RESUMEN
Atmospheric nitrogen (N) deposition could affect the structure and function of terrestrial plants. Non-N2-fixing lichens are used to monitor atmospheric N deposition because they rely on the deposited inorganic N (i.e., ammonium and nitrate) as N sources. However, the uptake capacities of lichen on ammonium and nitrate remain unclear, which hinders the application of lichen N content to accurate bioindication of atmospheric N deposition levels. We investigated ammonium and nitrate uptake capacities of Cladonia rangiferina, which was treated with ammonium alone, nitrate alone, and ammonium and nitrate mixture solutions with different mixing ratios under light and dark conditions. The results showed that N uptake rates increased with ammonium and nitrate concentrations in solutions and generally followed the Michaelis-Menten saturation kinetics. Ammonium uptake of C. rangiferina showed higher values of affinity, and was more efficient than the nitrate uptake. Both rates and amounts of nitrate uptake decreased with increasing ratios of ammonium to nitrate in solutions, while ammonium uptake showed no substantial variations, indicating an inhibition of ammonium on nitrate uptake capability. The darkness significantly decreased the maximum uptake rate and efficiency of nitrate, but had much weaker effects on lichen ammonium uptake. These findings highlight the preference of lichen on ammonium as a key N uptake strategy. It is thus necessary to consider the main types of atmospheric inorganic N deposition when using lichens to monitor atmospheric N pollution levels and evaluate N deposition based on lichen ecophysiology.
Asunto(s)
Compuestos de Amonio , Líquenes , Nitratos , Nitrógeno , Nitratos/metabolismo , Nitratos/análisis , Nitrógeno/metabolismo , Líquenes/metabolismo , Compuestos de Amonio/metabolismo , Cinética , Monitoreo del Ambiente/métodos , Compuestos de Amonio Cuaternario/metabolismo , Contaminantes Atmosféricos/metabolismo , Contaminantes Atmosféricos/análisisRESUMEN
Polymesoda erosa is a mangrove clam known for its water filtration ability. This clam was investigated for its bioremediation potential and growth in synthetic wastewater during 40 days of incubation. Variation in the nutrient composition of water, biochemical composition of the clams, and metagenomic analysis of the microorganisms associated with clam tissue were carried out. Significant differences in the concentration of ammonia (p ≤ 0.01), nitrite (p ≤ 0.001), and nitrate (p ≤ 0.05) in the wastewater were observed between day 0 and day 40. A reduction of approximately 89% in ammonia concentration at the end of the experiment was recorded indicating nitrification activity. However, biochemical parameters showed negligible differences before and after the incubation experiment. Thus suggesting that the chemosynthetic-based nutrition aids in the survival of the clam as no organic matter was added to the medium. The substantial decline in levels of ammonia in the presence of clams as compared to its absence suggests the significant role of clams in improving the water quality. Furthermore, the metagenomic analysis of the gill tissue of P. erosa revealed ~ 50% of the microbial population to consist of nitrifiers. The study highlights the contribution by the nitrifers associated with the clams not only to its growth and resilience but also to bioremediation.
Asunto(s)
Amoníaco , Biodegradación Ambiental , Bivalvos , Nitrificación , Aguas Residuales , Animales , Bivalvos/metabolismo , Bivalvos/microbiología , Amoníaco/metabolismo , Aguas Residuales/microbiología , Contaminantes Químicos del Agua/metabolismo , Nitritos/metabolismo , Nitratos/metabolismo , Eliminación de Residuos Líquidos/métodosRESUMEN
Biofuel can be generated by different organisms using various substrates. The green alga Chlorococcum humicola OQ934050 exhibited the capability to photosynthesize carbonate carbon, maybe via the activity of carbonic anhydrase enzymes. The optimum treatment is C:N ratio of 1:1 (0.2 mmoles sodium carbonate and 0.2 mmoles sodium nitrate) as it induced the highest dry mass (more than 0.5 mg.mL-1). At this combination, biomass were about 0.2 mg/mL-1 carbohydrates, 0.085 mg/mL-1 proteins, and 0.16 mg/mL-1 oil of this dry weight. The C/N ratios of 1:1 or 10:1 induced up to 30% of the Chlorococcum humicola dry mass as oils. Growth and dry matter content were hindered at 50:1 C/N and oil content was reduced as a result. The fatty acid profile was strongly altered by the applied C.N ratios. The defatted leftovers of the grown alga, after oil extraction, were fermented by a newly isolated heterotrophic bacterium, identified as Bacillus coagulans OQ053202, to evolve hydrogen content as gas. The highest cumulative hydrogen production and reducing sugar (70 ml H2/g biomass and 0.128 mg/ml; respectively) were found at the C/N ratio of 10:1 with the highest hydrogen evolution efficiency (HEE) of 22.8 ml H2/ mg reducing sugar. The optimum treatment applied to the Chlorococcum humicola is C:N ratio of 1:1 for the highest dry mass, up to 30% dry mass as oils. Some fatty acids were induced while others disappeared, depending on the C/N ratios. The highest cumulative hydrogen production and reducing sugar were found at the C/N ratio of 10:1.
