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1.
Chemosphere ; 262: 127843, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32777614

RESUMO

This study aimed to estimate the impact of an abandoned copper (Cu) mine on ecosystem environmental quality, using integrated ecological and biogeochemical analyses. Through a controlled experiment, the amount of Cu released by waste rocks, Cu adsorbed in soils, Cu geochemical behaviour and its leached amount were measured. Furthermore, to investigate the impacts of mine drainage on the adjacent ecosystem, samples of sediments, water and aquatic macroinvertebrates were analysed. We found that waste rocks still have high Cu concentration even after 30 years under weathering, ranging from 7782 to 8717 mg kg-1, associated mainly with carbonates, amorphous oxides and sulphides. It was estimated that 7.2 tonnes of Cu were released by waste rocks into the environment over last 30 years. The concentration of Cu observed in Ubari stream water was (


Assuntos
Cobre/análise , Monitoramento Ambiental/métodos , Poluentes Químicos da Água/análise , Brasil , Ecossistema , Poluição Ambiental/análise , Metais/análise , Mineração , Rios , Solo , Poluentes do Solo/análise , Sulfetos/análise
2.
Sci Total Environ ; 750: 141513, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32853935

RESUMO

Excessive nitrate in water systems is prevailing and a global risk of human health. Polluted river sediments are dominated by anaerobes and often the hotspot of denitrification. So far, little is known about the ecological effects of nitrate pollution on microbial dynamics, especially those in sulfide-rich sediments. Here we simulated a nitrate surge and monitored the microbial responses, as well as the changes of important environmental parameters in a sulfide-rich river sediment for a month. Our analysis of sediment microbial communities showed that elevated nitrate led to (i) a functional convergence at denitrification and sulfide oxidation, (ii) a taxonomic convergence at Proteobacteria, and (iii) a significant loss of biodiversity, community stability and other functions. Two chemolithotrophic denitrifiers Thiobacillus and Luteimonas were enriched after nitrate amendment, although the original communities were dominated by methanogens and syntrophic bacteria. Also, serial dilutions of sediment microbial communities found that Thiobacillus thiophilus dominated 18/30 communities because of its capability of simultaneous nitrate reduction and sulfide oxidation. Additionally, our network analysis indicated that keystone taxa seemed more likely to be native auxotrophs (e.g., syntrophic bacteria, methanogens) rather than dominant denitrifiers, possibly because of the extensive interspecific cross-feeding they estabilished, while environment perturbations probably disrupted that cross-feeding and simplified microbial interactions. This study advances our understanding of microbial community responses to nitrate pollution and possible mechanism in the sulfide-rich river sediment.


Assuntos
Microbiota , Rios , Desnitrificação , Sedimentos Geológicos , Nitratos , Sulfetos , Thiobacillus
3.
Sci Total Environ ; 750: 141626, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32858296

RESUMO

Challenges such as long-term cultivation and sludge floatation are common in flocculent sulfide-oxidizing autotrophic denitrification (SOAD) systems. The present study aims to optimize the granulation of SOAD sludge by mainly adjusting the reactor configuration and mixing mode. Three liquid-lift upflow reactors viz. a reactor equipped with a three-phase separator (Reactor A), a modified version of Reactor A equipped with a hydraulic regulator (Reactor B), and a reactor with a mounted baffle and intermittent mechanical mixing (Reactor C). These reactors were operated for more than 160 days. The results showed that dense and compact granules with 200 µm of diameter developed within 40 days and gradually increased to approximately 400 µm in Reactor C, which had a volatile suspended solids (VSS) concentration of 7500 mg VSS/L of sludge concentration; this Reactor C was also subject to modified reactor configuration and operating conditions. In comparison, filamentous granules formed in Reactor A due to a low substrate loading and granules formed in Reactor B but with significant biomass loss caused by sludge flotation. Both of the reactors only have ≤1000 mg VSS/L VS 7500 mg VSS/L in Reactor C. Also, Reactor C having 0.77 h of hydraulic retention time (HRT) and 0.94 kgNO3--N/m3 d & 1.87 kgS2--S/m3 d of nitrogen and sulfide loading rate, respectively, showed a better performance in terms of nitrate removal (89%) and sulfur conversion (above 70%) due to its enrichment by the typical autotrophic denitrifiers (39.0% of Thiobacillus, 22.4% of Sulfurimonas) in the granules. Our findings provide a method to optimize the design and operation of granulation reactors that can be extended to similar processes treating organic-deficient wastewaters.


