Natural Nitrogen Sources Research Articles

Nitrogen fertilizers activate siderophore production by the common scab causative agent Streptomyces scabiei.

Streptomyces scabiei is the causative agents of common scab on root and tuber crops. Life in the soil imposes intense competition between soil-dwelling microorganisms and we evaluated here the antimicrobial properties of S. scabiei. Under laboratory culture conditions, increasing peptone levels correlated with increased growth inhibitory properties of S. scabiei. Comparative metabolomics showed that production of S. scabiei siderophores (desferrioxamines, pyochelin, scabichelin and turgichelin) increased with the quantity of peptone thereby suggesting that they participate in growth inhibition. Mass spectrometry imaging further confirmed that the zones of secreted siderophores and growth inhibition coincided. Moreover, either the repression of siderophore production or the neutralization of their iron-chelating activity both led to increased microbial growth. Replacement of peptone by natural nitrogen sources regularly used as fertilizers such as ammonium nitrate, ammonium sulfate, sodium nitrate, and urea also triggered siderophore production in S. scabiei. The observed effect is not mediated by alkalinization of the medium as increasing the pH without providing additional nitrogen sources did not induce siderophore production. The nitrogen-induced siderophore production also inhibited the growth of important plant pathogens. Overall, our work suggests that not only the iron availability but also the nitrogen fertilizer sources could significantly impact the competition for iron between crop-colonizing microorganisms.

Reaction Discovery Using Spectroscopic Insights from an Enzymatic C-H Amination Intermediate.

Engineered hemoproteins can selectively incorporate nitrogen from nitrene precursors like hydroxylamine, O-substituted hydroxylamines, and organic azides into organic molecules. Although iron-nitrenoids are often invoked as the reactive intermediates in these reactions, their innate reactivity and transient nature have made their characterization challenging. Here we characterize an iron-nitrosyl intermediate generated from NH2OH within a protoglobin active site that can undergo nitrogen-group transfer catalysis, using UV-vis, electron paramagnetic resonance (EPR) spectroscopy, and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) techniques. The mechanistic insights gained led to the discovery of aminating reagents─nitrite (NO2-), nitric oxide (NO), and nitroxyl (HNO)─that are new to both nature and synthetic chemistry. Based on the findings, we propose a catalytic cycle for C-H amination inspired by the nitrite reductase pathway. This study highlights the potential of engineered hemoproteins to access natural nitrogen sources for sustainable chemical synthesis and offers a new perspective on the use of biological nitrogen cycle intermediates in biocatalysis.

Competition Indices and Economic Benefits of Winter Wheat and Winter Peas in Mixed Cropping

Intensive wheat production, which produces high yields through the excessive use of chemical inputs and non-renewable energy, is unsustainable in the long term. Innovative cultivation methods such as intercropping can address emerging challenges. This kind of plant association offers the possibility of achieving a balanced yield with the use of a natural nitrogen source. An experiment was conducted for three growing seasons (2020/2021, 2021/2022, 2022/2023) with a combination of three winter wheat varieties (GK Szilárd, Cellule, GK Csillag) and a winter pea variety (Aviron) in three sowing densities to determine the species interaction and the economics of mixed plots. The intercropping systems were evaluated in terms of the land equivalent ratio (LER), aggressivity (A), competitive ratio CR), actual yield loss (AYL), monetary advantage index (MAI), and intercropping advantage (IA). In almost all mixtures, the values of partial A, CR, and AYL indicated that wheat was more competitive than peas due to the overconcentration of mixtures. For MAI, the mixture Cellule/Aviron 75:50 was more profitable than the others in the first two years. Our results draw attention to the influence of the seeding rate, which can contribute to new directions for current research.

Overexpression of GmPAP4 Enhances Symbiotic Nitrogen Fixation and Seed Yield in Soybean under Phosphorus-Deficient Condition.

