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1.
Molecules ; 29(11)2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38893541

RESUMO

Ammonium polyphosphate (APP), a pivotal constituent within environmentally friendly flame retardants, exhibits notable decomposition susceptibility and potentially engenders ecological peril. Consequently, monitoring the APP concentration to ensure product integrity and facilitate the efficacious management of wastewater from production processes is of great significance. A fluorescent assay was devised to swiftly discern APP utilizing 4',6'-diamino-2-phenylindole (DAPI). With increasing APP concentrations, DAPI undergoes intercalation within its structure, emitting pronounced fluorescence. Notably, the flame retardant JLS-PNA220-A, predominantly comprising APP, was employed as the test substrate. Establishing a linear relationship between fluorescence intensity (F-F0) and JLS-PNA220-A concentration yielded the equation y = 76.08x + 463.2 (R2 = 0.9992), with a LOD determined to be 0.853 mg/L. The method was used to assess the degradation capacity of APP-degrading bacteria. Strain D-3 was isolated, and subsequent analysis of its 16S DNA sequence classified it as belonging to the Acinetobacter genus. Acinetobacter nosocomialis D-3 demonstrated superior APP degradation capabilities under pH 7 at 37 °C, with degradation rates exceeding 85% over a four-day cultivation period. It underscores the sensitivity and efficacy of the proposed method for APP detection. Furthermore, Acinetobacter nosocomialis D-3 exhibits promising potential for remediation of residual APP through environmental biodegradation processes.


Assuntos
Acinetobacter , Biodegradação Ambiental , Polifosfatos , Acinetobacter/metabolismo , Acinetobacter/genética , Polifosfatos/metabolismo , Polifosfatos/química , Indóis/metabolismo , Indóis/química , Compostos de Amônio/metabolismo , Compostos de Amônio/química , Retardadores de Chama/metabolismo , Retardadores de Chama/análise
2.
Appl Microbiol Biotechnol ; 108(1): 378, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38888816

RESUMO

Non-symbiotic N2-fixation would greatly increase the versatility of N-biofertilizers for sustainable agriculture. Genetic modification of diazotrophic bacteria has successfully enhanced NH4+ release. In this study, we compared the competitive fitness of A. vinelandii mutant strains, which allowed us to analyze the burden of NH4+ release under a broad dynamic range. Long-term competition assays under regular culture conditions confirmed a large burden for NH4+ release, exclusion by the wt strain, phenotypic instability, and loss of the ability to release NH4+. In contrast, co-inoculation in mild autoclaved soil showed a much longer co-existence with the wt strain and a stable NH4+ release phenotype. All genetically modified strains increased the N content and changed its chemical speciation in the soil. This study contributes one step forward towards bridging a knowledge gap between molecular biology laboratory research and the incorporation of N from the air into the soil in a molecular species suitable for plant nutrition, a crucial requirement for developing improved bacterial inoculants for economic and environmentally sustainable agriculture. KEY POINTS: • Genetic engineering for NH4+ excretion imposes a fitness burden on the culture medium • Large phenotypic instability for NH4+-excreting bacteria in culture medium • Lower fitness burden and phenotypic instability for NH4+-excreting bacteria in soil.


Assuntos
Compostos de Amônio , Azotobacter vinelandii , Microbiologia do Solo , Azotobacter vinelandii/genética , Azotobacter vinelandii/metabolismo , Compostos de Amônio/metabolismo , Fixação de Nitrogênio , Nitrogênio/metabolismo , Aptidão Genética , Fenótipo , Solo/química , Meios de Cultura/química , Engenharia Genética
3.
BMC Plant Biol ; 24(1): 572, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38890574

