  
Net Assimilation ◽  
Waterlogging Treatment

We investigated the root distribution and nitrogen fixation activity of American jointvetch (Aeschynomene americanaL.) cv. Glenn, under waterlogging treatment. The plants were grown in pots under three different treatments: no waterlogging (control), 30 days of waterlogging (experiment 1), and 40 days of waterlogging (experiment 2). The plants were subjected to the treatments on day 14 after germination. Root dry matter (DM) weight distribution of waterlogged plants was shallower than controls after day 20 of waterlogging. Throughout the study period, the total root DM weight in waterlogged plants was similar to that in the controls. Enhanced rooting (adventitious roots) and nodule formation at the stem base were observed in waterlogged plants after day 20 of waterlogging. The average DM weight of individual nodules on the region of the stem between the soil surface and water surface of waterlogged plants was similar to that of individual taproot nodules in the controls. Waterlogged plants had slightly greater plant DM weight than the controls after 40 days of treatment. The total nitrogenase activity (TNA) of nodules and nodule DM weight were higher in waterlogged plants than in the controls. Waterlogged American jointvetch had roots with nodules both around the soil surface and in the area between the soil surface and water surface after 20 days of waterlogging, and they maintained high nitrogenase activity and net assimilation rate that resulted in an increased growth rate.

Nitrogen Cycling

2001 ◽  
Author(s):  
Melany C. Fisk ◽  
Paul D. Brooks
Keyword(s):  
Spatial Variation ◽  
Water Availability ◽  
Growing Season ◽  
N Cycling ◽  
Alpine Tundra ◽  
N Transformations ◽  
Cold Temperatures ◽  
Niwot Ridge ◽  
N Cycle ◽  
Large N

In this chapter, we discuss the current understanding of internal N cycling, or the flow of N through plant and soil components, in the Niwot Ridge alpine ecosystem. We consider the internal N cycle largely as the opposing processes of uptake and incorporation of N into organic form and mineralization of N from organic to inorganic form. We will outline the major organic pools in which N is stored and discuss the transfers of N into and from those pools. With a synthesis of information regarding the various N pools and relative turnover of N through them, we hope to provide greater understanding of the relative function of different components of the alpine N cycle. Because of the short growing season, cold temperatures, and water regimes tending either toward very dry or very wet extremes, the alpine tundra is not a favorable ecosystem for either production or decomposition. Water availability, temperature, and nutrient availability (N in particular) all can limit alpine plant growth (chapter 9). Cold soils also inhibit decomposition so that N remains bound in organic matter and is unavailable for plant uptake (chapter 11). Consequently, N cycling in the alpine often is presumed to be slow and conservative (Rehder 1976a, 1976b; Holzmann and Haselwandter 1988). Nonetheless, studies reveal large spatial variation in primary production and N cycling in alpine tundra across gradients of snowpack accumulation, growing season water availability, and plant species composition (May and Webber, 1982, Walker et al., 1994, Bowman, 1994, Fisk et al. 1998; chapter 9). Furthermore, evidence for relatively large N transformations under seasonal snowcover (Brooks et al., 1995a, 1998) and maintenance of high microbial biomass in frozen soils (Lipson et al. 1999a) provide a complex temporal component of N cycling on Niwot Ridge. Our discussion of N cycling on Niwot Ridge will focus on two main points: first, the spatial variation in N turnover in relation to snowpack regimes and plant community distributions; and second, the temporal variability of N transformations during both snow-free and snow-covered time periods.

scholarly journals The effect of inoculation of pea plants with mycorrhizal fungi and Rhizobium on nitrogen and phosphorus assimilation

2011 ◽  
Vol 52 (No. 10) ◽  
pp. 435-440 ◽  
Author(s):  
M. Geneva ◽  
G. Zehirov ◽  
E. Djonova ◽  
N. Kaloyanova ◽  
G. Georgiev ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Mycorrhizal Fungi ◽  
Glomus Mosseae ◽  
Rhizobium Leguminosarum ◽  
Glomus Intraradices ◽  
Plant Biomass ◽  
Phosphorus Level ◽  
Nitrogen And Phosphorus ◽  
Nitrogen Fixation Activity ◽  
Fixation Activity

