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BackgroundMercury (Hg) is highly toxic and has the potential to cause severe health problems for humans and foraging animals when transported into edible plant parts. Soil rhizobia that form symbiosis with legumes may possess mechanisms to prevent heavy metal translocation from roots to shoots in plants by exporting metals from nodules or compartmentalizing metal ions inside nodules. Horizontal gene transfer has potential to confer immediate de novo adaptations to stress. We used comparative genomics of high quality de novo assemblies to identify structural differences in the genomes of nitrogen-fixing rhizobia that were isolated from a mercury (Hg) mine site that show high variation in their tolerance to Hg.ResultsOur analyses identified multiple structurally conserved merA homologs in the genomes of Sinorhizobium medicae and Rhizobium leguminosarum but only the strains that possessed a Mer operon exhibited 10-fold increased tolerance to Hg. RNAseq analysis revealed nearly all genes in the Mer operon were significantly up-regulated in response to Hg stress in free-living conditions and in nodules. In both free-living and nodule environments, we found the Hg-tolerant strains with a Mer operon exhibited the fewest number of differentially expressed genes (DEGs) in the genome, indicating a rapid and efficient detoxification of Hg from the cells that reduced general stress responses to the Hg-treatment. Expression changes in S. medicae while in bacteroids showed that both rhizobia strain and host-plant tolerance affected the number of DEGs. Aside from Mer operon genes, nif genes which are involved in nitrogenase activity in S. medicae showed significant up-regulation in the most Hg-tolerant strain while inside the most Hg-accumulating host-plant. Transfer of a plasmid containing the Mer operon from the most tolerant strain to low-tolerant strains resulted in an immediate increase in Hg tolerance, indicating that the Mer operon is able to confer hyper tolerance to Hg.ConclusionsMer operons have not been previously reported in nitrogen-fixing rhizobia. This study demonstrates a pivotal role of the Mer operon in effective mercury detoxification and hypertolerance in nitrogen-fixing rhizobia. This finding has major implications not only for soil bioremediation, but also host plants growing in mercury contaminated soils.

We describe the genome of an Eremiobacterota population from tundra soil that contains the minimal set of nif genes needed to fix atmospheric N2. This putative diazotroph population, which we name Candidatus Lamibacter sapmiensis, links for the first time Eremiobacterota and N2 fixation. The integrity of the genome and its nif genes are well supported by both environmental and taxonomic signals. Ca. Lamibacter sapmiensis contains three nifH homologues and the complementary set of nifDKENB genes that are needed to assemble a functional nitrogenase. The putative diazotrophic role of Ca. Lamibacter sapmiensis is supported by the presence of genes that regulate N2 fixation and other genes involved in downstream processes such as ammonia assimilation. Similar to other Eremiobacterota, Ca. Lamibacter sapmiensis encodes the potential for atmospheric chemosynthesis via CO2 fixation coupled with H2 and CO oxidation. Interestingly, the presence of a N2O reductase indicates that this population could play a role as a N2O sink in tundra soils. Due to the lack of activity data, it remains uncertain if Ca. Lamibacter sapmiensis is able to assemble a functional nitrogenase and participate in N2 fixation. Confirmation of this ability would be a testament to the great metabolic versatility of Eremiobacterota, which appears to underlie their ecological success in cold and oligotrophic environments.

Biological nitrogen fixation by free-living bacteria and rhizobial symbiosis with legumes plays a key role in sustainable crop production. Here, we study how different crop combinations influence the interaction between peanut plants and their rhizosphere microbiota via metabolite deposition and functional responses of free-living and symbiotic nitrogen-fixing bacteria. Based on a long-term (8 year) diversified cropping field experiment, we find that peanut co-cultured with maize and oilseed rape lead to specific changes in peanut rhizosphere metabolite profiles and bacterial functions and nodulation. Flavonoids and coumarins accumulate due to the activation of phenylpropanoid biosynthesis pathways in peanuts. These changes enhance the growth and nitrogen fixation activity of free-living bacterial isolates, and root nodulation by symbiotic Bradyrhizobium isolates. Peanut plant root metabolites interact with Bradyrhizobium isolates contributing to initiate nodulation. Our findings demonstrate that tailored intercropping could be used to improve soil nitrogen availability through changes in the rhizosphere microbiome and its functions.

Marine macroalgae produce abundant and diverse polysaccharides, which contribute substantially to the organic matter exported to the deep ocean. Microbial degradation of these polysaccharides plays an important role in the turnover of macroalgal biomass. Various members of the Planctomycetes-Verrucomicrobia-Chlamydia (PVC) superphylum are degraders of polysaccharides in widespread anoxic environments. In this study, we isolated a novel anaerobic bacterial strain NLcol2T from microbial mats on the surface of marine sediments offshore Santa Barbara, CA, USA. Based on 16S ribosomal RNA (rRNA) gene and phylogenomic analyses, strain NLcol2T represents a novel species within the Pontiella genus in the Kiritimatiellota phylum (within the PVC superphylum). Strain NLcol2T is able to utilize various monosaccharides, disaccharides, and macroalgal polysaccharides such as agar and ɩ-carrageenan. A near-complete genome also revealed an extensive metabolic capacity for anaerobic degradation of sulfated polysaccharides, as evidenced by 202 carbohydrate-active enzymes (CAZymes) and 165 sulfatases. Additionally, its ability of nitrogen fixation was confirmed by nitrogenase activity detected during growth on nitrogen-free medium, and the presence of nitrogenases (nifDKH) encoded in the genome. Based on the physiological and genomic analyses, this strain represents a new species of bacteria that may play an important role in the degradation of macroalgal polysaccharides and with relevance to the biogeochemical cycling of carbon, sulfur, and nitrogen in marine environments. Strain NLcol2T (= DSM 113125T = MCCC 1K08672T) is proposed to be the type strain of a novel species in the Pontiella genus, and the name Pontiella agarivorans sp. nov. is proposed.IMPORTANCEGrowth and intentional burial of marine macroalgae is being considered as a carbon dioxide reduction strategy but elicits concerns as to the fate and impacts of this macroalgal carbon in the ocean. Diverse heterotrophic microbial communities in the ocean specialize in these complex polymers such as carrageenan and fucoidan, for example, members of the Kiritimatiellota phylum. However, only four type strains within the phylum have been cultivated and characterized to date, and there is limited knowledge about the metabolic capabilities and functional roles of related organisms in the environment. The new isolate strain NLcol2T expands the known substrate range of this phylum and further reveals the ability to fix nitrogen during anaerobic growth on macroalgal polysaccharides, thereby informing the issue of macroalgal carbon disposal.

Nitrogen fixation is crucial for plant growth and global agriculture, especially with the projected population growth requiring a significant increase in food production. Traditional nitrogen fixation relies on the Haber-Bosch (H-B) process, which is energy-intensive and environmentally harmful due to greenhouse gas emissions. Emerging technologies, such as cold plasma, offer promising alternatives with lower energy consumption. Cold plasma facilitates reactive nitrogen species generation under ambient conditions, potentially improving the production efficiency of nitrogen oxides (NOx). However, optimizing cold plasma nitrogen fixation requires a synergy between experimental and theoretical approaches. Accurate input data are essential for refining theoretical models, which can then guide the design of more efficient processes. This integrated approach can leverage renewable energy, operate on smaller scales, and minimize environmental impacts, making cold plasma a sustainable solution for future nitrogen fixation needs. [ABSTRACT FROM AUTHOR]

Biological nitrogen fixation is a fundamental part of ecosystem functioning. Anthropogenic nitrogen deposition and climate change may, however, limit the competitive advantage of nitrogen-fixing plants, leading to reduced relative diversity of nitrogen-fixing plants. Yet, assessments of changes of nitrogen-fixing plant long-term community diversity are rare. Here, we examine temporal trends in the diversity of nitrogen-fixing plants and their relationships with anthropogenic nitrogen deposition while accounting for changes in temperature and aridity. We used forest-floor vegetation resurveys of temperate forests in Europe and the United States spanning multiple decades. Nitrogen-fixer richness declined as nitrogen deposition increased over time but did not respond to changes in climate. Phylogenetic diversity also declined, as distinct lineages of N-fixers were lost between surveys, but the "winners" and "losers" among nitrogen-fixing lineages varied among study sites, suggesting that losses are context dependent. Anthropogenic nitrogen deposition reduces nitrogen-fixing plant diversity in ways that may strongly affect natural nitrogen fixation. [ABSTRACT FROM AUTHOR]