Asunto(s)
Bacillus , Biocombustibles , Biomasa , Carbonatos , Hidrógeno , Nitratos , Hidrógeno/metabolismo , Bacillus/metabolismo , Nitratos/metabolismo , Carbonatos/metabolismo , Fermentación , Chlorophyta/metabolismo , Chlorophyta/crecimiento & desarrollo , Fotosíntesis , Ácidos Grasos/metabolismoRESUMEN
Flagellar swimming hydrodynamics confers a recognized advantage for attachment on solid surfaces. Whether this motility further enables the following environmental cues was experimentally explored. Motile E. coli (OD ~ 0.1) in a 100 µm-thick channel were exposed to off-equilibrium gradients set by a chemorepellent Ni(NO3)2-source (250 mM). Single bacterial dynamics at the solid surface was analyzed by dark-field videomicroscopy at a fixed position. The number of bacteria indicated their congregation into a wave escaping from the repellent source. Besides the high velocity drift in the propagation direction within the wave, an unexpectedly high perpendicular component drift was also observed. Swimming hydrodynamics CW-bends the bacteria trajectories during their primo approach to the surface (< 2 µm), and a high enough tumbling frequency likely preserves a notable lateral drift. This comprehension substantiates a survival strategy tailored to toxic environments, which involves drifting along surfaces, promoting the inception of colonization at the most advantageous sites.
Asunto(s)
Escherichia coli , Hidrodinámica , Escherichia coli/fisiología , Propiedades de Superficie , Flagelos/fisiología , Flagelos/metabolismo , Movimiento , Níquel/química , Nitratos/metabolismo , Nitratos/químicaRESUMEN
Nitrate-dependent anaerobic methane oxidation (Nitrate-DAMO) is a novel and sustainable process that removes both nitrogen and methane. Previously, the metabolic pathway of Nitrate-DAMO has been intensively studied with some results. However, the production and consumption of nitrous oxide (N2O) in the Nitrate-DAMO system were widely disregarded. In this study, a Nitrate-DAMO system was used to investigate the effect of operational parameters (C/N ratio, pH, and temperature) on N2O accumulation, and the optimal operating conditions were determined (C/N = 3, pH = 6.5, and temperature = 20 °C). In this study, an enzyme kinetic model was used to fit the nitrate nitrogen degradation and the nitrous oxide production and elimination under different operating conditions. The thermodynamic model of N2O production and elimination in the system also has been constructed. Multiple linear regression analysis found that pH was the most important factor influencing N2O accumulation. The Metagenomics sequencing results showed that alkaline pH promoted the abundance of Nor genes and denitrifying bacteria, which were significantly and positively correlated with N2O emissions. And alkaline pH also promoted the production of Mdo genes related to the N2O-driven AOM reaction, indicating that part of the N2O was consumed by denitrifying bacteria and the other part was consumed by the N2O-driven AOM reaction. These findings reveal the mechanism of N2O production and consumption in DAMO systems and provide a theoretical basis for reducing N2O production and greenhouse gas emissions in actual operation.
