Reduction Of Nitric Oxide Research Articles

The zinc transporter Slc30a1 (ZnT1) in macrophages plays a protective role against attenuated Salmonella.

The zinc transporter Slc30a1 plays an essential role in maintaining cellular zinc homeostasis. Despite this, its functional role in macrophages remains largely unknown. Here, we examine the function of Slc30a1 in host defense using mice models infected with an attenuated stain of Salmonella enterica Typhimurium and primary macrophages infected with the attenuated Salmonella. Bulk transcriptome sequencing in primary macrophages identifies Slc30a1 as a candidate in response to Salmonella infection. Whole-mount immunofluorescence and confocal microscopy imaging of primary macrophage and spleen from Salmonella-infected Slc30a1flag-EGFP mice demonstrate Slc30a1 expression is increased in infected macrophages with localization at the plasma membrane and in the cytosol. Lyz2-Cre-driven Slc30a1 conditional knockout mice (Slc30a1fl/fl;Lyz2-Cre) exhibit increased susceptibility to Salmonella infection compared to control littermates. We demonstrate that Slc30a1-deficient macrophages are defective in intracellular killing, which correlated with reduced activation of nuclear factor kappa B and reduction in nitric oxide (NO) production. Notably, the model exhibits intracellular zinc accumulation, demonstrating that Slc30a1 is required for zinc export. We thus conclude that zinc export enables the efficient NO-mediated antibacterial activity of macrophages to control invading Salmonella.

Dynamic Reconstruction of Cu Catalyst under Electrochemical NO Reduction to NH3.

The electrochemical reduction of nitric oxide (NO) to ammonia (NH3) offers a sustainable way of simultaneously treating the air pollutant and producing a useful chemical. Among catalyst candidates, Cu emerges as a stand-out choice for its superb NH3 selectivity and production rate. However, a comprehensive study concerning its catalytic behaviorin the NO reduction environment is lacking. Here, we unravel the dynamic rearrangement of Cu catalysts during NO reduction: the emergence of a bundled nanowire structure dependent on the applied potential. This unique structure is closely linked to an enhancement in double-layer capacitance, leading to a progressive increase in current density from 236 mA cm-2 by 20% over 1 h, while maintaining a Faradaic efficiency of 95% for NH3. Characterizations of Cu oxidation states suggest that the nanostructure results from the dissolution-redeposition of Cu in the aqueous electrolyte, influenced by the interaction with NO or other reactive intermediates. This understanding contributes to the broader exploration of Cu-based catalysts for sustainable and efficient NH3 synthesis from NO.

Limosilactobacillus reuteri HY7503 and Its Cellular Proteins Alleviate Endothelial Dysfunction by Increasing Nitric Oxide Production and Regulating Cell Adhesion Molecule Levels.

Endothelial dysfunction, which is marked by a reduction in nitric oxide (NO) production or an imbalance in relaxing and contracting factor levels, exacerbates atherosclerosis by promoting the production of cell adhesion molecules and cytokines. This study aimed to investigate the effects of Limosilactobacillus reuteri HY7503, a novel probiotic isolated from raw milk, on endothelial dysfunction. Five lactic acid bacterial strains were screened for their antioxidant, anti-inflammatory, and endothelium-protective properties; L. reuteri HY7503 had the most potent effect. In a mouse model of angiotensin II-induced endothelial dysfunction, L. reuteri HY7503 reduced vascular thickening (19.78%), increased serum NO levels (226.70%), upregulated endothelial NO synthase (eNOS) expression in the aortic tissue, and decreased levels of cell adhesion molecules (intercellular adhesion molecule-1 [ICAM-1] and vascular cell adhesion molecule-1 [VCAM-1]) and serum cytokines (tumor necrosis factor-alpha [TNF-α] and interleukin-6 [IL-6]). In TNF-α-treated human umbilical vein endothelial cells (HUVECs), L. reuteri HY7503 enhanced NO production and reduced cell adhesion molecule levels. In HUVECs, surface-layer proteins (SLPs) were more effective than extracellular vesicles (exosomes) in increasing NO production and decreasing cell adhesion molecule levels. These findings suggested that L. reuteri HY7503 may serve as a functional probiotic that alleviates endothelial dysfunction.