Molybdoenzymes are essential in global nitrogen, carbon, and sulfur cycling. To date, the only known bioavailable source of molybdenum (Mo) is molybdate. However, in the sulfidic and anoxic (euxinic) habitats that predominate in modern subsurface environments and that were pervasive prior to Earth's widespread oxygenation, Mo occurs as soluble tetrathiomolybdate ion and molybdenite mineral that is not known to be bioavailable. This presents a paradox for how organisms obtain Mo to support molybdoenzymes in these environments. Here, we show that tetrathiomolybdate and molybdenite sustain the high Mo demand of a model anaerobic methanogen, Methanococcus maripaludis, grown via Mo-dependent formate dehydrogenase, formylmethanofuran dehydrogenase, and nitrogenase. Cells grown with tetrathiomolybdate and molybdenite have similar growth kinetics, Mo content, and transcript levels of proteins involved in Mo transport and cofactor biosynthesis when compared to those grown with molybdate, implying similar mechanisms of transport and cofactor biosynthesis. These results help to reconcile the paradox of how Mo is acquired in modern and ancient anaerobes and provide new insight into how molybdoenzymes could have evolved prior to Earth's oxygenation. The nitrogen-fixing anaerobic methanogen, Methanococcus maripaludis, can utilize tetrathiomolybdate and molybdenite, previously considered non-bioavailable, as sources of molybdenum for enzymes involved in nitrogen fixation and anaerobic metabolism. [ABSTRACT FROM AUTHOR]

Plasmon-induced photocatalysis showed great potential to improve the photocatalytic nitrogen fixation efficiency, due to the localized surface plasmon resonance effect. The performances of the photocatalytic nitrogen fixation were evaluated by ammonia production rate, apparent quantum efficiency, solar-to-ammonia efficiency, and turnover frequency. The ammonia production rate was compared with three kinds of catalyst, i.e. nano-metals, nano-metal modified semiconductors and highly doped semiconductors. The outstanding contributions of hot electron injection effect, near-field enhancement effect, photothermal effect to nitrogen fixation efficiency were described. The creation of active sites, construct vacancies, and doping regulation were effective methods to prepare high performance catalysts for photocatalytic nitrogen fixation. • Nano-metal-modified semiconductor catalysts achieve ammonia production rate of 785 μmol g−1 h−1. • Highiy doped semiconductors re-define the landscape of photocatalytic NH 3 generation. • The ammonia production rate, apparent quantum efficiency and Solar-to-Ammonia can be used to evaluate the performance ofphotocatalyst. • Hot electron injection effect as a guide for the synthesis of plasma-induced photocatalysts. [ABSTRACT FROM AUTHOR]

Symbiotic nitrogen fixation (SNF) in legume-rhizobia serves as a sustainable source of nitrogen (N) in agriculture. However, the addition of inorganic N fertilizers significantly inhibits SNF, and the underlying mechanisms remain not-well understood. Here, we report that inorganic N disrupts iron (Fe) homeostasis in soybean nodules, leading to a decrease in SNF efficiency. This disruption is attributed to the inhibition of the Fe transporter genes Natural Resistance-Associated Macrophage Protein 2a and 2b (GmNRAMP2a&2b) by inorganic N. GmNRAMP2a&2b are predominantly localized at the tonoplast of uninfected nodule tissues, affecting Fe transfer to infected cells and consequently, modulating SNF efficiency. In addition, we identified a pair of N-signal regulators, nitrogen-regulated GARP-type transcription factors 1a and 1b (GmNIGT1a&1b), that negatively regulate the expression of GmNRAMP2a&2b, which establishes a link between N signaling and Fe homeostasis in nodules. Our findings reveal a plausible mechanism by which soybean adjusts SNF efficiency through Fe allocation in response to fluctuating inorganic N conditions, offering valuable insights for optimizing N and Fe management in legume-based agricultural systems. Symbiotic nitrogen fixation is a tightly regulated process serving as a sustainable source of nitrogen (N) in agriculture. Here it is shown that external N sources precisely regulate N fixation efficiency by modulating iron transport in nodules of legumes. [ABSTRACT FROM AUTHOR]

The major crop, soybean, forms root nodules with symbiotic rhizobia, providing energy and carbon to the bacteria in exchange for bioavailable nitrogen. The relationship is host-specific and highly host-regulated to maximize energy efficiency. Symbiotic nitrogen fixation (SNF) is greener than synthetic fertilizer for replenishing soil fertility, contributing to yield increase. Nodulation Outer Protein P (NopP) and NopI of the type 3 secretion system (T3SS) of the rhizobium determine host specificity. Sinorhizobium fredii CCBAU25509 (R2) and CCBAU45436 (R4) have different NopP and NopI variants, affecting their respective symbiotic compatibilities with the cultivated soybean C08 and the wild soybean W05. Swapping the NopP variants between R2 and R4 has been shown to switch their compatibility with C08 with the rj2/Rfg1 genotype. To understand the effects of Nops on host compatibility, analyses on the transcriptomic data of W05 roots and nodules inoculated with S. fredii strains containing Nop variants uncovered many differentially expressed genes related to nodulation and nodule functions, providing important information on the effects of Nops on hosts and nodules. [ABSTRACT FROM AUTHOR]

Tillandsia recurvata is an epiphytic plant commonly found in tropical regions and colonizes tree trunks, fences, and power wires. This plant plays an important role in interacting with trees, sharing microorganisms, and performing specific functions in the process of tree colonization. The objective of this study was to evaluate and compare the microbiomes of T. recurvata collected from two different locations (trees and fences) and two plant tissues (leaves and roots). The hypothesis of this study was that the microbiome of T. recurvata is composed of microorganisms that would provide nutritional support to compensate for the lack of nutrients in a particular growth support. The results showed significant differences in microbial diversity between trees and fences, with trees exhibiting higher richness and more complex microbial networks. Proteobacteria was the most prevalent bacterial phylum, with Actinobacteria and Sphingomonas also playing key roles in nitrogen fixation and plant growth. Fungal communities were similar across locations, with Ascomycota and Basidiomycota being predominant, but Paraconiothyrium and Nigrospora showed significant differences in abundance between trees and fences. Functional analysis indicated similar metabolic profiles across leaf and root samples, with key functions for T. recurvata including carbohydrate and amino acid metabolism, stress control, and biofertilization. [ABSTRACT FROM AUTHOR]

Wheat represents a fundamental component of the diet that contributes to ensuring global food security. However, its cultivation faces various abiotic and biotic constraints that result in fluctuating yields. The use of plant growth promoting rhizobacteria (PGPR) with the ability to solubilize phosphate presents itself as an environmentally friendly solution aimed to at enhancing sustainable agriculture practices. The objective of the present study is to assess the potential of PGPR in augmenting both yield and phosphorus (P) levels in wheat plants (Triticum durum L). under semi-controlled environmental conditions. Initially, the strains under investigation were screened for their capacity to dissolve different forms of mineral complex P, along with other plant growth promoting attributes such as iron chelation, Indole acetic acid (IAA) production, nitrogen fixation, and production of exopolysaccharides. Plant response to inoculation with PGPR was studied through an experiment conducted in a greenhouse involving four distinct treatments: (1) Control plants without any inoculation, (2) Inoculation with the PGP27 strain (Rahnella aquatilis), (3) Inoculation with the PGP25 strain (Erwinia persicina), and (4) Inoculation with the PGP374 strain (Raoultella terrigena). Results demonstrated that the studied strains exhibited significant promoting activities, including the solubilization of complex phosphate, the production of exopolysaccharides, IAA, siderophores, and atmospheric nitrogen fixation. Furthermore, the inoculation of plants with PGPR led to an increase in both biomass and plant phosphate concentrations, surpassing those observed in the control group. In conclusion, the findings propose that species like Raoultella and Erwinia have the potential to offer agronomic advantages as rhizobacteria that promote plant growth. [ABSTRACT FROM AUTHOR]

A novel bimetallic CoMoB-coupled carbon nitride with dual moiety defects (CN-TH 3/3) Schottky junction photocatalyst (CoMoB/CN-TH 3/3) was designed for photocatalytic nitrogen fixation. [Display omitted] • A novel CoMoB/(CN-TH 3/3) Schottky junction photocatalyst was designed for photocatalytic NRR. • Both of the intralayer exciton characteristics and the visible light adsorption capacity were altered. • The synergistic effect of CoMoB and CN-TH 3/3 accelerated charge transfer and enhanced the N 2 adsorption and activation. • The photocatalytic NRR performance of optimum CoMoB/CN-TH 3/3 is 6.2 times higher than CN. The sustainable generation of ammonia by photocatalytic nitrogen fixation under mild conditions is fascinating compared to conventional industrial processes. Nevertheless, owing to the low charge transfer efficiency, the insufficient light absorption capacity and limited active sites of the photocatalyst cause the difficult adsorption and activation of N 2 molecules, thereby resulting in a low photocatalytic conversion efficiency. Herein, a novel bimetallic CoMoB nanosheets (CoMoB) co-catalyst modified carbon nitride with dual moiety defects (CN-TH 3/3) Schottky junction photocatalyst is designed for photocatalytic nitrogen reduction reaction (NRR). The photocatalytic nitrogen reduction rate of the optimized CoMoB/CN-TH 3/3 photocatalyst is 4.81 mM·g−1·h−1, which is 6.2 and 2.2 times higher than carbon nitride (CN) (0.78 mM·g−1·h−1) and CN-TH 3/3 (2.21 mM·g−1·h−1), respectively. The excellent photocatalytic NRR performance is ascribed not only to the introduction of dual moiety defects (cyano and cyanamide groups) that extends the visible light absorption range and promotes exciton polarization dissociation, but also to the formation of interfacial electric field between CoMoB and CN-TH 3/3 , which effectively facilitates the interfacial charge transfer. Thus, the synergistic interaction between CN-TH 3/3 and CoMoB further increases the electron numble of CoMoB active sites, which effectively strengthens the adsorption and activation of N 2 and weakens the N N triple bond, thereby enhancing the photocatalytic NRR activity. This work highlights the introduced dual moiety defects and bimetallic CoMoB co-catalyst to synergistically enhance the photocatalytic nitrogen reduction performance. [ABSTRACT FROM AUTHOR]

