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1.
mSphere ; 9(3): e0077423, 2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38426801

RESUMO

Diabetic foot ulcers (DFUs) are the most common complications of diabetes resulting from hyperglycemia leading to ischemic hypoxic tissue and nerve damage. Staphylococcus aureus is the most frequently isolated bacteria from DFUs and causes severe necrotic infections leading to amputations with a poor 5-year survival rate. However, very little is known about the mechanisms by which S. aureus dominantly colonizes and causes severe disease in DFUs. Herein, we utilized a pressure wound model in diabetic TALLYHO/JngJ mice to reproduce ischemic hypoxic tissue damage seen in DFUs and demonstrated that anaerobic fermentative growth of S. aureus significantly increased the virulence and the severity of disease by activating two-component regulatory systems leading to expression of virulence factors. Our in vitro studies showed that supplementation of nitrate as a terminal electron acceptor promotes anaerobic respiration and suppresses the expression of S. aureus virulence factors through inactivation of two-component regulatory systems, suggesting potential therapeutic benefits by promoting anaerobic nitrate respiration. Our in vivo studies revealed that dietary supplementation of L-arginine (L-Arg) significantly attenuated the severity of disease caused by S. aureus in the pressure wound model by providing nitrate. Collectively, these findings highlight the importance of anaerobic fermentative growth in S. aureus pathogenesis and the potential of dietary L-Arg supplementation as a therapeutic to prevent severe S. aureus infection in DFUs.IMPORTANCES. aureus is the most common cause of infection in DFUs, often resulting in lower-extremity amputation with a distressingly poor 5-year survival rate. Treatment for S. aureus infections has largely remained unchanged for decades and involves tissue debridement with antibiotic therapy. With high levels of conservative treatment failure, recurrence of ulcers, and antibiotic resistance, a new approach is necessary to prevent lower-extremity amputations. Nutritional aspects of DFU treatment have largely been overlooked as there has been contradictory clinical trial evidence, but very few in vitro and in vivo modelings of nutritional treatment studies have been performed. Here we demonstrate that dietary supplementation of L-Arg in a diabetic mouse model significantly reduced duration and severity of disease caused by S. aureus. These findings suggest that L-Arg supplementation could be useful as a potential preventive measure against severe S. aureus infections in DFUs.


Assuntos
Diabetes Mellitus , Pé Diabético , Infecções Estafilocócicas , Animais , Camundongos , Staphylococcus aureus , Virulência , Nitratos , Infecções Estafilocócicas/complicações , Pé Diabético/tratamento farmacológico , Pé Diabético/complicações , Pé Diabético/microbiologia , Fatores de Virulência , Suplementos Nutricionais
2.
Chemosphere ; 353: 141551, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38430935

RESUMO

Groundwater pollution caused by the leakage of petroleum and various fuel oils is becoming a serious environmental problem. In this study, carbon-based materials including biochar and hydrochar were applied to investigate the effects of additives on the toluene removal in the extracted groundwater under microaerobic condition with the addition of nitrate. Biochar and hydrochar could adsorb toluene, and thus enhance the toluene removal in the system. The toluene removal efficiency was 8.2-8.9 mg/(g·h) at the beginning, and then decreased with time in the control and the hydrochar treatment, while it remained the stable values in the biochar treatment, owing to the fact that biochar could reduce the NO3--N loss by partial denitrification. Moreover, biochar could prompt the growth of toluene-degrading bacteria including Thauera, Rhodococcus, Ideonella and Denitratisoma, which had the capability of denitrification. However, hydrochar could stimulated the growth of denitrifiers without toluene-degrading capacity including Candidatus Competibacter and Ferrovibrio, which might play a key role in the partial denitrification of the system. The findings are helpful for developing remediation techniques of contaminated groundwater.


Assuntos
Carvão Vegetal , Água Subterrânea , Poluentes Químicos da Água , Nitratos/análise , Desnitrificação , Poluentes Químicos da Água/análise , Biodegradação Ambiental
3.
Chemosphere ; 353: 141595, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38438021