Regulatory Mechanisms and Synergistic Enhancement of the Diiron YtfE Protein in Nitric Oxide Reduction.

The diiron-containing YtfE protein in Escherichia coli is pivotal in counteracting nitrosative stress, a critical barrier to bacterial viability. This study delves into the biochemical complexity governing YtfE's conversion of nitric oxide (NO) to nitrous oxide, a key process for alleviating nitrosative stress. Through site-directed mutagenesis, we explored YtfE's molecular structure, with a particular focus on two internal transport tunnels important for its activity. Our findings illuminate Tunnel 1 as the primary conduit for substrate transport, regulated by conformational shifts within the N-terminal domain that enable substrate access to the diiron core in the C-terminal domain. Tunnel 2 emerges as a secondary, supportive route, activated when Tunnel 1 is compromised. This result challenges a previous model of distinct tunnels for substrate entry and product exit, suggesting both tunnels are capable of transporting substrates and products. Our engineering efforts enhanced the role of Tunnel 2, enabling a synergistic operation with Tunnel 1 and tripling YtfE's enzymatic activity compared to its wild-type form. This research not only deepens our understanding of YtfE's regulatory mechanism for NO reduction but also introduces a strategy to amplify its enzymatic efficiency. The outcomes offer new ravenues for modulating bacterial stress responses.

Electrode Materials for NO Electroreduction Based on Dithiolene Metal–Organic Frameworks: A Theoretical Study

To quickly and efficiently screen catalytic materials with both activity and selectivity for the nitric oxide reduction reaction (NORR), we adopted a strategy that considers the activity of the side reaction hydrogen evolution reaction (HER) first. It can be seen that Fe3(THT)2 (THT = triphenylene-2,3,6,7,10,11-hexathiol) has extremely excellent HER activity, with a Gibbs free energy change (ΔG) of 0.007 eV. Based on the relationship between ΔG and theoretical exchange current density, all TM3(THT)2 can be divided into two regions: one is the absolute values of ΔG greater than 1 eV, the other is the absolute values of ΔG greater than 0 eV and less than 1eV. Obviously, the candidates with the absolute values of ΔG greater than 1 eV have poor HER performance, but this precisely provides the possibility of obtaining NORR catalytic materials with both excellent selectivity and activity. Subsequent calculation results show that the maximum ΔG change of the rate-determining step of Ta3(THT)2 is unexpectedly only 0.05 eV. Therefore, Ta3(THT)2 may be regarded as the NORR catalytic material with both excellent performance and selectivity. Based on the electron transfer and partial density of states (PDOS) analysis, it can be seen that Ta plays a crucial role in the activation stage of NO. The approach that considers the activity of the side reaction HER first may provide a new idea for rapidly screening highly selective and active NORR catalysts.

Small archaea may form intimate partnerships to maximize their metabolic potential.

DPANN archaea have characteristically small cells and unique genomes that were long overlooked in diversity surveys. Their reduced genomes often lack essential metabolic pathways, requiring symbiotic relationships with other archaeal and bacterial hosts for survival. Yet a long-standing question remains, what is the advantage of maintaining ultrasmall cells. A recent study by Zhang et al. examined genomes of DPANN archaea from marine oxygen deficient zones (ODZs) (I. H. Zhang, B. Borer, R. Zhao, S. Wilbert, et al., mBio 15:e02918-23, 2024, https://doi.org/10.1128/mbio.02918-23). Surprisingly, these genomes contain a broad array of metabolic pathways including genes predicted to be involved in nitrous oxide (N2O) reduction. However, N2O levels are likely too low in ODZs to make this metabolically feasible. Modeling co-localization of DPANN archaea (N2O consumers) with other larger cells (N2O producers) demonstrates that N2O uptake rates can be optimized by maximizing the producer-to-consumer size ratio and proximity of consumer cells to producers. This may explain why such a diversity of archaea maintain extremely small cell sizes.

