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1.
Sci Total Environ ; 856(Pt 2): 159185, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36202359

RESUMO

Polarity reversal is one of the effective strategies to rapidly start up denitrifying BESs,but the long-term performances of the denitrifying BESs operated under polarity reversal receive little attention. This study investigated the effects of periodic polarity reversal (PPR) and polarity reversal once only (PRO) on the long-term performances of denitrifying BESs. Repeatable oxidative and reductive currents were observed in the BESs obtained by PPR (PPR-BESs). The peak reductive currents of the PPR-BESs reached 0.95 A/m2, and nitrate was mainly removed by dissimilatory nitrate reduction to ammonium pathway with removal rates higher than 95 %. In contrast, the peak reductive currents of the BESs obtained by PRO (PRO-BESs) progressively decreased from 1.01 A/m2 to 0.12 A/m2. The nitrate removal rates of the PRO-BESs were <50 %, and the product of nitrate reduction turned to N2 instead of ammonium. 16S rDNA sequencing and metatranscriptomic analysis revealed that Geobacter capable of bidirectional extracellular electron transfer (EET) and Afipia capable of autotrophic growth were the dominant genera in the two types of BESs. Outer membrane cytochrome c and formate dehydrogenase were potentially involved in the cathodic electron uptake. These findings contribute to a better understanding of the EET mechanisms of electroautotrophic denitrifiers.


Assuntos
Compostos de Amônio , Geobacter , Nitratos/metabolismo , Eletrodos , Geobacter/metabolismo , Processos Autotróficos , Oxirredução , Compostos de Amônio/metabolismo , Óxidos de Nitrogênio/metabolismo , Desnitrificação
2.
Chemosphere ; 311(Pt 1): 136855, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36243086

RESUMO

To alleviate the insufficiency of carbon source in sewage, many sulfur-containing inorganic electron donors were added into traditional heterotrophic denitrification process. However, the effects of extraneous inorganic electron donors on heterotrophic denitrification were still largely unknown. In this study, a hormesis-like effect of ferrous sulfide (FeS, a representative inorganic electron donors) on Paracoccus denitrificans was observed. Total nitrogen (TN) removal efficiency of P. denitrificans rose by 15% with the increase of FeS dosage from 0 to 0.3 g L-1 (low level), whereas the TN removal significantly decreased to 53% as the dosage of FeS mounted up to 5.0 g L-1 (high level). Furthermore, the impacts of FeS on glucose utilization and bacterial growth exhibited hormesis-like effects. A subsequent mechanistic study revealed that above influences were caused by its released ions (Fe2+, Fe3+, and S2-) rather than particle size. Further study illustrated that low dosage of FeS released a small amount of Fe2+ and Fe3+, which provided sufficient electrons via promoting glucose utilization, then improved denitrification. Conversely, FeS with high dosage inhibited denitrification via its released S2-, which suppressed the activity of key denitrifying enzymes rather than influenced glucose metabolism and electron provision. Our results provide an insight into improving denitrification efficiency of the mixotrophic process coexisting with autotrophic and heterotrophic denitrifiers.


Assuntos
Reatores Biológicos , Desnitrificação , Reatores Biológicos/microbiologia , Hormese , Nitratos/metabolismo , Processos Autotróficos , Nitrogênio/metabolismo , Glucose/farmacologia
3.
Sci Total Environ ; 856(Pt 1): 158795, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36115405

RESUMO

Simultaneous removal of ammonium and nitrate was achieved in a methane-fed moving bed biofilm reactor (MBBR). In the reactor, methanotrophic microorganisms oxidized methane under hypoxic conditions likely to methanol, hence providing an electron donor to denitrifiers to reduce nitrate to nitrite that then allowed anaerobic ammonium oxidizing bacteria (Anammox) to remove excess ammonium as N2. The ammonium and nitrate removal rates reached 72.09 ± 5.81 mgNH4+-N/L/d and 62.61 ± 4.17 mgNO3--N/L/d when the MBBR was operated in continuous mode. Nitrate removal by the methane-fed mixed consortia was confirmed in a batch test revealing a CH4/NO3- molar removal ratio of 1.15. The functional populations were unveiled by FISH analysis and 16S rRNA gene sequencing, which showed that the biofilm was dominated by Anammox bacteria (Candidatus Kuenenia) and diverse taxa associated with the capacity for denitrification: aerobic methanotrophs (Methylobacter, Methylomonas, and unclassified Methylococcaceae), methylotrophic denitrifiers (Opitutaceae and Methylophilaceae), and other heterotrophic denitrifiers (Ignavibacteriaceae, Anaerolineaceae, Comamonadaceae, Rhodocyclaceae and Thauera). Neither DAMO archaea nor DAMO bacteria were found in the sequencing analysis, indicating that more unknown community members possess the metabolic capacity of methanotrophic denitrification.


