Search Results (402)

Methionine residues in proteins and peptides are frequently oxidized by losing one electron. The presence of nearby amide groups is crucial for this process, enabling methionine to participate in long-range electron transfer. Hydroxyl radical (HO^•) plays an important role being generated in aerobic organisms by cellular metabolisms as well as by exogenous sources such as ionizing radiations. The reaction of HO^• with methionine mainly affords the one-electron oxidation of the thioether moiety through two consecutive steps (HO^• addition to the sulfur followed by HO⁻ elimination). We recently investigated the reaction of HO^• with model peptides mimicking methionine and its cysteine-methylated counterpart, i.e., CH₃C(O)NHCHXC(O)NHCH₃, where X = CH₂CH₂SCH₃ or CH₂SCH₃ at pH 7. The reaction mechanism varied depending on the distance between the sulfur atom and the peptide backbone, but, for a better understanding of various suggested equilibria, the analysis of the flux of protons is required. We extended the previous study to the present work at pH 4 using pulse radiolysis techniques with conductivity and optical detection of transient species, as well as analysis of final products by LC-MS and high-resolution MS/MS following γ-radiolysis. Comparing all the data provided a better understanding of how the presence of nearby amide groups influences the one-electron oxidation mechanism. Full article

Anthocyanins are important phenolic compounds in grape skins, affecting the color, oxidation resistance, and aging ability of red wine. In recent years, global warming has had a negative effect on anthocyanin biosynthesis in grape berries. Ethylene serves as a crucial phytohormone regulating the development and ripening processes of fruit; however, the specific molecular mechanism and the regulatory network between ethylene signaling and the anthocyanin biosynthesis pathway remain incompletely understood. In this study, 400 mg/L ethephon (ETH) solution was sprayed onto the surface of grape berries at the lag phase (EL-34), and the changes in anthocyanin-related genes and metabolites were explored through transcriptomic and metabolomic analysis. The results showed that ETH treatment increased Brix and pH in mature berries. In total, 35 individual anthocyanins were detected, in which 21 individual anthocyanins were enhanced by ETH treatment. However, the anthocyanin profile was not affected by exogenous ethylene. Transcriptomics analysis showed that there were a total of 825 and 1399 differentially expressed genes (DEGs) 12 h and 24 h after treatment. Moreover, key structural genes in the anthocyanin synthesis pathway were strongly induced, including VvPAL, VvCHS, VvF3H, VvF3′5′H, VvDFR and VvUFGT. At the maturity stage (EL-38), the expression levels of these genes were still higher in EHT-treated berries than in the control. ETH treatment also influenced the expression of genes related to hormone biosynthesis and signal transduction. The ethylene biosynthesis gene (VvACO), ethylene receptor genes (VvETR2, VvERS1 and VvEIN4), ABA biosynthesis gene (VvNCED2), and ABA receptor gene (VvPYL4) were up-regulated by ETH treatment, while the auxin biosynthesis gene (VvTAA3) and seven genes of the auxin-responsive protein were inhibited by exogenous ethylene. Meanwhile, ETH treatment promoted the expression of the sugar transporter gene (VvEDL16) and two sucrose synthase genes (VvSUS2 and VvSUS6). In EHT-treated berries, 19 MYB and 23 ERF genes were expressed differently compared with the control (p < 0.05). This study provides the theoretical foundation and technical support for the regulation of anthocyanin synthesis in non-climacteric fruit. Full article