Assuntos
Desnitrificação , Esgotos , Reatores Biológicos , Nitrogênio , Sulfetos , Eliminação de Resíduos Líquidos
4.
PLoS One ; 15(10): e0237643, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33064729

RESUMO

We previously reported that maternal cigarette smoke (CS) exposure resulted in impairment of central chemoreception and induced mitochondrial dysfunction in offspring parafacial respiratory group (pFRG), the kernel for mammalian central chemoreception. We also found that hydrogen sulfide (H2S) could attenuate maternal CS exposure-induced impairment of central chemoreception in the rat offspring in vivo. Mitochondrial ATP sensitive potassium (mitoKATP) channel has been reported to play a significant role in mitochondrial functions and protect against apoptosis in neurons. Thus, we hypothesize here that mitoKATP channel plays a role in the protective effects of H2S on neonatal central chemoreception in maternal CS-exposed rats. Our findings revealed that pretreatment with NaHS (donor of H2S, 22.4mM) reversed the central chemosensitivity decreased by maternal CS exposure, and also inhibited cell apoptosis in offspring pFRG, however, 5-HD (blocker of mitoKATP channels, 19mM) attenuated the protective effects of NaHS. In addition, NaHS declined pro-apoptotic proteins related to mitochondrial pathway apoptosis in CS rat offspring pFRG, such as Bax, Cytochrome C, caspase9 and caspase3. NaHS or 5-HD alone had no significant effect on above indexes. These results suggest that mitoKATP channels play an important role in the protective effect of H2S against impairment of central chemoreception via anti-apoptosis in pFRG of rat offspring exposed to maternal CS.


Assuntos
Células Quimiorreceptoras/efeitos dos fármacos , Fumar Cigarros/efeitos adversos , Sulfeto de Hidrogênio/metabolismo , Exposição Materna/efeitos adversos , Canais de Potássio/metabolismo , Animais , Animais Recém-Nascidos , Apoptose/efeitos dos fármacos , Células Quimiorreceptoras/patologia , Células Quimiorreceptoras/fisiologia , Feminino , Bulbo/efeitos dos fármacos , Bulbo/patologia , Bulbo/fisiopatologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Substâncias Protetoras/metabolismo , Substâncias Protetoras/farmacologia , Ratos , Ratos Sprague-Dawley , Mecânica Respiratória/efeitos dos fármacos , Mecânica Respiratória/fisiologia , Sulfetos/metabolismo , Sulfetos/farmacologia
5.
Water Sci Technol ; 82(8): 1628-1634, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33107856

RESUMO

This work assessed the effect of adding different concentrations of nitrate (50-300 mg NO3-·L-1) on the removal of dissolved and gaseous sulfide in an anaerobic reactor treating synthetic effluent containing sulfate (100 mg SO42-·L-1) and organic matter (1 g COD·L-1). Autotrophic denitrification, stimulated by the addition of nitrate, was demonstrated to be a very effective approach for removal of dissolved sulfide even in the presence of a high concentration of organic matter (complete removal with 50 mg NO3- mg·L-1). However, it had a minor effect on H2S(g). Sulfide remained partially oxidized to elemental sulfur even with excess nitrate (100-300 mg NO3- mg·L-1). Therefore, the competition for this electron acceptor between the autotrophic and heterotrophic denitrification pathways may have prevented the conversion of the generated sulfide into sulfate again. No evidence of inhibition of methanogenesis and sulfidogenesis was found during nitrate supplementation.


Assuntos
Reatores Biológicos , Desnitrificação , Anaerobiose , Processos Autotróficos , Nitratos , Sulfetos
6.
Zootaxa ; 4803(3): zootaxa.4803.3.1, 2020 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-33056003

RESUMO

All available information about the seven species of the digger wasp genus Palmodes Kohl known from Central Asia is summarized. A lectotype is designated for Sphex minor F. Morawitz, 1890. A new species Palmodes hissaricus Danilov is described and illustrated. Sphex mandarinius F. Smith, 1856 is resurrected from synonymy. The following new synonymy has been established: Palmodes mandarinius (F. Smith, 1856) (= Sphex montanus F. Morawitz, 1889), Palmodes melanarius (Mocsáry, 1883) (= Sphex pusillus Gussakovskij, 1930), Palmodes minor (F. Morawitz, 1890) (= Sphex parvulus Roth in de Beaumont, 1967), Palmodes occitanicus (Lepeletier de Saint Fargeau et Serville, 1828) (= Sphex palmetorum Roth, 1963). An original key to the Palearctic species is provided.


