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This study examined the capacity of the giant kelp, Macrocystis pyrifera, to exhibit surge uptake as a mechanism to enhance nitrogen assimilation during seasons when nitrate is depleted. Surge uptake of nitrate, ammonium, and urea was assessed in the spring and summer with whole-blade incubation experiments using 15 N tracers. The incubation experiments showed evidence of surge uptake lasting up to 5 min for ammonium and 1 min for nitrate during the summer only. Giant kelp showed little capacity for surge uptake of urea regardless of season. The ecological importance of the patterns of surge uptake observed for ammonium and nitrate, however, is questionable, given the small scale and ephemeral nature of ammonium pulses most likely experienced by giant kelp, and the longer duration pulses of nitrate associated with internal waves and upwelling. Rather it seems more likely that uptake of ammonium and urea at ambient concentrations, combined with normal uptake of nitrate during longer duration pulses of high concentrations, sustains giant kelp growth during seasons when ambient concentrations of nitrate are low. [ABSTRACT FROM AUTHOR]

Ammonium (NH4+) is a major nitrogen source for tea plant growth. Although NH4+-induced growth of tea plants were reported, it was still unclear to elucidate the mechanism of proteins in tea plants in responding to NH4+ resupply. In the present study, the proteomic profiles of tea leaves under N deficiency/resupply were investigated by using LC-MS/MS and PRM technique. Compared with N deficiency, there were 247 and 328 proteins significantly expressed after 3 h and 3d of N resupplied, respectively. And compared with 3 h of N resupplied, there were 186 proteins significantly expressed after 3d of N resupplied. According to bioinformatics analysis, the results showed that different expressed proteins participated in various biological processes, such as PsbO, Pbs27, PsaN, and PsaF were involved in photosynthesis, ADH1, AOC3, URE, GDH1-2, and argD were involved in amino acid metabolism, CHI and ANR were involved in flavonoid biosynthesis, GSTF9, APX, and GSS were involved in glutathione metabolism, and PdxT and PdxS were involved in vitamin B6 metabolism. Through PPI analysis, the results showed that the interactions between different expressed proteins mainly occurred in the photosynthetic pathway. Ammonium supply has a profound impact on photosynthesis, amino acid metabolism, flavonoid biosynthesis, glutathione metabolism, and vitamin B6 metabolism. [ABSTRACT FROM AUTHOR]

The ability of plants to acquire soil nitrogen (N) sources is plastic in response to abiotic and biotic factors. However, information about how plant preferences among N forms changes in response to internal plant N demand through growth phases, or to environmental stress such as ozone (O3), is scarce. Diploid and triploid Chinese white poplar were used to investigate N form preferences at two key developmental periods (spring, summer) and in response to summer O3 (ambient, 60 ppb above ambient). We used stable isotopes to quantify NH4+, NO3− and glycine N-uptake rates. Carbon acquisition was recorded simultaneously. Both ploidy levels differed in growth, N form preferences, and N and C use strategies. Diploid white poplars grew faster in spring but slower in summer compared with triploids. Diploid white poplars also showed plasticity among N form preferences through the season, with no preferences in spring, and NO3− preferred in summer, while triploids showed an overall preference for NO3−. Carbon acquisition and NO3− uptake were inhibited in both ploidy levels of poplar at elevated O3, which also reduced diploid total N uptake. However, triploid white poplars alleviated N uptake reduction, switching to similar preferences among N forms. We conclude that N form preferences by white poplar are driven by internal C and N use in response to nutrient demands, and external factors such as O3. [ABSTRACT FROM AUTHOR]

Historically, anthropogenic fixed nitrogen has been purposely increased to benefit food production and global development. One consequence of this increase has been to raise concentrations of nitrogen in aquatic ecosystems. To evaluate whether nitrogen pollution promotes changes in the estimates of niche space of fish communities, we examined 16 sites along a Brazilian river basin highly impacted by anthropogenic activities, especially discharge of domestic and industrial sewage from a region with more than 5 million inhabitants. We analysed the carbon (δ13C) and nitrogen (δ15N) isotope ratios of fish species and both autochthonous (periphyton) and allochthonous (course and fine particulate organic matter) basal food resources. To estimate the magnitude of nitrogen pollution, we measured the nitrate and ammonium concentrations at each site. Sampling was conducted in the dry and wet seasons to evaluate the influence of seasonality. Nitrogen pollution generally increased estimates of niche space, and seasonality influenced only the niche estimates of fish communities from polluted sites. In addition, isotopic analyses of nitrogen polluted sites yielded unrealistic estimates of trophic positioning (detritivores at the top of the food web). We conclude that changes in niche space estimates reflect both alterations in baseline isotopic values and differential trophic behaviour among fishes. Our study suggests that under conditions of high pollution, other factors appear to influence isotopic estimates of niche, such as isotopically distinct sources that have not been sampled, and/or differences in δ15N turnover rates between fish tissue and basal resources, creating isotopic baselines that are challenging to interpret. [ABSTRACT FROM AUTHOR]

Due to the diverse speciation and biochemical characteristics of nitrogen in urban runoff, excess nitrogen continues to be a major source of eutrophication in receiving waters. The performance of a nitrifying‐sorptive Clinoptilolite (ZT) was examined for use in a media‐based stormwater control measure (SCM) for ammonium removal. Results suggested that columns operated under continuous feed showed more nitrification as the media approached ammonium exhaustion. Influent concentrations of 2.5 and 5 mg NH4+‐N/L tested under continuous flow regimes both showed steady‐state operation after media exhaustion, with the average effluent [NO3—N] of 1.2 and 1.7 mg/L, respectively. The performance of the media under intermittent flow regime showed lower effluent ammonium, nitrification between simulated saturated periods, and could treat an additional 70 bed volumes of simulated runoff when compared to a column receiving identical continuous feed. However, nitrification was not sufficient to prevent desorption of ammonium during drops in influent NH4+‐N concentrations. Use of Clinoptilolite for ammonium sorption/nitrification is a systematic approach for capture and transformation of incoming/mineralized ammonium to nitrate prior to reaching an anoxic/denitrifying zone within SCMs. Practitioner Points: Clinoptilolite can accumulate stormwater ammonium, allowing it to be nitrified.Ammonium nitrification will regenerate exchange sites on the clinoptilolite.Intermittent flow conditions allowed more nitrification between stormwater events. [ABSTRACT FROM AUTHOR]

Mentha spicata L. is an aromatic and medicinal plant, known as mint and used in the pharmaceutical and cosmetic industry and in phytotherapy. Although the cultivation of medicinal plants is traditional, there are several questions about which practices are most appropriate in the management of these plants, especially regarding nutrition and availability of light. The objective of this work was to evaluate the growth, phytomass production and physiological aspects of M. spicata cultivated in proportions of nitrate (NO3-) and ammonium (NH4+) and light environments. The research was carried out in a greenhouse at the Universidade Federal do Recôncavo da Bahia, Cruz das Almas, BA, Brazil. The experimental design used was completely randomized, in a 5 x 3 factorial scheme, with five proportions of NO3-:NH4+ (0: 100; 25:75; 50:50; 75:25; 100: 0) and three light environments (ChromatiNet® meshes red, black and in full sun), with seven repetitions. There was a significant interaction between the proportions of ammonium and nitrate with the light environments for most of the evaluated parameters. It is concluded that M. spicata plants grown under balanced proportions of nitrate and ammonium in a light environment favorably favored the initial growth and physiological indications of this species. [ABSTRACT FROM AUTHOR]