Assuntos
Compostos de Amônio , Methylococcaceae , Desnitrificação , Nitrogênio/metabolismo , Biofilmes , Nitratos/metabolismo , Reatores Biológicos/microbiologia , Anaerobiose , RNA Ribossômico 16S , Compostos de Amônio/metabolismo , Metano/metabolismo , Methylococcaceae/metabolismo , Bactérias Anaeróbias/metabolismo , Bactérias/metabolismo , Oxirredução
4.
Sci Total Environ ; 856(Pt 1): 159082, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36174696

RESUMO

Nitrate promotes anodic denitrification and fasts organic matter removal in microbial fuel cells (MFCs). However, it suffers from poor total nitrogen (TN) removal and current recovery. In this study, some novel electroactive nitrifying/denitrifying bacteria (ENDB) were introduced in a single chambered air-cathode MFC to investigate the performance of this device and the microbial community shift by adding nitrate. Results showed a similar disturbance in current output by adding nitrate during a short-term operation. However, a stable and reproducible current increase was achieved in the continuous experiment. A maximum current of 0.76 A m-3 and a maximum TN removal of >99 % were accomplished. The corresponding corrected coulombic efficiency was approximately 18 %. Under repeatable batches, a sharp decrease in chemical oxygen demand (COD) with feeding nitrate confirmed the temporary competition on electron donors through heterotrophic denitrification. The later current increase and nitrite detection occurring without metabolized COD could be considered evidence of electroactive anodic nitrification. The ENDB biofilm successfully coupled mixotrophic denitrification and electroactive anodic nitrification. It eventually promoted TN removal. In the process, genera Pseudoxanthomonas, Thauera, and Pseudomonas were enriched in the anodic ENDB biofilms. Cyclic voltammetry data confirmed the promotion of the electron transfer process by biofilms. The bacterial function predication revealed that the genes related to nitrogen removal and electron transfer were upregulated. Therefore, mixotrophic denitrification and electroactive anodic nitrification processes facilitated power recovery with the high efficiency of pollutant removal, finally ensuring water body security.


Assuntos
Desnitrificação , Nitrificação , Nitrogênio/metabolismo , Nitratos/metabolismo , Eletrodos , Bactérias/metabolismo , Óxidos de Nitrogênio/metabolismo
5.
Planta ; 256(6): 113, 2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36367589

RESUMO

Since the discovery of somatic embryogenesis (SE), it has been evident that nitrogen (N) metabolism is essential during morphogenesis and cell differentiation. Usually, N is supplied to cultures in vitro in three forms, ammonium (NH4+), nitrate (NO3-), and amino N from amino acids (AAs). Although most plants prefer NO3- to NH4+, NH4+ is the primary form route to be assimilated. The balance of NO3- and NH4+ determines if the morphological differentiation process will produce embryos. That the N reduction of NO3- is needed for both embryo initiation and maturation is well-established in several models, such as carrot, tobacco, and rose. It is clear that N is indispensable for SE, but the mechanism that triggers the signal for embryo formation remains unknown. Here, we discuss recent studies that suggest an optimal endogenous concentration of auxin and cytokinin is closely related to N supply to plant tissue. From a molecular and biochemical perspective, we explain N's role in embryo formation, hypothesizing possible mechanisms that allow cellular differentiation by changing the nitrogen source.