RESUMO

BACKGROUND: Nitrogen (N) availability is crucial in regulating plants' abiotic stress resistance, particularly at the seedling stage. Nevertheless, plant responses to N under salinity conditions may vary depending on the soil's NH4+ to NO3- ratio. METHODS: In this study, we investigated the effects of different NH4+:NO3- ratios (100/0, 0/100, 25/75, 50/50, and 75/25) on the growth and physio-biochemical responses of soybean seedlings grown under controlled and saline stress conditions (0-, 50-, and 100-mM L- 1 NaCl and Na2SO4, at a 1:1 molar ratio). RESULTS: We observed that shoot length, root length, and leaf-stem-root dry weight decreased significantly with increased saline stress levels compared to control. Moreover, there was a significant accumulation of Na+, Cl-, hydrogen peroxide (H2O2), and malondialdehyde (MDA) but impaired ascorbate-glutathione pools (AsA-GSH). They also displayed lower photosynthetic pigments (chlorophyll-a and chlorophyll-b), K+ ion, K+/Na+ ratio, and weakened O2•--H2O2-scavenging enzymes such as superoxide dismutase, catalase, peroxidase, monodehydroascorbate reductase, glutathione reductase under both saline stress levels, while reduced ascorbate peroxidase, and dehydroascorbate reductase under 100-mM stress, demonstrating their sensitivity to a saline environment. Moreover, the concentrations of proline, glycine betaine, total phenolic, flavonoids, and abscisic acid increased under both stresses compared to the control. They also exhibited lower indole acetic acid, gibberellic acid, cytokinins, and zeatine riboside, which may account for their reduced biomass. However, NH4+:NO3- ratios caused a differential response to alleviate saline stress toxicity. Soybean seedlings supplemented with optimal ratios of NH4+:NO3- (T3 = 25:75 and T = 4 50:50) displayed lower Na+ and Cl- and ABA but improved K+ and K+/Na+, pigments, growth hormones, and biomass compared to higher NH4+:NO3- ratios. They also exhibited higher O2•--H2O2-scavenging enzymes and optimized H2O2, MDA, and AsA-GSH pools status in favor of the higher biomass of seedlings. CONCLUSIONS: In summary, the NH4+ and NO3- ratios followed the order of 50:50 > 25:75 > 0:100 > 75:25 > 100:0 for regulating the morpho-physio-biochemical responses in seedlings under SS conditions. Accordingly, we suggest that applying optimal ratios of NH4+ and NO3- (25/75 and 50:50) can improve the resistance of soybean seedlings grown in saline conditions.


Assuntos
Antioxidantes , Glycine max , Nitratos , Reguladores de Crescimento de Plantas , Tolerância ao Sal , Plântula , Glycine max/fisiologia , Glycine max/efeitos dos fármacos , Glycine max/metabolismo , Glycine max/crescimento & desenvolvimento , Plântula/fisiologia , Plântula/efeitos dos fármacos , Plântula/metabolismo , Plântula/crescimento & desenvolvimento , Antioxidantes/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Nitratos/metabolismo , Compostos de Amônio/metabolismo , Estresse Salino , Íons/metabolismo
4.
Arch Microbiol ; 206(7): 297, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38861039

RESUMO

The microbe-mediated conversion of nitrate (NO3-) to ammonium (NH4+) in the nitrogen cycle has strong implications for soil health and crop productivity. The role of prokaryotes, eukaryotes and their phylogeny, physiology, and genetic regulations are essential for understanding the ecological significance of this empirical process. Several prokaryotes (bacteria and archaea), and a few eukaryotes (fungi and algae) are reported as NO3- reducers under certain conditions. This process involves enzymatic reactions which has been catalysed by nitrate reductases, nitrite reductases, and NH4+-assimilating enzymes. Earlier reports emphasised that single-cell prokaryotic or eukaryotic organisms are responsible for this process, which portrayed a prominent gap. Therefore, this study revisits the similarities and uniqueness of mechanism behind NO3- -reduction to NH4+ in both prokaryotes and eukaryotes. Moreover, phylogenetic, physiological, and genetic regulation also shed light on the evolutionary connections between two systems which could help us to better explain the NO3--reduction mechanisms over time. Reports also revealed that certain transcription factors like NtrC/NtrB and Nit2 have shown a major role in coordinating the expression of NO3- assimilation genes in response to NO3- availability. Overall, this review provides a comprehensive information about the complex fermentative and respiratory dissimilatory nitrate reduction to ammonium (DNRA) processes. Uncovering the complexity of this process across various organisms may further give insight into sustainable nitrogen management practices and might contribute to addressing global environmental challenges.