Impaired Endothelium-Dependent Vasodilation and Increased Levels of Soluble Fms-like Tyrosine Kinase-1 Induced by Reduced Uterine Perfusion Pressure in Pregnant Rats: Evidence of Protective Effects with Sodium Nitrite Treatment in Preeclampsia.

Preeclampsia (PE) is a hypertensive disorder of pregnancy and is associated with increases in soluble fms-like tyrosine kinase-1 (sFlt-1) and reductions in nitric oxide (NO) levels. Placental ischemia and hypoxia are hypothesized as initial pathophysiological events of PE. Nitrite (NO metabolite) may be recycled back to NO in ischemic and hypoxic tissues. Therefore, this study examined the sodium nitrite effects in an experimental model of PE. Pregnant rats received saline (Preg group) or sodium nitrite (Preg + Na-Nitrite group). Pregnant rats submitted to the placental ischemia received saline (RUPP group) or sodium nitrite (RUPP + Na-Nitrite group). Blood pressure, placental and fetal weights, and the number of pups were recorded. Plasma levels of NO metabolites and sFlt-1 were also determined. Vascular and endothelial functions were also measured. Blood pressure, placental and fetal weights, the number of pups, NO metabolites, sFlt-1 levels, vascular contraction, and endothelium-dependent vasodilation in the RUPP + Na-Nitrite rats were brought to levels comparable to those in Preg rats. In conclusion, sodium nitrite may counteract the reductions in NO and increases in sFlt-1 levels induced by the placental ischemia model of PE, thus suggesting that increased blood pressure and vascular and endothelial dysfunctions may be attenuated by sodium nitrite-derived NO.

A Theoretical Perspective for Ammonia Synthesis: Nitric Oxide or Nitrate Electroreduction?

Ammonia is an important raw material for agricultural production, playing a key role in global food production. However, conventional ammonia synthesis resulted in extensive greenhouse gas emissions and huge energy consumption. Recently, researchers have proposed electrocatalytic reverse artificial nitrogen cycle (eRANC) routes to circumvent these issues, which can be driven by electrocatalysis and sustainable electricity. Here, a theoretical and computational perspective on the challenges and opportunities with the comparison with experimental results: electrochemical reduction of nitrate (eNO3RR) and nitrite (eNO2RR), electrochemical reduction of nitric oxide (eNORR) combined with oxidative nitrogen fixation are presented. By comparison, the N2→NO→NH3 route is proposed as the most promising in case the NO solubility can be solved well in reactor design. Its high efficiency of ammonia production is demonstrated. Instead, the eNO3RR can be another choice because it is non-toxic and the solid-liquid interface is usually efficient for electrochemical reactions, while its low selectivity at low overpotentials is an issue. These fundamentals highlight the potential and key factors of eRANC as an efficient and sustainable route for ammonia production.

Selective photocatalytic reduction of nitric oxide to dinitrogen via bimetallic bond incorporation

In this study, we addressed the challenge of optimizing the first rate-limiting NO adsorbate state, which has received limited attention in previous research on the photoreduction of NO. We prepared BiFeWO6 (BFWO), which improved not only the NO removal rate under illumination but also the selectivity of photocatalytic NO conversion to N2. To further optimize the performance, we introduced platinum into BFWO, achieving a 57.5 % NO conversion rate with ∼80 % N2 selectivity under 425 nm light-emitting diode illumination (50 mW/cm2), which is optimal for converting NO into less harmful compounds at low concentrations. FeOBi bonds were identified as the key active sites of the first rate-limiting NO adsorbate state in BFWO through time-resolved operando infrared (IR) spectroscopy and density functional theory (DFT) analysis. The specific adsorption configuration of NO on the FeOBi group accelerated the photoreduction reaction kinetics, resulting in superior photocatalytic NO removal performance.

