Agriculture alters protein evolution of respiratory nitrate reductase in soil bacteria at a global scale.

Ectoine modulates mixotrophic denitrification pathway partitioning to sustain stable nitrogen and phenol removal under hypersaline stress.

Removal of nitrate by aerobic denitrification granular sludge under strongly alkaline and low carbon to nitrogen ratio conditions: Performance and mechanism.

Synergistic enhancement of nitrogen and phosphorus removal by Pseudomonas sp. GD01 through g-C3N4 photocatalysis: performance and mechanisms.

Anthraquinone-2-sulfonate enhances endogenous denitrification and phosphorus removal: Electron shuttle-mediated syntrophic partnerships.

Oligochaete-driven resilience: Mitigating microplastic toxicity in constructed wetlands through integrated plant-microbe responses.

Exploiting natural variation to uncouple yield from nitrogen (N) input is essential for sustainable oilseed rape production. Here, we screened 505 accessions and discovered a 10-fold gradient in chlorate (ClO₃⁻) sensitivity that mirrors genotypic differences in nitrogen use efficiency (NUE). Chlorate-sensitive genotypes (CSG) exhibited 35% higher ¹⁵NO₃⁻ influx, 40%-62% greater root glutamine synthetase (GS) activity, and almost twice the seed yield of chlorate-insensitive genotypes (CIG) under high-N supply, whereas nitrate (NO₃⁻) reductase activity was unchanged. Chemical inhibition of GS using L-methionine-S-sulfoximine (MSX) resulted in the loss of ClO₃⁻ sensitivity, mechanistically linking assimilation flux to the observed phenotypic variation. Root proteomic analysis identified differentially abundant proteins between CSG and CIG and showed that BnaA02.GLN1;2 (a cytosolic GS1 homologue) was a hub protein with higher abundance in CSG. Overexpression of BnaA02.GLN1;2 enhanced rapeseed chlorate sensitivity under sufficient NO₃⁻ supply, promoted seedling growth, and enhanced both NO₃⁻ uptake and assimilation. Mature transgenic plants produced more pods and higher yields under normal N conditions while simultaneously reducing seed erucic acid and glucosinolate concentrations. Genome-wide association study mapped a major quantitative trait locus on chromosome A02, with BnaA02.GLN1;2 as the causal gene. Eleven single-nucleotide polymorphisms (SNPs) classified BnaA02.GLN1;2 into three haplotypes: BnaA02.GLN1;2Hap1 showed higher gene expression level, GS activity and shoot N content than BnaA02.GLN1;2Hap3. Our findings reposition GS1 as a key regulator that coordinates NO₃⁻ uptake and assimilation and establish BnaA02.GLN1;2Hap1 as a breeding-ready target to develop high-yield, low-input rapeseed.

Coupling heterotrophic and hydrogenotrophic partial denitrification via gel-based bio-carriers: microbial mechanisms and metabolic modeling.

Microbial-derived metabolites coordinate growth regulation and stress tolerance in Phalaenopsis orchids.

Rising vanadium(V) contamination severely threatens environmental safety and human health. Microbial-mediated pentavalent V [V(V)] reduction, an effective route to V detoxification, can be influenced by coexisting redox-sensitive matters. However, the interaction between V(V) and widely distributed ferric iron [Fe(III)] minerals still remains largely unknown. This study investigated the coupled transformations of V(V) and Fe(III) minerals in biosystems with Bacillus subtilis. Fe(III) minerals, particularly low-crystallinity ferrihydrite, markedly enhanced V(V) reduction. Concurrently, B. subtilis reduced structural Fe(III) to Fe(II), which abiotically drove V(V) reduction, contributing 62.6, 60.6, and 45.3% of total V(V) removal in ferrihydrite, goethite, and hematite biosystems, respectively. X-ray photoelectron spectroscopy, X-ray diffraction, and X-ray absorption near-edge structure analysis revealed that V(V) was reduced predominantly to VO(OH)2 precipitates. Nanoscale goethite formed concurrently in ferrihydrite biosystem, with goethite and hematite biosystems showing minimal mineralogical change. Elevated levels of cytochrome and extracellular polymeric substances enhanced extracellular electron transfer, facilitating V(V) and Fe(III) reductions. The upregulation of genes napA and cnorB with increased activities of nitrate reductase and nitric oxide reductase further reinforced reductive V(V) detoxification. These findings provide novel insights into biogeochemical interactions between V and Fe(III) minerals and offer a promising strategy for detoxifying V in sedimentary environments.