Assuntos
Compostos de Amônio , Archaea , Bactérias , Nitratos , Oxirredução , Filogenia , Nitratos/metabolismo , Compostos de Amônio/metabolismo , Bactérias/genética , Bactérias/metabolismo , Bactérias/classificação , Archaea/genética , Archaea/metabolismo , Archaea/classificação , Eucariotos/genética , Eucariotos/metabolismo , Células Procarióticas/metabolismo , Fungos/genética , Fungos/metabolismo , Fungos/classificação , Ciclo do Nitrogênio/genética , Nitrito Redutases/genética , Nitrito Redutases/metabolismo
5.
Methods Mol Biol ; 2796: 23-34, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38856893

RESUMO

Solid-state NMR allows for the study of membrane proteins under physiological conditions. Here we describe a method for detection of bound ions in the selectivity filter of ion channels using solid-state NMR. This method employs standard 1H-detected solid-state NMR setup and experiment types, which is enabled by using 15N-labelled ammonium ions to mimic potassium ions.


Assuntos
Compostos de Amônio , Canais Iônicos , Isótopos de Nitrogênio , Isótopos de Nitrogênio/análise , Compostos de Amônio/química , Compostos de Amônio/análise , Canais Iônicos/metabolismo , Canais Iônicos/química , Íons/química , Ressonância Magnética Nuclear Biomolecular/métodos , Espectroscopia de Ressonância Magnética/métodos
6.
Sci Adv ; 10(23): eadl3587, 2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38848370

RESUMO

Heterotrophic nitrifiers continue to be a hiatus in our understanding of the nitrogen cycle. Despite their discovery over 50 years ago, the physiology and environmental role of this enigmatic group remain elusive. The current theory is that heterotrophic nitrifiers are capable of converting ammonia to hydroxylamine, nitrite, nitric oxide, nitrous oxide, and dinitrogen gas via the subsequent actions of nitrification and denitrification. In addition, it was recently suggested that dinitrogen gas may be formed directly from ammonium. Here, we combine complementary high-resolution gas profiles, 15N isotope labeling studies, and transcriptomics data to show that hydroxylamine is the major product of nitrification in Alcaligenes faecalis. We demonstrated that denitrification and direct ammonium oxidation to dinitrogen gas did not occur under the conditions tested. Our results indicate that A. faecalis is capable of hydroxylamine production from an organic intermediate. These results fundamentally change our understanding of heterotrophic nitrification and have important implications for its biotechnological application.


Assuntos
Alcaligenes faecalis , Processos Heterotróficos , Hidroxilamina , Nitrificação , Alcaligenes faecalis/metabolismo , Alcaligenes faecalis/genética , Hidroxilamina/metabolismo , Compostos de Amônio/metabolismo , Nitritos/metabolismo , Oxirredução
7.
Microb Ecol ; 87(1): 82, 2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38831142

RESUMO

Denitrification and anaerobic ammonium oxidation (anammox) are key processes for nitrogen removal in aquaculture, reducing the accumulated nitrogen nutrients to nitrogen gas or nitrous oxide gas. Complete removal of nitrogen from aquaculture systems is an important measure to solve environmental pollution. In order to evaluate the nitrogen removal potential of marine aquaculture ponds, this study investigated the denitrification and anammox rates, the flux of nitrous oxide (N2O) at the water-air interface, the sediment microbial community structure, and the gene expression associated with the nitrogen removal process in integrated multi-trophic aquaculture (IMTA) ponds (Apostistius japonicus-Penaeus japonicus-Ulva) with different culture periods. The results showed that the denitrification and anammox rates in sediments increased with the increase of cultivation periods and depth, and there was no significant difference in nitrous oxide gas flux at the water-air interface between different cultivation periods (p > 0.05). At the genus and phylum levels, the abundance of microorganisms related to nitrogen removal reactions in sediments changed significantly with the increase of cultivation period and depth, and was most significantly affected by the concentration of particulate organic nitrogen (PON) in sediments. The expression of denitrification gene (narG, nirS, nosZ) in surface sediments was significantly higher than that in deep sediments (p < 0.05), and was negatively correlated with denitrification rate. All samples had a certain anammox capacity, but no known anammox bacteria were found in the microbial diversity detection, and the expression of gene (hzsB) related to the anammox process was extremely low, which may indicate the existence of an unknown anammox bacterium. The data of this study showed that the IMTA culture pond had a certain potential for nitrogen removal, and whether it could make a contribution to reducing the pollution of culture wastewater still needed additional practice and evaluation, and also provided a theoretical basis for the nitrogen removal research of coastal mariculture ponds.