Land use changes soil microbial and chemical properties, but the mechanism of biological nitrogen fixation under different land use patterns is rarely reported, so we used four types of soil: Natural forest soil (NS), healthy banana soil (HS), diseased banana soil (DS) and paddy soil (PS). Treatments included the control (CK), addition of glucose (G), addition of glucose and ammonium nitrate (GN), addition of banana straw (BS), addition of banana straw and ammonium nitrate (BSN), addition of banana root (BR), and addition of banana root and ammonium nitrate (BRN). The study found that the change of soil utilization types, glucose addition increased carbon dioxide emissions (Compared with the control, increased by 963.11%, 508.39%, 794.77% and 511.34%, respectively) and enhanced the ability of soil microbial nitrogen fixation. Importantly, natural forest soil microorganisms have a higher biological nitrogen fixation capacity compared to other types of soils. Glucose addition caused the accumulation of ammonium nitrogen (Compared with the control, increased by 426.08%, 934.21%, 420% and 1065.95%, respectively), indicating that microorganisms had higher utilization efficiency of soluble carbon and enhanced the biological nitrogen fixation capacity, and nitrogen addition caused the accumulation of ammonium nitrogen, thereby weakening the biological nitrogen fixation capacity. At the same time, glucose significantly increased the Fimicutes phylum (83.73%, 66.38%, 67.18% and 70.36%) and lowered the level of other bacterial phylums, thereby reducing the bacterial network structure, and the stability of the soil environment has decreased. Forest analysis showed that CO2 was an important factor in predicting the bacterial community structure of different soil types, an increase in CO2 content can predict drastic changes in the bacterial community. Bacteria at the Fimicutes phylum level preferred glucose, which may also have a negative effect on bacteria at the level of other phylums. [ABSTRACT FROM AUTHOR]

A nitrogen-fixing strain designated SG130T was isolated from paddy soil in Fujian Province, China. Strain SG130T was Gram-staining-negative, rod-shaped, and strictly anaerobic. Strain SG130T showed the highest 16S rRNA gene sequence similarities with the type strains Dendrosporobacter quercicolus DSM 1736T (91.7%), Anaeroarcus burkinensis DSM 6283T (91.0%) and Anaerospora hongkongensis HKU 15T (90.9%). Furthermore, the phylogenetic and phylogenomic analysis also suggested strain SG130T clustered with members of the family Sporomusaceae and was distinguished from other genera within this family. Growth of strain SG130T was observed at 25–45 °C (optimum 30 °C), pH 6.0–9.5 (optimum 7.0) and 0–1% (w/v) NaCl (optimum 0.1%). The quinones were Q-8 and Q-9. The polar lipids were phosphatidylserine (PS), phosphatidylethanolamine (PE), glycolipid (GL), phospholipid (PL) and an unidentified lipid (UL). The major fatty acids (> 10%) were iso-C13:0 3OH (26.6%), iso-C17:1 (15.6%) and iso-C15:1 F (11.4%). The genomic DNA G + C content was 50.7%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain SG130T and the most closely related type strain D. quercicolus DSM 1736T (ANI 68.0% and dDDH 20.3%) were both below the cut-off level for species delineation. The average amino acid identity (AAI) between strain SG130T and the most closely related type strain D. quercicolus DSM 1736T was 63.2%, which was below the cut-off value for bacterial genus delineation (65%). Strain SG130T possessed core genes (nifHDK) involved in nitrogen fixation, and nitrogenase activity (106.38 μmol C2H4 g−1 protein h−1) was examined using the acetylene reduction assay. Based on the above results, strain SG130T is confirmed to represent a novel genus of the family Sporomusaceae, for which the name Azotosporobacter soli gen. nov., sp. nov. is proposed. The type strain is SG130T (= GDMCC 1.3312T = JCM 35641T). [ABSTRACT FROM AUTHOR]

The chemical behaviors of alkali and alkaline earth metal hydrides including LiH, KH, MgH2, CaH2, and BaH2 under nitrogen plasma differ significantly from one another, exhibiting an ammonia production trend that contrasts with that observed under thermal conditions. A prominent feature of KH is its ability to facilitate plasma-assisted N2 fixation without generating H2 byproduct, showing high atomic economy in utilization of hydride ions for N2 reduction. [ABSTRACT FROM AUTHOR]

Photocatalytic nitrogen reduction presents a promising technology for environmentally friendly ammonia synthesis under mild conditions. However, the performance of photocatalysts is often hindered by high charge carrier recombination and insufficient adsorption and activation of nitrogen molecules. A novel Bi 12 O 17 Cl 2 /BiOCOOH/Bi 2 MoO 6 heterojunction photocatalyst was successful synthesis through surface ion-exchange technique by potassium chloride. The introduction of Bi-rich Bi 12 O 17 Cl 2 on BiOCOOH/Bi 2 MoO 6 heterojunction not only improves electron transfer efficiency due to the dual type-II heterojunction effect but also facilitates on-site N 2 adsorption and activation for solar ammonia production by promoting oxygen vacancies. The high photocatalytic nitrogen fixation activity of the Bi 12 O 17 Cl 2 /BiOCOOH/Bi 2 MoO 6 was 107.78 μmol g−1 h−1 without any sacrificial agent. DFT calculations indicate that oxygen vacancies serve as the active site for adsorbed N 2 , the hydrogenation process preferentially forms on the distal N 2 atom with a lower activation energy about 0.6 eV. Therefore, the combination of oxygen vacancies and band engineering accelerates the production of ammonia. This endeavor holds the potential to unleash the capabilities of engineering for Bi-rich heterojunctions materials with oxygen vacancies, thereby achieving high-efficiency solar-driven N 2 -to-NH 3 conversion in aqueous environments. [Display omitted] • A novel Bi 12 O 17 Cl 2 /BiOCOOH/Bi 2 MoO 6 heterojunction photocatalyst through surface ion-exchange technique by potassium chloride. • The high photocatalytic nitrogen fixation activity of the Bi 12 O 17 Cl 2 /BiOCOOH/Bi 2 MoO 6 was 107.78 μmol g−1 h−1 without any sacrificial agent. • The built-in double type-II heterojunction promotes the on-site N 2 adsorption and activation of vacancy oxygen. [ABSTRACT FROM AUTHOR]

Introduction: Understanding the microbial diversity and potential functional dynamics within the rhizocompartments of Dendrobium huoshanense is crucial for unraveling the plant--microbe interactions that influence its medicinal properties. Methods: This study is the first to characterize the microbiome associated with the rhizocompartments of D. huoshanense, including its cultivation medium, rhizosphere, rhizoplane, and root endosphere, using high-throughput sequencing and subsequent bioinformatic analysis. Results: Bacterial phylogenetic diversity was significantly higher in the endosphere than in the rhizosphere, while fungal α-diversity significantly decreased from the cultivation medium to the endosphere. Both bacterial and fungal niche widths decreased from the cultivation medium to the endosphere. β-Diversity analysis revealed distinct spatial patterns in both bacterial and fungal communities across the rhizocompartments, with the most pronounced differences between the cultivation medium and the endosphere. Taxonomically, Proteobacteria and Ascomycota were predominant in the endosphere for bacterial and fungal communities, respectively. Functional predictions showed significant enrichment of pathways related to xenobiotics biodegradation, lipid metabolism, and nitrogen fixation in the endosphere, while functions associated with plant pathogens and saprotrophs were significantly reduced. Discussion: The results indicate a shift from generalist to specialist microbes from the cultivation medium to the endosphere, suggesting that D. huoshanense exerts strong selective pressure for endophytic fungi. Interestingly, a high proportion of fungi with unknown functions were found in the endosphere, highlighting an area for further research regarding the medicinal efficacy of D. huoshanense. Overall, this study provides foundational data for understanding the adaptive evolution of these microbial communities in response to specific microhabitats. [ABSTRACT FROM AUTHOR]