This study reports the phytogenic synthesis and multifunctional evaluation of molybdenum oxide nanoparticles (MoONPs) using Pterocarpus santalinus leaf extract as a natural reducing and stabilising agent. The synthesised MoONPs exhibited a distinct surface plasmon resonance peak at 364nm, confirming their formation. FE-SEM/EDAX revealed spherical, high-purity nanoparticles, while XRD confirmed an orthorhombic crystalline phase with an average crystallite size of 35.71nm. FT-IR identified functional groups involved in capping and stabilisation. MoONPs demonstrated significant antioxidant activity (40.21% ABTS inhibition at 100µg/mL), comparable to ascorbic acid and superior to the extract alone. They also exhibited strong antimicrobial activity against phytopathogenic bacteria (X. campestris, P. syringae, C. michiganensis, S. aureus) and fungi (A. niger, A. flavus), demonstrating notable antimicrobial activity compared to standard controls. As a seed-priming agent for Arachis hypogaea, MoONPs enhanced germination (up to 227.5%), vigour index (up to 379.4), and root/shoot elongation. MoONPs boosted nitrate reductase activity by 67%, increased chlorophyll content by 79%, and improved biomass accumulation and plant height. Collectively, these findings indicate that Pterocarpus santalinus-mediated MoONPs exhibit multifunctional properties with potential applications as nano-fertilizers and biocontrol agents in agriculture; however, further studies are required to evaluate their safety and environmental impact before practical implementation.

Hematite-enhanced denitrification in bioelectrochemical system at low current density: kinetics, biofilm chemistry and metagenomic mechanisms.

Maladera insanabilis, a widespread and destructive agricultural pest in India, thrives in nitrogen-deficient subsoil environments due to its dependency on gut bacteria. In particular, the hindgut is an anaerobic fermentation chamber, supporting microbial-driven nitrogen transformations essential for larval development. Despite its ecological significance, detailed studies exploring gut bacterial diversity and functional role in M. insanabilis are lacking. This study integrates metagenomics, culture-based techniques, enzymatic assays, and gene expression analyses to characterize the nitrogen-cycling potential of gut microbiota along the different gut compartments. The culture-based analysis isolated 16 aerobic and 8 anaerobic bacterial strains, predominantly from Bacillota and Pseudomonadota. High-throughput 16S rRNA Illumina sequencing revealed 134 shared amplicon sequence variants (ASVs), with distinct bacterial assemblages, Burkholderia and Pseudomonas in the foregut, Paenibacillus in the midgut, and anaerobic genera such as Bacteroides and Desulfovibrio dominating the hindgut. Functional annotation using the KEGG database indicated that anaerobic gut bacteria are actively involved in nitrification, denitrification, and nitrogen fixation. The Enzyme assays confirmed high nitrate and nitrite reductase activity, with Burkholderia contaminans and Bacillus cepacia showing the highest activities. Michaelis-Menten kinetics and Lineweaver-Burk analysis (R² = 0.9871) showed a higher capacity (Vmax) for nitrate and nitrite reduction; a small Km indicates a high affinity for nitrate and nitrite. Gene expression studies viz., hzo, nifH, amx, nirS, and nirK revealed a significantly high expression level in the hindgut, especially under vermicompost treatment. This study provides the first comprehensive insight into nitrogen-cycling gut bacteria in M. insanabilis, highlighting their role in host nutrition and nitrogen transformation. These findings lay a foundation for future microbiome-targeted pest control strategies aimed at disrupting nutrient acquisition in soil-dwelling grubs.

LncRNAs modulate nitrogen metabolism gene expression in rice leaves under elevated CO₂ and/or Cd stress.

Acetic acid enhances stress tolerance, growth, and yield of mungbean (Vigna radiata L.) under arid conditions

Mixed cropping green manure can simultaneously improve the nutrient yield and quality of spring wheat grain under reduced chemical nitrogen supply