Assuntos
Aquicultura , Bactérias , Desnitrificação , Microbiota , Nitrogênio , Óxido Nitroso , Penaeidae , Lagoas , Nitrogênio/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Bactérias/isolamento & purificação , Lagoas/microbiologia , Animais , Penaeidae/microbiologia , Óxido Nitroso/metabolismo , Óxido Nitroso/análise , Sedimentos Geológicos/microbiologia , Oxirredução , Compostos de Amônio/metabolismo
8.
Microbes Environ ; 39(2)2024.
Artigo em Inglês | MEDLINE | ID: mdl-38825479

RESUMO

The nitrite oxidizing bacterial genus Ca. Nitrotoga was only recently discovered to be widespread in freshwater systems; however, limited information is currently available on the environmental factors and seasonal effects that influence its distribution in lakes. In a one-year study in a dimictic lake, based on monthly sampling along a vertical profile, the droplet digital PCR quantification of Ca. Nitrotoga showed a strong spatio-temporal patchiness. A correlation ana-lysis with environmental parameters revealed that the abundance of Ca. Nitrotoga correlated with dissolved oxygen and ammonium, suggesting that the upper hypolimnion of the lake is the preferred habitat.


Assuntos
Lagos , Estações do Ano , Lagos/microbiologia , Lagos/química , Nitritos/metabolismo , Nitritos/análise , Compostos de Amônio/metabolismo , Compostos de Amônio/análise , Oxigênio/metabolismo , Oxigênio/análise , Ecossistema
9.
Arch Microbiol ; 206(7): 310, 2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38896324

RESUMO

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.


Assuntos
Proteínas de Bactérias , Regulação Bacteriana da Expressão Gênica , Herbaspirillum , Nitratos , Nitrogênio , Herbaspirillum/metabolismo , Herbaspirillum/genética , Nitratos/metabolismo , Nitrogênio/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Compostos de Amônio/metabolismo , Adaptação Fisiológica , Redes e Vias Metabólicas/genética , Carbono/metabolismo
10.
Water Sci Technol ; 89(10): 2732-2745, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38822611

RESUMO

In this work, microalgae cultivation trials were carried out in a membrane bioreactor to investigate fouling when the cultures of Chlorellavulgaris were grown under mixotrophic, heterotrophic, and phototrophic cultivation regimes. The Chlorella cultures were cultivated in wastewater as a source of nutrients that contained a high concentration of ammonium. In mixotrophic cultivation trials, the results showed that the elevated contents of carbohydrates in the soluble microbial product and proteins in extracellular polymeric substances probably initiated membrane fouling. In this case, the highest protein content was also found in extracellular polymeric substances due to the high nitrogen removal rate. Consequently, transmembrane pressure significantly increased compared to the phototrophic and heterotrophic regimes. The data indicated that cake resistance was the main cause of fouling in all cultivations. Higher protein content in the cake layer made the membrane surface more hydrophobic, while carbohydrates had the opposite effect. Compared to a mixotrophic culture, a phototrophic culture had a larger cell size and higher hydrophobicity, leading to less membrane fouling. Based on our previous data, the highest ammonia removal rate was reached in the mixotrophic cultures; nevertheless, membrane fouling appeared to be the fundamental problem.


Assuntos
Compostos de Amônio , Reatores Biológicos , Membranas Artificiais , Microalgas , Águas Residuárias , Microalgas/metabolismo , Microalgas/crescimento & desenvolvimento , Águas Residuárias/química , Compostos de Amônio/metabolismo , Processos Heterotróficos , Eliminação de Resíduos Líquidos/métodos , Incrustação Biológica , Chlorella/crescimento & desenvolvimento , Chlorella/metabolismo , Processos Fototróficos
11.
Chemosphere ; 361: 142526, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38851507

RESUMO

The DEnitrifying AMmonium OXidation (DEAMOX) has been proven to be a promising process treating contaminated surface water containing ammonia and nitrate, while the enrichment of the slow-growing anammox bacteria (AnAOB) remains a challenge. In this study, a novel polyurethane-adhesion vermiculite/tourmaline (VTP) modified carrier was developed to achieve effective enrichment of AnAOB. The results demonstrated that the VTP-1 (vermiculite: tourmaline = 1:1) system exhibited the greatest performance with the total nitrogen removal efficiency reaching 87.6% and anammox contributing 63% to nitrogen removal. Scanning electron microscope analysis revealed the superior biofilm structure of the VTP-1 carrier, providing attachment for AnAOB. The addition of VTP-1 promoted the secretion of EPS (extracellular polymeric substances) by microorganisms, which increased to 85.34 mg/g VSS, contributing to the aggregation of anammox cells. The favorable substrate microenvironment created by NH4+ adsorption and NO2- supply via partial denitrification process facilitated the growth of AnAOB. The relative abundance of Candidatus Brocadia and Thauera increased from 0.04% to 0.3%-1.03% and 2.06% in the VTP-1 system, respectively. This study sheds new light on the anammox biofilm formation and provides a valid approach to initiate the DEAMOX process for low nitrogen polluted water treatment.