Efficient electrocatalytic reduction of nitric oxide (NO) to ammonia (NH3) on metal-free B4@g-C3N4 nanosheet

The combustion of fossil fuels releases substantial amounts of nitric oxide (NO), posing serious environmental and health risks. Addressing NO pollution effectively is, therefore, a pressing need. Conversion of NO into valuable chemicals is an appealing strategy with dual benefits, including waste utilization and sustainable energy transformation. In this study, we investigate the metal-free electrocatalytic reduction of NO (NORR) to NH3 on a B4 atomic cluster supported by a g-C3N4 nanosheet (B4@g-C3N4) using density functional theory (DFT). Our findings reveal that NO is efficiently activated on the B4@g-C3N4 catalyst, favoring side-on and N end-on adsorption configurations. Significant electron transfer and strong adsorption energies confirm the chemisorption of NO. The NORR exhibits an impressively low limiting potential (UL) of −0.29 V in the gas phase, which decreases further under solvent effects and varying charge states (−2e-, −1e-, +1e-, +2e-). Additionally, the high negative UL values for competing side reactions such as H2 (−0.42 V), N2 (−0.29 V), and N2O (−0.72 V) underscore the selectivity of B4@g-C3N4 for ammonia synthesis. These results highlight the promising potential of B4@g-C3N4 nanosheets for eco-friendly ammonia production from NO, providing a theoretical basis for future experimental efforts to combat NO pollution.

Efficient screening of single-atom Porphyrazine-coordinated transition metal catalysts for electrochemical nitric oxide reduction: Insights from first-principles calculations

The electrochemical conversion of NO to NH3 is gaining attention in green energy for its dual benefits of producing ammonia and eliminating toxic NO. However, the lack of efficient and durable electrocatalysts limits its application, highlighting the need for improved catalysts to advance this promising strategy. The emerging transition metal porphyrazine frameworks (TM − Pz), which combine the advantages of single-atom metal (SAC) centers with the coordination of surrounding 4 N ligands, present promising opportunities in the field of electrochemical catalysis. We have designed a series of 3d transition metal single-atom catalysts (SACs) and conducted high-throughput screening, based on first-principles computations, to identify effective catalysts for the electrocatalytic conversion of NO to NH3. Our findings reveal that the Ti − Pz, Fe − Pz, and V − Pz nanosheets exhibit significantly lower UL values of −0.11, −0.24, and −0.31 V, respectively, when compared to the experimentally and theoretically determined criterion of −0.32 V. The correlation between limiting potentials (UL) and a specific descriptor (φ) is particularly significant for constructing a volcano plot, which illustrates the intrinsic properties of metal atoms in various TM − Pz series and their associated remarkable nitric oxide reduction reaction (NORR) performance. Among the range of nanosheets evaluated, the Ti − Pz and Fe − Pz models emerge as particularly noteworthy, demonstrating significantly higher selectivity and NORR activity than their counterparts. This research deepens our comprehension of the distinctive and advantageous properties of SACs, presenting progressive perspectives that can directly facilitate the discovery and optimization of SACs for NORR applications.

Methane-driven microbial nitrous oxide production and reduction in denitrifying anaerobic methane oxidation cultures

Methane (CH4) and nitrous oxide (N2O) are two important greenhouse gases (GHGs), and it is very important to achieve the reduction of both gases in the case of increasingly serious climate change. The study confirms the simultaneous mitigation of potent GHGs N2O and CH4 in denitrifying anaerobic methane oxidation (DAMO) enrichment, supplementing the understanding that DAMO microorganisms do not produce and reduce N2O. We observed rapid accumulation and consumption of N2O in DAMO cultures subjected to high nitrate and nitrite loadings. Moreover, when N2O served as the sole electron acceptor, a significant correlation was found between the flux of N2O reduction and CH4 oxidation. Inhibition of the particulate methane monooxygenase (pMMO) led to a notable decrease of 95% in N2O reduction and 50% in CH4 oxidation. Metagenomic analysis revealed that Candidatus Methanoperedens and Candidatus Methylomirabilis were the dominant genera, with all functional genes related to denitrification and methane oxidation identified, including NO reductase (nor) of Ca. Methylomirabilis. Transcriptomic analysis further confirmed that the transcripts of nor were one order of magnitude higher than other functional genes. These results indicate that when the substrate NO2- surpasses the dismutation capacity of NO dismutase (nod), DAMO bacteria can alternatively induce nor to reduce NO to N2O. However, considering that N2O reductase (nosZ) is still missing in Ca. Methylomirabilis, the partner Methyloversatilis may be responsible for N2O reduction. Our results provide new insights into the link between GHG emissions in DAMO systems under anaerobic conditions.

