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The limitation of water and unfavorable soil conditions for plant's nutrient absorption present a hurdle to the growth and yield of red beans under drought stress conditions. Micronutrients, particularly zinc and molybdenum, show promise in mitigating drought effects. Various irrigation levels (100% and 70% of field capacity) and nutrient application methods were tested in the field (two locations) and the greenhouse in 2022. Parameters such as photosynthesis, gas exchange, root characteristics, nitrate reductase, antioxidant enzymes, and yield were evaluated. The combination of nano zinc priming (NZnP 150 mg L−1) and foliar spraying of nano zinc (FSNZn 0.04 mg L−1) at 100% field capacity resulted in the highest photosynthesis, gas exchange, and yield. Water stress increased the activity of antioxidant enzymes. In greenhouse test, NZnP (150 mg L−1) + FSNZn (0.04 mg L−1) at 100% field capacity promoted maximum root length and nitrate reductase activity. Overall, NZnP + FSNZn at 100% field capacity proved most effective for morphological and biochemical root characteristics and yield. Drought stress reduced red bean yield, but NZnP + FSNZn mitigated some adverse effects. Nano forms of zinc and molybdenum were more effective in mitigating drought stress. Location significantly influenced plant development, with lower temperatures delaying reproductive phase transition, leading to better vegetative and reproductive traits compared to the location with higher temperature. [ABSTRACT FROM AUTHOR]

BACKGROUND: Lung volume measurements are important for monitoring functional aeration and recruitment and may help guide adjustments in ventilator settings. The expiratory phase of airway pressure release ventilation (APRV) may provide physiologic information about lung volume based on the expiratory flow-time slope, angle, and time to approach a no-flow state (expiratory time [TE]). We hypothesized that expiratory flow would correlate with estimated lung volume (ELV) as measured using a modified nitrogen washout/washin technique in a large-animal lung injury model. METHODS: Eight pigs (35.2 ± 1.0 kg) were mechanically ventilated using an Engström Carescape R860 on the APRV mode. All settings were held constant except the expiratory duration, which was adjusted based on the expiratory flow curve. Abdominal pressure was increased to 15 mm Hg in normal and injured lungs to replicate a combination of pulmonary and extrapulmonary lung injury. ELV was estimated using the Carescape FRC INview tool. The expiratory flow-time slope and TE were measured from the expiratory flow profile. RESULTS: Lung elastance increased with induced lung injury from 29.3 ± 7.3 cm H2O/L to 39.9 ± 15.1cm H2O/L, and chest wall elastance increased with increasing intra-abdominal pressures (IAPs) from 15.3 ± 4.1 cm H2O/L to 25.7 ± 10.0 cm H2O/L in the normal lung and 15.8 ± 6.0 cm H2O/L to 33.0 ± 6.2 cm H2O/L in the injured lung (P = .39). ELV decreased from 1.90 ± 0.83 L in the injured lung to 0.67 ± 0.10 L by increasing IAP to 15 mm Hg. This had a significant correlation with a TE decrease from 2.3 ± 0.8 s to 1.0 ± 0.1 s in the injured group with increasing insufflation pressures (ρ = 0.95) and with the expiratory flow-time slope, which increased from 0.29 ± 0.06 L/s² to 0.63 ± 0.05 L/s² (ρ = 0.78). CONCLUSIONS: Changes in ELV over time, and the TE and flow-time slope, could be used to demonstrate evolving lung injury during APRV. Using the slope to infer changes in functional lung volume represents a unique, reproducible, real-time, bedside technique that does not interrupt ventilation and may be used for clinical interpretation. [ABSTRACT FROM AUTHOR]

Improving vegetable yield and optimizing its quality through nutrient management have long been central to plant nutrition and horticultural science. Copper (Cu) is recognized as an essential trace element that promotes plant growth and development. However, the mechanisms by which Cu influences nitrogen (N) metabolism remain largely unknown, with limited studies exploring the interaction between Cu and varying nitrate-to-ammonium (nitrate/ammonium) ratios. In this study, Chinese cabbage was exposed to two Cu concentrations (0 and 0.02 mg L-1) in combination with three nitrate/ammonium ratios (10/90, 50/50, and 90/10) under hydroponic conditions. The results showed that Cu application increased plant biomass, nitrate reductase (NR) and glutamine synthetase (GS) enzyme activities, the expression of NR (NIA) and GS2 (Gln2) genes, and N content in both shoots and roots. Additionally, Cu treatment decreased nitrate and free amino acid contents, as well as the expression of nitrate transporters NRT1.1 and NRT2.1 in roots while increasing these four parameters in shoots. Additionally, these effects were significantly modulated by the nitrate/ammonium ratios. In conclusion, Cu may facilitate nitrate transportation, enhance nitrate reduction, promote ammonium assimilation, and influence the transformation of organic N compounds, highlighting its potential role in improving N metabolism in Chinese cabbage. [ABSTRACT FROM AUTHOR]

A survey for bacteria of the genus Thiothrix indicated that they inhabited the area where the water of the Zmeiny geothermal spring (northern basin of Lake Baikal, Russia) mixed with the lake water. In the coastal zone of the lake oxygen (8.25 g/L) and hydrogen sulfide (up to 1 mg/L) were simultaneously present at sites of massive growth of these particular Thiothrix bacteria. Based on the analysis of the morphological characteristics and sequence of individual genes (16S rRNA, rpoB and tilS), we could not attribute the Thiothrix from Lake Baikal to any of the known species of this genus. To determine metabolic capabilities and phylogenetic position of the Thiothrix sp. from Lake Baikal, we analyzed their whole genome. Like all members of this genus, the bacteria from Lake Baikal were capable of organo-heterotrophic, chemolithoheterotrophic, and chemolithoautotrophic growth and differed from its closest relatives in the spectrum of nitrogen and sulfur cycle genes as well as in the indices of average nucleotide identity (ANI < 75–94%), amino acid identity (AAI < 94%) and in silico DNA-DNA hybridization (dDDH < 17–57%), which were below the boundary of interspecies differences, allowing us to identify them as novel candidate species. [ABSTRACT FROM AUTHOR]

The development and quality of tea plants (Camellia sinensis (L.) O. Ktze.) are greatly hampered by drought stress (DS), which affects them in a number of ways, includingby interfering with their metabolism of nitrogen (N). Arbuscular mycorrhizal fungi (AMF) are known to enhance water and nutrient absorption inplants, but their specific effects on tea plant N metabolism under DS and the associated regulatory mechanisms remain unclear. This study aimed to evaluate the impact of Claroideoglomus etunicatum inoculation on N assimilation in tea plants (C. sinensis cv. Fuding Dabaicha) under well-watered (WW) and DS conditions, and to explore potential molecularmechanisms. After 8 weeks of DS treatment, root my corrhizal colonization was significantly inhibited, and the biomass of tea shoots and roots, as well as the contents of various amino acids (AAs) were reduced. However, AMF inoculation significantly increased the contents of tea polyphenols and catechins in leaves by 13.74%-36.90% under both WW and DS conditions. Additionally, mycorrhizal colonization notably increased N content by 12.65%-35.70%, various AAs by 11.88%-325.42%, and enzymatic activities associated with N metabolism by 3.80%-147.62% in both leaves and roots. Gene expression analysis revealed a universal upregulation of Nassimilation-relatedgenes (CsAMT1;2,CsAMT3;1,CsGS1,CsNADHGOGAT, CsTS2,CsGGT1, andCsADC) inAMF-colonized tea roots, regardless of water status. UnderDS condition, AMF inoculation significantly upregulated the expressions of CsNRT1;2,CsNRT1;5,CsNRT2;5,CsNR,CsGS1,CsGDH1,CsGDH2,CsTS2,CsGGT1, CsGGT3, and CsSAMDC in tea leaves. These findings suggest that AMF improved tea plant adaptability toDS by enhancingNabsorption and assimilation, accompanied by the synthesis and accumulation of various AAs, such as Glu, Gln, Asp, Lys, Arg,GABA andPro. This is achieved throughtheupregulationofNmetabolism-relatedgenes and the activation of related enzymes in tea plants under DS condition. These findings provide valuable insights into the role of AMF in regulating tea plantNmetabolism and enhancing stress tolerance. [ABSTRACT FROM AUTHOR]

Ocean acidification (OA), caused by the rising concentration of atmospheric CO2, leads to changes in the marine carbonate system. This, in turn, affects the physiological processes of phytoplankton. In response to increased pCO2 levels, marine microalgae modulate their physiological responses to meet their energy and metabolic requirements. Nitrogen metabolism is a critical metabolic pathway, directly affecting the growth and reproductive capacity of marine microorganisms. Understanding the molecular mechanisms that regulate nitrogen metabolism in microalgae under OA conditions is therefore crucial. This study aimed to investigate how OA affects the expression profiles of key genes in the nitrogen metabolic pathway of the marine diatom Skeletonema costatum. Our findings indicate that OA upregulates key genes involved in the nitrogen metabolic pathway, specifically those related to nitrate assimilation and glutamate metabolism. Moreover, pCO2 has been identified as the predominant factor affecting the expression of these genes, with a more significant impact than pH variations in S. costatum. This research not only advances our understanding of the adaptive mechanisms of S. costatum in response to OA but also provides essential data for predicting the ecological consequences of OA on marine diatoms. [ABSTRACT FROM AUTHOR]