Assuntos
Silicatos de Alumínio , Compostos de Amônio , Biofilmes , Desnitrificação , Oxirredução , Compostos de Amônio/química , Silicatos de Alumínio/química , Bactérias/metabolismo , Nitrogênio/química , Poluentes Químicos da Água , Amônia/química , Nitratos
12.
Sci Adv ; 10(23): eadm9441, 2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38838143

RESUMO

Unlike aquaporins or potassium channels, ammonium transporters (Amts) uniquely discriminate ammonium from potassium and water. This feature has certainly contributed to their repurposing as ammonium receptors during evolution. Here, we describe the ammonium receptor Sd-Amt1, where an Amt module connects to a cytoplasmic diguanylate cyclase transducer module via an HAMP domain. Structures of the protein with and without bound ammonium were determined to 1.7- and 1.9-Ångstrom resolution, depicting the ON and OFF states of the receptor and confirming the presence of a binding site for two ammonium cations that is pivotal for signal perception and receptor activation. The transducer domain was disordered in the crystals, and an AlphaFold2 prediction suggests that the helices linking both domains are flexible. While the sensor domain retains the trimeric fold formed by all Amt family members, the HAMP domains interact as pairs and serve to dimerize the transducer domain upon activation.


Assuntos
Compostos de Amônio , Proteínas de Transporte de Cátions , Compostos de Amônio/metabolismo , Compostos de Amônio/química , Proteínas de Transporte de Cátions/metabolismo , Proteínas de Transporte de Cátions/química , Proteínas de Transporte de Cátions/genética , Transdução de Sinais , Modelos Moleculares , Sítios de Ligação , Cristalografia por Raios X , Domínios Proteicos , Ligação Proteica , Sequência de Aminoácidos
13.
J Environ Sci (China) ; 145: 180-192, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38844318

RESUMO

A pilot-scale filtration system was adopted to prepare filter media with catalytic activity to remove manganese (Mn2+) and ammonium (NH4+-N). Three different combinations of oxidants (KMnO4 and K2FeO4) and reductants (MnSO4 and FeCl2) were used during the start-up period. Filter R3 started up by KMnO4 and FeCl2 (Mn7+→MnOx) exhibited excellent catalytic property, and the NH4+-N and Mn2+ removal efficiency reached over 80% on the 10th and 35th days, respectively. Filter R1 started up by K2FeO4 and MnSO4 (MnOx←Mn2+) exhibited the worst catalytic property. Filter R2 started up by KMnO4 and MnSO4 (Mn7+→MnOx←Mn2+) were in between. According to Zeta potential results, the Mn-based oxides (MnOx) formed by Mn7+→MnOx performed the highest pHIEP and pHPZC. The higher the pHIEP and pHPZC, the more unfavorable the cation adsorption. However, it was inconsistent with its excellent Mn2+ and NH4+-N removal abilities, implying that catalytic oxidation played a key role. Combined with XRD and XPS analysis, the results showed that the MnOx produced by the reduction of KMnO4 showed early formation of buserite crystals, high degree of amorphous, high content of Mn3+ and lattice oxygen with the higher activity to form defects. The above results showed that MnOx produced by the reduction of KMnO4 was more conducive to the formation of active species for catalytic oxidation of NH4+-N and Mn2+ removal. This study provides new insights on the formation mechanisms of the active MnOx that could catalytic oxidation of NH4+-N and Mn2+.