Aloe ferox leaf gel extracts attenuate redox imbalance in oxidative renal injury and stimulates glucose uptake, whilst inhibiting key enzymes linked to diabetes and obesity

The worldwide prevalence of diabetes and obesity is growing rapidly. Both metabolic disorders are linked to chronic adverse complications, which include kidney dysfunctions. Medicinal plants play a crucial role in traditional healthcare, especially in developing countries. Aloe ferox, native to South Africa, has a long history of medicinal use, but its pharmacological potential is less studied compared to other Aloe species, necessitating further investigation. Therefore, the present study was conducted to determine the antioxidative, anti-obesogenic, and antidiabetic effects of A. ferox leaf gel extracts using in vitro, ex vivo, and in silico experimental models, with oxidative renal damage induced by ferrous sulfate (FeSO4). A. ferox leaf gel extracts exhibited strong antioxidant activity, inhibited digestive enzymes, and significantly improved glucose uptake. The aqueous extract demonstrated better antioxidant efficacy, leading to higher reduced glutathione (GSH) level, and superoxide dismutase (SOD) and catalase enzymes activity, along with a concurrent reduction of nitric oxide (NO) and malondialdehyde (MDA) levels. Likewise, the aqueous extract showed more potent in vitro DPPH, NO, and OH• radical scavenging activity with IC50 values of 3.64 ±0.3 μg/mL, 110.73±0.1 μg/mL, and 331.13 ±0.7 μg/mL, respectively. The aqueous extract had better inhibition of the enzyme α-amylase (IC50 = 25.73±2.5 µg/mL), whilst the ethanolic extract inhibited α-glucosidase (IC50 =663.2±0.3 µg/ml), and pancreatic lipase (IC50 =122.01±5.9 µg/mL) more strongly. Incubation of the extracts with yeast cells stimulated glucose uptake dose dependently, when ethanolic extract (IC50 = 308.01±0.7 µg/mL) showed the better activity compared to the aqueous extract (IC50 = 338.79±7.05 µg/mL). Furthermore, LC-MS analysis led to the identification of many compounds, when chlorogenic acid demonstrated a stronger molecular interaction with the active site amino acids of α-amylase and catalase compared to other compounds. However, Aloin B showed the highest affinity with α-glucosidase and 5-Hydroxyaloin A showed the lowest binding energy with lipase, and SOD enzyme. These results suggest the reno-protective effects of A. ferox leaf gel extracts against FeSO4-induced oxidative stress along with its anti-hyperglycaemic activity. Given these observed effects, A. ferox leaf gel could indeed be valuable in developing natural therapies and potential drug development for the management of these disorders. Further studies in animal models are needed to ascertain the results of this study.

Isolation and Characterization of the Cyanobacterial Macrolide Glycoside Moorenaside, an Anti-Inflammatory Analogue of Aurisides Targeting the Keap1/Nrf2 Pathway.