Assuntos
Vespas , Distribuição Animal , Estruturas Animais , Animais , Ásia Central , Abelhas , Chumbo , Sulfetos
7.
Huan Jing Ke Xue ; 41(9): 4124-4132, 2020 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124294

RESUMO

The adsorption performance of three iron ores (pyrite, hematite, and magnetite) on Sb(Ⅴ) was compared and pyrite was shown to exhibit the highest adsorption performance. The effects of particle size, concentration, and pH on the adsorption performance were investigated with pyrite as the absorbent. The rejection of Sb(Ⅴ) was the highest (>80%) when pyrite (particle size <0.074 mm) was used as the absorbent with a concentration of 1 g ·L-1 and pH=7. The ion competition experiment indicated that PO43- can inhibit the adsorption of Sb(Ⅴ), while SO42- and CO32- have no significant effects on the adsorption of Sb(Ⅴ) because PO43- can compete with Sb(Ⅴ) for active adsorption sites on the surface of pyrite. The results also showed that the quasi-second-order kinetic model and Langmuir model can better simulate the adsorption process, which shows a single-layer adsorption behavior and chemisorption plays a main role in the rejection of Sb(Ⅴ). FTIR analysis suggested that the removal of Sb(Ⅴ) by pyrite was a coordinated ion exchange reaction. EDS and XPS results further confirmed that Sb(Ⅴ) was adsorbed on the surface of pyrite and was not reduced to Sb(Ⅲ), which is more toxic.


Assuntos
Poluentes Químicos da Água , Água , Adsorção , Concentração de Íons de Hidrogênio , Ferro , Cinética , Sulfetos , Poluentes Químicos da Água/análise
8.
Water Res ; 186: 116358, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32898788

RESUMO

In this work, the ozonation properties of 2,2',3',4,5-pentachlorodiphenyl sulfide (PeCDPS) was systematically studied, with special emphasis on the underlying mechanism for the effects of inorganic ions. Kinetic experiments show that common ions can significantly reduce the oxidative properties of ozone, except for SO32- and Cu2+. The inhibition effect of anions has been explained through the scavenging effect of free radicals and the generation of other free radicals with weaker oxidation potentials, but no research has reported on the effect of free radicals generated by anions on the degradation pathway. However, SO32- and Cu2+ exerted a promoting effect through enhanced formation of ·OH via the hydrolysis effect and the catalyzed decomposition of O3, respectively. According to the intermediate products identified by high performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) analysis, direct oxidation of S atom, substitution of Cl atom with -OH group, and hydroxylation of the benzene ring were commonly observed. The addition of NO2- and SO32- produced new free radicals like ·NO2, ·SO3 and ·SO4-, which would attack the parent compound or its primary product, thus influencing the degradation efficiency and pathways. The radicals initiated reactions and the structures of the corresponding products were further rationalized by density functional theory (DFT) calculations. These findings provide new insights into the effects of common anions on ozone oxidation of organic compounds.


Assuntos
Ozônio , Poluentes Químicos da Água , Cinética , Oxirredução , Sílica Gel , Sulfetos , Espectrometria de Massas em Tandem
9.
Zhongguo Ying Yong Sheng Li Xue Za Zhi ; 36(3): 235-239, 2020 May.
Artigo em Chinês | MEDLINE | ID: mdl-32981278