Anthropogenic nitrogen (N) emissions and deposition have been increasing over past decades. However, spatiotemporal variations of N deposition levels and major sources remain unclear in many regions, which hinders making strategies of emission mitigation and evaluating effects of elevated N deposition. By investigating moss N contents and δ15N values in southwestern (SW) China in 1954–1964, 1970–1994, and 2005–2015, we reconstructed fluxes and source contributions of atmospheric ammonium (NH4+) and nitrate (NO3‐) deposition and evaluated their historical changes. For urban and non‐urban sites, averaged moss N contents did not differ between 1954–1964 and 1970–1994 (1.2%–1.3%) but increased distinctly in 2005–2015 (1.6%–2.3%), and averaged moss δ15N values decreased from +0.4‰ to +3.3‰ in 1954–1964 to −1.9‰ to −0.7‰ in 1974–1990, and to −4.8‰ to −3.6‰ in 2005–2015. Based on quantitative estimations, N deposition levels from the 1950s to the 2000s did not change in the earlier 20 years but were elevated substantially in the later 30 years. Moreover, the elevation of NH4+ deposition (by 12.2 kg‐N/ha/year at urban sites and 4.6 kg‐N/ha/year at non‐urban sties) was higher than that of NO3‐ deposition (by 6.0 and 2.9 kg‐N/ha/year, respectively) in the later 30 years. This caused a shifted dominance from NO3‐ to NH4+ in N deposition. Based on isotope source apportionments, contributions of combustion‐related NH3 sources (vehicle exhausts, coal combustion, and biomass burning) to the elevation of NH4+ deposition were two times higher than volatilization NH3 sources (wastes and fertilizers) in the later 30 years. Meanwhile, non‐fossil fuel NOx sources (biomass burning, microbial N cycles) contributed generally more than fossil fuel NOx sources (vehicle exhausts and coal combustion) to the elevation of NO3‐ deposition. These results revealed significant contributions of combustion‐related NH3 and non‐fossil fuel NOx emissions to the historical elevation of N deposition in SW China, which is useful for emission mitigation and ecological effect evaluation of atmospheric N loading. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is one of the most produced cereals in the world. Among the essential nutrients required by this crop, nitrogen (N) is of paramount importance to achieve optimum yields. In paddy fields, ammonium (NH4+) represents the main source of N. This work aimed to evaluate the root morphology, ammonium uptake kinetics and N accumulation in two upland rice varieties, Piauí and Manteiga from Maranhão – Brazil. The varieties were cultivated in hydroponic conditions and submitted to three different doses of ammonium: 1 – constant treatment with 0.2 mM NH4+, 2 – constant treatment with 1 mM NH4+ and 3 – constant treatment with 1 mM NH4+, followed by N starvation during 72 h and resupply with 1 mM NH4+. The varieties present contrasting behaviors when submitted to different doses of NH4+. Piauí showed higher biomass and root length under the treatment with 0.2 mM NH4+. The favorable kinetics parameters observed contributed to a higher N accumulation by Piauí in low dose of NH4+. Under 1 mM NH4+, a higher root biomass and favorable kinetics parameters was recorded by Manteiga. This variety presented a better performance with higher doses of N. Under the treatment of N resupply, Piauí variety showed to be more adapted, due to the greater root plasticity observed. For one hand, the results suggest that Piauí variety presents greater growth in environments with low dose or seasonal flux of NH4+. On the other hand, Manteiga variety presents better growth when submitted to higher levels of NH4+. [ABSTRACT FROM AUTHOR]

The increase of fossil‐fuel burning and nitrogen (N) fertilizer consumption continues to elevate global N deposition, leading to significant increases of soil NH4+ and NO3− concentrations, and thus N2O emissions. This is especially important for natural, unmanaged soils which are considered as areas that are sensitive to N input. However, uncertainties exist regarding the interactions of soil N2O emissions with soil NH4+ and NO3− concentrations in response to N input in different climatic regions, as well as their underlying potential mechanisms. Here, we conducted a meta‐analysis to investigate the responses of these three forms of N to external N input across global natural ecosystems, using data extracted from peer‐reviewed studies. The results show that soil NO3− concentrations are increased to a much larger extent by N input in temperate regions (136%) compared to tropical (62%) and subtropical (54%) regions, whereas the increase of soil NH4+ concentrations by N input is much less than soil NO3− concentrations, at 20%, 26% and 28% in temperate, tropical and subtropical regions, respectively. The significantly larger increase in soil NO3− concentrations but slightly lower increase in soil NH4+ concentrations in temperate regions compared to other climatic zones may be ascribed to the dominant nitrification process in temperate areas, which promotes the conversion of NH4+ to NO3−. Soil N2O emissions were increased to the greatest extent in subtropical regions (348%) in response to N input, followed by temperate regions (111%) and tropical regions (44%), which may be a result of the dominant denitrification process in subtropical regions, which promotes N2O production. It is likely that denitrification also dominates N2O production in tropical regions, but the dampened effect of N input on stimulating soil N2O emissions in these areas suggests that the loss of NO3− substrate due to intensive leaching might be an important issue. This study could provide a better understanding of the heterogeneous risks of soil N responses in different climatic zones in the context of increasing global N deposition. Highlights: Larger N input‐induced increases in soil NO3− concentrations in temperate regions may derive from increased nitrification. Larger N input‐induced increases in soil N2O emissions in subtropical regions may derive from increased denitrification. Less increase in soil N2O emissions in tropical regions after N input may be due to heavy precipitation‐induced NO3− leaching. Soil N2O emissions in subtropical regions may be more sensitive to increased N input compared to other climatic zones. [ABSTRACT FROM AUTHOR]

The anaerobic nitrogen removal performance of anammox at 30°C, 25°C, and 16°C were studied by using the UASB (Up flow Anaerobic Sludge Blanket) reactor and the influent concentration of NH4+-N and NO2−-N were 16.9 and 20.6 mg L−1 respectively. Experimental results showed that high-efficiency anammox nitrogen removal could be achieved at 30°C, when hydraulic retention time (HRT) was 0.14 h, the nitrogen removal rate (NRR) was 5.73 kg N m−3 d−1. The anammox reactor operated stably for more than 80 days under the condition of 16°C–20°C, and the high NRR of 2.78 kg N m−3 d−1 was obtained. In this experiment, DO had little effect on the activity of anammox granular sludge, and the nitrogen removal performance could be quickly recovered in a short period of time after being affected by DO. Moreover, the stoichiometric ratio of NO2−-N and NH4+-N consumption (ΔNO2−-N/ΔNH4+-N) and the stoichiometric ratio of NO3−-N production and NH4+-N conversion (ΔNO3−-N/ΔNH4+-N) were 1.21 ± 0.11and 0.25 ± 0.06 respectively at 30°C, which were very close to the theoretical value, it indicated that anammox bacteria were the dominant bacteria at 30°C. [ABSTRACT FROM AUTHOR]

The anaerobic nitrogen removal performance of anammox at 30°C, 25°C, and 16°C were studied by using the UASB (Up flow Anaerobic Sludge Blanket) reactor and the influent concentration of NH4+-N and NO2−-N were 16.9 and 20.6 mg L−1 respectively. Experimental results showed that high-efficiency anammox nitrogen removal could be achieved at 30°C, when hydraulic retention time (HRT) was 0.14 h, the nitrogen removal rate (NRR) was 5.73 kg N m−3 d−1. The anammox reactor operated stably for more than 80 days under the condition of 16°C–20°C, and the high NRR of 2.78 kg N m−3 d−1 was obtained. In this experiment, DO had little effect on the activity of anammox granular sludge, and the nitrogen removal performance could be quickly recovered in a short period of time after being affected by DO. Moreover, the stoichiometric ratio of NO2−-N and NH4+-N consumption (ΔNO2−-N/ΔNH4+-N) and the stoichiometric ratio of NO3−-N production and NH4+-N conversion (ΔNO3−-N/ΔNH4+-N) were 1.21 ± 0.11and 0.25 ± 0.06 respectively at 30°C, which were very close to the theoretical value, it indicated that anammox bacteria were the dominant bacteria at 30°C. [ABSTRACT FROM AUTHOR]

An experiment was carried out during four harvests (two in the cold season and two in spring) with the objective of determining the N losses by leaching and volatilization as well as their dynamics in a Brown Grayish soil in the Central Cuban region at the Experimental Station of Soil "Escambray" in corn crop. Six N levels were applied (0, 60, 120, 180, 240 y 300 kg ha-1 of N) a third of which with ammonium sulfate when planting and the remaining 35 days with urea. Volatilization of ammonium in form of ammonia was determined using Nömmik's method in levels 0, 120 and 240 kg ha-1 to 3, 7, 14, 21, 28 and 35 days after fertilization. The washing of NO3- and NH4+ was quantified using a lysimeter type Ebermeyer. Ammonia losses due to volatilization increased along with N doses in the two seasons, reaching its maximum level between the 3rd and 7th days after the second urea fertilization with values of 25 kg ha-1. NH4+ leaching was insignificant. while NO3- losses increased along with the doses and were approximately 13 % of the applied N reaching values of 47 kg ha-1 in the dose of 300 kg ha-1. It is concluded that in Brown Grayish soil the greatest losses due to ammonium volatilization occur with urea and the greatest leaching occurs in NO3-. [ABSTRACT FROM AUTHOR]