Melatonin (MT) can enhance plant stress tolerance by activating the internal defense system, but its application in rubber trees has been barely reported up to now. In this study, we found that the relative electrical conductivity (REC), H₂O₂, and malondialdehyde (MDA) contents were significantly higher in the leaves of rubber tree seedlings under drought stress compared to the control (water treatment), whereas chlorophyll contents were obviously lower in the leaves under drought stress compared to the control. MT partly relieves the aforementioned drought-induced adverse effects by dramatically reducing chlorophyll degradation, H₂O₂ accumulation, MDA content, and REC. Comparative transcriptomes among the PEG (P), MT (M), and PEG + MT (PM) treatments against the control showed that 213, 896, and 944 genes were differently expressed in rubber tree seedlings treated with M, P, and PM in contrast to the control. Among the 64 differently expressed genes (DEGs) being common among the three comparisons, the expression profiles of 25 were opposite in MH compared with PH. Intriguingly, all the KEGG pathways of the DEGs mentioned above belonged to metabolism including energy metabolism, carbohydrate metabolism, amino acid metabolism, and the metabolism of cofactors and vitamins. Exogenous application of MT mainly regulated the genes associated with photosynthesis and the anti-oxidative defense system, thereby enhancing the antioxidant protection of rubber tree seedlings under drought stress. These results suggest that exogenous melatonin application can effectively enhance drought tolerance by heightening ROS scavenging to decrease H₂O₂ accumulation in rubber tree seedlings. Our results elucidate the molecular mechanisms of MT’s roles in drought stress, which help to employ exogenous MT to boost drought tolerance in the rubber tree. Full article

Soil aggregates play critical roles in regulating the behavior of heavy metal in soils. To understand the distribution of cadmium (Cd) in aggregates of different soil types, as well as their roles in regulating the Cd bioavailability of bulk soils, four major arable soils, including acidic, neutral, and calcareous purple soils and calcareous yellow soil (APS, NPS, CPS, and CYS), were sampled from Chongqing, China, for aggregate separation and determination of the total Cd(T-Cd) distribution, fractionation, and extractability in various-sized aggregates. A pot experiment with ryegrass (Lolium perenne L.) was conducted to evaluate the Cd bioavailability in bulk soils as influenced by aggregates. The results show that the composition of soil aggregates varies a lot among soils: lower soil pH tends to increase the proportion of macroaggregates while decreasing that of smaller aggregates. The Cd distribution, HCl-extractability, and active fraction (AF, T-Cd/HCl-Cd) in aggregates are all soil type-dependent, with pH and particle size being the main determining factors; the distribution pattern of Cd concentrated in smaller aggregates is only found for CPS and CYS (pH > 7.5) upon exogenous Cd addition, though the finest aggregates (silt–clay, <0.053 mm) consistently exhibited the highest Cd enrichment for all tested soils. The Cd extractability and AF values in all aggregates show a sequence of APS > NPS > CPS > CYS, indicating the fundamental influence of soil pH on Cd availability. Higher AF values over bulk soils, either in silt–clay aggregates or in microaggregates (0.053–0.25 mm), whereas lower AF in macroaggregates (1–2 mm) are found for APS and NPS, which correspond to the relative portions of Ex-Cd and Fe/Mn oxide-bound Cd (Fe/Mn-Cd) in these aggregates. In contrast, less variation of AF values among aggregates is observed for CPS and CYS and for APS/NPS upon Cd addition. Pot experiments demonstrated strong positive correlations between ryegrass Cd uptake and HCl-Cd in silt–clay aggregates and T-Cd in microaggregates, while a negative correlation was observed with T-Cd in macroaggregates. These findings supply new insight into the mechanisms of aggregates in controlling Cd bioavailability in bulk soils and shed light on the development of new strategies for remediating Cd-polluted soils. Full article