RESUMO

Increasing aquaculture cultivation produces large quantities of wastewater. If not handled properly, it can have negative impacts on the environment. Constructed wetlands (CWs) are one of the phytoremediation methods that can be applied to treat aquaculture effluent. This research was aimed at determining the performance of Cyperus rotundus in removing COD, BOD, TSS, turbidity, ammonia, nitrate, nitrite, and phosphate from the batch CW system. Treatment was carried out for 30 days with variations in the number of plants (10, 15, and 20) and variations in media height (10, 12, and 14 cm). The result showed that aquaculture effluent contains high levels of organic compounds and nutrients, and C. rotundus can grow and thrive in 100% of aquaculture effluent. Besides that, the use of C. rotundus in CWs with the effect of numbers of plants and media height showed performance of COD, BOD, TSS, turbidity, ammonia, nitrate, nitrite, and phosphate with 70, 79, 90, 96, 64, 82, 92, and 48% of removal efficacy, respectively. There was no negative impact observed on C. rotundus growth after exposure to aquaculture effluent, as indicated by the increase in wet weight, dry weight, and growth rate when compared to the control. Thus, adding aquaculture effluent to CWs planted with C. rotundus supports the growth and development of plants while also performing phytoremediation.


Assuntos
Cyperus , Eliminação de Resíduos Líquidos/métodos , Áreas Alagadas , Nitratos , Nitritos , Amônia , Biodegradação Ambiental , Plantas , Fosfatos , Aquicultura
4.
Environ Sci Technol ; 58(12): 5442-5452, 2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38478878

RESUMO

New particle formation and growth greatly influence air quality and the global climate. Recent CERN Cosmics Leaving OUtdoor Droplets (CLOUD) chamber experiments proposed that in cold urban atmospheres with highly supersaturated HNO3 and NH3, newly formed sub-10 nm nanoparticles can grow rapidly (up to 1000 nm h-1). Here, we present direct observational evidence that in winter Beijing with persistent highly supersaturated HNO3 and NH3, nitrate contributed less than ∼14% of the 8-40 nm nanoparticle composition, and overall growth rates were only ∼0.8-5 nm h-1. To explain the observed growth rates and particulate nitrate fraction, the effective mass accommodation coefficient of HNO3 (αHNO3) on the nanoparticles in urban Beijing needs to be 2-4 orders of magnitude lower than those in the CLOUD chamber. We propose that the inefficient uptake of HNO3 on nanoparticles is mainly due to the much higher particulate organic fraction and lower relative humidity in urban Beijing. To quantitatively reproduce the observed growth, we show that an inhomogeneous "inorganic core-organic shell" nanoparticle morphology might exist for nanoparticles in Beijing. This study emphasized that growth for nanoparticles down to sub-10 nm was largely influenced by their composition, which was previously ignored and should be considered in future studies on nanoparticle growth.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Material Particulado/análise , Nitratos , Monitoramento Ambiental , Poluição do Ar/análise , Compostos Orgânicos , Tamanho da Partícula
5.
Environ Int ; 185: 108546, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38458116

RESUMO

Mangrove wetlands are hotspots of the global nitrogen (N) cycle and important sinks of microplastics (MPs) due to their ecotone location between terrestrial and marine ecosystems. However, the effects of MPs on N cycle processes in mangrove ecosystems are still poorly understood. Thus, the present study assessed the impacts by adding MPs to mangrove sediments in a microcosm incubation experiment. The results showed that MPs increased dissolved organic carbon and nitrate but reduced ammonium contents in the sediments. MPs increased C:N stoichiometric and N:C-acquiring enzymatic ratios, indicating an intensified N limitation in mangrove sediments following exposure of MPs. MPs decreased microbial community diversity and shifted sediment microbial communities from r- to K-strategists, consistent with the intensified N limitation. In response, dissimilatory nitrate reduction to ammonium (DNRA) rates increased while nitrous oxide (N2O) production reduced suggesting more efficient N utilization in MPs treatments. The MPs with heteroatoms such as PLA- and PVC-MPs, increased DNRA rates by 67.5-78.7%, exhibiting a stronger impact than PE-MPs. The variation partitioning analysis revealed that the variances of DNRA rates and N2O production could be attributed to synergistic effects of physicochemical properties, nutrient limitation, and microbial community in mangrove sediments. Overall, this study provides pertinent insights into the impacts of MPs as a new carbon source on nutrient limitation and N turnover in mangrove ecosystems.