Methanotrophs use methane as their sole carbon and energy source and represent an attractive platform for converting single-carbon feedstocks into valueadded compounds. Optimizing these species for biotechnological applications involves choosing an optimal growth substrate based on an understanding of cellular responses to different nutrients. Although many studies of methanotrophs have examined growth rate, yield, and central carbon flux in cultures grown with different carbon and nitrogen sources, few studies have examined more global cellular responses to different media. Here, we evaluated global transcriptomic and metabolomic profiles of Methylomicrobium album BG8 when grown with methane or methanol as the carbon source and nitrate or ammonium as the nitrogen source. We identified five key physiological changes during growth on methanol: M. album BG8 cultures upregulated transcripts for the Entner-Doudoroff and pentose phosphate pathways for sugar catabolism, produced more ribosomes, remodeled the phospholipid membrane, activated various stress response systems, and upregulated glutathione-dependent formaldehyde detoxification. When using ammonium, M. album BG8 upregulated hydroxylamine dehydrogenase (haoAB) and overall central metabolic activity, whereas when using nitrate, cultures upregulated genes for nitrate assimilation and conversion. Overall, we identified several nutrient source-specific responses that could provide a valuable basis for future research on the biotechnological optimization of these species. [ABSTRACT FROM AUTHOR]

Macroalgal growth in temperate coastal ecosystems is primarily regulated by light and inorganic nitrogen availability. The effect of light (photon irradiance) on NO3- and NH4+ uptake, and NO3- - assimilation, were studied in the red macroalga, Hemineura frondosa, which does not operate a carbon concentrating mechanism (non-CCM). Non-CCM macroalgae grow in low and high light environments but become increasingly dominant with depth, suggesting a mechanism for 'preserving energy' under low light levels. H. frondosa was acclimated to limiting (30 µmol photons m-2 s-1) and saturating (150 µmol photons m-2 s-1) irradiances for 8 days. Then, NO3- and NH4+ uptake rates were measured under limiting and saturating irradiances at six concentrations ranging from 2--64 µM. NO3- uptake did not follow saturating uptake kinetics at both irradiances suggesting multiple uptake mechanisms. NH4+ uptake saturated at concentrations <32 µM under limiting but not under saturating irradiance. Saturating irradiance resulted in greater maximum uptake rates of both NO3- and NH4+. There was no evidence that irradiance regulated NO3- reduction by nitrate reductase. Also illustrated is the importance of measuring nitrate reductase activity on fresh material, as freezing in liquid nitrogen and storage at -80°C for 7 days caused a 65% decline in activity. Photosynthetic pigments, soluble tissue nitrogen and % total tissue nitrogen were all higher in limiting irradiance. In this first study of the nitrogen physiology of a non-CCM seaweed, we show that light regulates NO3- and NH4+ uptake but not NO3- assimilation. [ABSTRACT FROM AUTHOR]

Nitrate (NO3−) and ammonium (NH4+) are the main inorganic nitrogen sources available to plants. However, exclusive ammonium nutrition may lead to stress characterized by growth inhibition, generally associated with a profound metabolic reprogramming. In this work, we investigated how metabolism adapts according to leaf position in the vertical axis of tomato (Solanum lycopersicum cv. M82) plants grown with NH4+, NO3−, or NH4NO3 supply. We dissected leaf biomass composition and metabolism through an integrative analysis of metabolites, ions, and enzyme activities. Under ammonium nutrition, carbon and nitrogen metabolism were more perturbed in mature leaves than in young ones, overall suggesting a trade-off between NH4+ accumulation and assimilation to preserve young leaves from ammonium stress. Moreover, NH4+-fed plants exhibited changes in carbon partitioning, accumulating sugars and starch at the expense of organic acids, compared with plants supplied with NO3−. We explain such reallocation by the action of the biochemical pH-stat as a mechanism to compensate the differential proton production that depends on the nitrogen source provided. This work also underlines that the regulation of leaf primary metabolism is dependent on both leaf phenological stage and the nitrogen source provided. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electro-oxidation of N-heterocycles produces N 2 , N H 3 / N H 4 + , N O 3 - , C O and C O 2. • N H 3 / N H 4 + and an apparent N 2 yield correlate linearly with carbon removal. • Both apparent N 2 and N O 3 - form directly from organic intermediates rather than N H 3 / N H 4 +. • Higher concentrations of parent compounds promote a higher apparent N 2 selectivity. • N O 3 - dominates when oxidation of carbon is mass transfer-limited or at basic pH. We report for the first time the carbon and nitrogen product distribution during the electrochemical oxidation (EO) of pyrazine and related N-heterocyclic compounds (NHCs) present in the hard-to-treat wastewater from a biofuel production process. The experimental study was carried out using a boron-doped diamond anode. Identified and quantified intermediate products included oxamic acid, formamide, oxalic acid, and formic acid. Analysis of the C and N yields as a function of the extent of carbon removal reveals the influence of the current- and mass transfer-control operating regimes on product distribution. Carbon monoxide, which was detected among the gaseous products, suggests a possible decarbonylation pathway in the current-controlled regime. An apparent nitrogen gas and ammonium yields correlated linearly with the carbon removal, while nitrate yields significantly increased in the mass transfer-controlled regime. Nitrate and apparent nitrogen gas appear to form directly from organic nitrogen intermediates, rather than from the ammonium that also forms in the process. The research gives new insights into the NHCs degradation pathways, product distribution, and final water composition as a function of operating regime in the EO of recalcitrant wastewater. [ABSTRACT FROM AUTHOR]

The effect of phosphorus limitation on the nitrogen removal performance of the anammox process was investigated using continuous feeding reactors. When the phosphorus supply was stopped under an influent nitrogen concentration of 256 mg-N L−1, a high nitrogen conversion rate of 1.88 kg-N m−3 d−1 was maintained for 17 days. However, during the next 25 days, the nitrogen conversion rate decreased by 16.5%. Subsequently, nitrogen removal activity was recovered entirely by re-adding 0.1 mg-P L−1 of phosphorus. Similar tests were performed at different influent nitrogen concentrations. The results showed that the minimum phosphorus concentrations (MPC) in the influent required to maintain anammox activity at influent nitrogen concentrations of 379 and 502 mg-N L−1 were 0.2 and 0.3 mg L−1, respectively. These results indicate that the MPC increased with N concentration, with an MPC/N of 0.0005. A microbial community analysis based on the 16S rRNA gene amplicon sequencing revealed that two genera of anammox bacteria (Candidatus Kuenenia and Candidatus Jettenia) were presented. The dominant anammox bacteria changed from Candidatus Kuenenia to Candidatus Jettenia after the phosphorus-limitation tests. • Minimum P concentrations (MPC) to maintain the anammox activity were determined. • MPC was determined at total nitrogen (T-N) concentrations of 256–502 mg L− 1. • MPC was increased with the increase in influent TN concentration. • MPC against the influent T-N concentration (MPC/T-N) was 0.0005. • Dominant species changed to Ca. Jettenia by P starvation. [ABSTRACT FROM AUTHOR]

There has been an increasing interest in soybean cultivation in hydroponic systems. Because soybean plants can utilize nitrogen derived from biological N2 fixation, the use of Rhizobium inoculated plants may eliminate or decrease the need for mineral nitrogen fertilization in hydroponic systems. Thus, the objective of this study was to establish effective methods for making inoculated soybean transplants for a substrate-based hydroponic system. Inoculated plants were effectively produced by rooting seedling stem cuttings in a medium containing a Rhizobium inoculant. We also investigated the effects of different nitrogen forms and sub-irrigated nutrient solution concentrations on the growth and root nodule formation of the inoculated plants. The application of a nitrogen-free nutrient solution had minimal positive effects on the growth and nodulation of the inoculated plants. Ammonium-fed plants lacked root nodules regardless of the ammonium concentration. Furthermore, a 50% nutrient solution combining with nitrate or urea as the nitrogen source did not promote root nodulation. Therefore, inoculated plants should be subirrigated with an approximately 25% nutrient solution supplemented with nitrate or urea to induce early growth and nodulation prior to transplantation. [ABSTRACT FROM AUTHOR]