Assuntos
Compostos de Amônio , Nitrogênio , Nitrogênio/metabolismo , Compostos de Amônio/metabolismo , Nitratos/metabolismo , Desenvolvimento Embrionário , Diferenciação Celular
6.
Front Endocrinol (Lausanne) ; 13: 995503, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36339434

RESUMO

Thyroid disruptors are found in food, atmosphere, soil, and water. These contaminants interfere with the thyroid function through the impairment of thyroid hormone synthesis, plasma transport, peripheral metabolism, transport into the target cells, and thyroid hormone action. It is well known that iodide uptake mediated by the sodium-iodide symporter (NIS) is the first limiting step involved in thyroid hormones production. Therefore, it has been described that several thyroid disruptors interfere with the thyroid function through the regulation of NIS expression and/or activity. Perchlorate, nitrate, and thiocyanate competitively inhibit the NIS-mediated iodide uptake. These contaminants are mainly found in food, water and in the smoke of cigarettes. Although the impact of the human exposure to these anions is highly controversial, some studies indicated their deleterious effects in the thyroid function, especially in individuals living in iodine deficient areas. Considering the critical role of thyroid function and the production of thyroid hormones for growth, metabolism, and development, this review summarizes the impact of the exposure to these NIS-inhibitors on thyroid function and their consequences for human health.


Assuntos
Poluentes Ambientais , Percloratos , Humanos , Percloratos/toxicidade , Percloratos/metabolismo , Tiocianatos/metabolismo , Tiocianatos/farmacologia , Nitratos/metabolismo , Nitratos/farmacologia , Glândula Tireoide/metabolismo , Poluentes Ambientais/metabolismo , Iodetos/metabolismo , Iodetos/farmacologia , Hormônios Tireóideos , Água/metabolismo
7.
Bioresour Technol ; 366: 128207, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36328173

RESUMO

This study constructed two thiosulfate-driven autotrophic denitrification biofilters filled with volcanic rock (VR-BF), sponge iron and volcanic rock (SIVR-BF), respectively. The nitrate removal load (3200 g/m3/d) and efficiency (98 %) of SIVR-BF were higher than those of VR-BF. The removal of phosphate in SIVR-BF was mainly through forming FePO4 and Fe3(PO4)2(OH)2. Sulfur and iron cycles in SIVR-BF contributed to Fe (II)/Fe (III) electron shuttle, as well as S2-, S0, Sn2- electron buffer and energy storage, which improved nitrate removal and electron utilization. The formation of multi-path collaborative denitrification dominated by sulfur autotrophic denitrification (64.2 âˆ¼ 89.6 %) in SIVR-BF. The other denitrification pathways, such as iron autotrophic denitrification, which buffered pH and reduced sulfate production. Thiobacillus (38.6 %) and Ferritrophicum (25.3 %) were the dominant genus of VR-BF and SIVR-BF, respectively, which played crucial roles in autotrophic denitrification of iron and sulfur. SIVR-BF was a promising process to realize iron-sulfur coupling autotrophic denitrification and phosphate removal.


Assuntos
Desnitrificação , Nitratos , Nitratos/metabolismo , Tiossulfatos , Ferro , Fosfatos , Reatores Biológicos , Processos Autotróficos , Enxofre , Óxidos de Nitrogênio , Nitrogênio
9.
Int J Mol Sci ; 23(21)2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36362101

RESUMO

Nitrogen (N) is a major limiting factor for plant growth and crop production. The use of N fertilizer in forestry production is increasing each year, but the loss is substantial. Mastering the regulatory mechanisms of N uptake and transport is a key way to improve plant nitrogen use efficiency (NUE). However, this has rarely been studied in pecans. In this study, 10 AMT and 69 NRT gene family members were identified and systematically analyzed from the whole pecan genome using a bioinformatics approach, and the expression patterns of AMT and NRT genes and the uptake characteristics of NH4+ and NO3- in pecan were analyzed by aeroponic cultivation at varying NH4+/NO3- ratios (0/0, 0/100,25/75, 50/50, 75/25,100/0 as CK, T1, T2, T3, T4, and T5). The results showed that gene duplication was the main reason for the amplification of the AMT and NRT gene families in pecan, both of which experienced purifying selection. Based on qRT-PCR results, CiAMTs were primarily expressed in roots, and CiNRTs were majorly expressed in leaves, which were consistent with the distribution of pecan NH4+ and NO3- concentrations in the organs. The expression levels of CiAMTs and CiNRTs were mainly significantly upregulated under N deficiency and T4 treatment. Meanwhile, T4 treatment significantly increased the NH4+, NO3-, and NO2- concentrations as well as the Vmax and Km values of NH4+ and NO3- in pecans, and Vmax/Km indicated that pecan seedlings preferred to absorb NH4+. In summary, considering the single N source of T5, we suggested that the NH4+/NO3- ratio of 75:25 was more beneficial to improve the NUE of pecan, thus increasing pecan yield, which provides a theoretical basis for promoting the scale development of pecan and provides a basis for further identification of the functions of AMT and NRT genes in the N uptake and transport process of pecan.