Legume crops establish symbiosis with nitrogen-fixing rhizobia for biological nitrogen fixation (BNF), a process that provides a prominent natural nitrogen source in agroecosystems; and efficient nodulation and nitrogen fixation processes require a large amount of phosphorus (P). Here, a role of GmPAP4, a nodule-localized purple acid phosphatase, in BNF and seed yield was functionally characterized in whole transgenic soybean (Glycine max) plants under a P-limited condition. GmPAP4 was specifically expressed in the infection zones of soybean nodules and its expression was greatly induced in low P stress. Altered expression of GmPAP4 significantly affected soybean nodulation, BNF, and yield under the P-deficient condition. Nodule number, nodule fresh weight, nodule nitrogenase, APase activities, and nodule total P content were significantly increased in GmPAP4 overexpression (OE) lines. Structural characteristics revealed by toluidine blue staining showed that overexpression of GmPAP4 resulted in a larger infection area than wild-type (WT) control. Moreover, the plant biomass and N and P content of shoot and root in GmPAP4 OE lines were also greatly improved, resulting in increased soybean yield in the P-deficient condition. Taken together, our results demonstrated that GmPAP4, a purple acid phosphatase, increased P utilization efficiency in nodules under a P-deficient condition and, subsequently, enhanced symbiotic BNF and seed yield of soybean.

Nitrogen sources enhance siderophore-mediated competition for iron between potato common scab and late blight causative agents.

How do pathogens affecting the same host interact with each other? We evaluated here the types of microbe-microbe interactions taking place between Streptomyces scabiei and Phytophthora infestans, the causative agents of common scab and late blight diseases in potato crops, respectively. Under most laboratory culture conditions tested, S. scabiei impaired or completely inhibited the growth of P. infestans by producing either soluble and/or volatile compounds. Increasing peptone levels correlated with increased inhibition of P. infestans. Comparative metabolomics showed that production of S. scabiei siderophores (desferrioxamines, pyochelin, scabichelin, and turgichelin) increased with the quantity of peptone, thereby suggesting that they participate in the inhibition of the oomycete growth. Mass spectrometry imaging further uncovered that the zones of secreted siderophores and of P. infestans growth inhibition coincided. Moreover, either the repression of siderophore production or the neutralization of their iron-chelating activity led to a resumption of P. infestans growth. Replacement of peptone by natural nitrogen sources such as ammonium nitrate, sodium nitrate, ammonium sulfate, and urea also triggered siderophore production in S. scabiei. Interestingly, nitrogen source-induced siderophore production also inhibited the growth of Alternaria solani, the causative agent of the potato early blight. Overall, our work further emphasizes the importance of competition for iron between microorganisms that colonize the same niche. As common scab never alters the vegetative propagation of tubers, we propose that S. scabiei, under certain conditions, could play a protective role for its hosts against much more destructive pathogens through exploitative iron competition and volatile compound production.

The impact of Klebsiella quasipneumoniae inoculation with nitrogen fertilization on baby corn yield and cob quality

In response to the escalating costs and diminishing efficiency of nitrogen fertilizers, the agricultural community is actively seeking sustainable alternatives that leverage natural nitrogen sources derived from biological N-fixation processes to enhance crop yield. This study investigates the combined effects of Klebsiella quasipneumoniae inoculation and varying nitrogen fertilizer doses on soil fertility, nutrient availability, and the yield and quality parameters of baby corn (Zea mays. L). The study involved the application of five nitrogen levels (0, 75, 150, 225, and 300 kg N ha-1) in conjunction with Klebsiella quasipneumoniae inoculum on HM-4 variety of baby corn, employing a comprehensive experimental design with five treatments and four replications. All treatments demonstrated increased ear count and weights of ear, silk, husk, edible cob, and biomass compared to the control. The study highlights the potential of Klebsiella quasipneumoniae inoculation in synergy with reduced nitrogen fertilizer to enhance total N contents in soil and positively impact baby corn yield and cob quality parameters. Optimal results were achieved with a 50% reduction in nitrogen fertilizer (150 kg N ha-1), emphasizing the importance of integrated nutrient management. The findings contribute valuable insights to sustainable agriculture, offering a promising strategy for increased baby corn production, improved nutritional quality, and environmental conservation. This integrated approach, involving microbial inoculation and nitrogen management, emerges as a key element in modern agricultural practices, promoting both productivity and nutritional content in baby corn crops.