A low-temperature-tolerant simultaneous nitrification-denitrification bacterial strain of Acinetobacter kyonggiensis (AKD4) was identified. It showed high efficiency in total nitrogen (TN) removal (92.45% at 10°C and 87.51% at 30℃), indicating its excellent low-temperature tolerance. Transcriptomic analysis revealed possible metabolic mechanisms under low-temperature stress. Genes involved in cell growth, including ATP synthase (atpADGH), amino acid (glyA, dctA, and ilvE), and TCA cycle metabolism (gltA, fumC, and mdh) were remarkably upregulated from 1.05-3.44-fold at 10℃, suggesting that their actions enhance survivability at low temperatures. The expression levels of genes associated with nitrogen assimilation (glnAE, gltBD, and gdhA), nitrogen metabolism regulation (ntrC, glnB, and glnD), and denitrification processes (napA) were increased from 1.01-4.38-fold at 10℃, which might have contributed to the bacterium's highly efficient nitrogen removal performance at low temperatures. Overall, this study offers valuable insights into transcriptome, and enhances the comprehension of the low-temperature-tolerant mechanism of simultaneous nitrification and denitrification processes. [ABSTRACT FROM AUTHOR]

This study investigated the ability of lactic acid bacteria (LAB) isolated from oranges to use fish by‐products (FB) and chicken by‐products (CB) as nitrogen sources alternative to yeast extract for lactic acid (LA) production in a papaya by‐product medium as a carbon source. Once the fermentation agents had been isolated, they were subjected to biochemical and molecular characterization. Inexpensive nitrogen sources, precisely CB and FB, were prepared, freeze‐dried, and yield evaluated. Also, before to the fermentation experiments, the Total Kjehdahl Nitrogen (TKN) of these by‐products and that of the yeast extract were determined. Then, three production media differing in terms of nitrogen source were formulated from these nitrogen sources. From the 22 LAB isolated from orange, two isolates of interest (NGO25 and NGO23) were obtained; all belonging to the Lactiplantibacillus plantarum species based on 16S rRNA gene sequencing. Furthermore, the production yield powder obtained after lyophilization of 1 L of CB and FB surpernatant were, respectively, 16.6 g and 12.933 g. The TKN of different nitrogen sources powder were 71.4 ± 0.000% DM (FB), 86.145 ± 0.001% DM (CB), and 87.5 ± 0.99% DM (yeast extract). The best kinetic parameters of LA production (LA (g/L): 31.945 ± 0.078; volumetric productivity (g/L.h): 1.331 ± 0.003; LA yield (mg/g) 63.89 ± 0.156; biomass (g/L) 7.925 ± 0.035; cell growth rate (g/L.h): 0.330 ± 0.001) were recorded by Lactiplantibacillus plantarum NGO25 after 24 h of fermentation. The latter data were obtained in the production medium containing CB as nitrogen sources. In addition, this production medium cost only $0.152 to formulate, compared to yeast extract which required $1.692 to formulate. Thus, freeze‐dried CB can be used as an alternative to yeast extract in large‐scale production of LA. [ABSTRACT FROM AUTHOR]

Under New Zealand grazing systems, a high proportion of the nitrogen consumed by ruminants is excreted. This experiment examined the effect of feeding morning and afternoon harvested annual ryegrass, fed shortly after harvest, on the timing of nitrogen excretion in one-year-old sheep during winter. Dry matter and water-soluble carbohydrate (WSC) content increased in the afternoon-harvested ryegrass. This resulted in increased protein and WSC intakes and a decrease in nitrogen loss in the sheep fed in the afternoon with afternoon-harvested grass. The pattern of urinary nitrogen excretion was related to feeding time with peak urinary urea excretion in the period 4–8 hours after feeding, with over 60% of the daily urinary urea excreted in the 12 hours after the feed was offered. This study suggests that shifting stock onto new pasture breaks in the afternoon could reduce nitrous oxide production by increasing the efficiency of nitrogen utilisation in animals and reducing the total amount of nitrogen excreted. It may be possible to utilise the potential diurnal differences in pasture composition to reduce nitrogen losses. This practise could also improve animal performance as well as change the timing of nitrogen excretion. [ABSTRACT FROM AUTHOR]

This study explores the genetic landscape of nitrous oxide (N2O) reduction in wastewater treatment plants (WWTPs) by profiling 1,083 high-quality metagenomeassembled genomes (HQ MAGs) from 23 Danish full-scale WWTPs. The focus is on the distribution and diversity of nitrous oxide reductase (nosZ) genes and their association with other nitrogen metabolism pathways. A custom pipeline for clade-specific nosZ gene identification with higher sensitivity revealed 503 nosZ sequences in 489 of these HQ MAGs, outperforming existing Kyoto Encyclopedia of Genes and Genomes (KEGG) module-based methods. Notably, 48.7% of the total 1,083 HQ MAGs harbored nosZ genes, with clade II being predominant, accounting for 93.7% of these genes. Taxonomic profiling highlighted the prevalence of nosZ-containing taxa within Bacteroidota and Pseudomonadota. Chloroflexota exhibited unexpected affiliations with both the sec and tat secretory pathways, and all were found to contain the accessory nosB gene, underscoring the importance of investigating the secretory pathway. The majority of non-denitrifying N2O reducers were found within Bacteroidota and Chloroflexota. Additionally, HQ MAGs with genes for dissimilatory nitrate reduction to ammonium and assimilatory nitrate reduction frequently co-occurred with the nosZ gene. Traditional primers targeting nosZ often focus on short-length amplicons. Therefore, we introduced custom-designed primer sets targeting near-full-length nosZ sequences. These new primers demonstrate efficacy in capturing diverse and well-characterized sequences, providing a valuable tool with higher resolution for future research. In conclusion, this comprehensive analysis enhances our understanding of N2O-reducing organisms in WWTPs, highlighting their potential as N2O sinks with the potential for optimizing wastewater treatment processes and mitigating greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Cold stress adversely affects rice growth, particularly at the early vegetative growth stage. In higher plants, nitrogen metabolism plays a central role in amino acid metabolism, plant defense mechanisms and productivity. This report investigated the effects of cold stress and supplemental γ-aminobutyric acid (GABA) under cold stress on nitrogen metabolism in rice seedlings. Cold stress resulted in a greater increase in the transformation to NH4+ by nitrate reductase (NR) in roots, it further resulted in lower levels of NO3 - content in roots, weakened glutamine glutamate (GOGAT/GS) pathway and elevated glutamate dehydrogenase (GDH) pathway of rice seedlings. Whereas, compared with cold stress, supplementation of GABA (2.5 mmol·L-1) could increase relative water content (79.43%) and biomass (34.15%) of rice seedlings. GABA could act as an amplifier of stress signal conduction/transduction to increase NR activity and promote NO3 - assimilation in leaves. In addition, GABA elicited the Ca2+ signaling pathway which could promote the GDH pathway and GABA shunt, increase the activities of GS and GDH, and the expression of OsGAD2 and OsGDH family. The GABA might increase the ratio of the Glu family and avoid NH4+ toxicity in order to raise the concentration of organic compounds and alleviate the harmful consequences of cold stress. Based on these observations, this study proposed that GABA mediated cold tolerance in rice seedlings by activating Ca2+ burst and subsequent crosstalk among Ca2+ signaling, GDH pathway and GABA shunt. [ABSTRACT FROM AUTHOR]

This study investigated the effects of exogenous nitric oxide (NO) on growth, antioxidant enzymes, and key nitrogen metabolism enzymes in pepper seedlings under high-temperature stress. In addition, targeted metabolomics was used to study the differential accumulation of amino acid metabolites, thereby providing theoretical support for the use of exogenous substances to mitigate high-temperature stress damage in plants. The results showed that high-temperature stress increased soluble sugar, soluble protein, amino acids, proline, malondialdehyde (MDA), and hydrogen peroxide (H2O2) content, electrolyte leakage, and superoxide anion (O2·-) production rate while altering the activities of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX)] and key nitrogen metabolism enzymes [nitrate reductase (NR), glutamine synthetase (GS), glutamate dehydrogenase (GDH), and nitric oxide synthase (NOS)]. c-PTIO (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, an NO scavenger) exacerbates oxidative stress and further reduces NO content and enzyme activities. However, exogenous SNP (sodium nitroprusside, an NO donor) effectively alleviated these adverse effects by enhancing antioxidant defense mechanisms, increasing NO content, and normalizing amino acid metabolite levels (kynurenine, N-acetyl-L-tyrosine, L-methionine, urea, and creatine), thereby maintaining normal plant growth. These findings suggest that SNP can enhance stress tolerance in pepper seedlings by improving osmotic regulation, antioxidant capacity, and nitrogen metabolism, effectively mitigating the damage caused by high-temperature stress. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) research has rarely focused on the response to low-nitrogen stress in different subtypes previously and lacked a low-nitrogen tolerance evaluation system. Here, we investigated the physiological characteristics under moderate and low-nitrogen stress conditions in two japonica cultivars (NG46 and NG9108) and two indica cultivars (LYP9 and 9311). Using subordinate function analysis and principal component analysis, the low-nitrogen tolerance of four rice varieties was comprehensively evaluated; stomatal conductance, total carotenoid content, and nitrate reductase NR activity were taken as the low-nitrogen tolerance evaluation system. Among the four rice cultivars, NG46 and LYP9 had significant advantages in photosynthetic gas-exchange capacity, optimizing the balance between light-harvesting capacity, the ratio of reaction center inactivation, the magnitude of decrease in heat dissipation, and nitrogen-metabolism enzyme activities. The results investigated the physiological mechanisms of rice adaptation to low-nitrogen stress and offered a reliable method for assessing low-nitrogen tolerance in rice.