Assuntos
Compostos de Amônio , Ecossistema , Nitratos/análise , Microplásticos , Plásticos , Nitrogênio/análise , Compostos Orgânicos , Sedimentos Geológicos/química
6.
BMC Public Health ; 24(1): 707, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38443853

RESUMO

BACKGROUND: Ambient air pollutants have been suggested to affect pubertal development. Nevertheless, current studies indicate inconsistent effects of these pollutants, causing precocious or delayed puberty onset. This study aimed to explore the associations between long-term exposure to particulate matter with aerodynamic diameters ≤ 2.5 µm (PM2.5) along with its components and menarche timing among Chinese girls. METHOD: Self-reported age at menarche was collected among 855 girls from China Health and Nutrition Survey 2004 to 2015. The pre-menarche annual average concentrations of PM2.5 and its components were calculated on the basis of a long-term (2000-2014) high-resolution PM2.5 components dataset. Generalized linear models (GLM) and logistic regression models were used to analyze the associations of exposure to a single pollutant (PM2.5, sulfate, nitrate, ammonium, black carbon and organic matter) with age at menarche and early menarche (< 12 years), respectively. Weighted quantile sum methods were applied to examine the impacts of joint exposure on menarche timing. RESULTS: In the adjusted GLM, per 1 µg/m3 increase of annual average concentrations of nitrate and ammonium decreased age at menarche by 0.098 years and 0.127 years, respectively (all P < 0.05). Every 1 µg/m3 increase of annual average concentrations of PM2.5 (OR: 1.04, 95% CI: 1.00-1.08), sulfate (OR: 1.23, 95% CI: 1.01-1.50), nitrate (OR: 1.23, 95% CI: 1.06-1.43) and ammonium (OR: 1.32, 95% CI: 1.06-1.66) were significantly positively associated with early menarche. Higher level of joint exposure to PM2.5 and its components was associated with 11% higher odds of early menarche (P = 0.04). Additionally, the estimated weight of sulfate was the largest among the mixed pollutants. CONCLUSIONS: Long-term exposure to PM2.5 and its components could increase the risk of early menarche among Chinese girls. Moreover, sulfate might be the most critical components responsible for this relationship. Our study provides foundation for targeted prevention of PM2.5 components.


Assuntos
Compostos de Amônio , Poluentes Ambientais , Feminino , Humanos , Adolescente , Menarca , Nitratos , China , Material Particulado/efeitos adversos , Sulfatos
7.
Nat Commun ; 15(1): 1911, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38429292

RESUMO

When the supply of inorganic carbon is limiting, photosynthetic cyanobacteria excrete nitrite, a toxic intermediate in the ammonia assimilation pathway from nitrate. It has been hypothesized that the excreted nitrite represents excess nitrogen that cannot be further assimilated due to the missing carbon, but the underlying molecular mechanisms are unclear. Here, we identified a protein that interacts with nitrite reductase, regulates nitrogen metabolism and promotes nitrite excretion. The protein, which we named NirP1, is encoded by an unannotated gene that is upregulated under low carbon conditions and controlled by transcription factor NtcA, a central regulator of nitrogen homeostasis. Ectopic overexpression of nirP1 in Synechocystis sp. PCC 6803 resulted in a chlorotic phenotype, delayed growth, severe changes in amino acid pools, and nitrite excretion. Coimmunoprecipitation experiments indicated that NirP1 interacts with nitrite reductase, a central enzyme in the assimilation of ammonia from nitrate/nitrite. Our results reveal that NirP1 is widely conserved in cyanobacteria and plays a crucial role in the coordination of C/N primary metabolism by targeting nitrite reductase.


Assuntos
Nitritos , Synechocystis , Nitritos/metabolismo , Nitratos/metabolismo , Nitrito Redutases/genética , Nitrito Redutases/metabolismo , Amônia/metabolismo , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica , Synechocystis/genética , Synechocystis/metabolismo , Nitrogênio/metabolismo , Carbono/metabolismo , Nitrato Redutase/genética , Nitrato Redutase/metabolismo
8.
Front Immunol ; 15: 1318737, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38495893