Asunto(s)
Metano , Nitratos , Óxido Nitroso , Óxido Nitroso/metabolismo , Nitratos/metabolismo , Cinética , Metano/metabolismo , Oxidación-Reducción , Anaerobiosis , Nitrógeno/metabolismo , Desnitrificación , Bacterias/metabolismoRESUMEN
Detecting chemical signals is important for identifying food sources and avoiding harmful agents. Like many animals, C. elegans use olfaction to chemotax towards their main food source, bacteria. However, little is known about the bacterial compounds governing C. elegans attraction to bacteria and the physiological importance of these compounds to bacteria. Here, we address these questions by investigating the function of a small RNA, P11, in the pathogen, Pseudomonas aeruginosa, that was previously shown to mediate learned pathogen avoidance. We discovered that this RNA also affects the attraction of untrained C. elegans to P. aeruginosa and does so by controlling production of ammonia, a volatile odorant produced during nitrogen assimilation. We describe the complex regulation of P. aeruginosa nitrogen assimilation, which is mediated by a partner-switching mechanism involving environmental nitrates, sensor proteins, and P11. In addition to mediating C. elegans attraction, we demonstrate that nitrogen assimilation mutants perturb bacterial fitness and pathogenesis during C. elegans infection by P. aeruginosa. These studies define ammonia as a major mediator of trans-kingdom signaling, implicate nitrogen assimilation as important for both bacteria and host organisms, and highlight how a bacterial metabolic pathway can either benefit or harm a host in different contexts.
Asunto(s)
Amoníaco , Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Nitrógeno , Pseudomonas aeruginosa , Caenorhabditis elegans/microbiología , Caenorhabditis elegans/metabolismo , Pseudomonas aeruginosa/metabolismo , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/fisiología , Animales , Nitrógeno/metabolismo , Amoníaco/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Infecciones por Pseudomonas/microbiología , Infecciones por Pseudomonas/metabolismo , Nitratos/metabolismo , Transducción de Señal , Interacciones Huésped-Patógeno , QuimiotaxisRESUMEN
In sweet potato, rational nitrogen (N) assimilation and distribution are conducive to inhibiting vine overgrowth. Nitrate (NO3-) is the main N form absorbed by roots, and cultivar is an important factor affecting N utilization. Herein, a hydroponic experiment was conducted that included four NO3- concentrations of 0 (N0), 4 (N1), 8 (N2) and 16 (N3) mmol L-1 with two cultivars of Jishu26 (J26, N-sensitive) and Xushu32 (X32, N-tolerant). For J26, with increasing NO3- concentrations, the root length and root surface area significantly decreased. However, no significant differences were observed in these parameters for X32. Higher NO3- concentrations upregulated the expression levels of the genes that encode nitrate reductase (NR2), nitrite reductase (NiR2) and nitrate transporter (NRT1.1) in roots for both cultivars. The trends in the activities of NR and NiR were subject to regulation of NR2 and NiR2 transcription, respectively. For both cultivars, N2 increased the N accumulated in leaves, growth points and roots. For J26, N3 further increased the N accumulation in these organs. Under higher NO3- nutrition, compared with X32, J26 exhibited higher expression levels of the NiR2, NR2 and NRT1.1 genes, a higher influx NO3- rate in roots, and higher activities of NR and NiR in leaves and roots. Conclusively, the regulated effects of NO3- supplies on root growth and NO3- utilization were more significant for J26. Under high NO3- conditions, J26 exhibited higher capacities of NO3- absorption and distributed more N in leaves and in growth points, which may contribute to higher growth potential in shoots and more easily cause vine overgrowth.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Ipomoea batatas , Nitratos , Nitrógeno , Raíces de Plantas , Nitratos/metabolismo , Ipomoea batatas/metabolismo , Ipomoea batatas/genética , Ipomoea batatas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/genética , Nitrógeno/metabolismo , Nitrato-Reductasa/metabolismo , Nitrato-Reductasa/genética , Hojas de la Planta/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/genética , Transportadores de Nitrato , Hidroponía , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Nitrito Reductasas/metabolismo , Nitrito Reductasas/genética , Proteínas de Transporte de Anión/metabolismo , Proteínas de Transporte de Anión/genéticaRESUMEN