RESUMO

Objective: To investigate the effects of exogenous NaHS on myelin basic protein (MBP) and learning and memory of hippocampal neurons in mice with spinocerebellar ataxia type 3 (SCA3) and its therapeutic significance.Methods: Twelve male normal mice were randomly selected as normal control group (NC Group), and 48 SCA3 mice were randomly selected as SCA3 model group (M Group), low dose group (NL Group, 10 µmol/kg), medium dose group (NM Group, 50µmol/kg) and high dose group (NH Group, 100 µmol/kg), 12 rats in each group. The drug treated groups were injected with NaHS intraperitoneally once a day for 4 weeks. The changes of learning and memory ability of SCA3 mice before and after the intervention of different doses of NaHS were determined by Morris water maze, the content of hydrogen sulfide (H2S) in hippocampus was measured by spectrophotometry, the expression of MBP was detected by immunohistochemistry, and the morphological changes of neuron myelin sheath were observed by electron microscope. Results: Compared with the control group, the learning and memory ability of SCA3 mice was decreased significantly (P<0.05), and the content of H2S in hippocampus was decreased (P<0.05). After different doses of exogenous NaHS treatment, the learning and memory ability was improved in different degrees (P<0.05), and the contents of H2S and MBP in hippocampus of SCA3 mice were also improved in different degrees (P<0.05). Conclusion: Exogenous NaHS may increase the contents of H2S and MBP in the hippocampus of SCA3 mice, which may have a protective effect on the neurons, and then improve the learning and memory ability of SCA3 mice, and provide a new idea for the treatment of SCA3.


Assuntos
Sulfeto de Hidrogênio , Aprendizagem , Memória , Ataxias Espinocerebelares , Sulfetos , Animais , Hipocampo/efeitos dos fármacos , Aprendizagem/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Camundongos , Proteína Básica da Mielina , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Ratos , Ataxias Espinocerebelares/tratamento farmacológico , Sulfetos/farmacologia , Sulfetos/uso terapêutico
10.
Nat Commun ; 11(1): 4899, 2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32994420

RESUMO

Chemical synthesis of amino acids from renewable sources is an alternative route to the current processes based on fermentation. Here, we report visible-light-driven amination of biomass-derived α-hydroxyl acids and glucose into amino acids using NH3 at 50 °C. Ultrathin CdS nanosheets are identified as an efficient and stable catalyst, exhibiting an order of magnitude higher activity towards alanine production from lactic acid compared to commercial CdS as well as CdS nanoobjects bearing other morphologies. Its unique catalytic property is attributed mainly to the preferential formation of oxygen-centered radicals to promote α-hydroxyl acids conversion to α-keto acids, and partially to the poor H2 evolution which is an undesired side reaction. Encouragingly, a number of amino acids are prepared using the current protocol, and one-pot photocatalytic conversion of glucose to alanine is also achieved. This work offers an effective catalytic system for amino acid synthesis from biomass feedstocks under mild conditions.


Assuntos
Alanina/síntese química , Compostos de Cádmio/química , Sulfetos/química , Alanina/química , Biomassa , Catálise/efeitos da radiação , Hidrogênio/química , Ácido Láctico/química , Luz , Modelos Químicos , Oxigênio/química
11.
Water Sci Technol ; 82(1): 185-193, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32910802

RESUMO

Orange G (OG), a typical azo dye in textile wastewaters, has been the subject of intense investigations. This study investigated oxidative degradation of OG in aqueous solution by persulfate (PS) activated with pyrite. A complete destruction of OG was achieved within 60 min in the pyrite/PS system. Lower solution pH, smaller pyrite particles and higher pyrite dosage was beneficial for OG degradation. Higher PS concentration was also in favour of OG degradation, but excess PS would decrease the removal efficiency of OG. The addition of HCO3- and H2PO4- but Cl- had inhibitory effects on the destruction of OG. The results of quenching experiments and electron paramagnetic resonance tests proved that SO4•- and •OH were the dominant reactive species responsible for OG degradation in the pyrite/PS system. The azo bond, naphthalene ring and benzene ring of OG were all destroyed by the generated reactive species. The mineralization rate of OG reached 34.4% after 60 min of reaction. This work will provide information for understanding azo dye degradation by pyrite activated PS.


Assuntos
Compostos Azo , Sulfatos , Ferro , Estresse Oxidativo , Sulfetos
12.
Rinsho Ketsueki ; 61(8): 885-887, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32908051

RESUMO

Dimethyl sulfoxide (DMSO) is used as a cryoprotectant for peripheral blood stem cells (PBSC) preservation. Dimethyl sulfide (DMS) is a metabolite of DMSO secreted through patients' breath after PBSC infusion. It possesses malodor causing an unpleasant environment. We evaluated the efficacy of a photocatalyst environment purifier, which has the potential to lyse toxic substances, in reducing DMS malodor. High DMS concentration in the air after PBSC infusion rapidly decreased after operating the device. Our results suggest that photocatalytic reaction has the potential to reduce the DMS odor associated with PBSC infusion.