Biosynthesis of poly(β-L-malic acid) from rubberwood enzymatic hydrolysates in co-fermentation by Aureobasidium pullulans

Co-fermentation of multiple substrates has emerged as the most effective method to improve the yield of bioproducts. Herein, sustainable rubberwood enzymatic hydrolysates (RWH) were co-fermented by Aureobasidium pullulans to produce poly(β-L-malic acid) (PMA), and RWH + glucose/xylose was also investigated as co-substrates. Owing to low inhibitor concentration and abundant natural nitrogen source content of RWH, a high PMA yield of 0.45 g/g and a productivity of 0.32 g/L/h were obtained by RWH substrate fermentation. After optimization, PMA yields following the fermentation of RWH + glucose and RWH + xylose reached 59.92 g/L and 53.71 g/L, respectively, which were 52 % and 36 % higher than that after the fermentation of RWH. RWH + glucose more significantly affected the correlation between PMA yield and substrate concentration than RWH + xylose. The results demonstrated that the co-fermentation of RWH co-substrate is a promising method for the synthesis of bioproducts.

Unlocking the secrets of peptide transport in wine yeast: insights into oligopeptide transporter functions and nitrogen source preferences.

Limited nitrogen supply can prevent the completion of alcoholic fermentation. Supplementation through peptides as an alternative, natural source of nitrogen for yeast offers an interesting solution for this issue. In this work, the S. cerevisiae peptide transporters of the Opt and Fot families were studied. We demonstrated that Fot and Opt2 have a broader peptide length preference than previously reported, enabling yeasts to acquire sufficient nitrogen from peptides without requiring additional ammonia or amino acids to complete fermentation. On the contrary, Opt1 was unable to consume any peptide in the given conditions, whereas it has been described elsewhere as the main peptide transporter for peptides longer than three amino acid residues in experiments in laboratory conditions. This controversy signifies the need in applied sciences for approaching experimental conditions to those prevalent in the industry for its more accurate characterization. Altogether, this work provides further evidence of the importance of peptides as a nitrogen source for yeast and their consequent positive impact on fermentation kinetics.

Evaluation of the Development Process of Winter Wheat (Triticum aestivum L.) and Winter Pea (Pisum sativum L.) in Intercropping by Yield Components

The future of wheat production depends on our ability to adapt to changing growing conditions. It is expected that intercropping will be more emphasized where natural source of nitrogen may increase the resilience of cereals. Our investigation was made in two growing seasons (2020–2021, 2021–2022) with three winter wheat varieties (GK Szilárd, Cellule, GK Csillag) and a winter pea variety (Aviron) in Szeged-Öthalom. Each plot was 10 square meters in four repeats in randomized block design. We used a seed mixture of both species with three sowing densities. In this study, we represent a development process of two winter-sown species, then yield components evaluated by cumulative yield production analysis and multivariate regression. Mixtures were only beneficial for wheat in the case of GK Szilárd 50% and Aviron 75%, Cellule 75% and Aviron 100% (in 2021), Cellule 100% and Aviron 50% (in 2022), GK Csillag 75% and Aviron 50%. The yield was determined by the number and weight of grains in both species (and also number of pea pods). Knowledge of the development process of the companion plants is a key issue in creating an effective intercrop. This self-sustaining, low input and energy efficient cropping practice has a great potential in temperate areas.

PENGARUH JENIS SUMBER NITROGEN TERHADAP KARAKTERISTIK NATA DE SAGO

Nata is a biotechnology product that utilizes Acetobacter xylinum in the fermentation process. Making nata requires materials that contain carbohydrates and nitrogen. The raw materials for making nata generally use coconut water, fruit extracts, and sago waste. Sago liquid waste can be used because it contains starch as a carbon source to form polysaccharides. In addition to starch content, making nata also requires nitrogen supply. Increased nitrogen supply can increase the amount of polysaccharide formed. This study aims to determine the effect of giving different types of nitrogen sources, namely urea, ZA, and touge extract and control without the addition of nitrogen on the characteristics of nata de sago. This study used the RAL method (Completely Randomized Design) which consisted of 4 treatments and 3 repetitions. The results showed that the addition of 1.5 g of urea produced the best nata characteristics based on thickness, color, and aroma, but based on texture characteristics the best value was obtained in the bean sprout extract treatment. The results of this study become an alternative to the use of sago leachate as a raw material for making nata and an alternative to the use of natural nitrogen sources from bean sprout extract which is organic and has no residue in the final product of nata.Key words: Nata de sago, nitrogen, organoleptic