The study evaluated the response of pea (Pisum sativum cv. Avola) to arbuscular mycorrhizal fungi (AM) species Glomus mosseae and Glomus intraradices and Rhizobium leguminosarum bv. viceae, strain D 293, regarding the growth, photosynthesis, nodulation and nitrogen fixation activity. Pea plants were grown in a glasshouse until the flowering stage (35 days), in 4 kg plastic pots using leached cinnamonic forest soil (Chromic Luvisols – FAO) at P levels 13.2 (P1) and 39.8 (P2) mg P/kg soil. The obtained results demonstrated that the dual inoculation of pea plants significantly increased the plant biomass, photosynthetic rate, nodulation, and nitrogen fixation activity in comparison with single inoculation with Rhizobium leguminosarum bv. viceae strain D 293. On the other hand, coinoculation significantly increased the total phosphorus content in plant tissue, acid phosphatase activity and percentage of root colonization. The effectiveness of coinoculation with Rhizobium leguminosarum and Glomus mosseae was higher at the low phosphorus level while the coinoculation with Glomus intraradices appeared to be the most effective at higher phosphorus level.

Nitrogen Transformations and Removal in Waste Stabilization Ponds in Portugal: Seasonal Variations

1987 ◽  
Vol 19 (12) ◽  
pp. 123-130 ◽  
Author(s):  
M. C. R. Santos ◽  
J. F. S. Oliveira
Keyword(s):  
Seasonal Variations ◽  
Climatic Factors ◽  
Weather Conditions ◽  
Organic N ◽  
Nitrogen Transformations ◽  
Waste Stabilization Ponds ◽  
N Transformations ◽  
Temperature And Precipitation ◽  
N Removal ◽  
In Series

Nitrogen transformations that can occur in WSP depend on pond and waste characteristics and are also influenced by climatic factors, like temperature and precipitation. Experiments described have been carried out using a system of three ponds in series: anaerobic, facultative and maturation, treating domestic sewage. In this paper we aim to identify the processes that might contribute to N transformations in each pond and the seasonal variations in the removal of nitrogen and its bioconversion throughout the year. Results have proved that there was an important organic N removal in the anaerobic pond, mainly due to mineralisation and not exclusively by sedimentation. Some of the processes of N transformation observed in the ponds were more strongly influenced by weather conditions than others. In some cases, the increase of biological activity that was induced by the increase in air temperature, was masked by reduced precipitation which produced less diluted treated effluents. These climatic factors can explain some of the variations observed along the year, in what concerns nitrogen compounds concentrations.

scholarly journals Didymella pinodes Affects N and P Uptakes and Their Efficiencies in a Tripartite Mutualism of Pea

Agronomy ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 52
Author(s):  
Getinet Desalegn ◽  
Reinhard Turetschek ◽  
Stefanie Wienkoop ◽  
Hans-Peter Kaul
Keyword(s):  
Nitrogen Fixation ◽  
Grain Yield ◽  
Mycorrhizal Fungi ◽  
Rhizobium Leguminosarum ◽  
Farming System ◽  
P Uptake ◽  
Plant Health ◽  
Health Conditions ◽  
Didymella Pinodes ◽  
Microbial Symbionts

In pea (Pisum sativum L.) production, Didymella pinodes (Berk. & A. Bloxam) Petr. is the most damaging aerial pathogen globally. In two completely randomized pot experiments with four replicates, we studied the effects of D. pinodes infection interaction with three symbiotic treatments (Rhizobium leguminosarum biovar viciae, arbuscular mycorrhizal fungi (AMF) and co-inoculation of both) and a non-symbiotic control on one or two pea cultivars. Grain yield and yield components of pea, uptakes and physiological efficiencies of N and P and nitrogen fixation were recorded. The results show that there were significant interaction effects among treatments. Therefore, productivity of crops and their uptakes and efficiencies of N and P are dependent on plant health conditions, effectiveness of microbial symbionts and response of pea genotypes. For cv. Protecta inoculated with both symbionts, pathogen infection compared to healthy plants significantly enhanced P acquisition. Overall, plants inoculated with rhizobia alone had higher grain yield by 20–30% and nitrogen fixation by 20–25% than in dual symbiosis independent of plant health conditions. In conclusion, aerial pathogen, pea genotypes and microbial symbionts interactions modified N and P uptake and their efficiencies, which can lead to improving final grain yield quantity and quality in a sustainable farming system.

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