Soil carbon is a crucial component of the global carbon cycle, and carbon mineralization is influenced by various factors. However, there is a lack of systematic analyses on the responses of carbon mineralization in different soil types to the addition of exogenous organic matter. This study investigates the effects of compost addition on the mineralization and kinetic characteristics of soil carbon across three typical agricultural soils: paddy soil, black soil, and cinnamon soil. A 210-day incubation study was conducted with four treatments: Control (un-amended soil), R (soil + straw), R1M (soil + straw + low compost application rate), R2M (soil + straw + high compost application rate). The results showed that the CO₂ emission rates of the three soils were higher during the early stage (1–37 days) and decreased afterward. The CO₂ emission rates of the paddy soil and the black soil were significantly higher than those of the cinnamon soil. The addition of compost significantly increased both the CO₂ emission rate and the cumulative release of CO₂, especially in the R2M treatment. At the end of the incubation, the SOC contents were higher in the R2M treatment than in the Control for all three soils (p < 0.05), with the most notable increase in the cinnamon soil (60.93%). Compost addition significantly enhanced the active carbon pool (C_a), slow carbon pool (C_s), and potentially mineralizable carbon pool (C_p), while decreasing the mineralization rate (k_a) of the C_a, but the effect on the mineralization rate (k_s) of the C_s and mineralization entropy (C_m) varied by soil types. The k_s of the paddy soil was significantly reduced by 23.08% under the R1M and R2M treatments compared with the Control and R treatment. The k_s of the black soil was significantly increased by 59.52% under the R2M treatment compared with the Control. The k_s of the cinnamon soil was elevated considerably by 79.31% under the R2M treatment compared with the Control, R, and R1M treatments (averaging 0.29 × 10⁻² d), and the k_s of the paddy soil and black soil were significantly higher than those of the cinnamon soil under the R2M treatment. The C_m was significantly higher in the organic material added treatments than in the Control for the black soil and the paddy soil, but showed a higher value in the R treatment than in the R2M and Control for the cinnamon soil. In conclusion, compost addition stimulated soil carbon mineralization and improved the SOC content, especially in the cinnamon soil, while reducing the mineralization rate of the active carbon pool across the three soils. The mineralization rate of the slow carbon pool and the changes in mineralization entropy were dependent on soil types, primarily related to the initial soil nutrient contents, pH, and particle compositions. These findings offer valuable insights for managing the soil carbon pool in agricultural ecosystems. Full article

Granulosa cells (GCs) are essential for follicular growth and development, and their functional state critically impacts folliculogenesis. TAp73α, a transcriptionally active isoform of the p73 gene, is crucial for maintaining follicular integrity. In this study, we demonstrate that TAp73α overexpression promotes ferroptosis in bovine GCs by downregulating SLC7A11, depleting intracellular glutathione (GSH), and enhancing lipid peroxidation, particularly under Erastin treatment. By contrast, TAp73α knockdown restores antioxidant capacity, elevates GSH levels, and attenuates ferroptosis. To elucidate the underlying mechanism, untargeted metabolomic profiling revealed that TAp73α overexpression significantly altered the metabolic landscape of GCs, with marked enrichment in the glutathione metabolism pathway. Notably, betaine—a metabolite closely linked to redox homeostasis—was markedly downregulated. Functional assays confirmed that exogenous betaine supplementation restored SLC7A11 expression, increased GSH levels, and alleviated oxidative damage induced by either H₂O₂ or TAp73α overexpression. Moreover, betaine co-treatment effectively reversed lipid peroxide accumulation and mitigated TAp73α-induced ferroptosis. Collectively, our findings identify a novel mechanism by which TAp73α promotes ferroptosis in granulosa cells through the suppression of betaine and glutathione metabolism, highlighting betaine as a key metabolic modulator with promising protective potential. Full article