During the boll formation stage, cotton bolls exhibit the lowest expression of Bacillus thuringiensis (Bt) insecticidal proteins. Resistance to insects varies notably among different organs, which poses challenges for controlling cotton bollworms. Consequently, an experimental strategy was designed in the 2020–2021 cotton growing season to coordinate the enhancement of protein synthesis and the attenuation of degradation. Two Bt cultivars of Gossypium hirsutum, namely the hybrid Sikang 3 and the conventional Sikang 1, were used as test materials. Three treatments were applied at the peak flowering period: CK (the control), T1 (amino acids), and T2 (amino acids and EDTA). The results show that, in comparison to the CK group, the Bt protein contents were significantly increased in both cotton bolls and their subtending leaves under the T1 and T2 treatments. The maximum levels of increase observed were 67.5% in cotton bolls and 21.7% in leaves. Moreover, the disparity in Bt protein content between cotton bolls and their subtending leaves notably decreased by 31.2%. Correlation analysis suggested that the primary physiological mechanisms for augmenting Bt protein content involve increased protein synthesis and reduced protein catabolism, which are independent of Bt gene expression levels. Stepwise regression and path analysis revealed that elevating the soluble protein content and transaminase activity, while reducing the catabolic enzyme activities, are instrumental in enhancing the Bt protein content. Consequently, the coordinated application of amino acids and EDTA emerges as a strategy that can improve the overall resistance of Bt cotton and mitigate the spatiotemporal variations in Bt toxin concentrations in both cotton bolls and leaves.

Dietary nutrient manipulation (e.g. protein fractions) could lower the environmental footprints of ruminants, especially reactive nitrogen (N). This study investigated the impacts of dietary soluble protein (SP) levels with decreased crude protein (CP) on intestinal N absorption, hindgut N metabolism, fecal microbiota and metabolites, and their linkage with N metabolism phenotype. Thirty-two male Hu sheep, with an age of six months and an initial BW of 40.37 ± 1.18 kg, were randomly assigned to four dietary groups. The control diet (CON), aligning with NRC standards, maintained a CP content of 16.7% on a dry matter basis. Conversely, the experimental diets (LPA, LPB, and LPC) featured a 10% reduction in CP compared with CON, accompanied by SP adjustments to 21.2%, 25.9%, and 29.4% of CP, respectively. Our results showed that low-protein diets led to significant reductions in the concentrations of plasma creatinine, ammonia, urea N, and fecal total short-chain fatty acids (SCFA) (P

Premium-tasty japonica rice, distinguished by its unique flavor and enriched nutritional value, has attracted significant attention across Asia. Nitrogen metabolism plays a crucial role in determining the growth, development, and quality of rice grains. This study investigates the effects of nitrogen application rates on the enzymatic activities related to nitrogen metabolism, nitrogen metabolites, and grain protein content in the premium-tasty japonica rice variety, Suxiangjing 100. Using a range of nitrogen application rates (0, 80, 160, 240, 320, and 400 kg per hectare), comprehensive analyses were conducted across various developmental stages. Results indicate that as nitrogen application increased, there were distinct patterns in the enzyme activities and metabolite concentrations related to nitrogen metabolism in the leaves of premium-tasty japonica rice. The activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT) peaked at moderate nitrogen applications, while excessive nitrogen led to a decrease in their activities. The activity of Glutamate Dehydrogenase (GDH) generally increased, but showed a decline after the filling stage. With increasing nitrogen application, the concentrations of nitrate nitrogen (NO3–N), ammonium nitrogen (NH4–N), free amino acids (FAA), and soluble proteins (SP) initially rose but declined at excessive application rates. The grain protein content increased, with levels of prolamin, glutelin, and globulin peaking at nitrogen applications of 240 kg/ha and 320 kg/ha, while changes in albumin levels were minimal. This study not only provides novel insights into the role of nitrogen in shaping the growth and quality of premium-tasty japonica rice, but also suggests refined nitrogen management strategies for sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Abstract Background Populus spp. is a crucial fast-growing and productive tree species extensively cultivated in the mid-latitude plains of the world. However, the impact of intensive cultivation management on gene expression in plantation remains largely unexplored. Results Precision water and fertilizer-intensive management substantially increased key enzyme activities of nitrogen transport, assimilation, and photosynthesis (1.12–2.63 times than CK) in Populus × euramericana 'Neva' plantation. Meanwhile, this management approach had a significant regulatory effect on the gene expression of poplar plantations. 1554 differential expression genes (DEGs)were identified in drip irrigation (ND) compared with conventional irrigation. Relative to ND, 2761–4116 DEGs, predominantly up-regulated, were identified under three drip fertilization combinations, among which 202 DEGs were mainly regulated by fertilization. Moreover, drip irrigation reduced the expression of cell wall synthesis-related genes to reduce unnecessary water transport. Precision drip and fertilizer-intensive management promotes the synergistic regulation of carbon and nitrogen metabolism and up-regulates the expression of major genes in nitrogen transport and assimilation processes (5 DEGs), photosynthesis (15 DEGs), and plant hormone signal transduction (11 DEGs). The incorporation of trace elements further enhanced the up-regulation of secondary metabolic process genes. In addition, the co-expression network identified nine hub genes regulated by precision water and fertilizer-intensive management, suggesting a pivotal role in regulating the growth of poplar. Conclusion Precision water and fertilizer-intensive management demonstrated the ability to regulate the expression of key genes and transcription factor genes involved in carbon and nitrogen metabolism pathways, plant hormone signal transduction, and enhance the activity of key enzymes involved in related processes. This regulation facilitated nitrogen absorption and utilization, and photosynthetic abilities such as light capture, light transport, and electron transport, which faintly synergistically regulate the growth of poplar plantations. These results provide a reference for proposing highly efficient precision intensive management to optimize the expression of target genes.

This study investigated the effects of β-alanine (β-Ala) on rumen fermentation, nutrient digestibility, nitrogen (N) metabolism, plasma biochemical parameters, and rumen bacterial communities in beef steers. Six steers with initial liveweight of 252.8 ± 5.2 kg and 3 treatments of supplementing with 0, 30, or 60 g β-Ala per day to basal diet were allocated in a replicated 3 × 3 Latin square design. Each experimental period was 20 d, of which the first 15 d were for adaptation and the subsequent 5 d were for sampling. The results showed that β-Ala linearly increased the ruminal concentration of microbial crude protein (MCP) (P = 0.005), but it did not affect the ruminal concentrations of ammonia N and total volatile fatty acids (P > 0.10). β-Ala also linearly increased the dry matter (DM) (P = 0.009), organic matter (OM) (P = 0.017) and crude protein (CP) (P = 0.043) digestibility, tended to decrease the acid detergent fiber digestibility (P = 0.077), but it did not affect the neutral detergent fiber digestibility (P = 0.641). β-Ala quadratically increased the relative abundance of ruminal Bacteroidota (P = 0.021) at the phylum level, and increased Prevotella (P = 0.028) and Prevotellaceae_UCG-003 (P = 0.014), and decreased the relative abundance of NK4A214_group (P = 0.009) at the genus level. Feeding steers with β-Ala linearly increased the urinary N (P = 0.006), urea excretions (P = 0.002) and the N retention (P = 0.004), but it did not affect the N utilization efficiency (P = 0.120). β-Ala quadratically increased the plasma concentration of the total antioxidant capacity (P = 0.011) and linearly increased the plasma concentration of insulin-like growth factor-1 (P

Brazilian soils are predominantly rich in aluminum, which becomes mobile at pH < 5, affecting sensitive plants; however, some species have developed aluminum tolerance mechanisms. The purpose of this study was to compare the physiological responses of Crotalaria genus species, family Fabaceae, which have the ability to associate with nitrogen-fixing bacteria under the influence of Al3+ in the soil. The soil used was Oxisol; the experimental design was in randomized blocks in a factorial scheme (2 × 3): soil factor (available toxic aluminum content; correction of dolomitic limestone—MgCO3) and species factor (C. juncea; C. spectabilis; C. ochroleuca); cultivated within 43, 53, and 53 days, respectively, with five replications; 30 experimental samples. Mass and length, pigments, gas exchange, and changes in nitrogen metabolism were evaluated. C. juncea showed a higher concentration of amino acids in the leaves, internal carbon, and stomatal conductance in soil with Al3+, as well as higher production of ureides, allantoinic acid, allantoic acid, proteins, and amino acids in the nodules, with 78% of the Al3+ accumulation occurring in the roots. C. ochroleuca demonstrated greater shoot length and nodule number production in limed soil; in soil with Al3+, it showed a 91% increase in chlorophyll a content and 93% in carotenoids. C. spectabilis showed a 93% increase in ureide production in the leaves in soil with Al3+. [ABSTRACT FROM AUTHOR]