Assuntos
Filtros de Ar , Células-Tronco de Sangue Periférico , Criopreservação , Humanos , Sulfetos
13.
Chemosphere ; 258: 127288, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947659

RESUMO

The discharge of toxic elements from tailings soils in the aquatic environments occurs chiefly in the presence of indigenous bacteria. The biotic components may interact in the opposite direction, leading to the formation of a passivation layer, which can inhibit the solubility of the elements. In this work, the influence of jarosite on the bio-immobilization of toxic elements was studied by native bacteria. In batch experiments, the bio-immobilization of heavy metals by an inhibitory layer was examined in the different aquatic media using pure cultures of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. A variety of analyses also investigated the mechanisms of metals bio-immobilization. Among different tests, the highest metal solubility yielded 99% Mn, 91% Cr, 95% Fe, and 78% Cu using A. ferrooxidans in 9KFe medium after ten days. After 22 days, these percentages decreased down to 30% Mn and about 20% Cr, Fe, and Cu, likely due to metal immobilization by biogenic jarosite. The formation of jarosite was confirmed by an electron probe micro-analyzer (EPMA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The mechanisms of metal bio-immobilization by biogenic jarosite from tailings soil confirmed three main steps: 1) the dissolution of metal sulfides in the presence of Acidithiobacillus bacteria; 2) the nucleation of jarosite on the surface of sulfide minerals; 3) the co-precipitation of dissolved elements with jarosite during the bio-immobilization process, demonstrated by a structural study for jarosite. Covering the surface of soils by the jarosite provided a stable compound in the acidic environment of mine-waste.


Assuntos
Compostos Férricos/química , Substâncias Perigosas/análise , Sulfatos/química , Acidithiobacillus , Acidithiobacillus thiooxidans , Bactérias , Substâncias Perigosas/toxicidade , Metais Pesados , Minerais , Solubilidade , Sulfetos/química , Difração de Raios X
14.
Bull Environ Contam Toxicol ; 105(3): 468-473, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32886144

RESUMO

Selenium (Se), iron (Fe), and free sulfides contents in pore waters were measured to study the liberation of soluble Se in suboxic conditions. The sediment core was collected in a salt marsh in Patos Lagoon estuary (southern Brazil), and it was obtained during a brackish water period, in a low intertidal stand vegetated by Spartina alterniflora. The redox potential (Eh), pH, andacid volatile sulfides (AVS) content were also investigated. Pore water results sustained the idea that S. alterniflora roots promote oxygen penetration to depths of ca. 10 cm below the salt marsh surface, increasing Eh and lowering the pH in this interval. High Se concentrations (e.g., 16.9 µg L-1), that are above US. EPA environmental criteria, were observed in the pore water to depths between 10 and 20 cm and are associated to low AVS contents and high concentrations of free sulfides. In the first 10 cm the lowering of Se contents probably happens due the low pH and biological volatilization of the metalloid.


Assuntos
Sedimentos Geológicos/química , Selênio/análise , Áreas Alagadas , Brasil , Estuários , Ferro/análise , Poaceae , Sulfetos/análise , Volatilização
15.
Mol Genet Genomics ; 295(6): 1529-1535, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32894358

RESUMO

Lanthipeptides are a subgroup of ribosomally encoded and post-translationally modified peptides (RiPPs) which frequently possess potent biological activity. Here we provide the first comprehensive bioinformatic analysis of the lanthipeptide-producing capability of the Salinispora genus, a marine actinomycete. One hundred twenty-two Salinispora arenicola, tropica, and pacifica genomic sequences were analyzed for lanthipeptide gene clusters, and the resulting 182 clusters were divided into seven groups based on sequence similarities. Group boundaries were defined based on LanB and LanM sequences with greater than 80% similarity within groups. Of the seven groups, six are predicted to encode class I lanthipeptides while only one group is predicted to encode class II lanthipeptides. Leader and core peptides were predicted for each cluster along with the number of possible lanthionine bridges. Notably, all of the predicted products of these clusters would represent novel lanthipeptide scaffolds. Of the 122 Salinispora genomes analyzed in this study, 92% contained at least one lanthipeptide gene cluster suggesting that Salinispora is a rich, yet untapped, source of lanthipeptides.