Global Grassland Diazotrophic Communities Are Structured by Combined Abiotic, Biotic, and Spatial Distance Factors but Resilient to Fertilization

Grassland ecosystems cover around 37% of the ice-free land surface on Earth and have critical socioeconomic importance globally. As in many terrestrial ecosystems, biological dinitrogen (N2) fixation represents an essential natural source of nitrogen (N). The ability to fix atmospheric N2 is limited to diazotrophs, a diverse guild of bacteria and archaea. To elucidate the abiotic (climatic, edaphic), biotic (vegetation), and spatial factors that govern diazotrophic community composition in global grassland soils, amplicon sequencing of the dinitrogenase reductase gene—nifH—was performed on samples from a replicated standardized nutrient [N, phosphorus (P)] addition experiment in 23 grassland sites spanning four continents. Sites harbored distinct and diverse diazotrophic communities, with most of reads assigned to diazotrophic taxa within the Alphaproteobacteria (e.g., Rhizobiales), Cyanobacteria (e.g., Nostocales), and Deltaproteobacteria (e.g., Desulforomonadales) groups. Likely because of the wide range of climatic and edaphic conditions and spatial distance among sampling sites, only a few of the taxa were present at all sites. The best model describing the variation among soil diazotrophic communities at the OTU level combined climate seasonality (temperature in the wettest quarter and precipitation in the warmest quarter) with edaphic (C:N ratio, soil texture) and vegetation factors (various perennial plant covers). Additionally, spatial variables (geographic distance) correlated with diazotrophic community variation, suggesting an interplay of environmental variables and spatial distance. The diazotrophic communities appeared to be resilient to elevated nutrient levels, as 2–4 years of chronic N and P additions had little effect on the community composition. However, it remains to be seen, whether changes in the community composition occur after exposure to long-term, chronic fertilization regimes.

Diversifying cropping sequence reduces nitrogen leaching risks

• We monitored soil mineral N during various cropping sequences. • We simulated a 20-year series of N leaching for the cropping sequences. • We found an impact of the preceding cop on N leaching after the following crop. • Catch crop and oilseed rape volunteers reduced N leaching risk. • Diversified cropping sequences can reduce N leaching by up to 40 %. Overuse of chemical fertiliser in cereal cropping systems has resulted in severe degradation of air and water quality. Diversifying cropping sequence with legumes provides a natural source of nitrogen (N), but also increases N leaching risks after their growing period. Here, we hypothesize that legumes and other break crops, i.e., crops grown to diversify the cropping sequence, reduce N leaching at the rotation scale due to their contribution to increasing nutrient use efficiency and crop N recovery of the following cereal crops. In two 4-year experiments conducted in northern France, we monitored agronomic performance and the changes in the soil mineral N content at field scale in six preceding crop-current crop combinations including winter wheat ( Triticum aestivum ), pea ( Pisum sativum L.) and oilseed rape ( Brassica napus L.). We quantified N leaching after each crop as a function of the preceding crop with a water-fluxes model based on soil mineral N content, climate data and soil characteristics. We then simulated N leaching at the rotation scale, for 20 years of climate conditions and various cropping management systems. We show that growing pea or oilseed rape reduced soil mineral N content at harvest of the following cereals (up to mean values of −28 and −19 kg N ha −1 respectively), and N leaching risks during winter of the following cereals compared to the wheat-wheat cropping sequence. Although N leaching was higher during the winter after pea was cultivated, the cumulative losses over four experimental years of the pea cropping sequences were not significantly higher than the no-break cropping sequences. Over the 20 climate years, sequences including pea, oilseed rape, volunteers or catch crops reduced simulated N leaching by up to 40 % compared to wheat monoculture. Our study confirms that N leaching not only depends on the current crop but is also affected by the preceding crop. A large potential reduction in nitrogen leaching could be achieved in many intensive cereal-growing regions with very limited cropping sequence diversity.