Background: Populus spp. is a crucial fast-growing and productive tree species extensively cultivated in the mid-latitude plains of the world. However, the impact of intensive cultivation management on gene expression in plantation remains largely unexplored. Results: Precision water and fertilizer-intensive management substantially increased key enzyme activities of nitrogen transport, assimilation, and photosynthesis (1.12–2.63 times than CK) in Populus × euramericana 'Neva' plantation. Meanwhile, this management approach had a significant regulatory effect on the gene expression of poplar plantations. 1554 differential expression genes (DEGs)were identified in drip irrigation (ND) compared with conventional irrigation. Relative to ND, 2761–4116 DEGs, predominantly up-regulated, were identified under three drip fertilization combinations, among which 202 DEGs were mainly regulated by fertilization. Moreover, drip irrigation reduced the expression of cell wall synthesis-related genes to reduce unnecessary water transport. Precision drip and fertilizer-intensive management promotes the synergistic regulation of carbon and nitrogen metabolism and up-regulates the expression of major genes in nitrogen transport and assimilation processes (5 DEGs), photosynthesis (15 DEGs), and plant hormone signal transduction (11 DEGs). The incorporation of trace elements further enhanced the up-regulation of secondary metabolic process genes. In addition, the co-expression network identified nine hub genes regulated by precision water and fertilizer-intensive management, suggesting a pivotal role in regulating the growth of poplar. Conclusion: Precision water and fertilizer-intensive management demonstrated the ability to regulate the expression of key genes and transcription factor genes involved in carbon and nitrogen metabolism pathways, plant hormone signal transduction, and enhance the activity of key enzymes involved in related processes. This regulation facilitated nitrogen absorption and utilization, and photosynthetic abilities such as light capture, light transport, and electron transport, which faintly synergistically regulate the growth of poplar plantations. These results provide a reference for proposing highly efficient precision intensive management to optimize the expression of target genes. [ABSTRACT FROM AUTHOR]

The issue of heavy metal pollution such as nickel poses a significant environmental concern, exerting detrimental effects on the growth and viability of plant life. Plants have various mechanisms to effectively manage heavy metal stress, including the ability to modify their amino acid type and content. This adaptive response allows plants to mitigate the detrimental effects caused by excessive heavy metal accumulation. The aim of this study was to investigate the effect of biofertilizers on nickel accumulation, nitrogen metabolism and amino acid profile of corn (Zea mays L.) cv. 'PL438' exposed to Ni stress. After disinfecting and soaking in water for 24 h, corn seeds were primed with bacterial biofertilizers (T2: NPK + FZ), fungal biofertilizers (T3: Arbuscular mycorrhizal fungi (AMF) + Trichoderma (T)), or a combination of them (T4: NPK + FZ + AMF + T) and were cultured by the hydroponic method in completely controlled conditions. Then, they were simultaneously exposed to nickel chloride at various rates (0, 75, or 150 µM) at the three-leaf stage. They were harvested two weeks later and were subjected to the measurement of Ni content, nitrate and nitrite content, nitrate reductase activity, and amino acid profile by high-performance liquid chromatography. The results showed that the application of Ni at higher rates increased Ni, nitrate, and nitrite contents and nitrate reductase activity. The study of Ni accumulation and TF revealed that Ni accumulated in the roots to a greater extent than in the shoots and TF was < 1 in all treatments. The shoot amino acid profile showed that the treatment of Ni+2 increased som amino acids such as aspartic acid, asparagine, serine, histidine, and glycine versus the control, whereas T4 Ni+2 increased aspartic acid, glutamic acid, threonine and arginine. The change in amino acids in Ni-treated plants may play a key role in their adaptation to Ni stress. The findings indicate that biofertilizers played a crucial role in mitigating the negative impacts of Ni on corn plants through alterations in amino acid composition and decreased absorption and translocation of Ni. [ABSTRACT FROM AUTHOR]

Aims: Enhancing crop yields is a contemporary challenge of the modern world, and selenium (Se) has been shown to improve plant health against various abiotic stressors. This study aimed to evaluate the influence of Se on the biosynthesis of photosynthetic pigments, nitrogen metabolism, antioxidant metabolism, flavonoid synthesis and nodulation of cowpea plants. Methods: We carried out a soil experiment with five Se application rates (0, 7.5, 15, 30, and 45 µg kg−1) and a hydroponics experiment with four Se concentrations (0, 5, 10, and 15 µmol L−1). Results: Both experiments revealed hormetic-like responses of cowpea plants to Se, at both molecular and whole-plant levels. Se dose-dependently increased the synthesis of chlorophylls, carotenoids and pheophytin as well as the efficiency of enzymatic antioxidant metabolism by decreasing MDA levels and increasing CAT and APX activity. Selenium also enhanced nitrate reductase activity, resulting in greater biosynthesis of amino acids and proteins in the leaves. However, the dose responses were not identical in the two experiments. Hormetic-like biphasic responses were uniquely revealed for daidzein, genistein, and kaempferol in the hydroponics experiment. Selenium also enhanced the number of nodules in roots, which generated increases in the production of ureides and greater production of shoot dry weight in both experiments. Low rates of Se stimulated the translocation of allantoic acid from nodules to leaves. Conclusions: This study adds new insights regarding Se effect on antioxidant and nitrogen metabolism, photosynthetic pigments and nodulation, which can increase cowpea yield. [ABSTRACT FROM AUTHOR]

Boron (B) deficiency has been shown to inhibit root cell growth and division. However, the precise mechanism underlying B deficiency-mediated root tip growth inhibition remains unclear. In this study, we investigated the role of BnaA3.NIP5;1, a gene encoding a boric acid channel, in Brassica napus (B. napus). BnaA3.NIP5;1 is expressed in the lateral root cap and contributes to B acquisition in the root tip. Downregulation of BnaA3.NIP5;1 enhances B sensitivity in B. napus, resulting in reduced shoot biomass and impaired root tip development. Transcriptome analysis was conducted on root tips from wild-type B. napus (QY10) and BnaA3.NIP5;1 RNAi lines to assess the significance of B dynamics in meristematic cells during seedling growth. Differentially expressed genes (DEGs) were significantly enriched in plant circadian rhythm and nitrogen (N) metabolism pathways. Notably, the circadian-rhythm-related gene HY5 exhibited a similar B regulation pattern in Arabidopsis to that observed in B. napus. Furthermore, Arabidopsis mutants with disrupted circadian rhythm (hy5/cor27/toc1) displayed heightened sensitivity to low B compared to the wild type (Col-0). Consistent with expectations, B deficiency significantly disrupted N metabolism in B. napus roots, affecting nitrogen concentration, nitrate reductase enzyme activity, and glutamine synthesis. Interestingly, this disruption was exacerbated in BnaA3NIP5;1 RNAi lines. Overall, our findings highlight the critical role of B dynamics in root tip cells, impacting circadian rhythm and N metabolism, ultimately leading to retarded growth. This study provides novel insights into B regulation in root tip development and overall root growth in B. napus. [ABSTRACT FROM AUTHOR]

Downy mildew is one of the main diseases that cause a reduction in cucumber yield. Chemical control not only increases pathogenic bacteria resistance and causes environmental pollution but also endangers the health of humans as they are abundant pesticide residues in fruits. Dopamine, a strong antioxidant that widely exists in plants, can effectively protect plants from the adverse effects of such chemicals. In this study, the susceptible cucumber cultivar 'Changchun Mici' and the disease-resistant cultivar 'Jinchun No. 4' were used as test materials to explore the alleviating effect of exogenous dopamine on cucumber downy mildew. After downy mildew infection, exogenous dopamine (100 µmol L−1) had the greatest significant effect on improving the disease resistance of cucumber, increasing the activities of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase in cucumber, thereby reducing the accumulation of the superoxide anion and hydrogen peroxide in leaves, the content of malondialdehyde, and the relative electrical conductivity in leaves, which significantly improved the antioxidant capacity of cucumber. Simultaneously, exogenous dopamine increased the leaf wax content and trichome density; the activities of polyphenol oxidase, chitinase, and β-1,3-glucanase; and the expression of CsPR1, so that the disease index was significantly reduced. As for nitrogen metabolism, exogenous dopamine significantly increased the activities of nitrate reductase, glutamine synthase, glutamate synthase, and glutamate dehydrogenase, as well as the content of nitrate nitrogen, whereas it decreased the accumulation of ammonium nitrogen, thereby promoting nitrogen metabolism in cucumber. As a consequence, exogenous dopamine improved the yield and quality of cucumbers infected by downy mildew. [ABSTRACT FROM AUTHOR]

The paper presents the experimental study of the influence of a 50 Hz extremely-low-frequency (ELF) electromagnetic field (EMF) on the growth of microalgae Chlorella vulgaris in a BG11 culture medium. Comparative experimental determinations carried out under reference conditions (microalgae growth without exposure to EMF) and with exposure to a homogeneous 50 Hz EMF of various intensities highlighted the fact that EMF has a major impact on both the growth speed and the nitrogen and phosphorus content of the obtained algal mass. Through spectrophotometry and gravimetric determinations, it was found that the lag time was reduced from approximately 8 h (reference) to approximately 6 h for EMF of 2 V/m, 4.5 h for EMF of 5 V/m, 3.2 h for EMF of 10 V/m, and 2.5 h for EMF of 15 V/m. In the stimulation with 15 V/m EMF, the maximum biomass growth rate was 2.75 times higher than the reference, leading to a 2-fold increase in the rate of exhaustion of nutrients, especially phosphorus, in the culture medium. The specific chemical analyses for N-NO3, total nitrogen TNb, and total phosphorus Pt highlighted that the N-NO3 content of the culture medium decreased by 58 mg/L/day at 15 V/m EMF compared to 43 mg/L for the reference. The Pt content decreased to 90% depletion after approximately 80 h for the reference culture medium, versus only 48 h of growth with exposure to 15 V/m ELF. The TNb content of the algal suspension in BG11 under the influence of 15 V/m EMF for 96 h of growth increased 14 times compared to the reference. This shows that nitrogen metabolization in the dispersed air was significantly stimulated. It was also found that the 50 Hz EMF also influences the nitrogen and phosphorus content of the increased algal mass. The results show the potential of EMF stimulation of Chlorella vulgaris growth, leading to an increased efficiency of algae growth reactors. [ABSTRACT FROM AUTHOR]