Soil selenium (Se) speciation characteristics and their influence on the Se enrichment pattern and physiological characteristics of wheat are poorly understood. Based on the rhizobag experiment, we systematically investigated rhizosphere dynamics, as well as biomass and antioxidant responses, in wheat at five exogenous Se levels (0, 1.0, 2.5, 5.0, and 10.0 mg kg⁻¹ Se in sodium selenite). The results showed that the rhizosphere pH and dissolved organic carbon (DOC) in the soil solution were higher than those in the non-rhizosphere soil solution and that the total and inorganic Se levels in the soil solution increased as the Se application concentration was increased. Meanwhile, in the rhizosphere soil, the concentrations of water-soluble Se (SOL-Se), exchangeable Se (EX-Se), and organically bound Se (OM-Se) significantly increased in response to increases in Se application rates. The ratio of the sum of the three forms of Se to total Se increased by 20.9–56.5%, 19.8–54.6%, and 17.9–53.0% at weeks 4, 6, and 8, respectively. The Se content in both the shoots and roots parts of wheat increased significantly as the Se application concentration was increased. The Se levels in the shoots and roots increased alongside wheat growth in low-level Se (≤2.5 mg kg⁻¹). However, when using high-concentration Se treatments (≥5.0 mg Se kg⁻¹), the trend in these plant parts was for the Se levels to initially increase and then decrease as the wheat grew, with the significant increases of 43-fold and 96-fold at week 6, reaching the highest levels. Under the 5 mg Se kg⁻¹ treatment, the shoot bioaccumulation factor (BCFss) increased by 1.5-fold, 2.0-fold, and 1.6-fold at weeks 4, 6, and 8, respectively. The root bioaccumulation factor (BCFrs) increased with increasing Se concentration. The root-to-shoot translocation factor (TF) tends to increase and then decrease with application concentration increased; all factors had values of less than 1. The TF reached its maximum value at weeks 4 and 6 under 2.5 mg Se kg⁻¹ treatment, while it was highest at week 8 under 5 mg Se kg⁻¹ treatment. When using 5 mg Se kg⁻¹ treatment, the shoot and root biomass of wheat increased by 17% and 22%, and 29% and 32%, respectively, at weeks 6 and 8, timepoints when the highest levels were reached. The application of 5.0 mg Se kg⁻¹ treatment significantly increased the activity of superoxide dismutase (32%, 68%, and 17%) and glutathione peroxidase (34%, 70%, and 43%) in wheat leaves at weeks 4, 6, and 8, while reducing the malondialdehyde content (37%, 46%, and 26%). In summary, applying 5 mg kg⁻¹ of Se to the soil is beneficial for wheat growth. The results of this study reveal the response of wheat to soil-applied Se in terms of wheat growth and physiological characteristics, rhizosphere and non-rhizosphere soil properties, and changes in the morphology of Se. Full article

The xeno-fungusphere, a novel microbial ecosystem formed by integrating exogenous fungi, indigenous soil microbiota, and electroactive microorganisms within microbial fuel cells (MFCs), offers a transformative approach for agricultural remediation and medicinal plant conservation. By leveraging fungal enzymatic versatility (e.g., laccases, cytochrome P450s) and conductive hyphae, this system achieves dual benefits. First, it enables efficient degradation of recalcitrant agrochemicals, such as haloxyfop-P, with a removal efficiency of 97.9% (vs. 72.4% by fungi alone) and a 27.6% reduction in activation energy. This is driven by a bioelectric field (0.2–0.5 V/cm), which enhances enzymatic activity and accelerates electron transfer. Second, it generates bioelectricity, up to 9.3 μW/cm², demonstrating real-world applicability. In medicinal plant soils, xeno-fungusphere MFCs restore soil health by stabilizing the pH, enriching dehydrogenase activity, and promoting nutrient cycling, thereby mitigating agrochemical-induced inhibition of secondary metabolite synthesis (e.g., ginsenosides, taxol). Field trials show 97.9% herbicide removal in 60 days, outperforming conventional methods. Innovations, such as adaptive electrodes, engineered strains, and phytoremediation-integrated systems, have been used to address soil and fungal limitations. This technology bridges sustainable agriculture and bioenergy recovery, offering the dual benefits of soil detoxification and enhanced crop quality. Future IoT-enabled monitoring and circular economy integration promise scalable, precision-based applications for global agroecological resilience. Full article