Symbiotic nitrogen fixation within nitrogen-fixing clade (NFC) plants is thought to have arisen from a single gain followed by massive losses in the genomes of ancestral non-nodulating plants. However, molecular evidence supporting this model is limited. Here, we confirm through bioinformatic analysis that NODULES WITH ACTIVATED DEFENSE1 (NAD1) is present only in NFC plants and is thus an NFC-specific gene. Moreover, NAD1 was specifically expressed in nodules. We identified three conserved nodulation-associated cis-regulatory elements (NACE1–3) in the promoter of LjNAD1 from Lotus japonicus that are required for its nodule specific expression. A survey of NFC plants revealed that NACE1 and NACE2 are specific to the Fabales and Papilionoideae, respectively, while NACE3 is present in all NFC plants. Moreover, we found that nodule inception (NIN) directly binds to all three NACEs to activate NAD1 expression. Mutation of L. japonicus LjNAD1 resulted in the formation of abnormal symbiosomes with enlarged symbiosome space and frequent breakdown of bacteroids in nodules, resembling phenotypes reported for Medicago truncatula Mtnad1 and Mtnin mutants. These data point to NIN–NAD1 as an important module regulating rhizobial accommodation in nodules. The regulation of NAD1 by NIN in the NFC ancestor represent an important evolutionary adaptation for nodulation. NODULE INCEPTION directly binds the promoter of the nitrogen-fixing clade-specific gene NODULES WITH ACTIVATED DEFENSE1 to regulate rhizobial intracellular accommodation in nodules. [ABSTRACT FROM AUTHOR]

Green ammonia is assumed to be an important part of the European hydrogen economy and one of the most important substrates of chemical industry. The future development of its manufacturing processes can be related to the electrocatalytic studies yielding in the development of the catalytic materials that would effectively break the nitrogen-nitrogen bond to successfully drive the N2RR—a process of molecular nitrogen electroreduction to ammonia. Molecular nitrogen is characterized with strong triple bond energies (942 kJ/mol) which leading into large dissociation energy of N2 (9,76 eV) and also large energy barrier of the first step of triple bond dissociation 410 kJ/mol (4,25 eV). Those large energies makes reduction to ammonia an extremely difficult task. Metal nitrides of d and f block became in interest due to their activity in ammonia production from molecular nitrogen and hydrogen. Practically all the transition elements occurs in one of the four types of crystalline structures: regular, regular face cantered, hexagonal and hexagonal close packed. The reactions of these metals with nitrogen (or ammonia) typically yields in nitride compounds of an identical type of crystalline structure as the initial metal. Dealing with single metal systems, their ternary counterparts and metal–metal nitride heterostructures, the presented review shows that nitrides are promising groups of electrocatalytic materials. Being property-prone to their internal structural features such as non-stoichiometry and correlated concentration of nitrogen vacancies, metal nitrides are a good candidate for joined investigations spanned between electrochemistry, inorganic chemistry and material engineering. [ABSTRACT FROM AUTHOR]

Context: Alpine pastures are seminatural grasslands which play a crucial role in biodiversity conservation, service provisioning, and mountain livestock systems. The soil microbial communities of pasture are fundamental in ecosystem nutrient cycles, but they are relatively underexplored in European Alpine pastures. Aims: We explored the many soil microbial genes encoding key functions in the nitrogen cycle in three historical alpine pastures grazed by dairy cattle, considering different soils, temporal dynamics, and exclusion of cattle grazing for one summer. Methods: 216 samples were collected across four sampling times. The abundance of genetic determinants involved in nitrogen fixation (nifH), nitrification (amoA bacterial and archaeal), and denitrification (nirK and nosZ) were quantified using real-time polymerase chain reaction. Key results: The terminal denitrification nosZ gene was the most sensitive indicator and responded significantly to soil chemical composition and animal grazing. Sampling time affected nitrogen fixation nifH and intermediate denitrification nirK in relation to rainfall cumulation dynamics. The amoA nitrification genes showed high variability but no significant effects from the tested factors. Conclusions: In spite of a general homeostatic trend occurring in these habitats and of the short term analysis, some genes acted as sensitive reporters of soil compositional differences, intraseasonal climatic variations, and grazing disturbance. Implications: A stocking rate of >0.6 livestock units per hectare can be recommended, to combine animal production with conditions that favour complete denitrification, thus potentially reducing the nitrous oxide greenhouse gas emissions. Higher livestock grazing intensity can be withstood by the ecosystem without denitrification-related drawbacks when the preceding 10 days display a cumulated rainfall lower than 22 mm. Soil microbial communities are fundamental for ecosystem nutrient cycles, but they are relatively underexplored in alpine pastures – seminatural grasslands important for mountain livestock systems. We investigated microbial functions related to the nitrogen cycle in three historical alpine pastures for one summer. Microbial nitrogen functions showed a general inertia in respect to soil variation and grazing disturbance. This has ramifications for future improvement of pasture management in mountain livestock systems. [ABSTRACT FROM AUTHOR]

Electrochemical nitrogen reduction reaction (NRR) is a promising route for realizing green and sustainable ammonia synthesis under ambient conditions. However, one of the major challenges of currently available Single-atom catalysts (SACs) is poor catalytic activity and low catalytic selectivity, which is far away from the requirements of industrial applications. Herein, first-principle calculations within the density functional theory were performed to evaluate the feasibility of a single Mo atom anchored on a g-C9N10 monolayer (Mo@g-C9N10) as NRR electrocatalysts. The results demonstrated that the gas phase N2 molecule can be sufficiently activated on Mo@g-C9N10, and N2 reduction dominantly occurs on the active Mo atom via the preferred enzymatic mechanism, with a low limiting potential of −0.48 V. In addition, Mo@g-C9N10 possesses a good prohibition ability for the competitive hydrogen evolution reaction. More impressively, good electronic conductivity and high electron transport efficiency endow Mo SACs with excellent activity for electrocatalytic N2 reduction. This theoretical research not only accelerates the development of NRR electrocatalysts but also increases our insights into optimizing the catalytic performance of SACs. [ABSTRACT FROM AUTHOR]

Catch crops are intermediate crops sown between two main crop cycles. Their adoption into the cropping system has increased considerably in the last years due to its numerous benefits, in particular its potential in carbon fixation and preventing nitrogen leaching during winter. The growth period of catch crops in Germany is often marked by dense cloud cover, which limits land surface monitoring through optical remote sensing. In such conditions, synthetic aperture radar (SAR) emerges as a viable option. Despite the known advantages of SAR, the understanding of temporal behavior of radar parameters in relation to catch crops remains largely unexplored. Hence, in this study, we exploited the dense time series of Sentinel-1 data within the Copernicus Space Component to study the temporal characteristics of catch crops over a test site in the center of Germany. Radar parameters such as VV, VH, VH/VV backscatter, dpRVI (dual-pol Radar Vegetation Index) and VV coherence were extracted, and temporal profiles were interpreted for catch crops and preceding main crops along with in situ, temperature, and precipitation data. Additionally, we examined the temporal profiles of winter main crops (winter oilseed rape and winter cereals), that are grown parallel to the catch crop growing cycle. Based on the analyzed temporal patterns, we defined 22 descriptive features from VV, VH, VH/VV and dpRVI, which are specific to catch crop identification. Then, we conducted a Kruskal–Wallis test on the extracted parameters, both crop-wise and group-wise, to assess the significance of statistical differences among different catch crop groups. Our results reveal that there exists a unique temporal pattern for catch crops compared to main crops, and each of these extracted parameters possess a different sensitivity to catch crops. Parameters VV and VH are sensitive to phenological stages and crop structure. On the other hand, VH/VV and dpRVI were found to be highly sensitive to crop biomass. Coherence can be used to detect the sowing and harvest events. The preceding main crop analysis reveals that winter wheat and winter barley are the two dominant main crops grown before catch crops. Moreover, winter main crops (winter oilseed rape, winter cereals) cultivated during the catch crop cycle can be distinguished by exploiting the observed sowing window differences. The extracted descriptive features provide information about sowing, harvest, vigor, biomass, and early/late die-off nature specific to catch crop types. In the Kruskal–Wallis test, the observed high H-statistic and low p-value in several predictors indicates significant variability at 0.001 level. Furthermore, Dunn's post hoc test among catch crop group pairs highlights the substantial differences between cold-sensitive and legume groups (p < 0.001). [ABSTRACT FROM AUTHOR]