Assuntos
Alanina/análogos & derivados , Proteínas de Bactérias/metabolismo , Genoma Bacteriano , Micromonosporaceae/metabolismo , Fragmentos de Peptídeos/metabolismo , Sulfetos/metabolismo , Alanina/isolamento & purificação , Alanina/metabolismo , Proteínas de Bactérias/genética , Genômica , Micromonosporaceae/genética , Micromonosporaceae/crescimento & desenvolvimento , Fragmentos de Peptídeos/isolamento & purificação , Sulfetos/isolamento & purificação
16.
Nat Commun ; 11(1): 4658, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938931

RESUMO

Dimethylsulfoniopropionate (DMSP) is an important marine osmolyte. Aphotic environments are only recently being considered as potential contributors to global DMSP production. Here, our Mariana Trench study reveals a typical seawater DMSP/dimethylsulfide (DMS) profile, with highest concentrations in the euphotic zone and decreased but consistent levels below. The genetic potential for bacterial DMSP synthesis via the dsyB gene and its transcription is greater in the deep ocean, and is highest in the sediment.s DMSP catabolic potential is present throughout the trench waters, but is less prominent below 8000 m, perhaps indicating a preference to store DMSP in the deep for stress protection. Deep ocean bacterial isolates show enhanced DMSP production under increased hydrostatic pressure. Furthermore, bacterial dsyB mutants are less tolerant of deep ocean pressures than wild-type strains. Thus, we propose a physiological function for DMSP in hydrostatic pressure protection, and that bacteria are key DMSP producers in deep seawater and sediment.


Assuntos
Bactérias/genética , Bactérias/metabolismo , Água do Mar/química , Água do Mar/microbiologia , Compostos de Sulfônio/metabolismo , Bactérias/isolamento & purificação , Clorofila A/análise , Clorofila A/metabolismo , Genes Bacterianos , Sedimentos Geológicos/química , Pressão Hidrostática , Marinobacter/genética , Marinobacter/isolamento & purificação , Marinobacter/metabolismo , Metagenoma , Mutação , Oceanos e Mares , Prochlorococcus/genética , Prochlorococcus/isolamento & purificação , Prochlorococcus/metabolismo , RNA Ribossômico 16S , Sulfetos/análise , Sulfetos/metabolismo , Compostos de Sulfônio/análise , Synechococcus/genética , Synechococcus/isolamento & purificação , Synechococcus/metabolismo
17.
Bioresour Technol ; 318: 124074, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32916462

RESUMO

Pseudomonas sp. C27 can effectively conduct denitrifying sulfide removal (DSR) reactions via autotrophic denitrification, heterotrophic denitrification and coupled-cycle pathway. This study is the first to cultivate strain C27 using nitrite as the sole nitrogen source, and to conduct shotgun proteomics analysis and investigate the characteristics of DSR growth of strain C27 with nitrate or nitrite as sole nitrogen source. Shotgun proteomics analysis identified a total of 42 specially expressed proteins of C27 in the nitrite medium, based on which, together with chemical analysis data, a supplementary pathway of sulfur metabolism for C27 from sulfate to thiosulfate via intermediate adenosine-5'-phosphosulfate and 3'-phosphoadenosine-5'-phosphosulfate was proposed. Based on the newly revised scheme, the use of nitrite as sole nitrogen source expands the assessible regime of DSR reactions by C27 and provides the potential to recover renewable chemicals such as pyruvate and succinate from the coupled-cycle pathway.


Assuntos
Nitritos , Nitrogênio , Desnitrificação , Nitratos , Proteômica , Pseudomonas , Sulfetos
18.
Bioresour Technol ; 318: 124105, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32932113

RESUMO

In this study, denitrification was performed using pyrite as sole electron donor. The nitrate reducing rate ranged from 0.61 to 0.95 mM/d. The production of nitrous oxide (N2O) was observed, accounting for 20% of the total nitrate reduction. The isotope fractionation indicated that N2O production was mainly caused by the bacterial denitrification, instead of chemical denitrification by Fe(Ⅱ). Thiobacillus was the predominant genus, of which relative abundance decreased after the incubation with pyrite. Conversely, other genera belonging to Actinobacteria, like Rhodococcus, increased by more than 10 times. These Actinobacteria-like bacteria lack nitrous oxide reductase, which might be the reason for high N2O production. Furthermore, the predicted microbial functions analysis by PICRUSt2 showed that the genes (menC/E/G) involved in the biosynthesis of electron shuttles (menaquinone-related redox-active molecule), which were remarkably enriched during the process, suggesting that the first step of pyrite oxidation might be driven by the microbial derived electron shuttles.