As versatile signaling molecules, melatonin (ML) and hydrogen sulfide (H2S) are well-known for their roles in response to abiotic stresses. However, their cross-talk to the regulation of biochemical defence responses and secondary metabolite synthesis during salinity has received less attention. Here, the role of ML-H2S interplay in inducing defensive responses and the biosynthesis of essential oil compounds in summer savoury plants under NaCl treatment was investigated. NaCl treatment, by increasing Na accumulation, disrupting nitrogen metabolism, and inducing oxidative stress, lowered photosynthetic pigments and savoury growth. NaCl treatment also resulted in a decrease in γ-terpinene (10.3%), α-terpinene (21.9%), and p-cymene (15.3%), while an increase in carvacrol (9.1%) was observed over the control. ML and ML + H2S increased the activity of antioxidant enzymes and the level of total phenols and flavonoids, resulting in decreased levels of hydrogen peroxide and superoxide anion and alleviation of oxidative damage under salinity. ML and ML + H2S increased K uptake and restored K/Na homeostasis, thus protecting the photosynthetic apparatus against NaCl-induced toxicity. ML and ML + H2S treatments also improved nitrate/ammonium homeostasis and stimulated nitrogen metabolism, leading to improved summer savoury adaptation to NaCl stress. ML and ML + H2S changed the composition of essential oils, leading to an increase in the monoterpene hydrocarbons and oxygenated monoterpenes in plants stressed with NaCl. However, the addition of an H2S scavenger, hypotaurine, inhibited the protective effects of the ML and ML + H2S treatments under NaCl stress, which could confirm the function of H2S as a signaling molecule in the downstream defence pathway induced by ML. [ABSTRACT FROM AUTHOR]

The glutamine synthetase/glutamic acid synthetase (GS/GOGAT) cycle plays important roles in N metabolism, growth, development, and stress resistance in plants. Excess ammonium (NH4+) restricts growth, but GS can help to alleviate its toxicity. In this study, the 84K model clone of hybrid poplar (Populus alba × P. tremula var. glandulosa), which has reduced biomass accumulation and leaf chlorosis under high-NH4+ stress, showed less severe symptoms in transgenic lines overexpressing GLUTAMINE SYNTHETASE 1;2 (GS1;2 -OE), and more severe symptoms in RNAi lines (GS1;2 -RNAi). Compared with the wild type, the GS1;2 -OE lines had increased GS and GOGAT activities and higher contents of free amino acids, soluble proteins, total N, and chlorophyll under high-NH4+ stress, whilst the antioxidant and NH4+ assimilation capacities of the GS1;2 -RNAi lines were decreased. The total C content and C/N ratio in roots and leaves of the overexpression lines were higher under stress, and there were increased contents of various amino acids and sugar alcohols, and reduced contents of carbohydrates in the roots. Under high-NH4+ stress, genes related to amino acid biosynthesis, sucrose and starch degradation, galactose metabolism, and the antioxidant system were significantly up-regulated in the roots of the overexpression lines. Thus, overexpression of GS1;2 affected the carbon and amino acid metabolism pathways under high-NH4+ stress to help maintain the balance between C and N metabolism and alleviate the symptoms of toxicity. Modification of the GS/GOGAT cycle by genetic engineering is therefore a potential strategy for improving the NH4+ tolerance of cultivated trees. [ABSTRACT FROM AUTHOR]

The RNA-Seq profiling of Herbaspirillum seropedicae SmR1 wild-type and ntrC mutant was performed under aerobic and three nitrogen conditions (ammonium limitation, ammonium shock, and nitrate shock) to identify the major metabolic pathways modulated by these nitrogen sources and those dependent on NtrC. Under ammonium limitation, H. seropedicae scavenges nitrogen compounds by activating transporter systems and metabolic pathways to utilize different nitrogen sources and by increasing proteolysis, along with genes involved in carbon storage, cell protection, and redox balance, while downregulating those involved in energy metabolism and protein synthesis. Growth on nitrate depends on the narKnirBDHsero_2899nasA operon responding to nitrate and NtrC. Ammonium shock resulted in a higher number of genes differently expressed when compared to nitrate. Our results showed that NtrC activates a network of transcriptional regulators to prepare the cell for nitrogen starvation, and also synchronizes nitrogen metabolism with carbon and redox balance pathways. [ABSTRACT FROM AUTHOR]

Neoadjuvant chemotherapy (NAC) is the preferred treatment option in locally advanced breast cancer (BC). The administration of NAC is associated with a wide range of adverse effects. This pilot observational prospective study examined the effect of NAC using anthracycline + cyclophosphamide (AC) followed by paclitaxel (PTx) on a portfolio of 22 plasma and urinary amino acids, plasma proteins (albumin, prealbumin, transferrin), and products of nitrogen metabolism (urea, creatinine, uric acid) in plasma and urine. Plasma and 24-h urine samples were obtained from ten patients with early breast cancer (N1-3 N0-2 M0), at the following time points: before the start of NAC and during the AC/PTx treatment period (a total of 8 measurements at three-weekly intervals). Amino acids were analyzed using ion exchange chromatography. There were no significant differences in the measured parameters in plasma and urine between pre-NAC and during AC- and PTx-treatment. No trend was detected. A significant difference in the portfolio of plasma and urinary amino acids was found only in the pre-treatment period compared to the control group. Levels of eight plasma amino acids (8/22) were significantly reduced and those of nine urine amino acids were increased (9/22). Nitrogenous catabolites in plasma and urine were not indicative of increased protein catabolism during the anthracycline and taxane treatment periods. A slightly positive nitrogen balance was accompanied by an average weight gain of 3.3 kg (range 0–6 kg). The AC/PTx treatment regimen did not cause significant changes in the monitored laboratory parameters. [ABSTRACT FROM AUTHOR]

Objective: To clarify the potential mechanism of Banxia Xiexin Decoction (BXD) on colorectal cancer (CRC) from the perspective of metabolomics. Methods: Forty male C57BL/6 mice were randomly divided into normal control (NC), azoxymethane/dextran sulfate sodium (AOM/DSS) model, low-dose BXD (L-BXD), high-dose BXD (H-BXD) and mesalamine (MS) groups according to a random number table, 8 mice in each group. Colorectal cancer model was induced by AOM/DSS. BXD was administered daily at doses of 3.915 (L-BXD) and 15.66 g/kg (H-BXD) by gavage for consecutive 21 days, and 100 mg/kg MS was used as positive control. Following the entire modeling cycle, colon length of mice was measured and quantity of colorectal tumors were counted. The spleen and thymus index were determined by calculating the spleen/thymus weight to body weight. Inflammatory cytokine and changes of serum metabolites were analyzed by enzyme-linked immunosorbent assay kits and ultra performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UPLC-Q/TOF-MS), respectively. Results: Notably, BXD supplementation protected against weight loss, mitigated tumor formation, and diminished histologic damage in mice treated with AOM/DSS (P<0.05 or P<0.01). Moreover, BXD suppressed expression of serum inflammatory enzymes, and improved the spleen and thymus index (P<0.05). Compared with the normal group, 102 kinds of differential metabolites were screened in the AOM/DSS group, including 48 potential biomarkers, involving 18 main metabolic pathways. Totally 18 potential biomarkers related to CRC were identified, and the anti-CRC mechanism of BXD was closely related to D-glutamine and D-glutamate metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, arginine biosynthesis, nitrogen metabolism and so on. Conclusion: BXD exerts partial protective effects on AOM/DSS-induced CRC by reducing inflammation, protecting organism immunity ability, and regulating amino acid metabolism. [ABSTRACT FROM AUTHOR]

Aminotransferases (ATs) are an ancient enzyme family that play central roles in core nitrogen metabolism, essential to all organisms. However, many of the AT enzyme functions remain poorly defined, limiting our fundamental understanding of the nitrogen metabolic networks that exist in different organisms. Here, we traced the deep evolutionary history of the AT family by analyzing AT enzymes from 90 species spanning the tree of life (ToL). We found that each organism has maintained a relatively small and constant number of ATs. Mapping the distribution of ATs across the ToL uncovered that many essential AT reactions are carried out by taxon-specific AT enzymes due to wide-spread nonorthologous gene displacements. This complex evolutionary history explains the difficulty of homology-based AT functional prediction. Biochemical characterization of diverse aromatic ATs further revealed their broad substrate specificity, unlike other core metabolic enzymes that evolved to catalyze specific reactions today. Interestingly, however, we found that these AT enzymes that diverged over billion years share common signatures of multisubstrate specificity by employing different nonconserved active site residues. These findings illustrate that AT family enzymes had leveraged their inherent substrate promiscuity to maintain a small yet distinct set of multifunctional AT enzymes in different taxa. This evolutionary history of versatile ATs likely contributed to the establishment of robust and diverse nitrogen metabolic networks that exist throughout the ToL. The study provides a critical foundation to systematically determine diverse AT functions and underlying nitrogen metabolic networks across the ToL. [ABSTRACT FROM AUTHOR]

There is a need to generate improved crop varieties adapted to the ongoing changes in the climate. We studied durum wheat canopy and central metabolism of six different photosynthetic organs in two yield-contrasting varieties. The aim was to understand the mechanisms associated with the water stress response and yield performance. Water stress strongly reduced grain yield, plant biomass, and leaf photosynthesis, and down-regulated C/N-metabolism genes and key protein levels, which occurred mainly in leaf blades. By contrast, higher yield was associated with high ear dry weight and lower biomass and ears per area, highlighting the advantage of reduced tillering and the consequent improvement in sink strength, which promoted C/N metabolism at the whole plant level. An improved C metabolism in blades and ear bracts and N assimilation in all photosynthetic organs facilitated C/N remobilization to the grain and promoted yield. Therefore, we propose that further yield gains in Mediterranean conditions could be achieved by considering the source–sink dynamics and the contribution of non-foliar organs, and particularly N assimilation and remobilization during the late growth stages. We highlight the power of linking phenotyping with plant metabolism to identify novel traits at the whole plant level to support breeding programmes. [ABSTRACT FROM AUTHOR]