The lateral root (LR) is an essential component of the plant root system, performing important functions for nutrient and water uptake in plants and playing a pivotal role in cereal crop productivity. Nitrate (NO3-) is an essential nutrient for plants. In this study, wheat plants were grown in 1/2 strength Hoagland's solution containing 5 mM NO3- (check; CK), 0.1 mM NO3- (low NO3-; LN), or 0.1 mM NO3- plus 60 mg/L 2,3,5-triiodobenzoic acid (TIBA) (LNT). The results showed that LN increased the LR number significantly at 48 h after treatment compared with CK, while not increasing the root biomass, and LNT significantly decreased the LR number and root biomass. The transcriptomic analysis showed that LN induced the expression of genes related to root IAA synthesis and transport and cell wall remodeling, and it was suppressed in the LNT conditions. A physiological assay revealed that the LN conditions increased the activity of IAA biosynthesis-related enzymes, the concentrations of tryptophan and IAA, and the activity of cell wall remodeling enzymes in the roots, whereas the content of polysaccharides in the LRP cell wall was significantly decreased compared with the control. Fourier-transform infrared spectroscopy and atomic microscopy revealed that the content of cell wall polysaccharides decreased and the cell wall elasticity of LR primordia (LRP) increased under the LN conditions. The effects of LN on IAA synthesis and polar transport, cell wall remodeling, and LR development were abolished when TIBA was applied. Our findings indicate that NO3- starvation may improve auxin homeostasis and the biological properties of the LRP cell wall and thus promote LR initiation, while TIBA addition dampens the effects of LN on auxin signaling, gene expression, physiological processes, and the root architecture.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos , Nitratos , Raíces de Plantas , Transducción de Señal , Triticum , Triticum/metabolismo , Triticum/genética , Triticum/crecimiento & desarrollo , Ácidos Indolacéticos/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Raíces de Plantas/genética , Raíces de Plantas/efectos de los fármacos , Nitratos/metabolismo , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Pared Celular/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Organogénesis de las Plantas/genética , Perfilación de la Expresión GénicaRESUMEN
BACKGROUND: Random-pattern skin flaps are commonly used to repair skin tissue defects in surgical tissue reconstruction. However, flap necrosis in the distal area due to ischemia injury is still challenging for its applications in plastic surgery. The complications of diabetes will further increase the risk of infection and necrosis. METHODS: This study induced type 2 diabetes mellitus (T2DM) rats with a high-fat diet and STZ. The survival rate of the skin flap was observed by adding inorganic sodium nitrate to drinking water. Histology and immunohistochemistry were used to detect the damage to the skin flap. The nitrate content was measured by total nitric oxide and nitrate/nitrite parameter assay. Dihydroethidium and malondialdehyde (MDA) assays were used to value oxidative stress. Rat colon feces were collected for 16s rRNA gene sequence. RESULTS: Our studies showed that nitrate administration leads to anti-obesity and anti-diabetic effects. Nitrate directly increased the survival area of skin flaps in diabetic rats and mean blood vessel density by enhancing angiogenesis, inhibiting apoptosis, and reducing oxidative stress. The 16s rRNA sequence revealed that nitrate may regulate the homeostasis of the gut microbiota and re-store energy metabolism. CONCLUSION: Dietary nitrate has been shown to maintain the homeostasis of oxidative stress and gut microbiota to promote flap survival in rats with T2DM.
Asunto(s)
Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Microbioma Gastrointestinal , Homeostasis , Nitratos , Estrés Oxidativo , Colgajos Quirúrgicos , Animales , Estrés Oxidativo/efectos de los fármacos , Ratas , Nitratos/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patología , Microbioma Gastrointestinal/efectos de los fármacos , Diabetes Mellitus Experimental/metabolismo , Masculino , Ratas Sprague-Dawley , Supervivencia de Injerto/efectos de los fármacos , Dieta Alta en Grasa/efectos adversosRESUMEN
In this study, the effect of modulating fulvic acid (FA) concentrations (0, 25 and 50 mg/L) on nitrogen removal in a bioelectrochemical hydrogen autotrophic denitrification system (BHDS) was investigated. Results showed that FA increased the nitrate (NO3--N) removal rate of the BHDSs from 37.8 to 46.2 and 45.2 mg N/(L·d) with a current intensity of 40 mA. The metagenomic analysis revealed that R2 (25 mg/L) was predominantly populated by autotrophic denitrifying microorganisms, which enhanced denitrification performance by facilitating electron transfer. Conversely, R3 (50 mg/L) exhibited an increase in genes related to the heterotrophic process, which improved the denitrification performance through the collaborative action of both autotrophic and heterotrophic denitrification pathways. Besides, the study also identified a potential for nitrogen removal in Serpentinimonas, which have been rarely studied. The interesting set of findings provide valuable reference for optimizing BHDS for nitrogen removal and promoting specific denitrifying genera within the system.