This study examined the effect- of starvation on the chemical composition (total protein, crude fat, dry matter, ash) and the excretion of nitrogen (N) and phosphorus (P) of the Antarctic fish Notothenia coriiceps and Notothenia rossii. Starvation resulted in a decrease in lipid content in both species. In Notothenia coriiceps the body fat content decreased from 2.3% to 1.88% and in Notothenia rossii from 0.82% to 0.6%. Excretion rates of N and P were highest on the first day of starvation, then gradually decreased. Average excretion rates (in µmol N or P h−1 100 g−1) of ammonium nitrogen, organic nitrogen, reactive phosphorus, and organic phosphorus respectively were higher for N. coriiceps (8.71, 2.93, 1.09, 0.46) than N. rossii (6.28, 4.94, 0.54, 0.13). During starvation, the proportion of TON in the total excreted nitrogen was on average 43.5% for N. rossi and 24.1% for N. coriiceps, and remained at a relatively stable level. The study confirmed the natural adaptation of the studied fish to the long-term lack of food, and that the excreted loads of N and P may be a source of biogens for autotrophs and serve as a chemical signal in trophochemoreception. The inter-species differences in the excretion of N and P could be due to the differences in fish size, gonad stage of maturity, and nutritional preferences. [ABSTRACT FROM AUTHOR]

BACKGROUND The quality of wine is highly dependent on the quality of berries. Development of berries is influenced by the type and ratio of different nitrogen supplies in the soil. To understand the impact of varying sources and levels of nitrate and ammonium on sucrose and nitrogen metabolism of Vitis vinifera cv. Cabernet Sauvignon, we tested nutrient solutions with four NO3−‐N:NH4+‐N ratios (100:0, 75:25, 50:50, 0:100) through the root system. RESULTS: The form and quantity of nitrogen affected berries and leaves with source–sink relationships. Soluble sugar levels were significantly higher in plants treated with mixed nitrogen sources (75:25 and 50:50) compared to single nitrogen sources (100:0 and 0:100). In particular, treating plants with mixed nitrogen source at a 75:25 ratio resulted in 22% higher fructose levels in berries compared to the 50:50 treatment. In addition, mixed nitrogen treatments resulted in significantly higher amino acid levels and protein content. Mixed nitrogen substrates also increased the expression of enzymes involved in both nitrogen and sucrose metabolism. CONCLUSION: Plants did not maximize the nitrogen supply when single form nitrogen was provided, and the mixed nitrogen substrates consistently increased the amount of available carbon and nitrogen in the berries and leaves. We found that NO3−-N:NH4+‐N ratio of 75:25 was the optimum formula for improving nitrogen and sucrose metabolism, and reducing the competition between nitrogen and sucrose. By examining the nutrient utilization of plants cultivated with different nitrogen forms, the present study provides insights into improving cultivation and production practices. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The aim of the present study was to explore the effects of dicyandiamide（DCD）and surfactant on the form and content of nitro⁃ gen in digested slurry, using a laboratory simulation experiment with different combinations of application of the treatments. Six treatments were used：single application of digested slurry, digested slurry+8%DCD, digested slurry+16%DCD, digested slurry+surfactant, digested slurry+8%DCD+surfactant, and digested slurry+16%DCD+sufactant. The total nitrogen（TN）, total Kjeldahl nitrogen（TKN）, ammonium ni⁃ trogen（NH4+-N）, and nitrate nitrogen（NO3--N）content of digested slurry were measured at 10, 30 min, and 1, 3, 10, 24, 48 h. The results revealed that, in the digested slurry+8%DCD and digested slurry+16%DCD treatments, the concentrations of NH4+-N, TKN, and NO3--N in⁃ creased by 0.74%~8.96%, 24.67~59.70 mg·L-1, 13.42~145.88 times, respectively, and the concentrations of all three increased with the quantity of DCD. The addition of surfactant had little effect on the form and concentration of nitrogen in digested slurry. [ABSTRACT FROM AUTHOR]

At the global scale, atmospheric inputs of nitrogen are an important source of the new nitrogen that supports new marine production, especially in oligotrophic open oceans and marginal seas. This study reports quantities of atmospheric deposition of dissolved inorganic nitrogen (DIN) to the largest marginal sea in the North Pacific (the oligotrophic South China Sea, SCS) based primarily on rainwater sampling in the open northwestern region (Yongxing Island) from 2013 to 2015, and aerosol sampling from the SCS basin in June 2017. Atmospheric wet and dry deposition of DIN and their potential contributions to productivity were estimated. The volume-weighted mean rainwater concentrations during the wet and dry seasons were 4.9 and 18.1 µmol L−1 for N+N(NO3−+NO2−), and 5.7 and 4.0 µmol L−1 for NH4+, respectively. Rainwater concentrations of DIN were lower in the marginal seas than in the open ocean. The aerosol NO3− concentration was 1.15±1.18 µg m−3 during the wet season, which is slightly lower than reported for the East China Sea and East Sea, but higher than in the Arabian Sea. Monthly wet and dry deposition rates ranged from 0.4–3.9 and 0.4–1.2 mmol m−2 mon−1 for NO3−, and 0.2–1.3 and 0.01–0.02 mmol m−2mon−1 for NH4+, respectively. The annual wet and dry deposition fluxes of DIN were estimated to be 16.8 and 10.1 mmol m−2yr−1, respectively. Compared to other marginal seas, the SCS receives less atmospheric NO3− inputs than the Yellow Sea, East China Sea, East Sea, and northeastern Mediterranean Sea. The total atmospheric DIN deposition may account for 1.8–11.1% of the nitrogen supporting new production and 0.7–1.8% of the nitrogen supporting primary production. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an essential macronutrient for plants, and mainly taken from the soil as ammonium (NH+4). It is particularly transported into the plants by AMmonium Transporters (AMTs), which are plasma membrane proteins. In the present study, genome-wide identification, physiological and expression analyses of tomato (Solanum lycopersicum L.) ammonium transporters 1 (SlAMT1) genes under drought and salt stresses were performed. Sequence analyses revealed the presence of variations in SlAMT1 s at nucleotide and protein levels. While all the SlAMT1s comprise an ammonium transporter domain (PF00909), the numbers of their transmembrane helices were found to be diverse. Digital expression analyses proved that SlAMT1–3 gene had different expression patterns compared to the others, suggesting its functional diversities. The expression analyses revealed that SlAMT1 genes were 0.16 and 5.94 -fold down-regulated under drought and salt stresses, respectively. The results suggested that expression of SlAMT1 genes were adversely affected by abiotic stress conditions. • The results of this study indicated there are genetic variations and divergences among SlAMT1 genes and proteins. • The expression profiles of SlAMT1 genes showed they were differently expressed under drought and salinity stresses. • Tomato-Arabidopsis separation was clearly observed for AMT1 proteins in the phylogenetic tree. [ABSTRACT FROM AUTHOR]

The increase of ammonia nitrogen, nitrite, nitrate, urea, and other dissolved nitrogen in prawn pond often causes eutrophication of water body and prawn poisoning, which brings great harm to aquaculture. Microalgae are the main biological factors in prawn pond, which can effectively utilize dissolved nitrogen. The goal of this study was to evaluate the effects of the forms and concentrations of various dissolved nitrogen on the uptake rate (ρ) by Oocystis borgei, and establish the relationship model between ammonia nitrogen uptake rate and key environmental factors using 15N isotope labeling technique. Temperature (A), light intensity (B), salinity (C), pH (D), and algal concentration (E) were the factors used to construct an empirical model. Study results showed that nitrogen concentrations had a significant effect on the uptake rates of ammonium, nitrate, nitrite, and urea (P < 0.05). Under various salinity and temperature conditions, the relative preference index (RPI) of ammonium was greater than that of nitrite, urea, and nitrate; Ammonium was the preferred nitrogen source for O. borgei. The optimal combination of environmental conditions for ρ(NH4+-N) was temperature of 20 °C, pH of 7.5, light intensity of 81 μmol m−2 s−1, salinity of 15‰, and algal concentration of 5.5 × 108 cell L−1. The model equation wasρ = 0.0017 × (A0.180B0.252C0.748D0.587E) + 0.0512, with the coefficient of determination (R2) of 0.89. No significant difference was observed between the model-predicted values and the measured values (F = 0.789, P > 0.05), which demonstrated the high fitting degree of simulation equation. This study provides valuable insight into the removal of dissolved nitrogen in a controllable prawn farming mode such as high-elevation ponds by O. borgei. [ABSTRACT FROM AUTHOR]