Mycobacterium abscessus (Mab) is an opportunistic pathogen afflicting individuals with underlying lung disease such as Cystic Fibrosis (CF) or immunodeficiencies. Current treatment strategies for Mab infections are limited by its inherent antibiotic resistance and limited drug access to Mab in its in vivo niches resulting in poor cure rates of 30-50%. Mab's ability to survive within macrophages, granulomas and the mucus laden airways of the CF lung requires adaptation via transcriptional remodeling to counteract stresses like hypoxia, increased levels of nitrate, nitrite, and reactive nitrogen intermediates. Mycobacterium tuberculosis (Mtb) is known to coordinate hypoxic adaptation via induction of respiratory nitrate assimilation through the nitrate reductase narGHJI. Mab, on the other hand, does not encode a respiratory nitrate reductase. In addition, our recent study of the transcriptional responses of Mab to hypoxia revealed marked down-regulation of a locus containing putative nitrate assimilation genes, including the orphan response regulator nnaR (nitrate/nitrite assimilation regulator). These putative nitrate assimilation genes, narK3 (nitrate/nitrite transporter), nirBD (nitrite reductase), nnaR, and sirB (ferrochelatase) are arranged contiguously while nasN (assimilatory nitrate reductase identified in this work) is encoded in a different locus. Absence of a respiratory nitrate reductase in Mab and down-regulation of nitrogen metabolism genes in hypoxia suggest interplay between hypoxia adaptation and nitrate assimilation are distinct from what was previously documented in Mtb. The mechanisms used by Mab to fine-tune the transcriptional regulation of nitrogen metabolism in the context of stresses e.g. hypoxia, particularly the role of NnaR, remain poorly understood. To evaluate the role of NnaR in nitrate metabolism we constructed a Mab nnaR knockout strain (MabΔnnaR) and complement (MabΔnnaR+C) to investigate transcriptional regulation and phenotypes. qRT-PCR revealed NnaR is necessary for regulating nitrate and nitrite reductases along with a putative nitrate transporter. Loss of NnaR compromised the ability of Mab to assimilate nitrate or nitrite as sole nitrogen sources highlighting its necessity. This work provides the first insights into the role of Mab NnaR setting a foundation for futurework investigating NnaR's contribution to pathogenesis. [ABSTRACT FROM AUTHOR]

Despite global warming, the response of rice yield to long-term warming in cool regions and its physiological mechanisms remain unknown. This study used the widely cultivated japonica rice Jiyang100 in Northeast China. Taking rice grown under natural temperatures as a control (CK), field warming treatments were conducted at the tillering-panicle initiation (T1), whole growth (T2), and grain-filling (T3) stages. The positive effects of T1, T2, and T3 on the total number of spikelets per hole increased the yield in both years, with average increases of 11.5%, 9.9% and 6.5% compared to CK, respectively. Warming treatments improved the stay-green traits, photosynthesis, sucrose synthesis, and nitrogen metabolism of rice. The yield was positively correlated with the relative chlorophyll content (SPAD), soluble sugar content, sucrose content, and the activities of sucrose phosphate synthase (SPS), nitrate reductase (NR), glutamine synthetase (GS), glutamine oxoglutarate aminotransferase (GOGAT) in flag leaves. In addition, SPAD had a positive correlation with soluble sugar content, soluble protein content, and the activities of NR, GS, GOGAT, glutamate dehydrogenase (GDH), but a negative correlation with acid invertase (AI) activity. The stay-green ability was positively correlated to the net photosynthetic rate (Pn), soluble sugar content and soluble protein content. The coupling interactions of stay-green traits, nitrogen and carbon metabolism increased the yield potential and yield supply capacity, increased yield under long-term warming conditions in the cool regions. Under gradual warming, the physiological response of rice in cool regions promotes plant growth and development, thereby increasing yield. [ABSTRACT FROM AUTHOR]

Background: Infants with kidney failure (KF) demonstrate poor growth partly due to obligate fluid and protein restrictions. Delivery of liberalized nutrition on continuous kidney replacement therapy (CKRT) is impacted by clinical instability, technical dialysis challenges, solute clearance, and nitrogen balance. We analyzed delivered nutrition and growth in infants receiving CKRT with the Cardio-Renal, Pediatric Dialysis Emergency Machine (Carpediem™). Methods: Single-center observational study of infants receiving CKRT with the Carpediem™ between June 1 and December 31, 2021. We collected prospective circuit characteristics, delivered nutrition, anthropometric measurements, and illness severity Score for Neonatal Acute Physiology-II. As a surrogate to normalized protein catabolic rate in maintenance hemodialysis, we calculated normalized protein nitrogen appearance (nPNA) using the Randerson II continuous dialysis model. Descriptive statistics, Spearman correlation coefficient, Mann Whitney, Wilcoxon signed rank, receiver operating characteristic curves, and Kruskal–Wallis analysis were performed using SAS version 9.4. Results: Eight infants received 31.9 (22.0, 49.7) days of CKRT using mostly (90%) regional citrate anticoagulation. Delivered nutritional volume, protein, total calories, enteral calories, nPNA, and nitrogen balance increased on CKRT. Using parenteral nutrition, 90 ml/kg/day should meet caloric and protein needs. Following initial weight loss of likely fluid overload, exploratory sensitivity analysis suggests weight gain occurred after 14 days of CKRT. Despite adequate nutritional delivery, goal weight (z-score = 0) and growth velocity were not achieved until 6 months after CKRT start. Most (5 infants, 62.5%) survived and transitioned to peritoneal dialysis (PD). Conclusions: Carpediem™ is a safe and efficacious bridge to PD in neonatal KF. Growth velocity of infants on CKRT appears delayed despite delivery of adequate calories and protein. [ABSTRACT FROM AUTHOR]

Background: Oxidative stress indicators affect chronic orofacial pain (COFP), but how to reduce these effects is uncertain. Objectives: 11 oxidative stress biomarkers were collected as exposures, while four forms of COFP were chosen as outcomes for Mendelian randomization (MR) study. Methods: The effect estimates between oxidative stress and COFP were calculated using inverse variance‐weighted MR (IVW‐MR). Then, functional mapping and annotation (FUMA) was utilized in order to carry out SNP‐based functional enrichment analyses. In addition, the IVW‐MR method was applied to combine effect estimates when using genetic variants associated with oxidative stress biomarkers as an instrument for exploring potential druggable targets. Results: The results indicated that oxidative stress biomarkers (causal OR of uric acid (UA), 0.998 for myofascial pain, 95% CI 0.996–1.000, p <.05; and OR of glutathione transferase (GST), 1.002 for dentoalveolar pain, 95% CI 1.000–1.003, p <.05) were significantly linked with the probability of COFP. Functional analysis also demonstrated that UA and myofascial pain genes were prominent in nitrogen and uracil metabolism, while GST and dentoalveolar pain genes were enriched in glutathione metabolism. Also, the study provided evidence that solute carrier family 2 member 9 (SLC2A9) and glutathione S‐transferase alpha 2 (GSTA2) cause discomfort in the myofascial pain (OR = 1.003, 95% CI 1.000–1.006; p <.05) and dentoalveolar region (OR = 1.001, 95% CI 1.000–1.002; p <.05), respectively. Conclusions: In conclusion, this MR study indicates that genetically predicted myofascial pain was significantly associated with decreased UA and dentoalveolar pain was significantly associated with increased GST level. SLC2A9 inhibitor and GSTA2 inhibitor were novel chronic orofacial pain therapies and biomarkers, but clinical trials are called to examine if these oxidative biomarkers have the protective effect against orofacial pain, and further research are needed to explore the underlying mechanisms. [ABSTRACT FROM AUTHOR]

The rhizospheric microorganisms of agricultural crops play a crucial role in plant growth and nutrient cycling. In this study, we isolated two Streptomyces strains, Streptomyces sp. LM32 and Streptomyces sp. LM65, from the rhizosphere of Vitis vinifera L. We then conducted genomic analysis by assembling, annotating, and inferring phylogenomic information from the whole genome sequences. Streptomyces sp. strain LM32 had a genome size of 8.1 Mb and a GC content of 72.14%, while Streptomyces sp. strain LM65 had a genome size of 7.3 Mb and a GC content of 71%. Through ANI results, as well as phylogenomic, pan-, and core-genome analysis, we found that strain LM32 was closely related to the species S. coelicoflavus, while strain LM65 was closely related to the species S. achromogenes subsp. achromogenes. We annotated the functional categories of genes encoded in both strains, which revealed genes involved in nitrogen and phosphorus metabolism. This suggests that these strains have the potential to enhance nutrient availability in the soil, promoting agricultural sustainability. Additionally, we identified gene clusters associated with nitrate and nitrite ammonification, nitrosative stress, allantoin utilization, ammonia assimilation, denitrifying reductase gene clusters, high-affinity phosphate transporter and control of PHO regulon, polyphosphate, and phosphate metabolism. These findings highlight the ecological roles of these strains in sustainable agriculture, particularly in grapevine and other agricultural crop systems. [ABSTRACT FROM AUTHOR]