RESUMO

Background: Perchlorates, nitrates, and thiocyanates are prevalent environmental chemicals. Their potential association with arthritis remains unexplored. This study aimed to investigate the link between perchlorate, nitrate, and thiocyanate exposure and arthritis, as well as the potential role of inflammation in this context. Methods: Utilizing the National Health and Nutrition Examination Survey (NHANES) data spanning from 2005 to 2016, the study enrolled 6597 participants aged 20-59 (young and middle-aged), of which 1045 had arthritis. Employing multivariate logistic regression modeling, multiple linear regression models, restricted cubic spline analysis, Bayesian kernel machine regression (BKMR) modeling, and mediation analysis, we assessed these relationships. Results: There was a significant positive association between elevated urinary thiocyanate levels and arthritis risk [1.19 (1.11, 1.28)]. This association held true across subgroups of osteoarthritis (OA) [1.24 (1.10, 1.40)] and rheumatoid arthritis (RA) [1.33 (1.15, 1.55)]. Thiocyanate levels displayed a dose-dependent relationship with arthritis risk, showing a linear trend (nonlinear P > 0.05). Conversely, perchlorate and nitrate did not exhibit associations with arthritis risk. BKMR outcomes highlighted a positive correlation between a mixture of perchlorate, nitrate, and thiocyanate and arthritis risk, with thiocyanate being the predominant predictors. Moreover, BKMR and generalized linear model analyses unveiled no significant synergistic effect of urinary perchlorate, nitrate, and thiocyanate on arthritis risk. Furthermore, thiocyanate exposure has been linked to elevated levels of inflammatory indicators (white blood cell, neutrophils, lymphocytes, and systemic immune-inflammatory index (SII)). Conclusion: Heightened thiocyanate exposure may be linked to elevated arthritis risk, either single or in combined effects. Additionally, thiocyanate exposure is associated with heightened inflammation levels.


Assuntos
Artrite , Nitratos , Adulto , Pessoa de Meia-Idade , Humanos , Nitratos/efeitos adversos , Nitratos/urina , Tiocianatos/urina , Percloratos/efeitos adversos , Percloratos/urina , Inquéritos Nutricionais , Teorema de Bayes , Inflamação/epidemiologia , Artrite/epidemiologia
9.
Proc Natl Acad Sci U S A ; 121(11): e2318320121, 2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38457518

RESUMO

Coordinated carbon and nitrogen metabolism is crucial for bacteria living in the fluctuating environments. Intracellular carbon and nitrogen homeostasis is maintained by a sophisticated network, in which the widespread signaling protein PII acts as a major regulatory hub. In cyanobacteria, PII was proposed to regulate the nitrate uptake by an ABC (ATP-binding cassette)-type nitrate transporter NrtABCD, in which the nucleotide-binding domain of NrtC is fused with a C-terminal regulatory domain (CRD). Here, we solved three cryoelectron microscopy structures of NrtBCD, bound to nitrate, ATP, and PII, respectively. Structural and biochemical analyses enable us to identify the key residues that form a hydrophobic and a hydrophilic cavity along the substrate translocation channel. The core structure of PII, but not the canonical T-loop, binds to NrtC and stabilizes the CRD, making it visible in the complex structure, narrows the substrate translocation channel in NrtB, and ultimately locks NrtBCD at an inhibited inward-facing conformation. Based on these results and previous reports, we propose a putative transport cycle driven by NrtABCD, which is allosterically inhibited by PII in response to the cellular level of 2-oxoglutarate. Our findings provide a distinct regulatory mechanism of ABC transporter via asymmetrically binding to a signaling protein.


Assuntos
Cianobactérias , Transportadores de Nitrato , Nitratos/metabolismo , Proteínas de Bactérias/metabolismo , Regulação Alostérica , Microscopia Crioeletrônica , Cianobactérias/metabolismo , Trifosfato de Adenosina/metabolismo , Nitrogênio/metabolismo , Carbono/metabolismo , Proteínas PII Reguladoras de Nitrogênio/genética , Proteínas PII Reguladoras de Nitrogênio/metabolismo
10.
Environ Geochem Health ; 46(4): 131, 2024 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-38483704

RESUMO

Potato is one of the essential food products whose health quality is greatly influenced by soil contamination and properties. In the current study, we have investigated the physicochemical characteristics of agricultural areas and the accumulation of nitrite/nitrate and metals in potato products in Hamedan, Iran. After determining the physicochemical characteristics of soil samples from four agricultural regions of Hamedan, 48 potato samples were collected from these regions. The heavy metals and nitrate/nitrite content were determined by ICP-OES and calorimetric methods, respectively. A negative correlation was observed between soil pH changes with nitrite/nitrate content and the accumulation of some heavy elements in potatoes. Furthermore, a positive correlation was found between soil phosphorus content and lead accumulation in potato. In present study, the amounts of lead, nitrate, and nitrite in 83.3%, 56%, and 12% of the collected samples were higher than the permissible limit reported by the World Health Organization (WHO), respectively. The EDI range for nitrate and nitrite was determined to be 130-260 and 1.4-2.7 µg/kg/day, respectively, which is much lower than the RfD set by the US Environmental Protection Agency (USEPA) for nitrite and nitrate. Among metal pollutants, the toxic risk caused by lead in potato consumers was higher than the threshold limit. In conclusion, our findings showed that the physicochemical characteristics of the soil could effectively increase the availability of metal pollutants and nitrite/nitrate to the potato product and significantly reduce its health quality. Therefore, monitoring these pollutants in the soil-potato system, preventing the entry of industrial wastewater, and managing the use of agricultural fertilizers can effectively improve the health of this product for consumers.