Assuntos
Compostos de Amônio , Filtração , Manganês , Óxidos , Manganês/química , Óxidos/química , Compostos de Amônio/química , Filtração/métodos , Poluentes Químicos da Água/química , Permanganato de Potássio/química , Compostos de Manganês/química , Oxirredução , Eliminação de Resíduos Líquidos/métodos , Compostos de Potássio/química , Adsorção , Compostos Férricos/química , Compostos de Ferro
14.
Nature ; 630(8015): 230-236, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38811725

RESUMO

Nitrosopumilus maritimus is an ammonia-oxidizing archaeon that is crucial to the global nitrogen cycle1,2. A critical step for nitrogen oxidation is the entrapment of ammonium ions from a dilute marine environment at the cell surface and their subsequent channelling to the cell membrane of N. maritimus. Here we elucidate the structure of the molecular machinery responsible for this process, comprising the surface layer (S-layer), using electron cryotomography and subtomogram averaging from cells. We supplemented our in situ structure of the ammonium-binding S-layer array with a single-particle electron cryomicroscopy structure, revealing detailed features of this immunoglobulin-rich and glycan-decorated S-layer. Biochemical analyses showed strong ammonium binding by the cell surface, which was lost after S-layer disassembly. Sensitive bioinformatic analyses identified similar S-layers in many ammonia-oxidizing archaea, with conserved sequence and structural characteristics. Moreover, molecular simulations and structure determination of ammonium-enriched specimens enabled us to examine the cation-binding properties of the S-layer, revealing how it concentrates ammonium ions on its cell-facing side, effectively acting as a multichannel sieve on the cell membrane. This in situ structural study illuminates the biogeochemically essential process of ammonium binding and channelling, common to many marine microorganisms that are fundamental to the nitrogen cycle.


Assuntos
Amônia , Archaea , Microscopia Crioeletrônica , Modelos Moleculares , Oxirredução , Amônia/metabolismo , Archaea/metabolismo , Archaea/ultraestrutura , Cátions/metabolismo , Cátions/química , Organismos Aquáticos/metabolismo , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Compostos de Amônio/metabolismo , Compostos de Amônio/química , Polissacarídeos/metabolismo , Polissacarídeos/química
15.
Environ Res ; 255: 119209, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38782336

RESUMO

Nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) process is a promising wastewater treatment technology, but the slow microbial growth rate greatly hinders its practical application. Although high-level nitrogen removal and excellent biomass accumulation have been achieved in n-DAMO granule process, the formation mechanism of n-DAMO granules remains unresolved. To elucidate the role of functional microbes in granulation, this study attempted to cultivate granules dominated by n-DAMO microorganisms and granules coupling n-DAMO with anaerobic ammonium oxidation (Anammox). After long-term operation, dense granules were developed in the two systems where both n-DAMO archaea and n-DAMO bacteria were enriched, whereas granulation did not occur in the other system dominated by n-DAMO bacteria. Extracellular polymeric substances (EPS) measurement indicated the critical role of EPS production in the granulation of n-DAMO process. Metagenomic and metatranscriptomic analyses revealed that n-DAMO archaea and Anammox bacteria were active in EPS biosynthesis, while n-DAMO bacteria were inactive. Consequently, more EPS were produced in the systems containing n-DAMO archaea and Anammox bacteria, leading to the successful development of n-DAMO granules. Furthermore, EPS biosynthesis in n-DAMO systems is potentially regulated by acyl-homoserine lactones and c-di-GMP. These findings not only provide new insights into the mechanism of granule formation in n-DAMO systems, but also hint at potential strategies for management of the granule-based n-DAMO process.


Assuntos
Archaea , Bactérias , Oxirredução , Archaea/metabolismo , Archaea/genética , Anaerobiose , Bactérias/metabolismo , Bactérias/genética , Metano/metabolismo , Eliminação de Resíduos Líquidos/métodos , Nitratos/metabolismo , Compostos de Amônio/metabolismo , Nitritos/metabolismo , Matriz Extracelular de Substâncias Poliméricas/metabolismo , Reatores Biológicos/microbiologia , Águas Residuárias/microbiologia
16.
Bioresour Technol ; 403: 130904, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38801957

RESUMO

Chlamydomonas reinhardtii prefers ammonium (NH4+) as a nitrogen source, but its late-stage growth under high-NH4+ concentrations (0.5 âˆ¼ 1 g/L) is retarded due to medium acidification. In this study, oyster shell powders were shown to increase the tolerance of C. reinhardtii to NH4+ supplementation at 0.7 g/L in TAP medium in 1-L bubble-column bioreactors, resulting in a 22.9 % increase in biomass production, 62.1 % rise in unsaturated fatty acid accumulation, and 19.2 % improvement in harvesting efficiency. Powdered oyster shell mitigated medium acidification (pH 7.2-7.8) and provided dissolved inorganic carbon up to 8.02 × 103 µmol/L, facilitating a 76.3 % NH4+ consumption, release of up to 189 mg/L of Ca2+, a 42.1 % reduction in ζ-potential and 27.7 % increase in flocculation activity of microalgae cells. This study highlights a promising approach to utilize powdered oyster shell as a liming agent, supplement carbon source, and bio-flocculant for enhancing biomass production and microalgae harvesting in NH4+-rich environments.