Assuntos
Carya , Plântula , Plântula/metabolismo , Carya/genética , Nitrogênio/metabolismo , Raízes de Plantas/metabolismo , Folhas de Planta/metabolismo , Nitratos/metabolismo
10.
Water Sci Technol ; 86(5): 1222-1231, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36358057

RESUMO

The high-rate partial denitrification (PD) via effluent residual nitrate controlling by carbon dosage optimization was investigated based on the analysis of microbial mechanism of nitrite accumulation in this study. When the COD/N was changed from 4.0 to 1.8 and the effluent nitrate was above 8.48 mg/L, the nitrate accumulation ratio (NAR) and nitrate removal ratio (NRR) achieved 60 and 90%, respectively. With the electron donor starvation (EDS) strategy, nitrite accumulation was increased, which is related to the reduced utilization of carbon sources. In addition, the rapid increase of Thauera (0.21% to 53.29%) and inhibition of Others and Unclassified (96.93% to 16.99%), and the significantly different expression between reductase genes contributed to nitrite production (narG, 1,727.44 copies/mg) and nitrite reduction (nirS, 208.27 copies/mg; nirK, 203.94 copies/mg) commonly involved in PD start-up and stable operation. Another reactor can be quickly started by controlling effluent residual nitrate within 19 days.


Assuntos
Nitratos , Nitritos , Nitritos/metabolismo , Nitratos/metabolismo , Desnitrificação , Carbono , Reatores Biológicos , Esgotos , Nitrogênio , Óxidos de Nitrogênio
11.
Int J Mol Sci ; 23(20)2022 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-36293112

RESUMO

The study focused on determining the microbial precipitation abilities of bacterial strains that were isolated from an industrially obtained Pb(II)-resistant microbial consortium. Previous research has demonstrated the effectiveness of the consortium on the bioprecipitation and adsorption of Pb(II) from solution. The bioremediation of Pb(II) using microbial precipitation provides an alternative option for Pb(II) removal from wastewater. Both strains, Klebsiella pneumoniae and Paraclostridium bifermentans, were successfully isolated from the consortium obtained from a battery recycling plant in South Africa. The experiments were conducted over both 30 h and 5 d, providing insight into the short- and long-term precipitation abilities of the bacteria. Various initial concentrations of Pb(II) were investigated, and it was found that P. bifermentans was able to remove 83.8% of Pb(II) from solution with an initial Pb(II) concentration of 80 mg L-1, while K. pneumoniae was able to remove 100% of Pb(II) with the same initial Pb(II) concentration after approximately 5 d. With the same initial Pb(II) concentration, P. bifermentans was able to remove 86.1% of Pb(II) from solution, and K. pneumoniae was able to remove 91.1% of Pb(II) from solution after 30 h. The identities of the precipitates obtained for each strain vary, with PbS and Pb0 being the main species precipitated by P. bifermentans and PbO with either PbCl or Pb3(PO4)2 precipitated by K. pneumoniae. Various factors were investigated in each experiment, such as metabolic activity, nitrate concentration, residual Pb(II) concentration, extracellular and intracellular Pb(II) concentration and the precipitate identity. These factors provide a greater understanding of the mechanisms utilised by the bacteria in the bioprecipitation and adsorption of Pb(II). These results can be used as a step towards applying the process on an industrial scale.