This study explores the spatiotemporal dynamics of SOC and microbial-mediated mechanisms in the Yellow River Delta wetlands. Using redundancy analysis and microbial community profiling, we show that vegetation drives distinct SOC storage patterns: Phragmites australis ecosystems exhibit the highest SOC sequestration, followed by Suaeda salsa and Tamarix chinensis habitats, where salt-tolerant taxa like Desulfobacterota and Halobacteriaota promote short-term carbon storage via anaerobic metabolism. The microbial community structure is shaped by both vegetation-induced microhabitats and environmental gradients: SOC and total nitrogen dominate community assembly, while electrical conductivity, pH, and sulfur/nitrogen nutrients regulate spatiotemporal differentiation. Seasonal turnover drives the reorganization of microbial community structures, shaping the dynamic equilibrium of carbon pools. Seasonal DOC dynamics, linked to tidal fluctuations and exogenous carbon inputs, highlight hydrology’s role in modulating active carbon pools. These findings reveal tight linkages among vegetation, microbial functional guilds, and soil biogeochemistry, critical for wetland carbon sequestration. Full article

Background: Adrenal incidentalomas are detected in various medical and surgical healthcare departments, including primary healthcare. One up to three out of ten individuals confirmed with nonfunctioning adrenal incidentalomas (NFAs) actually present a mild autonomous cortisol secretion (MACS), which is distinct from Cushing’s syndrome. Objective: We aimed to assess the cortisol secretion in newly detected adrenal incidentalomas in patients who were referred by their primary healthcare physician upon accidental detection of an adrenal tumor at abdominal computed tomography (CT) scan that was performed for unrelated (non-endocrine) purposes. Methods: This retrospective study included adults diagnosed with an adrenal incidentaloma via CT during the previous 3 months. Inclusion criteria: age ≥ 40 years (y). A triple stratification of exclusion criteria involved: (1) Clinical aspects and medical records such as active malignancies or malignancies under surveillance protocols, subjects under exogenous glucocorticoid exposure (current or during the previous year), or suggestive endocrine phenotypes for any hormonal ailment; (2) Radiological appearance of suspected/confirmed (primary or secondary) adrenal malignancy, adrenal cysts, or myelolipomas; (3) Endocrine assays consistent with active endocrine tumors. Protocol of assessment included baseline ACTH, morning plasma cortisol (C-B), cortisol at 6 p.m. (C-6 pm), and after 1 mg dexamethasone suppression testing (C-1 mg-DST), 24-h urinary free cortisol (UFC), and a second opinion for all CT scans. MACS were defined based on C-1 mg-DST ≥ 1.8 and <5 µg/dL (non-MACS: C-1 mg-DST < 1.8 µg/dL). Results: The cohort (N = 60, 78.33% female; 60.72 ± 10.62 y) associated high blood pressure (HBP) in 66.67%, respectively, type 2 diabetes (T2D) in 28.37% of the patients. Females were statistically significantly older than males (62.40 ± 10.47 vs. 54.62 ± 9.11 y, p = 0.018), while subjects with unilateral vs. bilateral tumors (affecting 26.67% of the individuals) and those with MACS-positive vs. MACS-negative profile had a similar age. Body mass index (BMI) was similar between patients with unilateral vs. bilateral incidentalomas, regardless of MACS. Patients were divided into five age groups (decades); most of them were found between 60 and 69 years (40%). Left-gland involvement was found in 43.33% of all cases. The mean largest tumor diameter was 26.08 ± 8.78 mm. The highest rate of bilateral tumors was 46.67% in the 50–59 y decade. The rate of unilateral/bilateral and tumor diameters was similar in females vs. males. The MACS-positive rate was similar in females vs. males (23.40% vs. 23.08%). A statistically significant negative correlation (N = 60) was found between BMI and C-B (r = −0.193, p = 0.03) and BMI and UFC (r = −0.185, p = 0.038), and a positive correlation was found between C-B and C-6 pm (r = 0.32, p < 0.001), C-B and UFC (r = 0.226, p = 0.011), and C-6 pm and C-1 mg-DST (r = 0.229, p = 0.010), and the largest tumor diameter and C-1 mg-DST (r = 0.241, p = 0.007). Conclusions: Adrenal incidentalomas belong to a complex scenario of detection in the modern medical era, requiring a multidisciplinary collaboration since the patients might be initially detected in different departments (as seen in the current study) and then referred to primary healthcare for further decision. In these consecutive patients, we found a higher female prevalence, a MACS rate of 23.33%, regardless of uni/bilateral involvement or gender distribution, and a relatively high rate (than expected from general data) of bilateral involvement of 26.67%. The MACS-positive profile adds to the disease burden and might require additional assessments during follow-up and a protocol of surveillance, including a tailored decision of tumor removal. The identification of an adrenal incidentaloma at CT and its hormonal characterization needs to be integrated into the panel of various chronic disorders of one patient. The collaboration between endocrinologists and primary healthcare physicians might improve the overall long-term outcomes. Full article