A new 14-membered ring brominated macrolide glycoside, named moorenaside (1), was discovered from a marine cyanobacterial sample collected from Shands Key in Florida. The structure of 1 was established by analysis of spectroscopic data including its relative configuration. The absolute configuration was inferred from optical rotation data and comparison with related compounds. The structure of 1 features an α,β-unsaturated carbonyl system, which is also found in aurisides. The presence of this motif in 1 prompted us to evaluate its effect on Keap1/Nrf2 signaling, a cytoprotective pathway culminating in the activation of antioxidant genes activated upstream by the cysteine alkylation of Keap1. Moorenaside exhibited moderate ARE luciferase activity at 32 μM. Due to the established crosstalk between Nrf2 and NF-κB pathways, we investigated the anti-inflammatory effects of 1 in LPS-induced mouse macrophages (RAW264.7 cells), a commonly used model for inflammation. Moorenaside significantly upregulated Nqo1 (Nrf2 target gene) and downregulated iNos (NF-κB target gene) at 32 μM by 5.0- and 2.5-fold, respectively, resulting in a significant reduction of nitric oxide (NO) levels. Furthermore, we performed RNA-sequencing and demonstrated the transcriptional activity of 1 on a global level and identified canonical pathways and upstream regulators involved in inflammation, immune response, and certain oxidative-stress-underlying diseases such as multiple sclerosis and chronic kidney disease.

Ethanolic Extract Clove-loaded Chitosan Nanoparticles Reduce Dyslipidemia, Enhance Liver and Kidney Functions, and Improve the Antioxidant System in Obese Rats

Background: Obesity, a chronic low-grade inflammatory disease characterized by multiple metabolic dysfunctions, poses a considerable worldwide health risk to adults and children. Clove has also shown that it possesses anti-inflammatory, anti-fungal, antibacterial, antioxidant, antiglycation, and anti-aging properties. Aim: The current study aimed to investigate the antiobesity effect of clove-loaded chitosan nanoparticles in obese rats. objective: The current study investigated the antiobesity effect of clove-loaded chitosan nanoparticles in obese rats. Method: Obesity is induced in rats by the administration of a High-Fat Diet (HFD) for 4 weeks. 24 rats were divided into 4 groups; Control group, in which rats were fed normal; HDF group, in which rats were HFD along with distilled water; HFD + empty nanoparticles (ENPs), in which rats were HFD along with ENPs (45 mg/kg); and HFD + clove nanoparticles (CNPs), in which rats were HFD along with CNPs (45 mg/kg) for four weeks. Results: Administration of ENPs and CNPs led to a notable reduction in glucose, aminotransferases, alkaline phosphatase, cholesterol, triglycerides, low-density lipoproteins, malondialdehyde, nitric oxide, caspase-3, PCNA, leptin, and DNA fragmentation. Additionally, it promoted an increase in total proteins, albumin, high-density lipoprotein, glutathione, catalase, and adiponectin. Also, the histopathological investigation of the liver and kidney showed the protective effect of ENPs and CNPs on the tissues of obese rats. Conclusion: The present investigation elucidated the preventive effects of chitosan nanoparticles loaded with clove on dyslipidemia in obese rats. Clove nanoparticles exhibited hypolipidemia, antioxidant, hypoglycemia, and hepatoprotective activities.

Copper(I) Catalysed Diboron(4) Reduction of Nitrous Oxide

AbstractA process for the catalytic reduction of nitrous oxide using NHC‐ligated copper(I) tert‐butoxide precatalysts and B2pin2 as the reductant is reported. These reactions proceed under mild conditions via copper(I)‐boryl intermediates which react with N2O by facile O‐atom insertion into the Cu−B bond and liberate N2. Turnover numbers >800 can be achieved at 80 °C under 1 bar N2O.

Copper(I) Catalysed Diboron(4) Reduction of Nitrous Oxide.

A process for the catalytic reduction of nitrous oxide using NHC-ligated copper(I) tert-butoxide precatalysts and B2pin2 as the reductant is reported. The reaction proceeds under mild conditions via copper(I)-boryl intermediates which react with N2O by facile O-atom insertion into the Cu-B bond and liberate N2. Turnover numbers > 800 can be achieved at 80 °C under 1 bar N2O.

Anti-Melanogenic Potential of Malabar Spinach (Basella alba) in Human Melanoma Cells with Oxidative Stress Suppression and Anti-Inflammatory Activities.