Utilizing solar energy for photocatalytic nitrogen fixation has been extensively regarded as a promising avenue towards renewable nitrogen energy production. 2D materials, renowned for their unique structures and properties, have sparked remarkable advancements in the realm of energy and environment sciences. In this review, we delve into the recent advancements pertaining to 2D materials for solar‐driven photocatalytic nitrogen fixation. This encompasses a diverse array of materials, including metal carbides/nitrides (MXenes), transition metal dichalcogenides (TMDs or TMDCs), graphitized carbon nitride (g‐C3N4), metal‐organic frameworks (MOFs), covalent organic frameworks (COFs), and covalent triazine‐based frameworks (CTFs). We offer a fundamental understanding of the functionalities exhibited by various 2D materials in enhancing photocatalytic nitrogen fixation activity. The photocatalytic properties of these 2D materials are meticulously examined from multiple perspectives, including visible light absorption capabilities, charge transfer within the energy band, and reaction mechanisms. Finally, we present an in‐depth discussion on the existing challenges and prospects surrounding the application of 2D materials in photocatalytic nitrogen fixation. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a one‐step nitrogen fixation (NF) process using ethanol solution and nitrogen as raw materials and a magnetic field stabilized glow discharge (MSGD) as a plasma reactor, in which the plasma is stabilized at a fixed position under the opposing forces of the Lorentz force and airflow. Compared to deionized water, the participation of ethanol promotes the generation of NH3 and NOx. This is because the addition of ethanol not only serves as a source of hydrogen but also facilitates the generation of OH, which further reacts to produce NO through N + OH → NO + H ${\rm{N}}+\text{OH}\to \text{NO}+{\rm{H}}$, thereby increasing NOx concentration and reducing energy consumption. Additionally, with an increase in ethanol volume fraction, the concentration of NF products also increases, reaching saturation when the ethanol volume fraction reaches 50%. At an ethanol volume fraction of 50%, the energy consumption for NF is lowest at a discharge current of 40 mA, at approximately 4.92 MJ/mol. The range of the reduced electric field strength of MSGD is calculated to be approximately 31.9 ~ 39.7 Td, at which about 90% of the electrical energy is converted into N2(v) vibrational states. At this point, NO is primarily formed by the Zeldovich mechanism (N 2 ( v ) + O → NO + N ${{\rm{N}}}_{2}({\rm{v}})+{\rm{O}}\to \text{NO}+{\rm{N}}$), which is the main reason for the lower energy consumption of NF in MSGD compared with the other two scenarios (opposite magnetic field and no magnetic field). Finally, the lower energy consumption of MSGD compared with the other two scenarios is discussed, highlighting that this is mainly due to its high gas utilization rate, high N2 vibrational energy, and high electrical energy utilization efficiency. [ABSTRACT FROM AUTHOR]

The development of a nonconventional nitrogen fertilizer, which can be fixed in agricultural fields using decentralized renewable energy sources, presents a feasible solution for sustainable on‐site nitrogen fixation and fertilization. This study focuses on plasma‐generated dinitrogen pentoxide (N2O5) as a prospective mediator for the on‐site nitrogen fertilization, allowing nitrogen fertilization directly into culture media. Basal dinitrogen pentoxide fertilization demonstrated almost 100% dinitrogen pentoxide dissolution efficiency as nitrate in a culture medium and nitrogen fertilization effect on plant growth without explicit symptoms of damage. Top‐dressing of dinitrogen pentoxide was also an efficient method for transferring nitrogen into the soil as nitrate, which improved plant growth and suppressed nitrogen deficiency symptoms, while overdose caused adverse effects. [ABSTRACT FROM AUTHOR]

Fixing earth‐abundant nitrogen elements into essential compounds is one of the ultimate issues for mankind. Electrochemical nitrogen fixation is regarded as promising to replace the Haber‐Bosch (HB) process at current stage. However, direct fixation of N2 is found skeptical recently due to the stable chemical properties of N2 molecule. In this regard, the more reactive nitrogen oxides (NOx) species came to light as an alternative of nitrogen sources. Since NOx species is one of the most prevalent pollutants in wastewater, it is also desired that NOx reduction can transform these detrimental ingredients into value‐added products such as ammonia. Like other chemical reactions, the performance of electrochemical NOx reduction to ammonia (eNOxRA) has a strong relation with the performance of catalysts. Previously, catalyst design of eNOxRA is dominantly based on transition metals. The role of p‐block elements in eNOxRA is not fully realized until very recent years. In this perspective, the up‐to‐date advances of p‐block‐contained catalysts in eNOxRA are concluded, with the role of p‐block elements specifically classified and discussed. Several strategies are also introduced to delicately investigate the interaction between p‐block elements and NOx species. At the end, some dilemmas and potential opportunities are proposed to achieve a more comprehensive understanding toward developing high‐efficient p‐block electrocatalyst for NOxRA. [ABSTRACT FROM AUTHOR]

The influence of climate on deep-time plant-insect interactions is becoming increasingly well known, with temperature, CO2 increases (and associated stoichiometric changes in plants), and aridity likely playing a critical role. In our modern climate, all three factors are shifting at an unprecedented rate, with uncertain consequences for biodiversity. To investigate effects of temperature, stoichiometry (specifically that of nitrogen), and aridity on insect herbivory, we explored insect herbivory in three modern floral assemblages and in 39 fossil floras, especially focusing on eight floras around a past hyperthermal event (the Paleocene-Eocene Thermal Maximum) from Bighorn Basin (BB). We find that higher temperatures were associated with increased herbivory in the past, especially among BB sites. In these BB sites, non-N2-fixing plants experienced a lower richness but higher frequency of herbivory damage than N2-fixing plants. Herbivory frequency but not richness was greater in BB sites compared with contemporaneous, nearby, but less arid sites from Hanna Basin. Compared with deep-time environments, herbivory frequency and richness are higher in modern sites, suggesting that current accelerated warming uniquely impacts plant-insect interactions. Overall, our work addresses multiple aspects of climate change using fossil data while also contextualizing the impact of modern anthropogenic change on Earth's most diverse interactions. [ABSTRACT FROM AUTHOR]

Biological nitrogen fixation (BNF) in legume crops is a crucial ecosystem service that enhances soil nitrogen and reduces the need for chemical fertilisers. This study evaluates the factors influencing the proportion of plant nitrogen derived from atmospheric fixation (Ndfa) in legume crops. We compiled a global dataset spanning from 1980 to 2018 and used the 15N method to assess the impacts of crop species, climatic conditions, stand composition and nitrogen fertilisation on Ndfa. The global meta‐analysis reveals that the percentage of nitrogen derived from atmospheric fixation (Ndfa) in legumes ranges from 5% to 99%, with an average of 68%. Fodder legumes exhibited higher Ndfa, averaging 75%, while grain legumes showed more variability, ranging from 38% to 85%, depending on species and climatic conditions. The significant variability in Ndfa underscores the complexity of the process, which is influenced by species‐specific traits, ecological conditions and competition in mixed stands. However, the current data is insufficient for precise Ndfa estimation in nitrogen balances and decision support tools. The study highlights the need for further research on the impact of nitrogen fertilisation and stand composition on Ndfa. These findings emphasise the potential of BNF to support sustainable agriculture by improving nitrogen availability and reducing dependence on synthetic fertilisers and particularly susceptibility to climate change challenges. To optimise the benefits of BNF, future research should focus on refining fertilisation regimes and exploring species‐specific responses to various ecological conditions. Exploring adaptive strategies, like selecting drought‐tolerant legumes and optimising irrigation, is essential. This will enhance the application of BNF in diverse agricultural systems, contributing to more sustainable and efficient farming practices. [ABSTRACT FROM AUTHOR]

The interaction between bean (Phaseolus vulgaris L.) genotypes and N-fixing microorganisms has the potential to be utilized in sustainable agricultural production. Thus, the aim of this study was to verify the effects of the interaction for growth, production and nodulation characteristics between the bacteria Rhizobium tropici and Azospirillum brasilense among different bean genotypes. The experiments were conducted in the Selvíria, Mato Grosso do Sul, Brazil, in 2018 and 2019, in randomized block design with three replicates in a 20 × 3 factorial scheme; 20 common bean genotypes were tested under three forms of inoculation (no inoculation, inoculation with R. tropici, co-inoculation of R. tropici + A. brasilense). The number of grains per pod and nodule mass had the most significant direct positive effect on grain yield. For nodulation, a positive correlation of strong magnitude was observed between mass of the aerial part and number of pods per plant (0.68), stem diameter and mass of nodules (0.92) and first pod insertion height and number of nodules (0.64). In the path analysis, the number of grains per pod had the most significant direct effect (0.57) on the grain productivity variable. Regarding nodulation characteristics, selection for nodule mass was preferred due to its direct effect on grain yield as opposed to the number of nodules, which has a negative effect. This suggests an advantage of larger nodules with greater individual mass than a large number of small nodules for both improved yield and N fixing by common bean plants. [ABSTRACT FROM AUTHOR]