Assuntos
Klebsiella pneumoniae , Águas Residuárias , Consórcios Microbianos , Nitratos/metabolismo , Biodegradação Ambiental , Bactérias/metabolismo , Adsorção
12.
Int J Mol Sci ; 23(20)2022 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-36293416

RESUMO

Curing salts composed of mixtures of nitrates and nitrites are preservatives widely used in processed meats. Despite many desirable technological effects, their use in meat products has been linked to methemoglobinemia and the formation of nitrosamines. Therefore, an increasing "anti-nitrite feeling" has grown among meat consumers, who search for clean label products. In this view, the use of natural compounds as alternatives represents a challenge for the meat industry. Processing (including formulation and fermentation) induces chemical or physical changes of food matrix that can modify the bioaccessibility of nutrients and the formation of peptides, impacting on the real nutritional value of food. In this study we investigated the effect of nitrate/nitrite replacement with a combination of polyphenols, ascorbate, and nitrate-reducing microbial starter cultures on the bioaccessibility of fatty acids, the hydrolysis of proteins and the release of bioactive peptides after in vitro digestion. Moreover, digested salami formulations were investigated for their impacts on cell proliferation and genotoxicity in the human intestinal cellular model (HT-29 cell line). The results indicated that a replacement of synthetic nitrates/nitrites with natural additives can represent a promising strategy to develop innovative "clean label" salamis without negatively affecting their nutritional value.


Assuntos
Produtos da Carne , Nitrosaminas , Humanos , Nitratos/metabolismo , Sais , Nitritos/metabolismo , Carne/análise , Nutrientes , Ácidos Graxos
13.
Int J Mol Sci ; 23(20)2022 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-36293526

RESUMO

Phaeocystis globosa is a marine-bloom-forming haptophyte with a polymorphic life cycle alternating between free-living cells and a colonial morphotype, that produces high biomass and impacts ecological structure and function. The mechanisms of P. globosa bloom formation have been extensively studied, and various environmental factors are believed to trigger these events. However, little is known about the intrinsic biological processes that drive the bloom process, and the mechanisms underlying P. globosa bloom formation remain enigmatic. Here, we investigated a P. globosa bloom occurring along the Chinese coast and compared the proteomes of in situ P. globosa colonies from bloom and dissipation phases using a tandem mass tag (TMT)-based quantitative proteomic approach. Among the 5540 proteins identified, 191 and 109 proteins displayed higher abundances in the bloom and dissipation phases, respectively. The levels of proteins involved in photosynthesis, pigment metabolism, nitrogen metabolism, and matrix substrate biosynthesis were distinctly different between these two phases. Ambient nitrate is a key trigger of P. globosa bloom formation, while the enhanced light harvest and multiple inorganic carbon-concentrating mechanisms support the prosperousness of colonies in the bloom phase. Additionally, colonies in the bloom phase have greater carbon fixation potential, with more carbon and energy being fixed and flowing toward the colonial matrix biosynthesis. Our study revealed the key biological processes underlying P. globosa blooms and provides new insights into the mechanisms behind bloom formation.


Assuntos
Haptófitas , Haptófitas/metabolismo , Proteômica , Proteoma/metabolismo , Nitratos/metabolismo , Carbono/metabolismo , Nitrogênio/metabolismo
14.
Int J Mol Sci ; 23(20)2022 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-36293552

RESUMO

We report herein a novel mechanism, unraveled by proteomics and validated by in vitro and in vivo studies, of the aberrant aging-associated upregulation of ovarian transferrin and ferritin in rat ovaries. The ovarian mass and serum estradiol titer plummeted while the ovarian labile ferrous iron and total iron levels escalated with age in rats. Oxidative stress markers, such as nitrite/nitrate, 3-nitrotyrosine, and 4-hydroxy-2-nonenal, accumulated in the aging ovaries due to an aberrant upregulation of the ovarian transferrin, ferritin light/heavy chains, and iron regulatory protein 2(IRP2)-mediated transferrin receptor 1 (TfR1). Ferritin inhibited estradiol biosynthesis in ovarian granulosa cells in vitro via the upregulation of a nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and p65/p50-induced oxidative and inflammatory factor inducible nitric oxide synthase (iNOS). An in vivo study demonstrated how the age-associated activation of NF-κB induced the upregulation of iNOS and the tumor necrosis factor α (TNFα). The downregulation of the keap1-mediated nuclear factor erythroid 2-related factor 2 (Nrf2), that induced a decrease in glutathione peroxidase 4 (GPX4), was observed. The aberrant transferrin and ferritin upregulation triggered an iron accumulation via the upregulation of an IRP2-induced TfR1. This culminates in NF-κB-iNOS-mediated ovarian oxi-inflamm-aging and serum estradiol decrement in naturally aging rats. The iron accumulation and the effect on ferroptosis-related proteins including the GPX4, TfR1, Nrf2, Keap1, and ferritin heavy chain, as in testicular ferroptosis, indicated the triggering of ferroptosis. In young rats, an intraovarian injection of an adenovirus, which expressed iron regulatory proteins, upregulated the ovarian NF-κB/iNOS and downregulated the GPX4. These novel findings have contributed to a prompt translational research on the ovarian aging-associated iron metabolism and aging-associated ovarian diseases.