Assuntos
Poluentes Ambientais , Metais Pesados , Poluentes do Solo , Solanum tuberosum , Solo , Nitratos , Nitritos , Irã (Geográfico) , Poluentes do Solo/toxicidade , Poluentes do Solo/análise , Metais Pesados/toxicidade , Metais Pesados/análise , Medição de Risco , Monitoramento Ambiental
11.
Bioresour Technol ; 398: 130522, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38437965

RESUMO

The enhancement of nitrate reduction in microbial fuel cells (MFCs) by acclimating biocathode potential was studied. An MFC system was started up, and measured by cyclic voltammetry to determine a suitable potential region for acclimating biocathode. The experimental results revealed that potential acclimation could efficiently improve denitrification performance by relieving the phenomenon of nitrite accumulation, and optimum performance was obtained at -0.4 V with a total nitrogen removal efficiency of 87.4 %. Subsequently, the characteristics of electron transfer behaviors were measured, suggesting that a positive correlation between nitrate reduction and the contribution of direct electron transfer emerged. Furthermore, a denitrification mechanism was proposed. The results indicated that potential acclimation was conducive to enhancing denitrifying enzyme activity and that the electron transport system activity could be increased by 5.8 times. This study provides insight into the electron transfer characteristics and denitrification mechanisms in MFCs for nitrate reduction at specific acclimatization potentials.


Assuntos
Fontes de Energia Bioelétrica , Microbiota , Nitratos , Nitritos , Aclimatação , Nitrogênio , Desnitrificação , Eletrodos , Reatores Biológicos
12.
Sci Total Environ ; 922: 171328, 2024 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-38428600

RESUMO

The co-contamination of antibiotics and nitrogen has attracted widespread concerns due to its potential harm to ecological safety and human health. Sulfur-driven autotrophic denitrification (SAD) with low sludge production rate was adopted to treat antibiotics laden-organic deficient wastewater. Herein, a lab-scale sequencing batch reactor (SBR) was established to explore the simultaneous removal of nitrate and antibiotics, i.e. Norfloxacin (NOR), as well as microbial response mechanism of SAD sludge system towards NOR exposure. About 80.78 % of NOR was removed by SAD sludge when the influent NOR level was 0.5 mg/L, in which biodegradation was dominant removal route. The nitrate removal efficiency decreased slightly from 98.37 ± 0.58 % to 96.58 ± 1.03 % in the presence of NOR. Thiobacillus and Sulfurimonas were the most abundant sulfur-oxidizing bacteria (SOB) in SAD system, but Thiobacillus was more sensitive to NOR. The up-regulated genes related to Xenobiotics biodegradation and metabolism and CYP450 indicated the occurrence of NOR biotransformation in SAD system. The resistance of SAD sludge to the exposure of NOR was mainly ascribed to antibiotic efflux. And the effect of antibiotic inactivation was enhanced after long-term fed with NOR. The NOR exposure resulted in the increased level of antibiotics resistance genes (ARGs) and mobile genetic elements (MGEs). Besides, the enhanced ARG-MGE co-existence patterns further reveals the higher horizontal mobility potential of ARGs under NOR exposure pressures. The most enriched sulfur oxidizing bacterium Thiobacillus was a potential host for most of ARGs. This study provides a new insight for the treatment of NOR-laden wastewater with low C/N ratio based on the sulfur-mediated biological process.


Assuntos
Antibacterianos , Águas Residuárias , Humanos , Antibacterianos/farmacologia , Antibacterianos/metabolismo , Esgotos/microbiologia , Norfloxacino , Nitratos/metabolismo , Desnitrificação , Bactérias/genética , Bactérias/metabolismo , Enxofre/metabolismo , Reatores Biológicos/microbiologia , Nitrogênio/metabolismo
13.
Sci Rep ; 14(1): 6533, 2024 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-38503773