Conventional tillage over the long term in more intensive-cropping systems is not sustainable as it enhances soil degradation, soil moisture loss, soil erosion, and cost of cultivation and disturbs beneficial micro-organisms. Retaining crop residues as mulch has been recognized as a desirable management practice for conserving soil moisture and lowering soil temperature, which ultimately helps in improving seed emergence. However, no-tillage or reduced tillage with crop residue produced better or non-significant differences in the growth and yield attributes and crop yield than that obtained under conventional tillage. However, zero or reduced tillage combined with crop residue improves biological nitrogen fixation, nitrogenase activity, symbiotic parameters and the uptake of nitrogen, phosphorus, and potassium. Continuous adoption of conservation tillage will have a positive effect on soil's physical, chemical, and biological properties and may also be better for the sustainability of crop production. The novelty of the study is that it examines the integrated effect of conservation tillage and residue retention through mulching on the crop emergence, symbiosis and quality of soybean along with growth, productivity, and profitability of soybean, nutrient uptake by the crop and soil properties together as sustainable agricultural technology. [ABSTRACT FROM AUTHOR]

Electrocatalytic and photocatalytic nitrogen fixation have become new ways to achieve green nitrogen reduction because of their environmentally friendly and cost‐effective characteristics. At present, there has been an increasing curiosity about using metal‐organic frameworks (MOFs) for photocatalysis and electrocatalysis. However, electrocatalytic and photocatalytic ammonia production is still not practical for practical applications. Having a thorough understanding of nitrogen fixation is necessary for the advancement of practical applications and the development of highly efficient catalysts in the future. The catalytic nitrogen fixation activity of MOF itself is limited. By adjusting the exposure of active sites through low‐temperature calcination and solvent addition, the photogenerated carrier recombination is inhibited, and the adsorption and activation of N2 are enhanced, improving its performance in nitrogen fixation applications. This review examines the reported photocatalysts, electrocatalysts, and photoelectrocatalysts based on MOFs and their associated materials. The underlying mechanism for photocatalysis and electrocatalysis is elucidated. Additionally, an inclusive survey of MOFs and related materials as catalysts for nitrogen reduction reaction (NRR) is presented, with representative examples discussed. Finally, the research progress of MOF‐based catalytic nitrogen fixation materials is summarized and prospected. [ABSTRACT FROM AUTHOR]

Agriculture is essential for nutrition and the global economy, becoming increasingly important due to population growth and higher food demand. This situation boosts interest in creating bioproducts that enhance productivity sustainably while reducing environmental issues and strain on natural resources. Bioinoculants are important innovations that use beneficial microorganisms to boost crop growth and resilience. They enhance the interaction between soil and plants by solubilizing essential nutrients and producing phytohormones. This not only boosts agricultural productivity but also promotes environmentally sustainable practices by decreasing reliance on chemical fertilizers. Considering the relevance of this subject to advances in agro-industrial biotechnology, this review analyzes recent studies and patent advances on the production and use of bioinoculants, as well as their integration into agricultural practices and plant development. It also explores the dynamics of production and downstream processes on an industrial scale, regulations in different countries, and growing market demands, which is an important feature of this review. Furthermore, future perspectives for the application of bioinoculants in agro-industrial biotechnology are discussed, emphasizing the critical role that these biological agents play in advancing agricultural sustainability. [ABSTRACT FROM AUTHOR]

Ammonia is a vital component in the fertilizer and chemical industries, as well as serving as a significant carrier of renewable hydrogen energy. Compared with the industry’s principal technique, the Haber-Bosch method, for ammonia synthesis, electro/photocatalytic ammonia synthesis is increasingly recognized as a viable and ecofriendly alternative. This method enables distributed small-scale deployment and can be powered by sustainable renewable energy sources. However, the efficiency of electro/photocatalytic nitrogen reduction reaction is hindered by the challenges in activating the N≡N bond and nitrogen’s low solubility, thereby limiting its large-scale industrial applications. In this review, recent advancements in electro/photocatalytic nitrogen reduction are summarized, encompassing the complex reaction mechanisms, as well as the effective strategies for developing electro/photocatalytic catalysts and advanced reaction systems. Furthermore, the energy efficiency and economic analysis of electro/photocatalytic nitrogen fixation are deeply discussed. Finally, some unsolved challenges and potential opportunities are discussed for the future development of electro/photocatalytic ammonia synthesis. [ABSTRACT FROM AUTHOR]

Background: Soil bacteria often form close associations with their host plants, particularly within the root compartment, playing a significant role in plant growth and stress resilience. Vachellia tortilis subsp. raddiana, (V. tortilis subsp. raddiana)a leguminous tree, naturally thrives in the harsh, arid climate of the Guelmim region in southern Morocco. This study aims to explore the diversity and potential plant growth-promoting (PGP) activities of bacteria associated with this tree. Results: A total of 152 bacterial isolates were obtained from the rhizosphere of V. tortilis subsp. raddiana. Rep-PCR fingerprinting revealed 25 distinct genomic groups, leading to the selection of 84 representative strains for further molecular identification via 16 S rRNA gene sequencing. Seventeen genera were identified, with Bacillus and Pseudomonas being predominant. Bacillus strains demonstrated significant tolerance to water stress (up to 30% PEG), while Pseudomonas strains showed high salinity tolerance (up to 14% NaCl). In vitro studies indicated variability in PGP activities among the strains, including mineral solubilization, biological nitrogen fixation, ACC deaminase activity, and production of auxin, siderophores, ammonia, lytic enzymes, and HCN. Three elite strains were selected for greenhouse inoculation trials with V. tortilis subsp. raddiana. Strain LMR725 notably enhanced various plant growth parameters compared to uninoculated control plants. Conclusions: The findings underscore the potential of Bacillus and Pseudomonas strains as biofertilizers, with strain LMR725 showing particular promise in enhancing the growth of V. tortilis subsp. raddiana. This strain emerges as a strong candidate for biofertilizer formulation aimed at improving plant growth and resilience in arid environments. [ABSTRACT FROM AUTHOR]

While the ambient N2 reduction to ammonia (NH3) using H2O as hydrogen source (2N2+6H2O=4NH3+3O2) is known as a promising alternative to the Haber–Bosch process, the high bond energy of N≡N bond leads to the extremely low NH3 yield. Herein, we report a highly efficient catalytic system for ammonia synthesis using the low‐temperature dielectric barrier discharge plasma to activate inert N2 molecules into the excited nitrogen species, which can efficiently react with the confined and concentrated H2O molecules in porous metal–organic framework (MOF) reactors with V3+, Cr3+, Mn3+, Fe3+, Co2+, Ni2+ and Cu2+ ions. Specially, the Fe‐based catalyst MIL‐100(Fe) causes a superhigh NH3 yield of 22.4 mmol g−1 h−1. The investigation of catalytic performance and systematic characterizations of MIL‐100(Fe) during the plasma‐driven catalytic reaction unveils that the in situ generated defective Fe−O clusters are the highly active sites and NH3 molecules indeed form inside the MIL‐100(Fe) reactor. The theoretical calculation reveals that the porous MOF catalysts have different adsorption capacity for nitrogen species on different catalytic metal sites, where the optimal MIL‐100(Fe) has the lowest energy barrier for the rate‐limiting *NNH formation step, significantly enhancing efficiency of nitrogen fixation. [ABSTRACT FROM AUTHOR]

Among 50 environments in the United States, we screened 35 hairy vetch (Vicia villosa Roth.) lines for traits of interest to cover cropping. We analyzed the influence of genotype, environment, and the genotype‐by‐environment interaction (G × E) on biomass, vigor, winter survival, emergence, flowering time, and nitrogen fixation. To explore how environments and G × E impacted each trait, we associated environment predictions and G × E loadings with weather and soil parameters. Environment had the largest influence on all traits, representing more than half of the variance. Environment predictions were significantly associated with weather and/or soil parameters for each trait. Biomass was associated with growing degree days, winter survival with freezing degree days without snow cover, growth stage with shortwave radiation, and emergence with soil texture. The G × E interaction was larger than genotypic variance for all traits except for winter survival and flowering time. The G × E interaction loadings were associated with soil sand content for biomass, air temperature for fall vigor and emergence, and snow cover for winter survival. Although it represented the smallest proportion of total variance, genetic effects were significant for all traits except for emergence, Ndfa, %N, and C:N. New hairy vetch breeding lines were superior to all commercially available lines for biomass and winter survival. Biomass harvest timing did not significantly change line rank, indicating that top‐performing lines can be used in diverse management systems. To select for high nitrogen contribution to subsequent crops, breeding programs can indirectly select for biomass rather than expensively evaluating symbiotic nitrogen fixation. [ABSTRACT FROM AUTHOR]

Electrochemical synthesis of NH3 from N2 utilizing single-atom catalysts (SACs) is a promising strategy for industrial nitrogen fixation and chemical raw material production. In this work, single transition metals (TMs) anchored on pyrazine-based graphene (TM@py-GY) are systematically studied to screen potential electrocatalysts for the nitrogen reduction reaction (NRR) using first-principles calculations. Particularly, the descriptor φ related to electronegativity and valence electron number is selected to clarify the trend of NRR activity, realizing a fast-scan/estimation among various candidates. After a four-step screening process, WI@py-GY and MoII@py-GY SACs are screened with good structural stability, high selectivity, and high activity. Meanwhile, the thermodynamic stability of WI@py-GY and MoII@py-GY SACs is demonstrated to ensure their feasibility in real experimental conditions. Furthermore, electronic properties are also examined in detail to analyze activity origin. This work not only provides an effective and reliable method for screening electrochemical NRR catalysts with excellent performance but also provides guidance for the rational design of SACs. [ABSTRACT FROM AUTHOR]