Assuntos
Ferroptose , NF-kappa B , Ratos , Animais , Feminino , NF-kappa B/metabolismo , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Ferritinas/metabolismo , Regulação para Cima , Nitritos/metabolismo , Transferrina/metabolismo , Estradiol/metabolismo , Nitratos/metabolismo , Ovário/metabolismo , Apoferritinas/metabolismo , Proteína 2 Reguladora do Ferro/metabolismo , Fosfolipídeo Hidroperóxido Glutationa Peroxidase , Envelhecimento , Estresse Oxidativo , Ferro/metabolismo , Receptores da Transferrina/metabolismo
15.
Water Res ; 226: 119165, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36257158

RESUMO

In the past 20 years, there has been a major stride in understanding the core mechanism of anaerobic ammonium-oxidizing (anammox) bacteria, but there are still several discussion points on their survival strategies. Here, we discovered a new genus of anammox bacteria in a full-scale wastewater-treating biofilm system, tentatively named "Candidatus Loosdrechtia aerotolerans". Next to genes of all core anammox metabolisms, it encoded and transcribed genes involved in the dissimilatory nitrate reduction to ammonium (DNRA), which coupled to oxidation of small organic acids, could be used to replenish ammonium and sustain their metabolism. Surprisingly, it uniquely harbored a new ferredoxin-dependent nitrate reductase, which has not yet been found in any other anammox genome and might confer a selective advantage to it in nitrate assimilation. Similar to many other microorganisms, superoxide dismutase and catalase related to oxidative stress resistance were encoded and transcribed by "Ca. Loosdrechtia aerotolerans". Interestingly, bilirubin oxidase (BOD), likely involved in oxygen resistance of anammox bacteria under fluctuating oxygen concentrations, was identified in "Ca. Loosdrechtia aerotolerans" and four Ca. Brocadia genomes, and its activity was demonstrated using purified heterologously expressed proteins. A following survey of oxygen-active proteins in anammox bacteria revealed the presence of other previously undetected oxygen defense systems. The novel cbb3-type cytochrome c oxidase and bifunctional catalase-peroxidase may confer a selective advantage to Ca. Kuenenia and Ca. Scalindua that face frequent changes in oxygen concentrations. The discovery of this new genus significantly broadens our understanding of the ecophysiology of anammox bacteria. Furthermore, the diverse oxygen tolerance strategies employed by distinct anammox bacteria advance our understanding of their niche adaptability and provide valuable insight for the operation of anammox-based wastewater treatment systems.


Assuntos
Compostos de Amônio , Compostos de Amônio/metabolismo , Anaerobiose , Catalase , Nitratos/metabolismo , Oxigênio/metabolismo , Bactérias Anaeróbias/genética , Bactérias Anaeróbias/metabolismo , Oxirredução , Bactérias/metabolismo
16.
Water Res ; 226: 119269, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36279615

RESUMO

Biological nitrogen removal (BNR) is one of the most important environmental concerns in the field of wastewater treatment. The conventional BNR process based on heterotrophic nitrogen removal (HeNR) is suffering from several limitations, including external carbon source dependence, excessive sludge production, and greenhouse gas emissions. Through the mediation of autotrophic nitrogen removal (AuNR), mixed/mixotrophic nitrogen removal (MixNR) offers a viable solution to the optimization of the BNR process. Here, the recent advance and characteristics of MixNR process guided by sulfur-driven autotrophic denitrification (SDAD) and anammox are summarized in this review. Additionally, we discuss the functional microorganisms in different MixNR systems, shedding light on metabolic mechanisms and microbial interactions. The significance of MixNR for carbon reduction in the BNR process has also been noted. The knowledge gaps and the future research directions that may facilitate the practical application of the MixNR process are highlighted. Overall, the prospect of the MixNR process is attractive, and this review will provide guidance for the future implementation of MixNR process as well as deciphering the microbially metabolic mechanisms.