RESUMO

Nitrogen (N) and phosphorus (P) are vital for crop growth. However, most agricultural systems have limited inherent ability to supply N and P to crops. Biochars (BCs) are strongly advocated in agrosystems and are known to improve the availability of N and P in crops through different chemical transformations. Herein, a soil-biochar incubation experiment was carried out to investigate the transformations of N and P in two different textured soils, namely clay loam and loamy sand, on mixing with rice straw biochar (RSB) and acacia wood biochar (ACB) at each level (0, 0.5, and 1.0% w/w). Ammonium N (NH4-N) decreased continuously with the increasing incubation period. The ammonium N content disappeared rapidly in both the soils incubated with biochars compared to the unamended soil. RSB increased the nitrate N (NO3-N) content significantly compared to ACB for the entire study period in both texturally divergent soils. The nitrate N content increased with the enhanced biochar addition rate in clay loam soil until 15 days after incubation; however, it was reduced for the biochar addition rate of 1% compared to 0.5% at 30 and 60 days after incubation in loamy sand soil. With ACB, the net increase in nitrate N content with the biochar addition rate of 1% remained higher than the 0.5% rate for 60 days in clay loam and 30 days in loamy sand soil. The phosphorus content remained consistently higher in both the soils amended with two types of biochars till the completion of the experiment.


Assuntos
Compostos de Amônio , Poluentes do Solo , Solo/química , Fósforo , Areia , Argila , Nitratos , Nitrogênio , Carvão Vegetal/química , Poluentes do Solo/análise
14.
Nat Commun ; 15(1): 2473, 2024 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-38503798

RESUMO

Hadal trenches are extreme environments situated over 6000 m below sea surface, where enormous hydrostatic pressure affects the biochemical cycling of elements. Recent studies have indicated that hadal trenches may represent a previously overlooked source of fixed nitrogen loss; however, the mechanisms and role of hydrostatic pressure in this process are still being debated. To this end, we investigate the effects of hydrostatic pressure (0.1 to 115 MPa) on the chemical profile, microbial community structure and functions of surface sediments from the Mariana Trench using a Deep Ocean Experimental Simulator supplied with nitrate and oxygen. We observe enhanced denitrification activity at high hydrostatic pressure under oxic conditions, while the anaerobic ammonium oxidation - a previously recognized dominant nitrogen loss pathway - is not detected. Additionally, we further confirm the simultaneous occurrence of nitrate reduction and aerobic respiration using a metatranscriptomic dataset from in situ RNA-fixed sediments in the Mariana Trench. Taken together, our findings demonstrate that hydrostatic pressure can influence microbial contributions to nitrogen cycling and that the hadal trenches are a potential nitrogen loss hotspot. Knowledge of the influence of hydrostatic pressure on anaerobic processes in oxygenated surface sediments can greatly broaden our understanding of element cycling in hadal trenches.


Assuntos
Microbiota , Nitratos , Pressão Hidrostática , Nitrogênio
15.
PeerJ ; 12: e16733, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38515457

RESUMO

Background: Biochar amendments enhance crop productivity and improve agricultural quality. To date, studies on the correlation between different amounts of biochar in pakchoi (Brassica campestris L.) quality and rhizosphere soil microorganisms are limited, especially in weakly alkaline soils. The experiment was set up to explore the effect of different concentrations of biochar on vegetable quality and the correlation between the index of quality and soil bacterial community structure changes. Methods: The soil was treated in the following ways via pot culture: the blank control (CK) without biochar added and with biochar at different concentrations of 1% (T1), 3% (T2), 5% (T3), and 7% (T4). Here, we investigatedthe synergistic effect of biochar on the growth and quality of pakchoi, soil enzymatic activities, and soil nutrients. Microbial communities from pakchoi rhizosphere soil were analyzed by Illumina MiSeq. Results: The results revealed that adding 3% biochar significantly increased plant height, root length, and dry weight of pakchoi and increased the contents of soluble sugars, soluble proteins, Vitamin C (VC), cellulose, and reduced nitrate content in pakchoi leaves. Meanwhile, soil enzyme activities and available nutrient content in rhizosphere soil increased. This study demonstrated that the the microbial community structure of bacteria in pakchoi rhizosphere soil was changed by applying more than 3% biochar. Among the relatively abundant dominant phyla, Gemmatimonadetes, Anaerolineae, Deltaproteobacteria and Verrucomicrobiae were reduced, and Alphaproteobacteria, Gammaproteobacteria, Bacteroidia, and Acidimicrobiia relative abundance increased. Furthermore, adding 3% biochar reduced the relative abundance of Gemmatimonas and increased the relative abundances of Ilumatobacter, Luteolibacter, Lysobacter, Arthrobacter, and Mesorhizobium. The nitrate content was positively correlated with the abundance of Gemmatimonadetes, and the nitrate content was significantly negatively correlated with the relative abundance of Ilumatobacter. Carbohydrate transport and metabolism in the rhizosphere soil of pakchoi decreased, and lipid transport and metabolism increased after biochar application. Conclusion: Overall, our results indicated that applying biochar improved soil physicochemical states and plant nutrient absorption, and affected the abundance of dominant bacterial groups (e.g., Gemmatimonadetes and Ilumatobacter), these were the main factors to increase pakchoi growth and promote quality of pakchoi. Therefore, considering the growth, quality of pakchoi, and soil environment, the effect of using 3% biochar is better.