Biochar and green manure have been widely applied in agricultural production and are important means to achieve sustainable agriculture. However, there is limited research systematically and comprehensively exploring the response of soil microbiota and the changes in soil metabolomics after the addition of two different carbon source amendments to the soil, and the differential mechanisms of soil metabolomics between them remain unclear. In this study, a long-term field experiment (initiated in 2019) was conducted to investigate the effects of biochar and green manure application on soil nutrients and soil functions driven by soil microbes. Compared to the pure fertilizer treatment, biochar increased soil total carbon by 14.54% to 27.04% and soil available potassium by 4.67% to 27.46%. Ryegrass significantly increased soil available phosphorus and organic matter. Under different fertilization regimes, the ecological niches of soil microbes changed significantly. Network analysis revealed that long-term ryegrass returning reduced the complexity of soil microbial networks. Ryegrass and biochar increased dispersal limitation in fungal assemblages (reaching 93.33% and 86.67%, respectively), with biochar particularly enhancing variable selection in bacterial assemblages (accounting for 53.33%). Variation partitioning analysis based on redundancy analysis indicated that humic substances had the highest explanatory power for microbial community variation, with humic substances explaining 38.49% of bacteria and 52.19% of fungi variation. The ryegrass treatment mainly changed the abundance of carbohydrates (CH), amines (AM), c (AH), and lipids (LP), while the BC treatment mainly altered the abundance of organic acids (AC), amines (AM), and carbohydrates (CH). Meanwhile, both treatments significantly reduced the bisphenol A, one of the soil pollutants. Ryegrass incorporation significantly increased the abundance of genes related to soil C, N, P, and S cycling, especially genes involved in carbon decomposition, while biochar significantly enhanced the abundance of nitrogen fixation genes nifH and Hao in soil. Random forest model results indicated that carbohydrates, alcohols, aromatics (AR), and ester (ES) were the main categories of metabolites in soil influenced by differential microbes, and Finegoldia served as a common important metabolic driving species. In summary, this study reveals the processes of soil function, microbial community succession, and metabolism driven by ryegrass and biochar, providing important insights for optimizing soil management and improving soil quality. Highlights: Ryegrass green manure (RG) and biochar (BC) induced the simplification of microbial networks and an increase in fungi's random assembly processes. RG promoted denitrification and carbon degradation functional genes, while BC enhanced nitrogen fixation genes. RG accelerated soil energy flow by promoting M00307 and M00061. In RG-treated soil, the main metabolites were Carbohydrates, while in BC-treated soil, the main metabolites were Acids and Amines. Both treatments reduced soil pollutant bisphenol A. [ABSTRACT FROM AUTHOR]

Cyanobacteria, renowned for their nitrogen‐fixing characteristics, are important for sustainable biomanufacturing and agricultural innovation. This review explores the synergy between cyanobacteria and nitrogen fixation, highlighting their potential to revolutionize biobased compound production and reduce the ecological impact of traditional nitrogen sources. It focuses on genetic enhancements and synthetic biology techniques, which transform these microorganisms into sustainable nitrogen providers. Current applications range from agricultural enhancement to cutting‐edge biotechnology, highlighting the important consequences of cyanobacterial nitrogen fixation. Challenges persist, however, requiring a meticulous analysis of ecological, regulatory, and scalability concerns. The untapped potential of cyanobacteria in nitrogen fixation promises a significant shift in biomanufacturing and environmental stewardship. The aim of this article is to inspire high‐impact research and transformative applications in biotechnology and sustainability. [ABSTRACT FROM AUTHOR]

Bush bean (Phaseolus vulgaris L.) production is undermined by soil degradation and low biological nitrogen fixation (BNF) capacity. This study evaluated the effect of black soldier fly frass fertilizer (BSFFF) on bush bean growth, yield, nutrient uptake, BNF, and profitability, in comparison with commercial organic fertilizer (Phymyx, Phytomedia International Ltd., Kiambu, Kenya), synthetic fertilizer (NPK), and rhizobia inoculant (Biofix, MEA Fertilizers, Nairobi, Kenya). The organic fertilizers were applied at rates of 0, 15, 30, and 45 kg N ha-1 while the NPK was applied at 40 kg N ha-1, 46 kg P ha-1, and 60 kg K ha-1. The fertilizers were applied singly and in combination with rhizobia inoculant to determine the interactive effects on bush bean production. Results showed that beans grown using BSFFF were the tallest, with the broadest leaves, and the highest chlorophyll content. Plots treated with 45 kg N ha-1 BSFFF produced beans with more flowers (7 - 8%), pods (4 - 9%), and seeds (9 - 11%) compared to Phymyx and NPK treatments. The same treatment also produced beans with 6, 8, and 18% higher 100-seed weight, compared to NPK, Phymyx, and control treatments, respectively. Beans grown in soil amended with 30 kg N ha-1 of BSFFF had 3-14-fold higher effective root nodules, fixed 48%, 31%, and 91% more N compared to Phymyx, NPK, and rhizobia, respectively, and boosted N uptake (19 - 39%) compared to Phymyx and NPK treatments. Application of 45 kg N ha-1 of BSFFF increased bean seed yield by 43%, 72%, and 67% compared to the control, NPK and equivalent rate of Phymyx, respectively. The net income and gross margin achieved using BSFFF treatments were 73 - 239% and 118 - 184% higher than the values obtained under Phymyx treatments. Our findings demonstrate the high efficacy of BSFFF as a novel soil input and sustainable alternative for boosting BNF and improving bush bean productivity. [ABSTRACT FROM AUTHOR]

Comprehensive Summary The reaction between tripodal trisamidophosphine ligand H3PN3Ar and V(Mes)3(THF) (Mes = mesityl) yields the vanadium(III) complex (PN3Ar)V (1) with an open site in the axial position, which could coordinate with THF, pyridine, and NH3 to form the corresponding adducts (2—4). The vanadium(III) center is redox‐active, as demonstrated by cyclic voltammetry methods and chemical oxidation or reduction. Notably, a novel dinitrogen divanadium complex with a bridging N2 ligand, {K(THF)}2{[PN3Ar]V}2(μ‐N2) (6), was synthesized via treatment of 1 with 1 equivalent of potassium naphthalenide in THF under a N2 atmosphere. The electronic structures and binding properties of 6 are evaluated and discussed based on its DFT calculations. Additionally, these vanadium complexes (1, 5, 6) can serve as catalysts for the conversion of N2 into N(SiMe3)3 in the presence of reductants and Me3SiCl. [ABSTRACT FROM AUTHOR]

While traditionally perceived as yield‐reducing elements in rice (Oryza sativa L.) cultivation, weed communities in paddy fields play a crucial role in the ecosystem. These communities, when selectively retained, can significantly enhance ecosystem services. This review examines the impact of various weed communities on rice in different paddy fields, their response to field nutrients, and the ecological benefits they offer. These benefits include nitrogen retention, promotion of microbial diversity, and reduction of diseases, pests, and weed proliferation. Examples of such benefits are seen in weeds like Lemna minor L. and Azolla imbricata (Roxb.) Nakai, which help in nitrogen fixation and act as biocontrol agents against harmful pests. However, current research in this area faces challenges, including the lack of intelligent and precise weed control technologies, comprehensive green control strategies, and expertise in weed management. Our findings suggest a strategic approach to weed control in paddy fields, emphasizing the importance of preserving weed species that have minimal impact on rice yields but offer significant ecological advantages. These practices can lead to grass‐mediated weed control and enhanced nutrient absorption, thereby reducing fertilizer loss. Ultimately, this approach could reduce the reliance on chemical fertilizers and herbicides in paddy fields, laying the groundwork for greener rice cultivation and sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Millions of small scale legume farmers lack access to rhizobia bacterial inoculants that improve crop protein and yield, and minimize fossil-fuel based nitrogen fertilizers, through biological nitrogen fixation (BNF). BNF converts atmospheric nitrogen gas into ammonia, required to synthesize chlorophyll and amino acids. BNF is catalyzed by rhizobia that inhabit nodule organs in legume roots (e.g., soybean, cowpea, chickpeas, lentil, fava, peas, beans). Rhizobia inoculant access in remote communities is limited by centralized facilities to grow bacteria, inadequate transportation networks and refrigeration. Recently, we proposed that rhizobia inoculants can be diffused by farmers themselves, simply, by crushing nodules onto seeds, and demonstrated its efficacy under field conditions. A concern was whether nodules remain viable between growing seasons. Here we provide preliminary evidence that bean nodules, dried and stored at room temperature after 6 months, retain nodulation potential. We discuss: (1) the feasibility, constraints and risks of nodule crushing; (2) scaling up strategies; (3) entrepreneurship that benefits women farmers (e.g., noduleselling microenterprises); and (4) empowering farmers to directly select, evolve and indigenize rhizobia for the first time. Finally, we prioritize research questions and encourage the formation of a global participatory research network, with the goal of decentralizing and democratizing rhizobia inoculants. [ABSTRACT FROM AUTHOR]