Assuntos
Nitrogênio , Águas Residuárias , Desnitrificação , Reatores Biológicos , Oxirredução , Processos Autotróficos , Carbono , Nitratos/metabolismo
17.
Artigo em Inglês | MEDLINE | ID: mdl-36232201

RESUMO

The general toxicity of fine particulate matter (PM2.5) has been intensively studied, but its pulmonary toxicities are still not fully understood. To investigate the changes of lung tissue after PM2.5 exposure and identify the potential mechanisms of pulmonary toxicity, PM2.5 samples were firstly collected and analyzed. Next, different doses of PM2.5 samples (5 mg/kg, 10 mg/kg, 20 mg/kg) were intratracheally instilled into rats to simulate lung inhalation of polluted air. After instillation for eight weeks, morphological alterations of the lung were examined, and the levels of oxidative stress were detected. The data indicated that the major contributors to PM2.5 mass were organic carbon, elemental carbon, sulfate, nitrate, and ammonium. Different concentrations of PM2.5 could trigger oxidative stress through increasing reactive oxygen species (ROS) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, and decreasing expression of antioxidant-related proteins (nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 1 (SOD1) and catalase). Histochemical staining and transmission electron microscopy displayed pulmonary inflammation, collagen deposition, mitochondrial swelling, and a decreasing number of multilamellar bodies in alveolar type II cells after PM2.5 exposure, which was related to PM2.5-induced oxidative stress. These results provide a basis for a better understanding of pulmonary impairment in response to PM2.5.


Assuntos
Compostos de Amônio , Pneumopatias , Lesão Pulmonar , 8-Hidroxi-2'-Desoxiguanosina , Animais , Antioxidantes/metabolismo , Carbono/metabolismo , Catalase/metabolismo , Regulação para Baixo , Pulmão/metabolismo , Lesão Pulmonar/induzido quimicamente , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Nitratos/metabolismo , Estresse Oxidativo , Material Particulado , Ratos , Espécies Reativas de Oxigênio/metabolismo , Sulfatos/metabolismo , Superóxido Dismutase/metabolismo , Superóxido Dismutase-1/metabolismo
18.
Int J Mol Sci ; 23(19)2022 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-36232700

RESUMO

Nickel (Ni) is an essential trace element for plant growth and a component of the plant body that has many different functions in plants. Although it has been confirmed that nickel ions (Ni2+) havea certain regulatory effect on nitrogen (N) metabolism, there are not enough data to prove whether exogenous Ni2+ can increase the carbon (C) and N metabolism in the roots of tomato seedlingsunder low-nitrogen (LN) conditions. Therefore, through the present experiment, we revealed the key mechanism of Ni2+-mediated tomato root tolerance to LN levels. Tomato plants were cultured at two different N levels (7.66 and 0.383 mmol L-1) and two different Ni2+ levels (0 and 0.1 mg L-1 NiSO4 6H2O) under hydroponic conditions. After nine days, we collected roots for physiological, biochemical, and transcriptome sequencing analyses and found that the activities of N assimilation-related enzymes decreased at LN levels. In contrast, Ni2+ significantly increased the activities of N assimilation-related enzymes and increased the contents of nitrate (NO3-), ammonium (NH4+), and total amino acids. Through root transcriptomic analysis, 3738 differentially expressed genes (DEGs) were identified. DEGs related to C and N metabolism were downregulated after LN application. However, after Ni2+ treatment, PK, PDHB, GAPDH, NR, NiR, GS, GOGAT, and other DEGs related to C and N metabolism were significantly upregulated. In conclusion, our results suggest that Ni2+ can regulate the C and N metabolism pathways in tomato roots to alleviate the impact of LN levels.