The enzymatic controlled metabolic processes in cells occur at their optimized pH ranges, therefore cellular pH homeostasis is fundamental for life. In plants, the nitrogen (N) source for uptake and assimilation, mainly in the forms of nitrate (NO3–) and ammonium (NH4+) quantitatively dominates the anion and cation equilibrium and the pH balance in cells. Here we review ionic and pH homeostasis in plant cells and regulation by N source from the rhizosphere to extra- and intracellular pH regulation for short- and long-distance N distribution and during N assimilation. In the process of N transport across membranes for uptake and compartmentation, both proton pumps and proton-coupled N transporters are essential, and their proton-binding sites may sense changes of apoplastic or intracellular pH. In addition, during N assimilation, carbon skeletons are required to synthesize amino acids, thus the combination of NO3– or NH4+ transport and assimilation results in different net charge and numbers of protons in plant cells. Efficient maintenance of N-controlled cellular pH homeostasis may improve N uptake and use efficiency, as well as enhance the resistance to abiotic stresses. [ABSTRACT FROM AUTHOR]

In-stream nutrient retention is an important ecosystem function because it can regulate nutrient fate and export to downstream ecosystems. Temporal variation in nutrient retention in streams has been studied extensively at the annual and seasonal scale but less thoroughly at the diel scale. However, understanding temporal variability in nutrient uptake at the diel scale can increase understanding of the role of photoautotrophic primary production on nutrient uptake in streams, especially open-canopy streams. We hypothesized that nutrient retention mostly depends on autotrophic demand in open-canopy streams and that it varies following the diel pattern of gross primary production (GPP). We therefore evaluated the temporal variation in phosphate (PO43−) and ammonium (NH4+) uptake at a daily scale in a highly-productive Pampean stream that is dominated by a dense assemblage of macrophytes and filamentous algae. We conducted 6 slug additions of PO43− and NH4+ over a 24-h period and quantified reach-scale nutrient uptake concurrently with measurements of whole-stream metabolism and chemical variables during additions (including nitrates and nitrites). The study stream had extremely high uptake of PO43− and NH4+ (>90 and >75% retention of the P and N mass added, respectively). Uptake of PO43− did not vary throughout the day. Estimated PO43− uptake from GPP accounted for only a small fraction of observed PO43− uptake. Thus, another mechanism, such as heterotrophic demand by microbial assemblages or adsorption onto sediments, could also have contributed to PO43− uptake in the study stream. In contrast, NH4+ uptake clearly varied throughout the day. Up to 48% of the observed NH4+ uptake rate could be explained by NH4+ estimated from GPP, and NH4+ demand was positively associated with GPP, indicating a high dependence on photoautotrophic demand. An increase of nitrite (NO2−) concentration during additions (representing up to 70% of the added mass of NH4+) suggests that nitrification contributed to the diel pattern of NH4+ uptake. Our results indicate that nutrient uptake does not always rely on autotrophic demand in open-canopy streams and that other abiotic and dissimilatory mechanisms may explain the diel patterns of nutrient retention. In addition, our study highlights the need to measure uptake metrics throughout the day to obtain an accurate estimate of nutrient retention on a daily scale. [ABSTRACT FROM AUTHOR]

Questions: To what extent does the long‐term process of grassland succession reflect changes in nutrient availability or other effects of grassland history? Plant communities in ancient, semi‐natural pastures include many species associated with nutrient‐poor soils. However, semi‐natural pasture communities can also develop on previously arable sites — as nutrient levels decline over time. In Europe, Ellenberg N‐values represent species' overall nutrient preferences and are often used as a proxy for soil nutrient availability. But how well do N‐values actually reflect species' relationships with measured nutrient concentrations during grassland succession? Location: A successional series of grazed, previously arable to ancient, grasslands on the Baltic island of Öland, Sweden. Methods: We collected data on community composition and soil nutrient (phosphorus, ammonium, nitrate) concentrations. We used Bayesian joint‐community modelling to parameterize species' relationships with nutrients and grassland age, and quantified the relative contributions of the variables. Species responses were then compared with Ellenberg N‐values. Results: Phosphorus was the best explanatory variable for most species. However, species occurrences were not simply explained by gradients in particular nutrients, but by combinations of different nutrients and grassland age. There was overall agreement between N‐values and species' nutrient responses — although the occurrences of species with identical N‐values may be explained by different nutrients. Species with high and low N‐values represent more reliable nutrient indicators than intermediate‐N species, but their occurrences also reflect other factors that, as with nutrients, depend on the grassland age. Conclusions: Our results confirm that Ellenberg N provides a robust indication of the overall nutrient preferences of individual grassland species. However, in grassland sites developing on previously arable land — where nutrient availability is strongly associated with habitat age — N‐values may represent an integrated response not only to nutrients but also to other historical processes that drive grassland community assembly. [ABSTRACT FROM AUTHOR]

A new bacterium capable of heterotrophic nitrogen removal was isolated and identified as Oligella sp. XS68. The strain exhibited efficient heterotrophic nitrogen removal capabilities, with a low accumulation of nitrification products. Single-factor experiments indicated that efficient nitrogen removal and growth of the strain XS68 occurred with sodium succinate as the carbon source, C/N ratio 15, pH 6.0-9.0, temperature 30-37 °C, and shaking speed 160-200 rpm. The removal efficiency of ammonium nitrogen could achieve 98 % within 96 h when the initial nitrogen concentration was 421.3 mg L-1. These findings demonstrate that XS68 is a promising candidate for nitrogen removal in wastewater treatments. [ABSTRACT FROM AUTHOR]

A shift has been predicted in future nitrogen emission scenarios from nitrous oxide to higher proportions of ammonium compounds. To investigate the interaction between increasing nitrogen load and varying nitrate:ammonium ratios (NO3−:NH4+), we performed a mesocosm experiment in an oligotrophic lake in southern Germany. We fertilized mesocosms with both roughly natural and four times the natural nitrogen wet deposition amounts in molar NO3−:NH4+ ratios of 4:1 and 1:4. We observed greater phytoplankton biomass in treatments with a relatively higher ammonium supply, but not in those with nitrate and total nitrogen load. Ammonium significantly increased the total chlorophyll a concentrations, and especially the growth of small nanophytoplankton species. The effects observed indicate that NH4+ was taken up preferentially and that spring phytoplankton in oligotrophic lakes appear to be able to respond to variations in nitrogen forms (available NO3−:NH4+ ratios) by adjusting their community composition. Such communal changes at the base of the food web may affect higher trophic levels. Therefore, the effects of varying available forms of nitrogen should also be considered in primarily phosphorus-limited aquatic systems. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox), a promising technology for bio-nitrogen removal, has been a research hotspot in the field of leachate treatment. However, the inhibitory effect of organic matter and high-strength nitrogen on anammox bacteria and the limitation of the theoretical total nitrogen removal efficiency of anammox (<90%) are obstacles to its wider application. The mechanisms of the inhibitory effects of organic matter, ammonium, and nitrite on anammox bacteria, and the corresponding control strategies are summaries. The anammox-based processes developed for advanced nitrogen removal (ANR) in recent years, including anammox-based heterotrophic denitrification, anammox-based partial denitrification, and anammox-based constructed wetlands are systematically discussed. An integrated anaerobic system of simultaneous denitrification and methanogenesis (anaerobic membrane bioreactor) + anammox-based processes was proposed for the ANR and optimal energy recovery from leachate. This process showed a 16% increase in biogas yield, a 64% decrease in aeration energy consumption, and the decrease in the external carbon source is expected to be 100% compared to conventional leachate treatment processes such as anoxic/oxic-membrane bioreactors. Finally, a few research perspectives on leachate treatment using anammox-based processes are reviewed. The conclusions drawn from the studies presented herein provide guidance for further research and engineering applications in the field of leachate treatment. AnMBR pretreatment is proposed for energy recovery and elimination of inhibition of anammox bacteria by organics. Anammox-based heterotrophic denitrification, partial denitrification, and anammox-based constructed wetlands are discussed for ANR. SDM is proposed for ANR from leachate via anammox effluent recirculation. An SDM(AnMBR)+anammox based process is proposed for energy saving and recovery. [ABSTRACT FROM AUTHOR]