Assuntos
Carvão Vegetal , Microbiota , Solo , Solo/química , Rizosfera , Nitratos , Microbiologia do Solo , Bactérias , Plantas
16.
J Environ Manage ; 355: 120468, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38430883

RESUMO

Soil depth plays a crucial role in shaping the interactions between soil microbes and nutrient availability. However, there is limited understanding of how bacterial, fungal, and protistan communities respond to different soil depths, particularly in the unique geological context and soil properties of karst regions. Organic matter, total nitrogen, and phosphorus, ammonium, nitrate, and plant root biomass, as well as bacterial and fungal abundances, bacterial and protistan diversity were higher in the 0-20 cm soil layer than those in the 20-40 cm and soil-rock mixing layers. In contrast, soil pH was higher in the 20-40 cm and soil-rock mixing layers than that in the 0-20 cm soil layer. The soil exchange of calcium, nitrate, and root biomass were identified as the primary factors regulating microbial assemblages across the depth transect. Moreover, co-occurrence network analysis revealed a greater degree of connectivity between protistan taxa and fungal taxa in the 0-20 cm soil layer than those in the 20-40 cm and soil-rock mixing layers. In contrast, the number of association links between protist-bacteria and bacteria-bacteria was higher in the soil-rock mixing layers compared to the 0-20 cm soil layer. Actinobacteria, Ascomycota, and unclassified protistan taxa were identified as keystones, displaying the highest number of connections with other microbial taxa. Collectively, these results suggested that the increased plant root biomass, coupled with sufficient available nutrient inputs in the upper 0-20 cm soil layer, facilitates strong interactions among fungal and protistan taxa, which play crucial roles in the topsoil. However, as nutrients become less available with increasing depth, competition among bacterial taxa and the predation between bacterial and protistan taxa intensify. Therefore, these findings indicate the interactions among keystone taxa at different soil depths has the potential to generate ecological implications during vegetation restoration in fragile ecosystems.


Assuntos
Ecossistema , Solo , Biomassa , Solo/química , Fungos , Nitratos , Bactérias , Microbiologia do Solo
17.
J Plant Physiol ; 295: 154205, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38437759

RESUMO

Ammonium (NH4+) concentrations in rice fields show heterogeneous spatial distribution under the combined influences of nitrogen fertilizer application and modern agronomic practices. However, the characteristics and mechanisms of rice roots in response to heterogeneous NH4+ supply are not well understood. Here, we found a systemic response of rice roots to heterogeneous and high (10 mM) NH4+ supply using a split-root experiment, and show root growth on the NH4+-free (NO3-) side was also inhibited by localized high-NH4+ supply. Moreover, OsEIL1 (encoding a core transcription factor in the ethylene signaling pathway) was found to be involved in the response of rice roots to heterogeneous NH4+. OsEIL1 mutation significantly increased the inhibitory effect of localized high-NH4+ on root growth of the NO3- side, as well as significantly increased NH4+ efflux there. Furthermore, our results indicate that the mitigating effect of OsEIL1 on NH4+ efflux is related to the regulated expression of OsVTC1-3 (encoding a GDP-mannose pyrophosphorylase). These findings provide insight into the mechanisms by which OsEIL1 responds to heterogeneous high NH4+ and contribute to our understanding of rice adaptation to heterogeneous NH4+ supply.