Sustaining Rice Production through Biofertilization with N2-Fixing Cyanobacteria

Current agricultural productivity depends on an exogenous nutrient supply to crops. This is of special relevance in cereal production, a fundamental part of the trophic chain that plays a vital role in the human diet. However, our agricultural practices entail highly detrimental side-effects from an environmental point of view. Long-term nitrogen fertilization in croplands results in degradation of soil, water, and air quality, producing eutrophication and subsequently contributing to global warming. In accordance with this, there is a biotechnological interest in using nitrogen-fixing microorganisms to enhance crop growth without adding chemically synthesized nitrogen fertilizers. This is particularly beneficial in paddy fields, where about 60% of the synthetic fertilizer that has been applied is dissolved in the water and washed away. In these agricultural systems, N2-fixing cyanobacteria show a promising biotechnological potential as biofertilizers, improving soil fertility while reducing the environmental impact of the agricultural practice. In the current study, Andalusian paddy fields have been explored to isolate N2-fixing cyanobacteria. These endogenous microorganisms have been subsequently re-introduced in a field trial in order to enhance rice production. Our results provide valuable insights regarding the use of an alternative natural source of nitrogen for rice production.

Pembuatan nata de cassava dari limbah cair tapioka dengan menggunakan sumber nitrogen alami yang berbeda

Liquid waste from processing cassava into tapioca starch is carbohydrate-rich waste and can be used as a growth medium for the Acetobacter xylinum, which is useful in producing one of the fermentation products, i.e. nata. Several factors influence the production of nata, one of them is the addition of nutrients in the form of nitrogen in the fermentation medium. The nitrogen source used is usually from inorganic fertilizers, such as urea and ammonium sulfate. In this study, fermentation of tapioca starch wastewater was developed, using a natural sources of nitrogen derived from soybean and green bean sprouts extract. Nata was made by treating various concentrations of soybean and green bean sprouts extract (3%, 4%, 5%) and fermentation time (6 days, 7 days, 8 days, 9 days and 10 days). The characteristics of the nata product were seen from the thickness and yield of the nata. The nata de cassava product's optimum results were tested for thickness, yield, and moisture content. The results showed that the best type of natural nitrogen source was soybean sprouts extract 5%, fermentation time of 10 days with a thickness of 0.55 cm, the water content of 97.58%, and yield of 63.09%

Nitrogen Fixing Azotobacter Species as Potential Soil Biological Enhancers for Crop Nutrition and Yield Stability.

Biological nitrogen fixation (BNF) refers to a microbial mediated process based upon an enzymatic “Nitrogenase” conversion of atmospheric nitrogen (N2) into ammonium readily absorbable by roots. N2-fixing microorganisms collectively termed as “diazotrophs” are able to fix biologically N2 in association with plant roots. Specifically, the symbiotic rhizobacteria induce structural and physiological modifications of bacterial cells and plant roots into specialized structures called nodules. Other N2-fixing bacteria are free-living fixers that are highly diverse and globally widespread in cropland. They represent key natural source of nitrogen (N) in natural and agricultural ecosystems lacking symbiotic N fixation (SNF). In this review, the importance of Azotobacter species was highlighted as both important free-living N2-fixing bacteria and potential bacterial biofertilizer with proven efficacy for plant nutrition and biological soil fertility. In addition, we described Azotobacter beneficial plant promoting traits (e.g., nutrient use efficiency, protection against phytopathogens, phytohormone biosynthesis, etc.). We shed light also on the agronomic features of Azotobacter that are likely an effective component of integrated plant nutrition strategy, which contributes positively to sustainable agricultural production. We pointed out Azotobacter based-biofertilizers, which possess unique characteristics such as cyst formation conferring resistance to environmental stresses. Such beneficial traits can be explored profoundly for the utmost aim to research and develop specific formulations based on inoculant Azotobacter cysts. Furthermore, Azotobacter species still need to be wisely exploited in order to address specific agricultural challenges (e.g., nutrient deficiencies, biotic and abiotic constraints) taking into consideration several variables including their biological functions, synergies and multi-trophic interactions, and biogeography and abundance distribution.