This study extensively analyzed the bacterial information of biofilms and activated sludge in oxic reactors of full-scale moving bed biofilm reactor-integrated fixed-film activated sludge (MBBR-IFAS) systems. The bacterial communities of biofilms and activated sludge differed statistically (R = 0.624, p < 0.01). The denitrifying genera Ignavibacterium, Phaeodactylibacter, Terrimonas, and Arcobacter were more abundant in activated sludge (p < 0.05), while comammox Nitrospira was more abundant in biofilms (p < 0.05), with an average relative abundance of 8.13%. Nitrospira and Nitrosomonas had weak co-occurrence relationships with other genera in the MBBR-IFAS systems. Potential function analysis revealed no differences in pathways at levels 1 and 2 based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) between biofilms and activated sludge. However, in terms of pathways at level 3, biofilms had more potential in 26 pathways, including various organic biodegradation and membrane and signal transportation pathways. In comparison, activated sludge had more potential in only five pathways, including glycan biosynthesis and metabolism. With respect to nitrogen metabolism, biofilms had greater potential for nitrification (ammonia oxidation) (M00528), and complete nitrification (comammox) (M00804) concretely accounted for methane/ammonia monooxygenase (K10944, K10945, and K10946) and hydroxylamine dehydrogenase (K10535). This study provides a theoretical basis for MBBR-IFAS systems from the perspective of microorganisms. [ABSTRACT FROM AUTHOR]

Sorghum seed germination is delayed/inhibited by salt stress, and moringa leaf extract (MLE), a natural growth enhancer, acts as a low-cost seed priming agent which promotes the germination under stress condition. Therefore, during the current investigation two sweet sorghum genotypes (salt tolerant and salt susceptible) were exposed to 100 mM salt stress (NaCl) and data pertaining to seedling growth, enzymatic activities, ionic balance and gene expression were recorded at 10 days after germination (DAG) in shoot and root tissues. The seeds were primed with MLE extract (10% v/v) to mitigate the effects of salt stress. Results showed that salt stress inhibited the seedling growth of sweet sorghum. MLE priming positively enhanced the seedling growth by inducing production of total phenols, total sugars and improving the chlorophyll content with improved nitrogen metabolism under salt treatment. Under salt stress, MLE priming resulted in a significantly enhanced antioxidant enzyme activities (SOD, APX, CAT and PPO) and related gene expression, whereas it reduced the Na+ /K+ ratio, due to induced expression of the HKT-6 and HAK genes in roots. Overall, salt-tolerant sorghum genotype performed better than susceptible genotype under salt stress. The present investigation suggested that MLE priming provided an early seedling protection by improving germination, enzymatic activities and expression of nitrogen metabolizing and antioxidant genes under salt stress. [ABSTRACT FROM AUTHOR]

ABSTRACT Cordyceps militaris infects insects and forms sclerotia within the insect remains, establishing insect–microbe complexes. Here, C. militaris sclerotia samples from a single location in China over a 5-year period were subjected to high-throughput DNA sequencing, and the core microbes (which were stably enriched in the sclerotia over the 5 years) were identified. Next, seven bacterial strains were isolated from the C. militaris sclerotia, their biochemical characteristics were assessed, and they were co-cultured with C. militaris to study their effects on C. militaris metabolite production and biomass. Furthermore, the effects of NH4, NO3, and peptone media on C. militaris were compared. The results showed that Rhodococcus, Phyllobacterium, Pseudomonas, Achromobacter, Ensifer, Stenotrophomonas, Sphingobacterium, Variovorax, and Acinetobacter were the core microbes. Although co-culture of C. militaris with the seven bacterial strains isolated from the sclerotia did not directly increase the cordycepin level, they all had NO3 reduction ability, and four had urea decomposition ability. Meanwhile, C. militaris in NH4 medium had an increased cordycepin level compared to C. militaris in the other two media. From this, we inferred that bacteria in the sclerotia can convert NO3 to NH4, and then cordycepin is produced using NH4, which was confirmed by RNA-seq and real-time fluorescence quantitative PCR. Thus, bacteria in the sclerotia may indirectly affect the C. militaris metabolite production by regulating nitrogen metabolism. In summary, there are stable core microbes in the C. militaris sclerotia, and they may directly and indirectly affect the growth and metabolite production of C. militaris.IMPORTANCEThe model Cordyceps species Cordyceps militaris is rich in therapeutic compounds. It has recently been demonstrated that symbiotic microbes in sclerotia affect Cordyceps’ growth, development, and secondary metabolite production. In this study, core microbes were identified based on C. militaris sclerotia samples obtained from the same site over 5 years. Additionally, bacterial strains isolated from C. militaris sclerotia were found to affect metabolite production and nitrogen utilization, based on functional tests. Moreover, based on the bacterial nitrogen metabolism capacity in the sclerotia and its influence on C. militaris metabolite production, we deduced that bacteria in the sclerotia can indirectly affect C. militaris metabolite production by regulating nitrogen metabolism. This is the first report on how bacteria in the sclerotia affect C. militaris metabolite production from the perspective of the nitrogen cycle. The results increase our understanding of microbial functions in C. militaris sclerotia.

ABSTRACT Aspergillus flavus conidia are widespread in air; they attach to food and feed crops and secrete aflatoxins, which results in serious contamination. Germination of A. flavus conidia is the most critical step in contamination of food by A. flavus. This study aims to gain an insight into A. flavus conidia through dormancy to germination to provide a theoretical basis for inhibition of A. flavus conidia germination. The morphological changes and regulation mechanism of A. flavus conidia germination at 0, 4, 8, and 12 hours were observed. Transcriptomic and metabolomic analyses showed that conidia became active from dormancy (0 hour) to the initial stage of germination (4 hours), cellular respiration and energy metabolism increased, and amino acids and lipids were synthesized rapidly. The number of differentially expressed genes and differential metabolites was highest at this stage. Besides, we found that conidia germination had selectivity for different carbon and nitrogen sources. Compared with monosaccharides, disaccharides, as the only carbon source, significantly promoted the germination of conidia. Moreover, MepA, one of genes in the ammonium transporter family was studied. The gene deletion mutant ΔMepA had a significant growth defect, and the expression of MeaA was significantly upregulated in ΔMepA compared with the wild-type, indicating that both MepA and MeaA played an important role in transporting ammonium ions.IMPORTANCEThis is the first study to use combined transcriptomic and metabolomics analyses to explore the biological changes during germination of Aspergillus flavus conidia. The biological process with the highest changes occurred in 0–4 hours at the initial stage of germination. Compared with polysaccharides, monosaccharides significantly increased the size of conidia, while significantly decreasing the germination rate of conidia. Both MeaA and MepA were involved in ammonia transport and metabolism during conidia germination.

The rhizospheric microorganisms of agricultural crops play a crucial role in plant growth and nutrient cycling. In this study, we isolated two Streptomyces strains, Streptomyces sp. LM32 and Streptomyces sp. LM65, from the rhizosphere of Vitis vinifera L. We then conducted genomic analysis by assembling, annotating, and inferring phylogenomic information from the whole genome sequences. Streptomyces sp. strain LM32 had a genome size of 8.1 Mb and a GC content of 72.14%, while Streptomyces sp. strain LM65 had a genome size of 7.3 Mb and a GC content of 71%. Through ANI results, as well as phylogenomic, pan-, and core-genome analysis, we found that strain LM32 was closely related to the species S. coelicoflavus, while strain LM65 was closely related to the species S. achromogenes subsp. achromogenes. We annotated the functional categories of genes encoded in both strains, which revealed genes involved in nitrogen and phosphorus metabolism. This suggests that these strains have the potential to enhance nutrient availability in the soil, promoting agricultural sustainability. Additionally, we identified gene clusters associated with nitrate and nitrite ammonification, nitrosative stress, allantoin utilization, ammonia assimilation, denitrifying reductase gene clusters, high-affinity phosphate transporter and control of PHO regulon, polyphosphate, and phosphate metabolism. These findings highlight the ecological roles of these strains in sustainable agriculture, particularly in grapevine and other agricultural crop systems.

Abstract Experiments were conducted to evaluate the role of exogenously applied jasmonic acid (JA; 0.1 and 0.5 µM) in alleviating the toxic effects of arsenic (As; 5 and 10 µM) stress in rice. Plants treated with As showed considerable decline in growth attributes like height, fresh and dry weight of plant. Arsenic stress reduced the content of δ-amino livulenic acid (δ-ALA), glutamate 1-semialdehyde (GSA), total chlorophylls and carotenoids, with more reduction evident at higher (10 µM) As concentrations, however exogenously supplied JA alleviated the decline to considerable extent. Arsenic stress mediated decline in photosynthetic gas exchange parameters, Fv/Fm (PSII activity) and Rubisco activity was alleviated by the exogenous treatment of JA. Arsenic stress caused oxidative damage which was evident as increased lipid peroxidation, lipoxygenase activity and hydrogen peroxide concentrations however, JA treatment declined these parameters. Treatment of JA improved the activity of nitrate reductase and glutamate synthase under unstressed conditions and also alleviated the decline triggered by As stress. Activity of antioxidant enzymes assayed increased due to As stress, and the supplementation of JA caused further increase in their activities. Moreover, the content of proline, free amino acids and total phenols increased significantly due to JA application under stressed and unstressed conditions. Treatment of JA increased the content of nitrogen and potassium while as reduced As accumulation significantly.