Recent studies have shown that invasive earthworms can dramatically reduce native biodiversity, both above and below the ground. However, we still lack a synthetic understanding of the underlying mechanisms behind these changes, such as whether earthworm effects on soil chemical properties drive such relationships. Here, we investigated the effects of invasive earthworms on soil chemical properties (pH, water content, and the stocks and fluxes of carbon, nitrogen, and phosphorus) by conducting a meta‐analysis. Invasive earthworms generally increased soil pH, indicating that the removal of organic layers and the upward transport of more base‐rich mineral soil caused a shift in soil pH. Moreover, earthworms significantly decreased soil water content, suggesting that the burrowing activities of earthworms may have increased water infiltration of and/or increased evapotranspiration from soil. Notably, invasive earthworms had opposing effects on organic and mineral soil for carbon and nitrogen stocks, with decreases in organic, and increases in mineral soil. Nitrogen fluxes were higher in mineral soil, whereas fluxes in organic soil were not significantly affected by the presence of invasive earthworms, indicating that earthworms mobilize and redistribute nutrients among soil layers and increase overall nitrogen loss from the soil. Invasive earthworm effects on element stocks increased with ecological group richness only in organic soil. Earthworms further decreased ammonium stocks with negligible effects on nitrate stocks in organic soil, whereas they increased nitrate stocks but not ammonium stocks in mineral soil. Notably, all of these results were consistent across forest and grassland ecosystems underlining the generality of our findings. However, we found some significant differences between studies that were conducted in the field (observational and experimental settings) and in the lab, such as that the effects on soil pH decreased from field to lab settings, calling for a careful interpretation of lab findings. Our meta‐analysis provides strong empirical evidence that earthworm invasion may lead to substantial changes in soil chemical properties and element cycling in soil. Furthermore, our results can help explain the dramatic effects of invasive earthworms on native biodiversity, for example, shifts towards the dominance of grass species over herbaceous ones, as shown by recent meta‐analyses. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an essential macronutrient for crops. Plants have developed several responses to N fluctuations, thus optimizing the root architecture in response to N availability. Nitrate and ammonium are the main inorganic N forms taken up by plants, and act as both nutrients and signals, affecting gene expression and plant development. In this study, RNA-sequencing was applied to gain comprehensive information on the pathways underlying the response of maize root, pre-treated in an N-deprived solution, to the provision of nitrate or ammonium. The analysis of the transcriptome shows that nitrate and ammonium regulate overlapping and distinct pathways, thus leading to different responses. Ammonium activates the response to stress, while nitrate acts as a negative regulator of transmembrane transport. Both the N-source repress genes related to the cytoskeleton and reactive oxygen species detoxification. Moreover, the presence of ammonium induces the accumulation of anthocyanins, while also reducing biomass and chlorophyll and flavonoids accumulation. Furthermore, the later physiological effects of these nutrients were evaluated through the assessment of shoot and root growth, leaf pigment content and the amino acid concentrations in root and shoot, confirming the existence of common and distinct features in response to the two nitrogen forms. [ABSTRACT FROM AUTHOR]

A new bacterium capable of heterotrophic nitrogen removal was isolated and identified as Oligella sp. XS68. The strain exhibited efficient heterotrophic nitrogen removal capabilities, with a low accumulation of nitrification products. Single-factor experiments indicated that efficient nitrogen removal and growth of the strain XS68 occurred with sodium succinate as carbon source, C/N ratio 15, pH 6.0-9.0, temperature 30-37 °C, and shaking speed 160-200 rpm. The ammonium nitrogen removal efficiency could achieve 98% within 96 h when the initial nitrogen concentration was 421.3 mgL-1. These findings demonstrate that XS68 was a promising candidate for nitrogen removal in wastewater treatments. [ABSTRACT FROM AUTHOR]

Excessive nitrogen (N) deposition can impact lichen diversity in forest ecosystems, and this is a particular situation in China. Here, we examined the N uptake, assimilation, and the impact of excessive N deposition on the symbiotic balance of dominant epiphytic lichens in the subtropical forests in the Mts. Shennongjia of central China. The results show that lichen species took up, assimilated and utilized more ammonium than nitrate in a species‐specific way, following the increase of N availability. The photobiont of the lichens decreased with the increase of N concentration following an initial increase, while the mycobiont response to the N addition was not apparent. Considerable variation in response to excessive N deposition exists among the lichen species. Usnea longissima could regulate its N uptake, resulting in a stable photobiont‐mycobiont ratio among N treatments. In contrast, the photobiont‐mycobiont ratio of other four lichens increased initially but decreased when N concentration exceeded a certain level, and N stress may have broken the balance between photobiont and mycobiont of these lichens. Our results suggest that most epiphytic lichens in subtropical forest of central China could uptake and assimilate more ammonium than nitrate and that the balance between photobiont and mycobiont of many epiphytic lichens might change with the increasing N deposition load, which could impact the lichen diversity of this forest ecosystem. [ABSTRACT FROM AUTHOR]

To assess the contribution of reactive nitrogen from groundwater to surface waters, we need more knowledge on how reactive nitrogen behaves in the glacial till systems underlying many agricultural fields. Groundwater sampled from suction cups and piezometers placed in the glacial till underlying a winter wheat field shows the nitrate concentration in water leaching to deeper than 2 m below ground surface (mbg) is ~ 60 mg L−1. Within 5 mbg, all of the nitrate is removed and this appears to take place within a redox zone rather than at a sharp redox front. Ammonium released from the till is negligible. A 2D dataset reveals that the depth to the redox zone undulates between 3 and 5 mbg, perhaps a result of local variations in infiltration. It appears that the nitrate is generally reduced by the oxidation of pyrite and locally by organic matter in lenses within the till. [ABSTRACT FROM AUTHOR]

Coexistence between trees and grasses in savannas is generally assumed to be due to a combination of partial niche separation for water acquisition and disturbances impacting the demography of trees and grasses. We propose a mechanism of coexistence solely based on the partitioning of the two dominant forms of mineral nitrogen (N), ammonium (NH4+) and nitrate (NO3−). We built a mean-field model taking into account the capacity of grasses and trees to alter nitrification fluxes as well as their relative preferences for NH4+ versus NO3−. Two models were studied and parameterized for the Lamto savanna (Côte d'Ivoire): In the first model, the nitrification only depends on the quantity of available NH4+, and in the second model the nitrification rate is also controlled by tree and grass biomass. Consistent with coexistence theories, our results show that taking these two forms of mineral N into account can allow coexistence when trees and grasses have contrasting preferences for NH4+ and NO3−. Moreover, coexistence is more likely to occur for intermediate nitrification rates. Assuming that grasses are able to inhibit nitrification while trees can stimulate it, as observed in the Lamto savanna, the most likely case of coexistence would be when grasses prefer NH4+ and trees NO3−. We propose that mineral N partitioning is a stabilizing coexistence mechanism that occurs in interaction with already described mechanisms based on disturbances by fire and herbivores. This mechanism is likely relevant in many N-limited African savannas with vegetation composition similar to the one at the Lamto site, but should be thoroughly tested through empirical studies and new models taking into account spatiotemporal heterogeneity in nitrification rates. [ABSTRACT FROM AUTHOR]

• Denitrification alone does not govern N removal in woodchip and coconut husk bioreactors. • Substantial N removal can be achieved via the anammox pathway. • Relative contributions of denitrification and anammox vary between media types used. • Anammox becomes more dominant when denitrification is carbon limited. Denitrification has been considered the main pathway converting nitrate (NO 3 –) to dinitrogen gas (N 2) in denitrifying bioreactors. Here, the importance of an alternative nitrogen (N) removal process, namely anaerobic ammonium oxidation (anammox), was assessed by monitoring the removal of N species from partially nitrified municipal wastewater passing through fifteen mesocosm scale (∼700 L) bioreactors containing woodchip, coconut husk or gravel during their initial and eighth year of operation. Additionally, lab experiments using a 15N isotope-pairing technique were performed to partition production of N 2 to these different microbial processes. The effective removal of both NO 3 – and ammonium (NH 4 +) and the formation of hybrid N 2 (i.e. 29N 2) observed in this study demonstrated that, along with denitrification, anammox was an effective pathway for N removal when both NO 3 – and NH 4 + were present. Anammox removal rates ranged from 0.6 to 3.8 g N per m3 per day, while denitrification rates ranged from 0.7 to 2.6 g N per m3 per day. The contributions of anammox to N removal was dependent on media, with anammox becoming more dominant in bioreactors where denitrification was carbon limited. Designing denitrifying bioreactors to support both denitrification and anammox expands the utility of these passive approaches for improving treatment of wastewater. [ABSTRACT FROM AUTHOR]