Asunto(s)
Procesos Autotróficos , Benzopiranos , Desnitrificación , Hidrógeno , Hidrógeno/metabolismo , Nitratos/metabolismo , Nitrógeno , Bacterias/metabolismo , Técnicas Electroquímicas/métodosRESUMEN
The conversion of nitrate to ammonium, i.e., nitrate reduction, is a major consumer of reductants in plants. Previous studies have reported that the mitochondrial alternative oxidase (AOX) is upregulated under limited nitrate reduction conditions, including no/low nitrate or when ammonium is the sole nitrogen (N) source. Electron transfer from ubiquinone to AOX bypasses the proton-pumping complexes III and IV, thereby consuming reductants efficiently. Thus, upregulated AOX under limited nitrate reduction may dissipate excessive reductants and thereby attenuate oxidative stress. Nevertheless, so far there is no firm evidence for this hypothesis due to the lack of experimental systems to analyze the direct relationship between nitrate reduction and AOX. We therefore developed a novel culturing system for A. thaliana that manipulates shoot activities of nitrate reduction and AOX separately without causing N starvation, ammonium toxicity, or lack of nitrate signal. Using shoots processed with this system, we examined genome-wide gene expression and growth to better understand the relationship between AOX and nitrate reduction. The results showed that, only when nitrate reduction was limited, AOX deficiency significantly upregulated genes involved in mitochondrial oxidative stress, reductant shuttles, and non-phosphorylating bypasses of the respiratory chain, and inhibited growth. Thus, we conclude that AOX alleviates mitochondrial oxidative stress and sustains plant growth under limited nitrate reduction.
Asunto(s)
Arabidopsis , Mitocondrias , Proteínas Mitocondriales , Nitratos , Oxidación-Reducción , Estrés Oxidativo , Oxidorreductasas , Proteínas de Plantas , Arabidopsis/genética , Arabidopsis/metabolismo , Nitratos/metabolismo , Oxidorreductasas/metabolismo , Oxidorreductasas/genética , Proteínas Mitocondriales/metabolismo , Proteínas Mitocondriales/genética , Mitocondrias/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Regulación de la Expresión Génica de las Plantas , Compuestos de Amonio/metabolismoRESUMEN
Zero-valent iron acts as an indirect electron donor, supplying ferrous iron for the nitrate-dependent ferrous oxidation (NDFO) process. The addition of activated carbon (AC) increased the specific NDFO activity in situ and ex situ by 0.4 mg-N/(d·g VSS) and 2.2 mg-N/(d·g VSS), respectively, due to the enrichment of NDFO bacteria. Furthermore, AC reduced the nitrous oxide emission potential of the sludge, a mechanism that metagenomic analysis suggests may act as a cellular energy storage strategy. During a 196-day experiment, a total nitrogen removal efficiency of 53.7 % was achieved, which may be attributed to the upregulation of key genes involved in iron oxidation and denitrification. Based on these findings, a model involving pilin, 'nanowires,' and a cyc2/?â/(FoxEâFoxY)/?âcymA/Complex III/?-mediated pathway for extracellular electron uptake was proposed. Overall, this work provides a feasible strategy for enhancing the nitrogen removal performance of the ZVI-NDFO process.