Assuntos
Compostos de Amônio , Oryza , Compostos de Amônio/metabolismo , Oryza/metabolismo , Fatores de Transcrição/metabolismo , Nitrogênio/metabolismo , Raízes de Plantas/metabolismo , Nitratos/metabolismo
18.
J Environ Manage ; 355: 120547, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38452621

RESUMO

The synergistic partial-denitrification, anammox, and fermentation (SPDAF) process presents a promising solution to treat domestic and nitrate wastewaters. However, its capability to handle fluctuating C/N ratios (the ratios of COD to total inorganic nitrogen) in practical applications remains uncertain. In this study, the SPDAF process was operated for 236 days with C/N ratios of 0.7-3.5, and a high and stable efficiency of nitrogen removal (84.9 ± 7.8%) was achieved. The denitrification and anammox contributions were 6.1 ± 7.1% and 93.9 ± 7.1%, respectively. Batch tests highlighted the pivotal role of in situ fermentation at low biodegradable chemical oxygen demand (BCOD)/NO3- ratios. As the BCOD/NO3- ratios increased from 0 to 6, the NH4+ and NO3- removal rates increased, while the anammox contribution decreased from 100% to 80.1% but remained the primary pathway of nitrogen removal. The cooperation and balanced growth of denitrifying bacteria, anammox bacteria, and fermentation bacteria contributed to the system's robustness under fluctuating C/N ratios.


Assuntos
Nitratos , Águas Residuárias , Fermentação , Desnitrificação , Esgotos , Oxidação Anaeróbia da Amônia , Reatores Biológicos/microbiologia , Oxirredução , Nitrogênio/análise
19.
J Environ Manage ; 355: 120530, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38452622

RESUMO

Antibiotic contamination and excessive nitrate loads are generally concurrent in aquatic ecosystems. However, little is known about the effects of nitrate input on the biodegradation of antibiotics. In this study, the effects of nitrate input on microbial degradation of erythromycin, a typical macrolide antibiotic widely detected in lake sediments, were investigated. The results showed that the nitrate input significantly inhibited the erythromycin removal and such an inhibitory effect was strengthened with the increased input dosages. Nitrate input significantly increased sediment nitrite concentration, indicating enhanced denitrification under high nitrate pressure. Bacterial network module and keystone species analysis showed that nitrate input enriched the keystone species involved in denitrification (e.g., Simplicispira and Denitratisoma). In contrast, some potential erythromycin-degrading bacteria (e.g., Desulfatiglandales, Pseudomonadales, Nitrospira) were inhibited by nitrate input. The variations in dominant bacterial groups implied competition between denitrification and erythromycin degradation in response to nitrate input. Based on the partial least squares path modeling analysis, keystone species (total effect: 0.419) and bacterial module (total effect: 0.403) showed strong association with erythromycin removal percentage. This indicated that the inhibitory effect of nitrate input on erythromycin degradation was mainly explained by bacterial network modules and keystone species. These findings will help us to assess the bioremediation potential of antibiotic-contaminated sediments suffering from excessive nitrogen discharge concurrently.


Assuntos
Eritromicina , Nitratos , Nitratos/análise , Biodegradação Ambiental , Lagos/microbiologia , Ecossistema , Bactérias/metabolismo , Antibacterianos/farmacologia , Sedimentos Geológicos , Desnitrificação
20.
Am Nat ; 203(4): E128-E141, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38489776

RESUMO

AbstractSome plants, via their action on microorganisms, control soil nitrification (i.e., the transformation of ammonium into nitrate). We model how the covariation between plant control of nitrification and preference for ammonium versus nitrate impacts ecosystem properties such as productivity, nitrogen (N) losses, and overall resilience. We show that the control of nitrification can maximize productivity by minimizing total inorganic N losses. We initially predicted that plants with an ammonium preference should achieve the highest biomass when inhibiting nitrification, and conversely that plants preferring nitrate should achieve the highest biomass by stimulating nitrification. With a parametrization derived from the Lamto savanna (Ivory Coast), we find that productivity is maximal for plants that slightly prefer ammonium and inhibit nitrification. Such situations, however, lead to strong positive feedbacks that can cause abrupt shifts from a highly to a lowly productive ecosystem. The comparison with other parameter sets (Pawnee short-grass prairie [United States], intensively cultivated field, and a hypothetical parameter set in which ammonium is highly volatilized and nitrate inputs are high) shows that strategies yielding the highest biomass may be counterintuitive (i.e., preferring nitrate but inhibiting nitrification). We argue that the level of control yielding the highest productivity depends on ecosystem properties (quantity of N deposition, leaching rates, and baseline nitrification rates), not only preference. Finally, while contrasting N preferences offer, as expected, the possibility of coexistence through niche partitioning, we stress how control of nitrification can be framed as a niche construction process that adds an additional dimension to coexistence conditions.


Assuntos
Compostos de Amônio , Resiliência Psicológica , Nitrificação , Nitratos/análise , Ecossistema , Retroalimentação , Solo , Plantas , Nitrogênio
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