Efficient bioconversion of lignocellulosic biomass into ruminant feed requires advanced strategies to enhance fiber degradation and ruminal fermentation efficiency. This study evaluates the synergistic effects of gamma irradiation (150 kGy) and exogenous fibrolytic enzyme (EFE) supplementation (4 µL/g dry matter) from Trichoderma longibrachiatum on the structural composition and ruminal fermentation of Typha latifolia. Gamma irradiation significantly reduced neutral detergent fiber (NDF) while increasing non-fiber carbohydrates (NFCs), reducing sugars (RS) and antioxidant activity. These modifications enhanced ruminal bacterial proliferation, suppressed ruminal protozoal populations, and improved ruminal fermentation efficiency by increasing gas production, dry matter degradability, and NDF degradability. Additionally, irradiation decreased ruminal NH₃-N concentrations and branched-chain volatile fatty acids (VFAs) without affecting total VFA production and ruminal pH. While EFE alone accelerated only ruminal fermentation, its combination with irradiation further reduced NDF content, enriched NFC and RS, and enhanced fermentation efficiency. This dual treatment increased total VFA production, shifted fermentation pathways toward propionate synthesis, and reduced acetate and branched-chain VFA levels. It also stimulated ruminal bacterial populations without altering ruminal pH. These findings highlight gamma irradiation as an effective pretreatment to enhance EFE hydrolysis, offering a promising strategy to improve the nutritional value of low-quality forages to integrate into ruminant diets. Full article

Lodging imposes substantial constraints on maize yield potential and agronomic efficiency, critically undermining productivity and resource optimization in cultivation systems. This study aimed to elucidate the mechanism whereby ethephon enhances lodging resistance and analyze the sensitivity differences to ethephon among distinct maize inbred lines. Through exogenous application of ethephon (200 and 400 mg/L, S1 and S2 treatments) to four classic maize inbred lines (Zheng58, Chang7-2, PH6WC, and PH4CV), we systematically evaluated its effects on plant morphology, stalk biomechanical properties, and lignin biosynthesis. Results demonstrated that ethephon optimized plant morphology through reductions in plant height, ear height, leaf area, leaf angle, and internode length. Significant augmentations in stalk bending resistance (a maximum increase of 52.61% in PH4CV) and puncture strength (most pronounced in Zheng58) were mechanistically associated with increased lignin content and enhanced activity of key biosynthetic enzymes [cinnamyl alcohol dehydrogenase (CAD), phenylalanine ammonia-lyase (PAL), and 4-coumarate-CoA ligase (4CL)], with PH6WC exhibiting the most robust enzymatic response. These findings underscored genotype-specific regulatory effects of ethephon, bridging the knowledge gap regarding its molecular–physiological interplay with maize genotypes. The study provides critical insights for precision breeding and optimization strategies employing plant growth regulators to improve maize lodging resistance. Full article