Assuntos
Compostos de Amônio , Lycopersicon esculentum , Oligoelementos , Aminoácidos/metabolismo , Compostos de Amônio/metabolismo , Compostos de Amônio/farmacologia , Carbono/metabolismo , Níquel/metabolismo , Níquel/farmacologia , Nitratos/metabolismo , Nitrogênio/metabolismo , Raízes de Plantas/metabolismo , Plantas/metabolismo , Oligoelementos/metabolismo
19.
Int J Mol Sci ; 23(19)2022 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-36232819

RESUMO

Oxygen (O2) is the most crucial substrate for numerous biochemical processes in plants. Its deprivation is a critical factor that affects plant growth and may lead to death if it lasts for a long time. However, various biotic and abiotic factors cause O2 deprivation, leading to hypoxia and anoxia in plant tissues. To survive under hypoxia and/or anoxia, plants deploy various mechanisms such as fermentation paths, reactive oxygen species (ROS), reactive nitrogen species (RNS), antioxidant enzymes, aerenchyma, and adventitious root formation, while nitrate (NO3-), nitrite (NO2-), and nitric oxide (NO) have shown numerous beneficial roles through modulating these mechanisms. Therefore, in this review, we highlight the role of reductive pathways of NO formation which lessen the deleterious effects of oxidative damages and increase the adaptation capacity of plants during hypoxia and anoxia. Meanwhile, the overproduction of NO through reductive pathways during hypoxia and anoxia leads to cellular dysfunction and cell death. Thus, its scavenging or inhibition is equally important for plant survival. As plants are also reported to produce a potent greenhouse gas nitrous oxide (N2O) when supplied with NO3- and NO2-, resembling bacterial denitrification, its role during hypoxia and anoxia tolerance is discussed here. We point out that NO reduction to N2O along with the phytoglobin-NO cycle could be the most important NO-scavenging mechanism that would reduce nitro-oxidative stress, thus enhancing plants' survival during O2-limited conditions. Hence, understanding the molecular mechanisms involved in reducing NO toxicity would not only provide insight into its role in plant physiology, but also address the uncertainties seen in the global N2O budget.


Assuntos
Gases de Efeito Estufa , Nitritos , Antioxidantes/metabolismo , Hipóxia , Nitratos/metabolismo , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Dióxido de Nitrogênio , Óxido Nitroso/metabolismo , Oxigênio/metabolismo , Plantas/metabolismo , Espécies Reativas de Nitrogênio/metabolismo , Espécies Reativas de Oxigênio/metabolismo
20.
Environ Pollut ; 314: 120312, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36183874

RESUMO

Nitrogen pollution caused serious environmental problems in reservoir ecosystems. Reducing nitrogen pollution by enhancing nitrogen removal in river sediments deserved intensive research. Distributions of nitrogen contents in sediment-water interface were characterized along the Xiangxi bay (XXB), a eutrophic tributary in Three Gorges Reservoir, China. More than 47% of total Kjeldahl nitrogen (TKN) and 67% of total organic nitrogen (TON) were degraded during burial. Higher TN, TON and NH4+ consuming at downstream sites indicated stronger nitrogen mineralization and release due to higher turbulence of the overlying density currents. Nitrifying bacteria, denitrifying bacteria, anaerobic ammonium oxidizing (anammox) bacteria and nitrite/nitrate-dependent anaerobic methane oxidation (N-DAMO) bacteria were detected in nitrate-ammonium transition zone. Nitrogen contents transitions were responded to microbial stakeholders indicated microbially mediated nitrogen cycling in sediments. The dissolved oxygen and nitrate availabilities were the key limits of denitrification and associated reactions. These results suggested microbial mediated nitrogen cycling processes in sediments were critical for nitrogen removal in aquatic ecosystems, and replenishing dissolved oxygen and nitrate was expected to enhance sediment denitrification and strengthen potential environmental self-purification.


Assuntos
Compostos de Amônio , Microbiota , Nitrogênio/metabolismo , Desnitrificação , Nitratos/metabolismo , Nitritos/metabolismo , Reatores Biológicos/microbiologia , Compostos de Amônio/metabolismo , Metano/metabolismo , Oxirredução , Oxigênio , Água , Anaerobiose
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