Nitrification inhibitors (NIs), DCD (dicyandiamide), and DMPP (3,4‐dimethylpyrazole phosphate), in combination with urea (UR) and ammonium sulfate nitrate (ASN) fertilizers were studied under contrasting soil textures (sand, loam, and clay) from cultivated soils collected in Brazil and Germany. Soil samples were incubated over 50 days and the content of ammonium (N-NH4+), nitrate (N-NO3-), and soil pH were measured periodically. Applied NIs delayed the nitrification process across all soil textures. Correlation analysis indicated that combining ASN with NIs resulted in higher NH4+ content and efficiency in delaying the nitrification process with high N‐conversion rate (r = –0.82). The combination of ASN+ DMPP increased the efficiency of the N‐conversion rate (r = –0.86) due to H+ release in soil, while UR+DCD (r = –0.50) had an efficiency of the N‐conversion rate similar to UR (r = –0.42). All the NIs had a better performance in reducing N-NO3- formation in sandy soils as compared to the loam and clay textured soils. Use of DMPP with an N fertilizer results in a soil pH decrease and can be an option to increase the efficiency of the N‐conversion rate, reducing N losses in soil. Overall, our results suggest that NIs have a better performance in reducing N-NO3- formation in sandy soils as compared to that of the loam and clay textured soils. Use of DMPP with ASN results in a soil pH decrease and can be an option to reduce N losses in soil. [ABSTRACT FROM AUTHOR]

Nitrogen is an essential nutrient for yeast during alcoholic fermentation. Nitrogen is involved in the biosynthesis of protein, amino acids, nucleotides, and other metabolites, including volatile compounds. However, recent studies have called several mechanisms that regulate its role in biosynthesis into question. An initial focus on S. cerevisiae has highlighted that the concept of "preferred" versus "non-preferred" nitrogen sources is extremely variable and strain-dependent. Then, the direct involvement of amino acids consumed in the formation of proteins and volatile compounds has recently been reevaluated. Indeed, studies have highlighted the key role of lipids in nitrogen regulation in S. cerevisiae and their involvement in the mechanism of cell death. New winemaking strategies using non- Saccharomyces yeast strains in co- or sequential fermentation improve nitrogen management. Indeed, recent studies show that non- Saccharomyces yeasts have significant and specific needs for nitrogen. Moreover, sluggish fermentation can occur when they are associated with S. cerevisiae , necessitating nitrogen addition. In this context, we will present the consequences of nitrogen addition, discussing the sources, time of addition, transcriptome changes, and effect on volatile compound composition. • State of the art regarding nitrogen influence on wine alcoholic fermentation. • Preferential and non-preferential nitrogen sources for S. cerevisiae and non-Saccharomyces. • Interactions between lipid and nitrogen metabolism. • Summary of contradictory results regarding the effect of nitrogen addition in must. • Synthesis of the influence of nitrogen addition on volatile compounds production. [ABSTRACT FROM AUTHOR]

A dynamic analysis approach for determining nitrite production and consumption rates was established to systematically investigate the characteristics of nitrogen transformation and N 2 O emission of the completely autotrophic nitrogen removal over nitrite (CANON) process coupled with denitrification using a sequencing batch biofilm reactor (SBBR). The results indicate that anaerobic ammonium-oxidizing bacteria was not inhibited significantly by low C/N ratios. There were no obvious differences in the nitrite production rate, nitrite consumption rate or nitrogen removal among reactors operated with C/N ratios of 0, 0.67 and 1.00, which suggested that the certain carbon source did not significantly affect the nitrite conversion and nitrogen removal in the process. More than 60% of total N 2 O emission is generated during the initial phase of each period in the SBBR. More than 94.5% of N 2 O was generated by NO 2 −-N consumption via denitrification in the process. Interestingly, total N 2 O production drops by 16.7%, when the C/N ratio increases from 0 to 1. This phenomenon may be caused by the inhibition of N 2 O production via AOB denitrification. Therefore, an appropriate carbon source (C/N = 1.00) has the beneficial effect of reducing N 2 O emission by CANON coupled with denitrification. The results of this study provide an important empirical foundation for the mitigation of N 2 O emission in the CANON process coupled with denitrification. Image 1 • N conversion and N 2 O emission were investigated in a CANON coupled with DN process. • AOB and AnAOB were not inhibited significantly by low C/N ratios. • Low C/N ratios did not evidently affect nitrite conversion and nitrogen removal. • More than 94.5% of N 2 O was generated by NO 2 −-N consumption via denitrification. • The C/N ratio should be maintained at 1.00 for the N 2 O emission reduction. [ABSTRACT FROM AUTHOR]

The release of ammonia (as NH 4 +) into water bodies causes serious environmental problems. Therefore, the removal of ammonia from wastewater effluents has become a worldwide concern. New autotrophic biological alternatives for ammonia removal could reduce the limitations of conventional organic carbon-dependent nitrification-denitrification methods. Here, the potential of anaerobic ammonium oxidation coupled to Fe3+ reduction (a process known as Feammox) is studied in wastewater treatment plants of the yeast and beer production industry, not related to ammonium or iron treatment. This process is presented as a viable option to improve the efficiency of ammonia removal from wastewater. The results of this study show that enrichments under Feammox conditions achieved removals of 28.19–32.25% of the total NH 4 +. The highest rates of ammonium removal and Fe3+ reduction were achieved using FeCl 3 as iron source and pH = 7.0. Different environmental conditions for the enrichments were studied and it was found that the use of sodium acetate as a carbon source and an incubation temperature of 35 °C presented higher rates of iron reduction and higher increase in nitrate concentration, related to ammonium oxidative processes. Likewise, the presence of relevant species of the iron and nitrogen cycles as Ferrovum myxofaciens, Geobacter spp , Shewanella spp , Albidiferax ferrireducens and Anammox was verified, supporting the findings of this study. These results provide information that may be relevant to the potential applicability of Feammox to treat wastewater with high ammonia load and could help develop cost-effective and environmentally friendly methods for ammonium removal in wastewater treatment plants. [Display omitted] • Feammox microorganisms were enriched from anaerobic sewage sludge. • NH 4 + removal of 32% in enrichments from inoculums not related to N and Fe processes. • FeCl 3 as Fe3+ source showed the highest NH 4 +/Fe3+ oxidation/reduction rates. • Functional genes and Feammox-related bacteria were found in enrichments. • ASVs relative to Campylobacterota and Proteobacteria increased in enrichments. [ABSTRACT FROM AUTHOR]

• Both SMX and N-SMX exposure inhibited denitrification and DNRA rates in a short time. • Denitrification and DNRA rates recovered under SMX/N-SMX exposure in a long time. • The removal of nitrogen, SMX, and N-SMX can be achieved simultaneously. • Nitrogen-reducing bacteria that also degrade antibiotics were detected. Constructed wetlands (CWs) are increasingly used to treat complex pollution such as nitrogen and emerging organic micropollutants from anthropogenic sources. In this study, the denitrification, anaerobic ammonium oxidation, dissimilatory nitrate reduction to ammonium, and nitrous oxide release rates following exposure to the frequently detected sulfonamides sulfamethoxazole (SMX) and its human metabolite, N-acetylsulfamethoxazole (N-SMX), were investigated in lab-scale CWs. Over a period of 190 d, the denitrification rates were noticeably inhibited in the SMX and N-SMX groups at week 5. Subsequently, the denitrification rates recovered, accompanied by an increase in the relevant nitrogen reduction and antibiotic resistance genes (ARGs). The composition of the microbial community also changed during this process. After the denitrification rates recovered, Burkholderia _ Paraburkholderia and Gordonia exhibited a significant positive correlation with SMX exposure, which simultaneously reduced nitrate concentrations and degraded antibiotics. Burkholderia _ Paraburkholderia is a key carrier of ARGs. Finally, nitrogen reduction (> 90%) and antibiotic removal (> 80%) also recovered in both SMX- and N-SMX-exposed lab-scale CWs during the operation, which revealed the interaction of SMX or N-SMX removal and nitrogen reduction. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Isolated a bacterial consortium to enable P recovery. • Nitrate is participate in phosphorus bio-recovery process. • Different N species has little influence on the characteristics of products. • Acinetobacter genus dominates phosphorus recovery in different nitrogen species. Recovering finite and non-substitutable phosphorus from liquid waste streams through bio-mediated techniques has attracted increasing interest, but current approaches are incredibly dependent on ammonium. Herein, a process to recover phosphorus from wastewater under multiple nitrogen species conditions was developed. This study compared the effects of nitrogen species on the recovery of phosphorus resources by a bacterial consortium. It found that the consortium could not only efficiently utilize ammonium to enable phosphorus recovery but also utilize nitrate via dissimilatory nitrate reduction to ammonium (DNRA) to recover phosphorus. The characteristics of the generated phosphorus-bearing minerals, including magnesium phosphate and struvite, were evaluated. Furthermore, nitrogen loading positively influenced the stability of the bacterial community structure. The genus Acinetobacter was dominant under nitrate and ammonium conditions, with a relatively stable abundance of 89.01% and 88.54%, respectively. The finding may provide new insights into nutrient biorecovery from phosphorus-containing wastewater contaminated with multiple nitrogen species. [ABSTRACT FROM AUTHOR]