Ammonium and nitrate sources and transformation mechanism in the Quaternary sediments of Jianghan Plain, China

Excessive inorganic nitrogen (IN) compound content in groundwater is generally attributed to anthropogenic activities. Here, natural nitrogen sources in Quaternary sediments from aquifers and aquitards of Jianghan Plain (JHP), China were identified. Ammonium and nitrate content in groundwater samples collected from 129 well sites were determined through chemical analysis. Subsequent 4 boreholes were drilled at areas with high nitrogen concentration in the Quaternary aquifer. Indicators from hydrochemistry and soil geochemistry analysis, as well as optically stimulated luminescence dating and various of radioactive isotope δ14C-CO2 and stable isotopes including δ15N-NH4+, δ15N-total organic nitrogen (TON), δ15N-NO3−, δ18O-NO3−, δ18O-H2O, δD-H2O, and δ13C-total organic carbon (TOC) were used to identify high-concentration N compound sources and transformation mechanisms (NO3−: 0.02–770 mg L−1; NH4-N: 0–30.5 mg L−1) in the porous media. The thick clay layer protected the underlying media. Paleo-precipitation characteristics were preserved in the porewater; that is, it had not been affected by anthropogenic activities. The high nitrate concentration in the shallow oxidized aquifer was mostly attributed to manure and sewage (δ15N-NO3− was 14‰). The ammonium-N in the deep strata and part of ammonium-N in the shallow strata (aquifers and aquitards) were from natural sources, mainly from natural TON mineralization. Adsorption was an auxiliary factor for ammonium enrichment in the shallow strata, as were dissimilatory nitrate reduction to ammonium (DNRA) and low ammonia volatilization. Organic matter (OM) involved in mineralization was a mixture of lacustrine algae and terrigenous clastic sediments (from river upstream). The algae were traced to lake formation and frequent evolutionary changes in river environments, as indicated by alterations in sedimentary facies. The present findings may encourage researchers to consider natural IN sources' contribution to N contamination using quantitative models. They also serve as a valuable reference for understanding other pollutants' transformation mechanism in similar environments and provide research ideas for similar areas.

The utilization of peanut sprout extract as a green nitrogen source for the physicochemical and organoleptic properties of Nata de coco

Abstract In this study, the effect of peanut sprout extract as a new nitrogen source in the production of Nata de coco was evaluated. A completely randomized experimental design consisting of six treatments and three repeatabilities was performed. The results showed that the treatment with the addition of 100.0 g/L peanut sprout extract in coconut water offered good physicochemical properties including the moisture content, crude fiber content, wet weight, and thickness of Nata de coco product fermented for 7 and 11 days. The addition of peanut sprout extract exhibited a significant effect for the Nata de coco. Based on the single-factor ANOVA analysis at a significance level of 0.05, the Tcal values of the physicochemical properties were higher than the Ttab values with a p-value less than 0.05, indicating the significant effect of the peanut sprout extract. The Fisher's Least Significance Difference (LSD) post-hoc test also proved the significant effect of the extract for the Nata de coco product. The organoleptic testings were performed in which the average assessment on the texture, taste, and color of Nata de coco were more chewy, sweet, and white, respectively. The addition of extract affected the texture of Nata de coco while the extract did not affect the taste and color of Nata de coco. Therefore, the addition of peanut sprout extract as a new natural nitrogen source is a good alternative and eco-friendly material than the common nitrogen sources in the production of Nata de coco.