Basella alba has been used in Thai remedies to treat skin disorders, but scientific evidence supporting its efficacy is currently limited. In this study, we investigated the inhibitory effects of B. alba extracts on melanin production using melanoma cells, as well as their impact on oxidative stress and inflammation in keratinocytes. The results demonstrate that B. alba extracts inhibited melanin content and cellular tyrosinase activity in 3-isobutyl-1-methylxanthine (IBMX)-induced melanoma cells by downregulating MITF and the pigmentary genes TYR, TRP-1, and DCT. Interestingly, the MITF regulator gene was inhibited by both the 50% and 95% ethanolic extracts of B. alba with levels of 0.97 ± 0.19 and 0.92 ± 0.09 of the control, respectively, which are comparable to those observed in the arbutin treatment group at 0.84 ± 0.05 of the control. Moreover, after hydrogen peroxide (H2O2) exposure, pretreatment with B. alba reduced lipid peroxidation byproducts and increased the levels of antioxidant-related genes, including SOD-1, GPX-1, and NRF2. Notably, the suppression of the POMC promoter gene in keratinocytes was observed, which may disrupt melanogenesis in melanocytes involving the MC1R signaling pathway. MC1R mRNA expression decreased in the treatments with 50% and 95% ethanolic extracts of B. alba, with relative levels of 0.97 ± 0.18 and 0.90 ± 0.10 of the control, respectively, similar to the arbutin-treated group (0.88 ± 0.25 of control). A significant reduction in nitric oxide was also observed in the B. alba-treated groups, along with a decrease in genes associated with pro-inflammatory cytokines, including IL-1β, IL-6, and COX-2. These findings suggest that B. alba has potential in the prevention of skin-related problems.

Unraveling the genetic potential of nitrous oxide reduction in wastewater treatment: insights from metagenome-assembled genomes.

This study provides critical insights into the genetic diversity of nitrous oxide reductase (nosZ) genes and the microorganisms harboring them in wastewater treatment plants (WWTPs) by exploring 1,083 high-quality metagenome-assembled genomes (MAGs) from 23 Danish full-scale WWTPs. Despite the pivotal role of nosZ-containing organisms, their diversity remains largely unexplored in WWTPs. Our custom pipeline for detecting nosZ provides near-full-length genes with detailed information on secretory pathways and accessory nos genes. Using these genes as templates, we developed taxonomically diverse clade-specific primers that generate nosZ amplicons for phylogenetic annotation and gene-to-MAG linkage. This approach improves detection and expands the discovery of novel sequences, highlighting the prevalence of non-denitrifying N2O reducers and their potential as N2O sinks. These findings have the potential to optimize nitrogen removal processes and mitigate greenhouse gas emissions from WWTPs by fully harnessing the capabilities of the microbial communities.

Highly-selective Electrocatalytic Reduction of NO to NH3 using Cu Embedded WS2 Monolayer as Single-atom Catalyst: A DFT Study.

Electrocatalytic nitric oxide reduction reaction (NORR) is a promising method for generating NH3. However, developing a NORR catalyst for NH3 synthesis with low cost and high efficiency is still challenging. We here report a series of single-atom catalysts (SACs), designed by embedding nine different transition metals from Sc to Cu in S-vacant WS2 monolayer (TM@WS2), and investigate the electrocatalytic performance for NORR process using the dispersion-corrected density functional theory (DFT) calculations. Among them, Cu-based SACshows a strong binding to the WS2 surface and high selectivity towards NORR process, and also it greatly inhibits the competing hydrogen evolution reaction (HER). Through ab initio molecular dynamics (AIMD) simulations, the thermal stability of SAC is assessed and found no structure deformation even at 500 K temperature. All possible reactive pathways including distal and alternating mode at both N- and O-end configurations for NH3 production were explored. We predicted that the Cu@WS2 SAC exhibits remarkable catalytic activity and selectivity with lowest limiting potential of -0.41 V via the N-alternating pathway. Our study emphasize that the transition metal dichalcogenide (TMDC) based SACs are potential candidates for converting NO to NH3, and this opens a new avenue in designing NORR catalysts with high catalytic performance.