In this study the effects of nitrogen efluent from a permeable constructed sewage tank on groundwater quality were investigated. Sampling took place before and 1.5 years after the closure. Using a 3D hydrogeological model, the spatial distribution of dissolved inorganic nitrogen (DIN), comprising the species NH4+, NO2- and NO3-, was modelled in the saturated zone and the amounts and changes in the ratio of NH4-N, NO2-N, NO3-N were determined. The first part of our general hypothesis, that the groundwater was heavily contaminated in the area surrounding the sewage tank, was clearly verified, since every investigated nitrogen compound exceeded the contamination limit values; but the second part of our hypothesis, that the degree of contamination would significantly decrease after the sewage tank was taken out of use has not been confirmed, since the amount of nitrogen present in inorganic forms increased in the modelled zone. The increase in DIN and the relatively high concentration of NH4+ (35 mg/L) in the immediate vicinity of the tank can be explained by the fact that organic matter (OM) accumulated over the decades provided a constant supply of inorganic nitrogen forms. [ABSTRACT FROM AUTHOR]

Summary: In legumes, nitrogen (N) can be stored as ureide allantoin and transported by ureide permease (UPS) from nodules to leaves where it is catabolized to release ammonium and assimilation to amino acids. In non‐leguminous plants especially rice, information on its roles in N metabolism is scarce. Here, we show that OsUPS1 is localized in plasma membranes and are highly expressed in vascular tissues of rice. We further evaluated an activation tagging rice overexpressing OsUPS1 (OsUPS1OX) under several N regimes. Under normal field conditions, panicles from OsUPS1OX plants (14 days after flowering (DAF)) showed significant allantoin accumulation. Under hydroponic system at the vegetative stage, plants were exposed to N‐starvation and measured the ammonium in roots after resupplying with ammonium sulphate. OsUPS1OX plants displayed higher ammonium uptake in roots compared to wild type (WT). When grown under low‐N soil supplemented with different N‐concentrations, OsUPS1OX exhibited better growth at 50% N showing higher chlorophyll, tiller number and at least 20% increase in shoot and root biomass relative to WT. To further confirm the effects of regulating the expression of OsUPS1, we evaluated whole‐body‐overexpressing plants driven by the GOS2 promoter (OsUPS1GOS2) as well as silencing plants (OsUPS1RNAi). We found significant accumulation of allantoin in leaves, stems and roots of OsUPS1GOS2 while in OsUPS1RNAi allantoin was significantly accumulated in roots. We propose that OsUPS1 is responsible for allantoin partitioning in rice and its overexpression can support plant growth through accumulation of allantoin in sink tissues which can be utilized when N is limiting. [ABSTRACT FROM AUTHOR]

• A Capsicum cultivar with higher fruit set and lower fruit size is less affected by excess N. • Vegetative and reproductive organs play important roles in responses to N supply. • Reproductive sink strength is an important factor for plant tolerance to NH 4 + toxicity. Yield-related traits of Capsicum chinense are highly dependent on coordination between vegetative and reproductive growth, since the formation of reproductive tissues occurs iteratively in new sympodial bifurcations. In this study, we used two C. chinense cultivars (Biquinho and Habanero), contrasting for fruit size and fruit set, to investigate the responses of nitrogen (N) deficiency and excess on growth, photosynthesis, carbon (C) and N metabolisms as well as yield-related traits. Both cultivars increased biomass allocation to leaves in conditions of higher N supply and exhibited a parabolic behavior for fruit biomass allocation. Plants growing under N-deficiency produced a lower number of flowers and heavier fruits. Contrarily, plants under high N condition tended to decrease their CO 2 assimilation rate, harvest index and fruit weight. Biquinho, the cultivar with lower fruit size and higher fruit set, was initially less affected by excess of N due to its continuous formation of new reproductive sinks in relation to Habanero (which has lower fruit set and higher fruit size). The results suggest that N amount influences sucrose supply to different organs and can differentially affect yield-related traits between Capsicum cultivars with contrasting source-sink relations. [ABSTRACT FROM AUTHOR]

Biological nitrogen fixation (BNF) is controlled by intricate regulatory mechanisms to ensure that fixed nitrogen is readily assimilated into biomass and not released to the environment. Understanding the complex regulatory circuits that couple nitrogen fixation to ammonium assimilation is a prerequisite for engineering diazotrophic strains that can potentially supply fixed nitrogen to non-legume crops. In this review, we explore how the current knowledge of nitrogen metabolism and BNF regulation may allow strategies for genetic manipulation of diazotrophs for ammonia excretion and provide a contribution towards solving the nitrogen crisis. [ABSTRACT FROM AUTHOR]

Highlights • Laboratory experiments were made to study the NH 4 -carrier phase detected on Ceres. • An ammoniation technique was tested on ten different phyllosilicate samples. • The ammonium treated samples were analysed by means of VIS-NIR spectroscopy. • Only the smectite samples incorporated the ammonium ion in their structure. • A scenario for the thermal evolution of a smectite-bearing surface is presented. Abstract The identification of NH 4 -bearing phyllosilicates on Ceres poses the question on the NH 4 -carrier phase(s) and in this study we describe the laboratory production and IR spectroscopic measurements of a suite of ten NH 4 -phyllosilicates, starting from the corresponding NH 4 -free minerals. For each mineral, we prepared three types of powder samples: raw (R), ammoniated (A), and leached (L). All samples have been spectrally characterized by means of visible/infrared spectroscopy in the INAF-IAPS laboratories with the FieldSpec Pro in the 0.35–2.5 µm range, and with the FT-IR, using a Vertex 80 spectrometer operating in the range of 2–14 µm. The samples were also measured with the SPectral IMager, an imaging spectrometer operating in the spectral range 0.2–5.1 µm, which is a replica of the VIR spectrometer on-board Dawn spacecraft. Reflectance spectra of the ammoniated clays show bands near 1.56 µm, 2.05 µm, 2.12 µm, 3.06 µm, 3.25 µm, 3.55 µm, 4.2 µm, 5.7 µm and 7.0 µm that are related to the presence of nitrogen complexes. Treatment of phyllosilicates with ammonia shows that different minerals behave in different ways: NH 4 + ions are easily accepted by the smectites, while other non-expandable structures do not accept these ions. The obtained results can be used to better constrain the NH 4 -bearing species present on Ceres and, possibly, other bodies of the solar system. [ABSTRACT FROM AUTHOR]

Abstract More than half of the applied conventional fertiliser nitrogen (N) in cropping systems can be lost to the environment, resulting in water and air pollution. Farming systems that ensure efficient fertiliser use are crucial to sustain crop productivity without harming the environment. One avenue to achieve this is the use of bio-fertilisers with recognised benefits for plant nutrition and soil heath. Within this area, plant growth promoting rhizobacteria (PGPR) are increasingly applied to enhance plant nutrient acquisition and assimilation. Here, we investigated if PGPR can improve fertiliser performance. We show that the addition of PGPR to soils amended with 50% organic and 50% conventional N fertilisers increased the growth of kikuyu grass (Pennisetum clandestinum), producing yields similar to those obtained using 100% conventional N fertiliser. Encouragingly, this combination also reduced mineral N leaching by 95% relative to the all conventional fertiliser treatment. These findings suggest that using organic and synthetic fertilisers together in the presence of PGPR is a promising approach for sustaining plant growth while reducing potential pollution from inefficient use of conventional N fertilisers. Graphical abstract Image 1 Highlights • The PGPR tested had little effects when applied with organic fertiliser alone. • PGPR improved plant growth and N uptake when applied together with inorganic and organic fertilisers. • Combined use of fertilisers and PGPR decreased N loss from fertilisers. [ABSTRACT FROM AUTHOR]