Mercury is one of the most toxic pollutants that has drawn the attention of scientists. This study investigates the phytoremediation capabilities of Vigna radiata L. in conjunction with microbial biostimulators. The inoculated seeds were cultivated in soil under controlled greenhouse conditions. The concentration of Hg, biomass, and photosynthetic pigments was investigated under amendment factor including EDTA, bacterial, fungal (Mycorrhiza and Trichoderma), biochar, and combined levels, as well as the pollution factor with three levels of HgCl2 as two factorial experiments. Results showed that Plant Growth-Promoting Microorganisms (PGPMs) influenced mercury absorption and distribution in different plant organs. Aside from biochar, all stimulators increased the plant's Hg concentration. Although EDTA greatly increased mercury accumulation in plants, it reduced biomass. Fungal and bacterial treatments increased total mercury in the plant but decreased its concentration in the leaves. The combination of bacteria and fungi resulted in the highest mercury absorption, while the biochar in combination with PGPMs produced the greatest biomass. Analysis of mercury concentration in seeds indicated that V radiata effectively prevented its contamination in seeds. The results disclosed that microbial combinations of bacteria and fungi could increase the plant's potential to cope with heavy metal pollution. This improvement is due to the different roles of these two organisms, like nitrogen fixation by bacteria and phosphorus absorption by mycorrhiza fungi. Moreover, biochar as a soil amendment and microorganism carrier was noticed. Finally, considering the plant's inherent capacity to stabilize mercury in the roots, phytostabilization with the benefit of combined levels of biochar and microorganisms can be introduced as the best approach. [ABSTRACT FROM AUTHOR]

Photocatalytic nitrogen oxidation reactions has emerged as promising techniques for air‐based nitrate synthesis, bolstering sustainable nitrogen fixation in industrial chains centered around nitrates. However, significant disparities in orbital energy levels impose constraints on N2 conversion, highlighting the pivotal role of nitrogen activation, particularly in oxygen‐rich environments. Herein, a novel Ir‐WO3 catalyst with cation vacancy chains is fabricated and utilized as a highly efficient catalyst for thermal‐assisted nitrogen oxidation under an innovative discontinuous light illumination strategy. Remarkably, an unexpected NO3− yield of 381.21 µmol g−1 h−1 is achieved, marking a 10.4‐fold increase compared to regular continuous light illumination. This exceptional performance is attributed to the unique structure and discontinuous light illumination, which lowered the energy barrier of the rate‐determining step for forming *NN(OH) intermediates and enhanced the abundance of •OH. Furthermore, a novel •OH assisted nitrogen activation mechanism is proposed based on the identification of crucial N2O intermediate and operando experiments. This work offers novel insights into free radicals‐based photocatalytic conversion processes and also presents a potential nitrate synthesis pathway for nitrates‐centric industrial nitrogen fixation chains. [ABSTRACT FROM AUTHOR]

Non-CG DNA methylation, a plant-specific epigenetic mark mainly regulated by chromomethylase (CMT), is known to play important roles in Arabidopsis thaliana. However, whether and to what extent non-CG DNA methylation modulates agronomic traits in crops remain to be explored. Here, we describe the consequences of non-CG DNA hypomethylation on development, seed composition, and yield in soybean (Glycine max). We created a Gmcmt mutant line lacking function of all four CMT genes. This line exhibited substantial hypomethylation of non-CG (CHG and CHH) sites. Non-CG hypomethylation enhanced chromatin accessibility and promoted or repressed the expression of hundreds of functionally relevant genes, including upregulation of GOLDEN-LIKE 10 (GmGLK10), which led to enhanced photosynthesis and, unexpectedly, improved nitrogen fixation efficiency. The Gmcmt line produced larger seeds with increased protein content. This study provides insights into the mechanisms of non-CG methylation-based epigenetic regulation of soybean development and suggests viable epigenetic strategies for improving soybean yield and nutritional value. [ABSTRACT FROM AUTHOR]

Background: The proportion of nitrogen (N) derived from the atmosphere (Ndfa) is a fundamental component of the plant N demand in legume species. To estimate the N benefit of grain legumes for the subsequent crop in the rotation, a simplified N balance is frequently used. This balance is calculated as the difference between fixed N and removed N by grains. The Ndfa needed to achieve a neutral N balance (hereafter θ ) is usually estimated through a simple linear regression model between Ndfa and N balance. This quantity is routinely estimated without accounting for the uncertainty in the estimate, which is needed to perform formal statistical inference about θ . In this article, we utilized a global database to describe the development of a novel Bayesian framework to quantify the uncertainty of θ . This study aimed to (i) develop a Bayesian framework to quantify the uncertainty of θ , and (ii) contrast the use of this Bayesian framework with the widely used delta and bootstrapping methods under different data availability scenarios. Results: The delta method, bootstrapping, and Bayesian inference provided nearly equivalent numerical values when the range of values for Ndfa was thoroughly explored during data collection (e.g., 6–91%), and the number of observations was relatively high (e.g., ≥ 100 ). When the Ndfa tested was narrow and/or sample size was small, the delta method and bootstrapping provided confidence intervals containing biologically non-meaningful values (i.e. < 0% or > 100%). However, under a narrow Ndfa range and small sample size, the developed Bayesian inference framework obtained biologically meaningful values in the uncertainty estimation. Conclusion: In this study, we showed that the developed Bayesian framework was preferable under limited data conditions ─by using informative priors─ and when uncertainty estimation had to be constrained (regularized) to obtain meaningful inference. The presented Bayesian framework lays the foundation not only to conduct formal comparisons or hypothesis testing involving θ , but also to learn about its expected value, variance, and higher moments such as skewness and kurtosis under different agroecological and crop management conditions. This framework can also be transferred to estimate balances for other nutrients and/or field crops to gain knowledge on global crop nutrient balances. [ABSTRACT FROM AUTHOR]

The surge in global energy demand mandates a significant expansion of electric power substations. Nevertheless, the ecological consequences of electric power substation operation, particularly concerning the electromagnetic field, on soil microbial communities and nitrogen enrichment remain unexplored. In this study, we collected soil samples from six distinct sites at varying distances from an electric power substation in Xintang village, southeastern China, and investigated the impacts of electromagnetic field on the microbial diversity and community structures employing metagenomic sequencing technique. Our results showed discernible dissimilarities in the fungal community across the six distinct sites, each characterized by unique magnetic and electric intensities, whereas comparable variations were not evident within bacterial communities. Correlation analysis revealed a diminished nitrogen fixation capacity at the site nearest to the substation, characterized by low moisture content, elevated pH, and robust magnetic induction intensity and electric field intensity. Conversely, heightened nitrification processes were observed at this location compared to others. These findings were substantiated by the relative abundance of key genes associated with ammonium nitrogen and nitrate nitrogen production. This study provides insights into the relationships between soil microbial communities and the enduring operation of electric power substations, thereby contributing fundamental information essential for the rigorous environmental impact assessments of these facilities. [ABSTRACT FROM AUTHOR]

The use of solar-driven semiconductor photocatalysis to solve energy and environmental issues is an intriguing and difficult subject. As a consequence, various types of photocatalysts have been developed subsequently to fulfill the requirements of photocatalysis.Since graphene was discovered, materials based on graphene have garnered considerable interest. The aloe-vera derived (ADG)/nickel oxide (NiO) nanocomposite is a notable example of a graphene derivative.The uniform structure of graphene fibre is altered by nickel oxide(NiO) which tunes its band gap and causes electronic arrangements within graphene that is requiste for photocatalysis. Herein, we have used a one-pot chemical approach to design aloe vera-derived graphene/nickel oxide nanocomposites (ADG/NiO), a novel photocatalyst that show high molar absorbance, suitable band gap of 2.68 eV, good photo-stability and reusability. Under solar light irradiation, the ADG/NiO nanocomposite exhibited remarkable photocatalytic activity. It effectively fixed nitrogen into ammonia with an apparent quantum efficiency(AQE) of 0.64% and efficiently photo-oxidized dyes. Specifically, it achieved a dye removal efficiency of 94.2% for methylene blue (MB) and 86.41% for Eosin-B, converting them into harmless inorganic species like CO2 and H2O within just 90 minutes. The cost-effective ADG/NiO nanocomposite shows significant potential as a photocatalyst activated by solar light for practical applications such as the selective generation of NH3 and the purification of industrial wastewater containing dyes. [ABSTRACT FROM AUTHOR]