Nitroxides are stable organic free radicals with a wide range of applications. They have found applications in chemistry, biochemistry, biophysics, molecular biology, and biomedicine as EPR/NMR imaging techniques. As spin labels and probes, they are used in electron paramagnetic resonance (EPR) spectroscopy in the study of proteins, lipids, nucleic acids, and enzymes, as well as for measuring oxygen concentration in cells and cellular organelles, as well as tissues and intracellular pH. Their unique redox properties have allowed them to be used as exogenous antioxidants. In this review, we have discussed the chemical properties of nitroxides and their antioxidant properties. Furthermore, we have considered their use as radioprotectors and protective agents in ischemia/reperfusion in vivo and in vitro. We also presented other applications of nitroxides in protecting cells and tissues from oxidative stress and in protein studies and discussed their use in EPR/MRI. Full article

It has been reported that applying silicon (Si) to agricultural soils can reduce N₂O emissions. But, we do not fully understand how this might work in forest ecosystems, especially in Phyllostachys edulis plantations. This study set out to determine how exogenous Si impacts soil nitrification and denitrification. Also, it aimed to assess their separate contributions to N₂O emissions. A pot incubation experiment that lasted 28 days was carried out under controlled conditions. The soil used was collected from a bamboo plantation that is intensively managed. The treatments included adding silicon. Also, 3,4-dimethylpyrazole phosphate (DMPP) and acetylene (C₂H₂) were applied to specifically hold back nitrification and denitrification. We measured the rates of soil N₂O emissions, the cumulative fluxes, and the concentrations of NH₄⁺-N, NO₃⁻-N, and NO₂⁻-N. A positive correlation that was significant (p < 0.05) was found between N₂O emissions and the levels of soil NO₃⁻-N. Adding Si continued to reduce both the emission rate and the cumulative flux in all of the treatment groups. Also worth mentioning is that the relative contribution of denitrification to N₂O emissions dropped from 38.2% to 11.4%. Meanwhile, nitrification’s contribution went up from 61.8% to 88.6%. These findings show that adding Si mainly suppresses denitrification. And, by doing so, it lessens N₂O emissions in bamboo plantations. This study underlines the potential of Si amendments. They could be used as an effective management strategy to reduce greenhouse-gas emissions in forest soils. It also provides a scientific basis for making Phyllostachys edulis ecosystems more sustainable. Full article

Growing evidence supports the use of nitrate-reducing bacterial strains as probiotics to enhance the benefits of nitrate metabolism for both oral and systemic health. This study aimed to test the nitrate reductase activity of Levilactobacillus brevis CD2 (DSM-27961/CNCM I-5566), a strain widely used as a starter culture in fermented foods and recognized for its multifaceted health-promoting probiotic properties. We also sought to determine whether the probiotic lysate enhances nitrate reduction ex vivo using six salivary samples from healthy subjects while evaluating its potential influence on pH and buffering capacity. Considering the established link between lactate metabolism and nitrite production, we assessed the salivary levels of D-lactate after a 3-hour incubation with or without Lv. brevis. The results indicate that Lv. brevis CD2 exhibits significant intrinsic and concentration-dependent nitrate reductase activity. Additionally, treatment with Lv. brevis for 3 h significantly increased nitrite generation across all saliva samples, with further enhancement observed after the addition of exogenous nitrates. Lv. brevis also significantly improved salivary pH and buffering capacity, particularly when combined with nitrate. Furthermore, the probiotic treatment resulted in reduced levels of salivary D-lactate. To further support and validate our in vitro and ex vivo findings, we evaluated the oral nitrate-reducing activity in saliva samples from healthy individuals treated for four weeks with Lv. brevis CD2 lozenges. Of note, the results indicated that the probiotic group showed a significant increase in oral nitrate-reducing capacity compared to baseline and placebo after four weeks of treatment. Overall, our study suggests that Lv. brevis CD2 acts as a nitrate-reducing probiotic, providing new insights into its health benefits and complementing findings from previous studies. Full article