Assuntos
Compostos de Amônio , Biomassa , Chlamydomonas reinhardtii , Ostreidae , Animais , Chlamydomonas reinhardtii/metabolismo , Chlamydomonas reinhardtii/crescimento & desenvolvimento , Exoesqueleto , Pós , Floculação , Carbono , Concentração de Íons de Hidrogênio , Reatores Biológicos , Nitrogênio
17.
Bioresour Technol ; 403: 130903, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38801958

RESUMO

Sulfate-dependent ammonium oxidation (Sulfammox) is a critical process linking nitrogen and sulfur cycles. However, the metabolic pathway of microbes driven Sulfammox is still in suspense. The study demonstrated that ammonium was not consumed with sulfate as the sole electron acceptor during long-term enrichment, probably due to inhibition from sulfide accumulation, while ammonium was removed at âˆ¼ 10 mg N/L/d with sulfate and nitrate as electron acceptors. Ammonium and sulfate were converted into nitrogen gas, sulfide, and elemental sulfur. Sulfammox was mainly performed by Candidatus Brocadia sapporoensis and Candidatus Brocadia fulgida, both of which encoded ammonium oxidation pathway and dissimilatory sulfate reduction pathway. Not sulfide-driven autotrophic denitrifiers but Candidatus Kuenenia stuttgartiensis converted nitrate to nitrite with sulfide. The results of this study reveal the specialized metabolism of Sulfammox bacteria (Candidatus Brocadia sapporoensis and Candidatus Brocadia fulgida) and provide insight into microbial relationships during the nitrogen and sulfur cycles.


Assuntos
Nitrogênio , Oxirredução , Sulfatos , Enxofre , Enxofre/metabolismo , Sulfatos/metabolismo , Nitrogênio/metabolismo , Anaerobiose , Compostos de Amônio/metabolismo , Nitratos/metabolismo , Sulfetos/metabolismo
18.
Water Res ; 258: 121789, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38772320

RESUMO

Recovery of ammonium from wastewater represents a sustainable strategy within the context of global resource depletion, environmental pollution and carbon neutralization. The present study developed an advanced self-reporting electroswitchable colorimetric platform (SECP) to realize smart ammonium recovery based on the electrically stimulated transformation of Prussian blue/Prussian white (PB/PW) redox couple. The key to SECP was the selectivity of ammonium adsorption, sensitivity of desorption to electric signals and visualability of color change during switchable adsorption/desorption transformation. The results demonstrated the electrochemical intercalation-induced selective adsorption of NH4+ (selectivity coefficient of 3-19 versus other cations) and deintercalation-induced desorption on the PB-film electrode. At applied voltage of 1.2 V for 20 min, the negatively charged PB-film electrode achieved the maximum adsorption capacity of 3.2 mmol g-1. Reversing voltage to -0.2 V for 20 min resulted in desorption efficiency as high as 99%, indicating high adsorption/desorption reversibility and cyclic stability. The Fe(III)/Fe(II) redox dynamics were responsible for PB/PW transformation during reversible intercalation/deintercalation of NH4+. Based on the blue/transparence color change of PB/PW, the quantitative relationship was established between amounts of NH4+ adsorbed and extracted RGB values by multiple linear regression (R2 = 0.986, RMSE = 0.095). Then, the SECP was created upon the unique capability of real-time monitoring and feedback of color change of electrode to realize the automatic control of NH4+ adsorption/desorption. During five cycles of tests, the adsorption process consistently peaked at an average value of 3.15±0.04 mmol g-1, while desorption reliably approached the near-zero average of 0.06±0.04 mmol g-1. The average time of duration was 19.6±1.67 min for adsorption and 18.8±1.10 min for desorption, respectively. With electroswitchability, selectivity and self-reporting functionalities, the SECP represents a paradigm shift in smart ammonium recovery from wastewater, making wastewater treatment and resource recovery more efficient, more intelligent and more sustainable.