Soil properties and heavy metal concentrations affect the composition and diversity of the diazotrophs communities associated with different land use types in a mining area

Biological nitrogen fixed by diazotrophs is important because it is the largest natural source of nitrogen to support primary productivity and maintain ecosystem sustainability when anthropogenic nitrogen inputs are lacking, especially in mining areas. The present study selected six different land use types (a corn field, a vegetable field, an area of shrubs, a mine tailing, a forest and a citrus orchard) as variables related to the mining activities around the Siding mining area, Liuzhou, Guangxi Province, China. A 0–10 cm soil layer was sampled, and the heavy metal concentrations and soil physicochemical properties were measured. Illumina MiSeq sequencing technology was used to analyze the abundance and structural diversity of the diazotroph community. The distribution of diazotroph assemblages among the different land use types and the main soil environmental properties that drive diazotroph community compositions were determined. The results indicated that the phylum Cyanobacteria (85.89%) was the most dominant taxon in the diazotrophic community in the citrus orchard. However, in the soils of the five other land use types, Proteobacteria was the most dominant taxon in the diazotrophic community, with a high abundance that ranged from 60.08% to 99.96%. Spearman's correlation analysis and redundancy analysis results indicated that the soil organic matter (OM) content in the citrus orchard was significantly higher than that in other areas, and the difference in soil OM content might be the main reason for the difference in the diazotrophic communities. The diazotrophic communities and their associated diversity under different land use types were driven by soil heavy metal and soil N (including NH4+-N, NO3−-N and total N (TN)) contents. Specifically, TN was highly correlated with the NMDS1 score of the soil diazotrophic community, which indicated that the soil TN content was the main reason for the high similarity among the diazotrophic communities in the corn field, vegetable field and shrub soils. Overall, our study offers a detailed description of the characteristics of the diazotroph community structure under different land use types around a mining area.

Different nitrogen sources speed recovery from corallivory and uniquely alter the microbiome of a reef-building coral.

Corals are in decline worldwide due to local anthropogenic stressors, such as nutrient loading, and global stressors, such as ocean warming. Anthropogenic nutrient loading, which is often rich in nitrate, inhibits coral growth and worsens corals’ response to warming while natural sources of nitrogen, such as ammonium from fish excretion, promotes coral growth. Although the effects of nutrient loading and ocean warming have been well-studied, it remains unclear how these factors may interact with biotic processes, such as corallivory, to alter coral health and the coral microbiome. This study examined how nitrate vs. ammonium enrichment altered the effects of increased seawater temperature and simulated parrotfish corallivory on the health of Pocillopora meandrina and its microbial community. We tested the effects of nitrogen source on the response to corallivory under contrasting temperatures (control: 26 °C, warming: 29 °C) in a factorial mesocosm experiment in Moorea, French Polynesia. Corals were able to maintain growth rates despite simultaneous stressors. Seawater warming suppressed wound healing rates by nearly 66%. However, both ammonium and nitrate enrichment counteracted the effect of higher temperatures on would healing rates. Elevated seawater temperature and ammonium enrichment independently increased Symbiodiniaceae densities relative to controls, yet there was no effect of nitrate enrichment on algal symbiont densities. Microbiome variability increased with the addition of nitrate or ammonium. Moreover, microbial indicator analysis showed that Desulfovibrionaceae Operational taxonomic units (OTUs) are indicators of exclusively temperature stress while Rhodobacteraceae and Saprospiraceae OTUs were indicators of high temperature, wounding, and nitrogen enrichment. Overall, our results suggest that nitrogen source may not alter the response of the coral host to simultaneous stressors, but that the associated microbial community may be distinct depending on the source of enrichment.

Solvent-free and mechanochemical synthesis of N-doped mesoporous carbon from tannin and related gas sorption property

The commercialization of nitrogen-doped mesoporous carbons (N-doped MCs) is highly pursued by chemical engineers. This paper focuses on the clean and simple synthesis of N-doped MCs via mechanochemistry and their applications in gas sorption. Biomass tannin as the carbon precursor together with various natural nitrogen sources was assembled with F127 by ball milling in solid-state, and then directly carbonized into N-doped MCs with tunable nitrogen contents (up to 9.7 wt%), high surface area (up to 707 m2g−1), large pore size (~8 nm), narrow pore size distribution and high pore volume (up to 0.78 cm3g−1). The CO2/N2 and C2/C3 light hydrocarbon static adsorption experiments by N-doped MCs showed a higher CO2 adsorption capacity and a better adsorption selectivity, in comparison to the control sample without nitrogen species. The IAST separation selectivity of CO2/N2 (15:85, v/v) could be about 30, meanwhile the preferred selectivity for gas molecules of alkyne was also observed.