Assuntos
Desnitrificação , Elétrons , Ferro , Nitratos , Óxido Nitroso , Sulfetos
19.
J Environ Manage ; 276: 111354, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32956940

RESUMO

A monolithic new attitude utilizing Aspen Plus software and Taguchi method has been applied to evaluate a novel configuration for removal of toxic heavy metals during sulfide ores recovery using potassium permanganate (KMnO4). In this new configuration, KMnO4 has been produced by sludge recovery of cobalt purification step containing manganese (IV) oxide (MnO2). Also, in this suggested configuration, the required sulfuric acid (H2SO4) solvent has been provided by recovery of sulfur compounds released during leaching process of sulfide ores. The optimum condition obtained by Taguchi experimental design has been used as initial data for the simulation and sensitivity analysis of process via Aspen Plus software. A systematic study of the design and operating condition has been made for key performance metrics such as removal of toxic heavy metal from sulfide ores, recovery of KMnO4 from sludge containing MnO2 and conversion of released sulfide gases to H2SO4 at the different operating condition such as H2SO4 concentration of 60-90 g/L, operating temperature of 60-150 °C, agitation rate of 100-400 rpm, reaction time of 0.5-2 h, solid to liquid ratio of 1:1-1:4, particle size of 10-500 µm, additive amount of 10-40 wt% and oxygen pressure of 0.5-2 MPa. The optimum condition for removal of toxic heavy metal have been found to be H2SO4 concentration of 70 g/L, temperature of 90 °C, agitation rate of 200 rpm, reaction time of 1.5 h, particle size of 500 µm, solid to liquid ratio of 1:2, additive amount of 40 wt% and oxygen pressure of 1.5 MPa. According to simulation results, the maximum conversion of released sulfide gases to H2SO4, recovery of KMnO4 and toxic heavy metals removal during designed process at optimized condition are 98%, 91% and 99%, respectively.


Assuntos
Metais Pesados , Gerenciamento de Resíduos , Compostos de Manganês , Óxidos , Permanganato de Potássio , Sulfetos
20.
Met Ions Life Sci ; 202020 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-32851826

RESUMO

Nitrous oxide reductase catalyzes the reduction of nitrous oxide (N2O) to dinitrogen (N2) and water at a catalytic tetranuclear copper sulfide center, named CuZ, overcoming the high activation energy of this reaction. In this center each Cu atom is coordinated by two imidazole rings of histidine side-chains, with the exception of one named CuIV. This enzyme has been isolated with CuZ in two forms CuZ(4Cu1S) and CuZ(4Cu2S), which differ in the CuI-CuIV bridging ligand, leading to considerable differences in their spectroscopic and catalytic properties. The Cu atoms in CuZ(4Cu1S) can be reduced to the [4Cu1+] oxidation state, and its catalytic properties are compatible with the nitrous oxide reduction rates of whole cells, while in CuZ(4Cu2S) they can only be reduced to the [1Cu2C-3Cu1C] oxidation state, which has a very low turnover number. The catalytic cycle of this enzyme has been explored and one of the intermediates, CuZ0, has recently been identified and shown to be in the [1Cu2+-3Cu1+] oxidation state. Contrary to CuZ(4Cu2S), CuZ0 is rapidly reduced intramolecularly by the electron transferring center of the enzyme, CuA, to [4Cu1+] by a physiologically relevant redox partner. The three-dimensional structure of nitrous oxide reductase with the CuZ center either as CuZ(4Cu1S) or as CuZ(4Cu2S) shows that it is a unique functional dimer, with the CuZ of one subunit receiving electrons from CuA of the other subunit. The complex nature of this center has posed some questions relative to its assembly, which are only partially answered, as well as to which is the active form of CuZ in vivo. The structural, spectroscopic, and catalytic features of the two forms of CuZ will be addressed here, as well as its assembly. The understanding of its catalytic features, activation, and assembly is essential to develop strategies to decrease the release of nitrous oxide to the atmosphere and to reduce its concentration in the stratosphere, as well as to serve as inspiration to synthetic inorganic chemists to develop new models of this peculiar and challenging copper sulfide center.


Assuntos
Oxirredutases/metabolismo , Cobre , Oxirredução , Sulfetos
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