ABSTRACT Tropospheric ozone (O3), an emerging climate change-induced stressor, enters leaf tissues via stomata, triggering reactive oxygen species (ROS) generation and suppressing key N assimilation enzymes like nitrate reductase and glutamine synthetase impairing nitrogen metabolism and reducing grain yield and nitrogen use efficiency (NUE) in rice. This study evaluated the impact of elevated O3 (e[O3]) on nitrogen (N) uptake, NUE components, and yield attributes across two contrasting seasons using Open Top Chambers (OTCs) with four treatments: UC (ambient, open field, 30 ± 5 ppb), CC (ambient, OTC, 30 ± 5 ppb), EO40 (40 ± 5 ppb), and EO60 (60 ± 5 ppb), across three N levels. Partial Least Squares Path Modeling (PLS-PM) was used to analyze trait interrelationships affecting grain yield. Results showed that e[O3] significantly reduced total N uptake (17–28%), agronomic NUE (27–35%), N recovery efficiency (22–28%), physiological NUE (6–10%), and partial factor productivity of N (14–23%) compared to CC. Grain yield declined by 14–23%, with greater reductions observed during Kharif season, likely due to higher stomatal conductance facilitating increased O3 uptake. Higher N application only partially mitigated O3-induced NUE impairment. PLS-PM identified spikelet fertility as the strongest direct yield determinant under O3 stress.

Metabolic enhancement of AnAOB via enzyme and cofactor regulation for nitrogen removal in wastewater: a critical review.

Abstract Plants depend on nitrogen (N) for their growth, development, and metabolic functions. However, the regulatory mechanisms modulating N assimilate allocation under varying N forms are unclear. This study examines N metabolism and spatial distribution in maize seedlings subjected to four N treatments (T1 to T4): T1, 1 mM NO 3 − (sole NO 3 − ); T2, substitution of 1 mM NO 3 − with 1 mM NH 4 + (N form substitution, NFS); T3, 1 mM NH 4 + (sole NH 4 + ); and T4, 0.5 mM NH 4 NO 3 (mixed N supply). The NFS treatment induced significant physiological and molecular adaptations, such as enhanced growth and total biomass under fluctuating N conditions. NFS-treated plants exhibited improved photosynthesis, increased protein and amino acid synthesis, and increased NO₃⁻ and NH₄⁺ accumulation. Activities of key N metabolism enzymes, such as nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT), were significantly upregulated, supporting efficient assimilation of both NO 3 − and NH 4 + . Furthermore, spatial and diurnal analyses revealed dynamic N partitioning and adaptive regulation, with NFS-treated plants maintaining consistently higher NO 3 − and NH 4 + levels in leaves, roots, sheaths, and developing ears. These findings highlight the robust plasticity of maize N metabolism under NFS conditions and provide valuable insights into optimizing N use efficiency (NUE) for sustainable crop production. Future studies will focus on exploring these adaptive mechanisms across different maize genotypes and under field conditions to improve NUE and productivity in varying N environments.

Light availability is a key environmental factor regulating nitrogen assimilation, carbon metabolism, and nutritional quality in leafy vegetables grown in controlled environments. However, how practical lighting regimes used in plant factories with artificial lighting (PFALs) influence the coordination between nitrogen assimilation and central carbon metabolism across different lettuce cultivar types remains insufficiently understood. This study investigated how moderate differences in photosynthetic photon flux density (PPFD) influence nitrogen metabolism and metabolic coordination in hydroponically cultivated lettuce. Two cultivars representing contrasting morphological types, iceberg lettuce (‘Celebration’) and leaf lettuce (‘Sunny’), were grown under LED light intensities of 150 and 200 µmol·m−2·s−1. Nitrate, nitrite, and ammonium concentrations were measured together with the activities of nitrate reductase (NRA) and nitrite reductase (NiRA), as well as ascorbic acid content. Metabolomic profiling was additionally performed to characterize broader metabolic responses. Higher light intensity enhanced nitrate reduction capacity in both cultivars, but the resulting patterns of nitrogen accumulation were strongly genotype-dependent. The leaf lettuce cultivar ‘Sunny’ exhibited increased NRA and reduced nitrate accumulation under higher light intensity, whereas the iceberg lettuce cultivar ‘Celebration’ accumulated more nitrate under the same conditions. Ammonium responses further suggested differences in downstream nitrogen assimilation processes. Elevated light intensity also increased ascorbic acid levels in both cultivars. Metabolomic analysis revealed contrasting cultivar-specific shifts in central carbon metabolism, particularly involving soluble sugars and tricarboxylic acid cycle intermediates, indicating differential coordination between carbon metabolism and nitrogen utilization. Overall, these findings demonstrate that moderate changes in light intensity within the practical PFAL cultivation range can significantly influence the integration of carbon and nitrogen metabolism in lettuce. Importantly, cultivar-specific physiological traits determine how these metabolic responses translate into nitrate accumulation and nutritional quality in controlled-environment production systems.