Asunto(s)
Procesos Autotróficos , Desnitrificación , Electrones , Hierro , Nitrógeno , Hierro/metabolismo , Nitrógeno/metabolismo , Carbón Orgánico/química , Oxidación-Reducción , Aguas del Alcantarillado/microbiología , Bacterias/metabolismo , Reactores Biológicos , Nitratos/metabolismoRESUMEN
The sulfur powder as electron donor in driving dual-chamber microbial fuel cell denitrification (S) process has the advantages in economy and pollution-free to treat nitrate-contained groundwater. However, the low efficiency of electron utilization in sulfur oxidation (ACE) is the bottleneck to this method. In this study, the addition of calcined pyrite to the S system (SCP) accelerated electron generation and intra/extracellular transfer efficiency, thereby improving ACE and denitrification performance. The highest nitrate removal rate reached to 3.55 ± 0.01 mg N/L/h in SCP system, and the ACE was 103 % higher than that in S system. More importantly, calcined pyrite enhanced the enrichment of functional bacteria (Burkholderiales, Thiomonas and Sulfurovum) and functional genes which related to sulfur metabolism and electron transfer. This study was more effective in removing nitrate from groundwater without compromising the water quality.
Asunto(s)
Fuentes de Energía Bioeléctrica , Desnitrificación , Hierro , Nitratos , Sulfuros , Azufre , Azufre/metabolismo , Nitratos/metabolismo , Sulfuros/metabolismo , Sulfuros/química , Transporte de Electrón , Hierro/metabolismo , Hierro/química , Agua Subterránea/química , Electrones , Bacterias/metabolismo , Oxidación-ReducciónRESUMEN
In mammals, nitric oxide (NO) is generated either by the nitric oxide synthase (NOS) enzymes from arginine or by the reduction of nitrate to nitrite by tissue xanthine oxidoreductase (XOR) and the microbiome and further reducing nitrite to NO by XOR or several heme proteins. Previously, we reported that skeletal muscle acts as a large nitrate reservoir in mammals, and this nitrate reservoir is systemically, as well as locally, used to generate nitrite and NO. Here, we report identifying two additional nitrate storage organs-bone and skin. We used bolus of ingested 15N-labeled nitrate to trace its short-term fluxes and distribution among organs. At baseline conditions, the nitrate concentration in femur bone samples was 96 ± 63 nmol/g, scalp skin 56 ± 22 nmol/g, with gluteus muscle at 57 ± 39 nmol/g. In comparison, plasma and liver contained 34 ± 19 nmol/g and 15 ± 5 nmol/g of nitrate, respectively. Three hours after 15N-nitrate ingestion, its concentration significantly increased in all organs, exceeding the baseline levels in plasma, skin, bone, skeletal muscle, and in liver 5-, 2.4-, 2.4-, 2.1-, and 2-fold, respectively. As expected, nitrate reduction into nitrite was highest in liver but also substantial in skin and skeletal muscle, followed by the distribution of 15N-labeled nitrite. We believe that these results underline the major roles played by skeletal muscle, skin, and bone, the three largest organs in mammals, in maintaining NO homeostasis, especially via the nitrate-nitrite-NO pathway.
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Huesos , Músculo Esquelético , Nitratos , Nitritos , Isótopos de Nitrógeno , Piel , Animales , Músculo Esquelético/metabolismo , Nitratos/metabolismo , Nitratos/análisis , Piel/metabolismo , Huesos/metabolismo , Nitritos/metabolismo , Nitritos/análisis , Porcinos , Isótopos de Nitrógeno/análisis , Óxido Nítrico/metabolismo , Hígado/metabolismo , Luminiscencia , MasculinoRESUMEN
The polymer-based denitrification system is an effective nitrate removal process for treating low carbon/nitrogen wastewater. However, in polymer denitrification systems, carbon used for the denitrification reaction is weakly targeted. Improving the efficiency of carbon utilization in denitrification is important to reduce carbon wastage. In this study, a symbiotic biofilm-sludge denitrification system was constructed using polycaprolactone as electron donors. Results show that the carbon release amount in 120 days was 85.32±0.46 g, and the unit mass of polycaprolactone could remove 1.55±0.01 g NO3--N. Meaningfully, the targeted carbon utilization efficiency for denitrification could achieve 79%-85%. The quantitative results showed that the release of electron donors can be well matched to the demand for electron acceptors in the biofilm-sludge denitrification system. Overall, the symbiotic system can improve the nitrate removal efficiency and reduce the waste of carbon source.