【Objective】High-quality flue-cured tobacco varieties are important guarantees for showcasing the quality characteristics of tobacco producing areas. Exploring the differences in nitrogen metabolism and carotenoid metabolism characteristics between high-quality flue-cured tobacco varieties and conventional main varieties during the field growth period in Jiangxi tobacco region, and analyzing the common physiological metabolism characteristics of high-quality flue-cured tobacco varieties can provide theoretical and technical support for in-depth exploration of variety characteristics and optimization of variety matching cultivation techniques.【Method】The Minyan 312, Minyan 12 with good sensory quality and the conventional variety of Yunyan 87 (CK) were used as materials. The changes in the contents of related substances and gene expression levels in middle leaves of different varieties during key growth periods were analyzed.【Result】In terms of carotenoid metabolism, the contents of lutein and β-carotene in Minyan 312 and Minyan 12 were 3.27-6.14 mg/g and 0.67-1.59 mg/g respectively during the budding stage to foot leaf mature period, which were significantly lower than those in Yunyan 87. However, the contents of lutein in the middle leaf maturity of the two varieties were 2.31 mg/g and 2.58 mg/g, respectively, which were significantly higher than those in Yunyan 87 (0.17 mg/g and 0.44 mg/g). The peak expression of carotenoid synthesis-related genes mainly occurred in the vigorous growing period to budding stage. The relative expression of PSY and other carotenoid synthesis-related genes in Minyan 312 and Minyan 12 were higher than those in Yunyan 87 before the maturity of waist leaf, with a maximum difference of 2.53. In terms of nitrogen metabolism, the total nitrogen content (1.58%-3.36%) and protein content (7.14%-14.81%) in Minyan 312 and Minyan 12 were significantly lower than those in Yunyan 87 during the budding stage to foot leaf mature period. The expression levels of NR, NIR1 and GS1-5 genes in Minyan 312 and Minyan 12 were higher than those in Yunyan 87 during the vigorous growing period to foot leaf mature period, while the expression levels of GS1-5 genes were lower during the waist leaf mature period. In terms of correlation analysis, there was a significant or extremely significant positive correlation between NIRI, GS1-5, PSY, CRTISO and other genes, lutein and β-carotene.【Conclusion】There was a significant correlation between nitrogen metabolism and carotenoid metabolism. Compared with Yunyan 87, the middle leaves of high-quality flue-cured tobaccos Minyan 312 and Minyan 12 exhibited stronger activity of carotenoid synthesis related genes before maturity and higher lutein content during maturity in terms of carotenoid metabolism. In addition, the Minyan 312 and Minyan 12 had higher nitrogen absorption and assimilation ability before maturity, and had lower nitrogen utilization ability at maturity in terms of nitrogen metabolism.

The development of drought tolerant genotypes for peanuts has now become a priority due to the growing number of drought-prone areas. The effects of drought stress on nitrogen metabolism was studied in leaves of two groundnut cultivars with differential sensitivity to drought stress, K-134 (drought tolerant) and JL-24 (drought sensitive) subjected to different regimes of water stress conditions for a duration of 12 days. The total protein content in leaves of both cultivars declined with progressive accumulation of free amino acid levels. Concurrently, the protease activity in the tissues was also increased. Ammonia content was increased in both cultivars and comparatively higher ammonia levels were recorded for cv. JL-24. A gradual increase in the activities of key enzymes involved in nitrogen metabolism such as glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate dehydrogenase (NADH-GDH and NADPH-GDH), aspartate aminotransferase (AAT) and alanine aminotransferase (ALAT) was observed in both cultivars subjected to water stress. The increase in enzyme activities was more pronounced in the drought tolerant than in the drought sensitive cultivar. Contrarily, the activities of nitrate reductase (NR) and nitrite reductase (NiR) were decreased in the stressed plants. The extent of decrease was more in cv. K134 than cv. JL-24. The results indicate that drought tolerance of cultivar K-134 may be attributed at least in part to the ability to shift the metabolic rate leading to a greater accumulation of amino acids coupled with lower levels of ammonia and largely by reassimilation as evidenced by relatively greater activities of GS and GOGAT in the tissue. The physiological importance of enzyme alterations under water stress was investigated in relation to plant metabolism.

The use of bio-nanotechnology in agriculture—such as the biological applications of metal oxide nanoparticles (NPs)—greatly improves crop yield and quality under different abiotic stress factors including soil metal contamination. Here, we explore the effectiveness of zinc oxide (ZnO)-NPs (0, 50 mg/L) foliar spraying to ameliorate the detrimental effects of cadmium (Cd) on the water transport and nitrogen metabolism in tomato (Solanum lycopersicum Mill. cv. Chibli F1) plants grown on a Cd-supplied (CdCl2; 0, 10, 40 μM) Hoagland nutrient solution. The results depicted that the individually studied factors (ZnO-NPs and Cd) had a significant impact on all the physiological parameters analyzed. Independently to the Cd concentration, ZnO-NPs-sprayed plants showed significantly higher dry weight (DW) in both leaves and roots compared to the non-sprayed ones, which was in consonance with higher and lower levels of Zn2+ and Cd2+ ions, respectively, in these organs. Interestingly, ZnO-NPs spraying improved water status in all Cd-treated plants as evidenced by the increase in root hydraulic conductance (L0), apoplastic water pathway percentage, and leaf and root relative water content (RWC), compared to the non-sprayed plants. This improved water balance was associated with a significant accumulation of osmoprotectant osmolytes, such as proline and soluble sugars in the plant organs, reducing electrolyte leakage (EL), and osmotic potential (ψπ). Also, ZnO-NPs spraying significantly improved NO3− and NH4+ assimilation in the leaf and root tissues of all Cd-treated plants, leading to a reduction in NH4+ toxicity. Our findings point out new insights into how ZnO-NPs affect water transport and nitrogen metabolism in Cd-stressed plants and support their use to improve crop resilience against Cd-contaminated soils. [ABSTRACT FROM AUTHOR]

Many contaminated soils contain several toxic elements (TEs) in elevated contents, and plant–TE interactions can differ from single TE contamination. Therefore, this study investigated the impact of combined contamination (As, Cd, Pb, Zn) on the physiological and metabolic processes of lettuce. After 45 days of exposure, TE excess in soil resulted in the inhibition of root and leaf biomass by 40 and 48%, respectively. Oxidative stress by TE accumulation was indicated by markers—malondialdehyde and 5-methylcytosine—and visible symptoms of toxicity (leaf chlorosis, root browning) and morpho-anatomical changes, which were related to the change in water regime (water potential decrease). An analysis of free amino acids (AAs) indicated that TEs disturbed N and C metabolism, especially in leaves, increasing the total content of free AAs and their families. Stress-induced senescence by TEs suggested changes in gas exchange parameters (increase in transpiration rate, stomatal conductance, and intercellular CO2 concentration), photosynthetic pigments (decrease in chlorophylls and carotenoids), a decrease in water use efficiency, and the maximum quantum yield of photosystem II. These results confirmed that the toxicity of combined contamination significantly affected the processes of lettuce by damaging the antioxidant system and expressing higher leaf sensitivity to TE multicontamination. [ABSTRACT FROM AUTHOR]

Background and Aims: Rhizosphere microorganisms play an important role in promoting plant growth and maintaining soil health. Bacillus altitudinis LZP02 (LZP02) is an efficient plant growth-promoting rhizobacterium that interacts closely with rice radicals. However, the mechanisms mediating the rhizosphere interactions of beneficial strains of microorganisms in native soil are mostly unclear. Methods: This study analysed the rhizosphere-enriched taxonomic and functional properties of the rhizosphere-associated microbiome and determined how they were affected by LZP02 using metagenome sequencing and ITS sequencing after the inoculation of LZP02 in soil. And microorganisms from the rice rhizosphere were identified and cultivated using high-throughput sequencing. Results: LZP02 stimulated some beneficial bacteria, such as Novosphingobium, Acidovorax, Sphingomonas, and Devosia, to the rhizosphere. The enrichment of functional attributes, nitrogen metabolism and bacterial chemotaxis demonstrated an increase in active microbe-microbe interactions in the rhizosphere. This study showed that LZP02 stimulated plant growth in three ways: (1) by increasing the relative abundance of most rhizosphere-enriched genus; (2) by increasing the relative abundance of the functional attributes involved in microbe-microbe interactions; and (3) by enriching functional components that are essential for plant fitness, such as nitrogen fixation and bacterial chemotaxis in the rhizosphere microbiome. Finally, inoculation of enriched single strains or synthetic consortia isolated from the radical-associated microbiome using high-throughput cultivation could improve plant growth. Conclusion: This study proposes a new mechanism by which LZP02 influences the nitrogen metabolism of rhizosphere microorganisms and bacterial chemotaxis for rice growth by reshaping the rhizosphere microbiome. [ABSTRACT FROM AUTHOR]

When treating municipal wastewater, nitrogen removal is often limited due to low C/N, which needs to be compensated for by additional carbon source injections. This study investigated the feasibility of using industrial-waste polyglycolic acid (PGA) as a carbon source for denitrification in an SBR to obtain an economical carbon source. The results revealed that an optimal denitrification performance in a methanol-fed activated sludge system was achieved with a PGA dosage of 1.2 mL/L, a pH of 7–8, and a dissolved-oxygen (DO) concentration of 3 ± 0.5 mg/L. Under these conditions, all quality parameters for effluent water met the required criteria [COD < 50 mg/L; TN < 15 mg/L; NH4+-N < 5(8) mg/L]. PGA enhanced the variety and richness of microbial communities, thereby markedly increasing the relative abundance of major phyla such as Proteobacteria and Bacteroidota and major genera such as Paracoccus and Dechloromonas. Furthermore, PGA upregulated the expression of nitrogen-metabolism-related genera, including amo, hao, nar, and nor, which improved the denitrification performance of the system. This study provides a reference for applying PGA as a carbon source for low-C/N-wastewater treatment and solid-waste utilization. [ABSTRACT FROM AUTHOR]