Assuntos
Compostos de Amônio , Colorimetria , Águas Residuárias , Águas Residuárias/química , Poluentes Químicos da Água , Adsorção , Eletrodos , Oxirredução
19.
J Environ Manage ; 359: 121007, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38703646

RESUMO

Single-stage microaerobic systems have been proven to be effective for concurrent removal of ammonium and organic carbon from sewage. While mechanistic models derived from activated sludge models (ASMs) have simulated nutrients removal under microaerobic conditions, classic ASMs exhibit limitations in capturing the intricate effects of carbon to nitrogen (C/N) ratio on nitrogen removal performance. To address this issue, a mechanistic model modified from the classic ASMs was proposed to capture the combined inhibitory effects of carbon and ammonium on microaerobic systems. This modified model was established based on experimental data from a single-stage microaerobic reactor encompassing simultaneous nitrification-denitrification and anammox processes. The inhibition coefficient of C/N ratio was integrated into the process rate equations, and its effectiveness was validated through model performance evaluation. Compared to the classic models, the modified one achieved superior predictions for nitrite and nitrate nitrogen concentrations. Simulations revealed that under optimized conditions with a C/N of 4.57 and a dissolved oxygen (DO) of 0.41 mg/L, the system could achieve up to 95.5% of total nitrogen (TN) removal efficiency. Based on the simulation of substrate uptake/production rate, increasing the nitrogen loading rate (NLR) rather than organic loading rate (OLR) was crucial for efficient nitrogen removal. The proposed modified model served as a valuable tool for designing and optimizing similar biological wastewater treatment systems.


Assuntos
Carbono , Nitrogênio , Esgotos , Nitrogênio/metabolismo , Eliminação de Resíduos Líquidos/métodos , Reatores Biológicos , Compostos de Amônio , Nitrificação , Desnitrificação , Modelos Teóricos
20.
Sci Total Environ ; 931: 172970, 2024 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-38705293

RESUMO

Rivers in agricultural countries widely suffer from diffuse nitrate (NO3-) pollution. Although pollution sources and fates of riverine NO3- have been reported worldwide, the driving mechanisms of riverine NO3- pollution associated with mineral dissolution in piedmont zones remain unclear. This study combined hydrogeochemical compositions, stable isotopes (δ18O-NO3-, δ15N-NO3-, δ18O-H2O, and δ2H-H2O), and molecular bioinformation to determine the pollution sources, biogeochemical evolution, and natural attenuation of riverine NO3- in a typical piedmont zone (Qingshui River). High NO3- concentration (37.5 ± 9.44 mg/L) was mainly observed in the agricultural reaches of the river, with ~15.38 % of the samples exceeding the acceptable limit for drinking purpose (44 mg/L as NO3-) set by the World Health Organization. Ammonium inputs, microbial nitrification, and HNO3-induced calcite dissolution were the dominant driving factors that control riverine NO3- contamination in the piedmont zone. Approximately 99.4 % of riverine NO3- contents were derived from NH4+-containing pollutants, consisted of manure & domestic sewage (74.0 % ± 13.0 %), NH4+-synthetic fertilizer (16.1 % ± 8.99 %), and soil organic nitrogen (9.35 % ± 4.49 %). These NH4+-containing pollutants were converted to HNO3 (37.2 ± 9.38 mg/L) by nitrifying bacteria, and then the produced HNO3 preferentially participated in the carbonate (mainly calcite) dissolution, which accounted for 40.0 % ± 12.1 % of the total riverine Ca2+ + Mg2+, also resulting in the rapid release of NO3- into the river water. Thus, microbial nitrification could be a new and non-negligible contributor of riverine NO3- pollution, whereas the involvement of HNO3 in calcite dissolution acted as an accelerator of riverine NO3- pollution. However, denitrification had lesser contribution to natural attenuation for high NO3- pollution. The obtained results indicated that the mitigation of riverine NO3- pollution should focus on the management of ammonium discharges, and the HNO3-induced carbonate dissolution needs to be considered in comprehensively understanding riverine NO3- pollution in piedmont zones.


Assuntos
Compostos de Amônio , Carbonato de Cálcio , Monitoramento Ambiental , Nitratos , Nitrificação , Rios , Poluentes Químicos da Água , China , Rios/química , Nitratos/análise , Poluentes Químicos da Água/análise , Carbonato de Cálcio/química
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