Asunto(s)
Biopelículas , Carbono , Desnitrificación , Aguas del Alcantarillado , Aguas del Alcantarillado/microbiología , Nitratos/metabolismo , Electrones , Poliésteres/química , Poliésteres/metabolismo , Polímeros/química , Simbiosis/fisiología , Purificación del Agua/métodos , Reactores BiológicosRESUMEN
Anammox is recognized as a prospective alternative for future biological nitrogen removal technologies. However, the nitrate by-products produced by anammox bacteria limit its overall nitrogen removal efficiency below 88 %. This study introduced Fe(III) into the anammox bioreactor to enhance the nitrogen removal efficiency to approximately 95 %, surpassing the biochemical limit of 88 % imposed by anammox stoichiometry. Anammox sludge was demonstrated to utilize extracellular polymeric substances to reduce Fe(III) into Fe(II), and this process promoted the dominance of Ca. Brocadia. The iron addition improved the abundance of narGHI genes and facilitated the partial dissimilatory nitrate reduction to ammonium, with nitrite as the end product. The accumulated nitrite was then eliminated through the anammox pathway, along with the excess ammonium (30 mg/L) in the influent. Overall, this study deepens our understanding of the enhanced nitrogen removal triggered by Fe(III) in anammox sludge and offers an effective approach to boost anammox process.
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Reactores Biológicos , Nitratos , Nitrógeno , Oxidación-Reducción , Aguas del Alcantarillado , Nitrógeno/metabolismo , Nitratos/metabolismo , Aguas del Alcantarillado/microbiología , Compuestos de Amonio/metabolismo , Compuestos Férricos/metabolismo , Anaerobiosis , Hierro/metabolismo , Bacterias/metabolismoRESUMEN
The phytopromotional root endophytic fungus Piriformospora indica was introduced into the wetland plant Canna indica L. to explore its impact on nitrogen (N) removal in constructed wetlands (CWs) to treat normal and saline (0.9 % NaCl) wastewater. P. indica colonization increased total nitrogen, NH4+-N, and NO3--N removal efficiencies under normal and saline conditions, with NO3--N removal rates significantly increasing by 17.5 % under saline conditions (P<0.05). N removal by plant uptake improved by 26.1 % and 27.7 % under normal and saline conditions due to P. indica-mediated growth-promoting effects. Salt-tolerant denitrifiers and nitrifiers guaranteed the dominant role of microbial degradation in N removal under saline conditions. P. indica inoculation considerably improved the contribution of Nocardioides and Nitrosomnas to dissimilatory/assimilatory nitrate reduction and nitrification genes, respectively. These findings elucidate the mechanisms and potential applications of P. indica-mediated phytoremediation in practical wastewater treatment under varying salty conditions.
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Basidiomycota , Biodegradación Ambiental , Nitrógeno , Humedales , Nitrógeno/metabolismo , Basidiomycota/metabolismo , Aguas Residuales/microbiología , Aguas Residuales/química , Purificación del Agua/métodos , Nitrificación , Salinidad , Nitratos/metabolismo , Cloruro de Sodio/farmacología , Raíces de Plantas/microbiología , Raíces de Plantas/metabolismoRESUMEN
A novel A. pittii J08 with heterotrophic nitrification and aerobic denitrification (HN-AD) isolated from pond sediments could rapidly degrade inorganic nitrogen (N) and total nitrogen (TN-N) with ammonium (NH4+-N) preference. N degradation rate of NH4+-N, nitrite (NO2--N) and nitrate (NO3--N) were 3.9 mgL-1h-1, 3.0 mgL-1h-1 and 2.7 mgL-1h-1, respectively. In addition, strain J08 could effectively utilize most of detected low-molecular-weight carbon (LMWC) sources to degrade inorganic N with a wide adaptability to various culture conditions. Whole genome sequencing (WGS) analysis revealed that assembled genome of stain J08 possessed the crucial genes involved in dissimilatory/assimilatory NO3--N reduction and NH4+-N assimilation. These results indicated that strain J08 could be applied to wastewater treatment in aquaculture.
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Acinetobacter , Nitrógeno , Nitrógeno/metabolismo , Acinetobacter/metabolismo , Acinetobacter/genética , Genoma Bacteriano , Desnitrificación , Compuestos de Amonio/metabolismo , Genómica/métodos , Nitratos/metabolismo , Biodegradación Ambiental , Nitrificación , Nitritos/metabolismo , Filogenia , Aguas Residuales/microbiología , Secuenciación Completa del GenomaRESUMEN
Nitric oxide (NO) and S-nitrosothiol (SNO) are signal molecules and the products of nitrogen metabolism. Nitrate (NO3-) is the main nitrogen source, and nitrate transporters (NRTs) are responsible for NO3- absorption or transport. However, the interactive effect between NO3-/NRT and NO/SNO in tree plants remains ambiguous. In the present study, 25 mmol L-1 NO3- and 1 mmol L-1 NO donor sodium nitroprusside (SNP) treatment that was conducted for 24 h enhanced NO/SNO and NO3- metabolism, whereas 2.5 mmol L-1 NO3- and 80 µmol L-1 N6022 (a compound that increases SNO content) treatment reduced them in seedling leaves of Fraxinus mandshurica and Betula platyphylla. Among the nine NRT family members examined, the gene expression level of NRT2.1 had a greater response to NO/SNO and NO3- treatment in the seedling leaves of F. mandshurica and B. platyphylla. Meanwhile, FmNRT2.1 mediated NO and SNO production in seedling leaves of F. mandshurica using Agrobacterium-mediated transient transformation. These findings shed light on the reciprocal regulation between NO3- and NO/SNO in seedlings of F. mandshurica and B. platyphylla, and NRT2.1 may act as a key regulatory hub.
Asunto(s)
Betula , Fraxinus , Nitratos , Óxido Nítrico , Hojas de la Planta , Plantones , Hojas de la Planta/metabolismo , Hojas de la Planta/genética , Nitratos/metabolismo , Fraxinus/metabolismo , Fraxinus/genética , Plantones/metabolismo , Plantones/genética , Plantones/efectos de los fármacos , Betula/metabolismo , Betula/genética , Óxido Nítrico/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Proteínas de Transporte de Anión/metabolismo , Proteínas de Transporte de Anión/genética , Transportadores de NitratoRESUMEN
Woodchips are widely used as a low-cost and renewable organic carbon source for denitrifying biofilms in passive nutrient removal systems. One limitation of wood-based biofiltration systems is their relatively poor removal of phosphorus (P) from subsurface drainage and stormwaters, necessitating the use of additional filter media when co-treatment of nitrogen (N) and P is required. Here, we show that anoxic-oxic cycling of woodchip media, which enhances nitrate (NO3-) removal by increasing the mobilization of organic carbon from wood, also improves orthophosphate (Pi) uptake onto woodchips. Orthophosphate removal rates in flow-through woodchip columns ranged from 0 to 34.9 µg PO43- L-1 h-1 under continuously-saturated (anoxic) conditions, and increased to 17.5 to 71.9 µg PO43- L-1 h-1 in columns undergoing drying-rewetting (oxic-anoxic) cycles. The highest Pi removal efficiencies were observed in the first 20 h after reactors were re-flooded, and were concurrent with maxima in polyphosphate kinase (ppk) gene expression by the polyphosphate accumulating organisms (PAOs) Accumulibacter spp. and Pseudomonas spp. Batch experiments confirmed that anoxic-anaerobic-oxic pre-incubation conditions led to orthophosphate uptake onto woodchips as high as 74.9 ± 0.8 mg PO43-/kg woodchip, and batch tests with autoclaved woodchips demonstrated that Pi uptake was due to biological processes and not adsorption. NO3- removal in batch tests was also greatest under oxic incubation conditions, attributed to greater carbon availability in hypoxic to anoxic zones in woodchip biofilms. While further research is needed to elucidate the mechanisms controlling enhanced Pi uptake by woodchip biofilms under anoxic-(anaerobic-)oxic cycling, these results suggest a role for enhanced Pi uptake by PAOs in a nature-based system for treatment of nonpoint source nutrients.