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1.
Food Chem ; 303: 125381, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31473459

RESUMO

To reduce food loss from stored products by insect attack, monitoring and early detection of insects are essential. Presently, monitoring with pheromone traps is the primary method for detection; however, traps are effective only after the insects propagate. Detection and identification of the early volatile biomarkers arising from insect-infested brown rice was performed in this study to develop an alternative detection strategy. Brown rice was infested with eggs of seven insect species, including Sitophilus zeamais and Plodia interpunctella. Infested rice emitted at least one of the volatile compounds prenol, isoprenol, dimethyl disulfide, and dimethyl trisulfide (DMTS). In particular, isopentenols were generated by moths within one week of infestation, whereas they were not released from non-infested rice. DMTS was detected from all insect-infested brown rice, especially S. zeamais and P. interpunctella. These volatiles are potential early biomarkers for the presence of insects in brown rice.


Assuntos
Contaminação de Alimentos/análise , Insetos/metabolismo , Oryza , Pentanóis/análise , Sulfetos/análise , Animais , Biomarcadores/análise , Biomarcadores/metabolismo , Dissulfetos/análise , Dissulfetos/metabolismo , Hemiterpenos , Insetos/fisiologia , Larva/metabolismo , Pentanóis/metabolismo , Sulfetos/metabolismo , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/metabolismo
2.
Bioelectrochemistry ; 131: 107349, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31476657

RESUMO

Several textile industry processes produce complex organics, azo dyes and sulfide streams that pose a severe challenge to environmental protection. In this work, single-chamber air cathode microbial fuel cells were used to investigate the interaction mechanisms among Congo red decolorization, sulfide oxidation and bioelectricity generation. The results showed that effective removal of sulfide (>98%) and azo dyes (>88%) was achieved at an initial sulfide/dye ratio of 0.9 under neutral conditions, accompanied by a maximum power output of approximately 23.50 mW m-2. In this study, biogenic sulfide played a major role in azo dye decolorization and power generation compared with the chemical sulfide. The results indicated that bulk reduction of sulfide and cell lysis products during biogenic sulfide production by sulfate-reduction bacteria could accelerate the chemical reduction of azo dyes. Moreover, S0, SO42- and S2O32- were identified as degradation products, and the intermediates primarily included 3,4-diaminonaphthalene-1-sulfonic acid, sodium 4-aminonaphthalene-1-sulfonate and 4, 4'-diamine biphenyl. Microbial community analysis showed that Proteobacteria (80.7%), Gammaproteobacteria (48.1%), and Dokdonella (29.5%) dominated at the phylum, class, and genus levels, respectively, of the anodic biofilm. This study offers a feasible option for the treatment of recalcitrant organics, azo dyes and sulfide pollutants using single-chamber air cathode MFCs.


Assuntos
Compostos Azo/metabolismo , Fontes de Energia Bioelétrica , Eletrodos , Microbiota , Sulfetos/metabolismo , Compostos Azo/isolamento & purificação , Cor , Vermelho Congo/metabolismo , Gammaproteobacteria/metabolismo , Filogenia , Proteobactérias/metabolismo
3.
Mol Immunol ; 116: 140-150, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31654938

RESUMO

BACKGROUND: Non-specific lipid transfer proteins (LTPs) are important allergens in fruits, pollen, vegetables, nuts and latex. Due to their compact structure, LTPs are highly resistant to heat treatment. Here, Art v 3 from mugwort pollen and Pru p 3 from peach were used as model allergens to in-depth investigate structural and immunological properties upon thermal treatment at different buffer conditions. METHODS: Recombinant Art v 3 and Pru p 3 were purified from E. coli and incubated at 95 °C up to 120 min using sodium phosphate buffer pH 3.4 or 7.3. Physicochemical properties of allergens were analyzed in circular dichroism spectroscopy, Fourier transform infrared spectroscopy, dynamic light scattering, size exclusion chromatography, and mass spectrometry. The crystal structure of Art v 3.0201 was determined to 1.9 Šresolution. IgG and IgE binding was investigated in ELISA using murine and LTP allergic patients' sera. RESULTS: Highly pure and homogenous recombinant allergens were obtained from bacterial production. The crystal structure of Art v 3.0201 revealed an antiparallel four helix bundle with a C-terminal extension mediating an asymmetric, transient dimer interface and differently sized cavities. Both allergens showed high thermal stability at acidic conditions. In contrast, extensive heat treatment in neutral buffer induced irreversible structural changes due to lanthionine-based cysteine rearrangement. This fostered loss of the typical α-helical structure, increased molecular size and abrogation of IgG and IgE binding epitopes. Pru p 3 lost its structural integrity at shorter heat stress duration than Art v 3, which did however only partially affect the molecule's IgE binding epitopes. CONCLUSION: During thermal treatment, susceptibility to structural changes of the LTP-fold is highly dependent on the surrounding environment but also on intrinsic features of individual LTPs. This is a crucial fact to consider when processing LTP-containing food or food products as this will directly influence their allergenic potential.


Assuntos
Alanina/análogos & derivados , Antígenos de Plantas/metabolismo , Proteínas de Transporte/metabolismo , Cisteína/metabolismo , Proteínas de Plantas/metabolismo , Sulfetos/metabolismo , Alanina/metabolismo , Sequência de Aminoácidos , Animais , Artemisia/metabolismo , Reações Cruzadas/fisiologia , Epitopos/metabolismo , Escherichia coli/metabolismo , Hipersensibilidade Alimentar/metabolismo , Humanos , Imunoglobulina E/metabolismo , Imunoglobulina G/metabolismo , Camundongos , Pólen/metabolismo , Prunus/metabolismo
4.
Nat Commun ; 10(1): 4556, 2019 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-31591394

RESUMO

The chemistry of the Early Earth is widely inferred from the elemental and isotopic compositions of sulfidic sedimentary rocks, which are presumed to have formed globally through the reduction of seawater sulfate or locally from hydrothermally supplied sulfide. Here we argue that, in the anoxic Archean oceans, pyrite could form in the absence of ambient sulfate from organic sulfur contained within living cells. Sulfides could be produced through mineralization of reduced sulfur compounds or reduction of organic-sourced sulfite. Reactive transport modeling suggests that, for sulfate concentrations up to tens of micromolar, organic sulfur would have supported 20 to 100% of sedimentary pyrite precipitation and up to 75% of microbial sulfur reduction. The results offer an alternative explanation for the low range of δ34S in Archean sulfides, and raise a possibility that sulfate scarcity delayed the evolution of dissimilatory sulfate reduction until the initial ocean oxygenation around 2.7 Ga.


Assuntos
Compostos Orgânicos/metabolismo , Sulfatos/metabolismo , Compostos de Enxofre/metabolismo , Enxofre/metabolismo , Sedimentos Geológicos/química , Ferro/metabolismo , Oxirredução , Água do Mar/química , Sulfetos/metabolismo , Sulfitos/metabolismo , Isótopos de Enxofre/metabolismo
5.
Chem Asian J ; 14(21): 3898-3914, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31545553

RESUMO

Simultaneous incorporation of both CoII and CoIII ions within a new thioether S-bearing phenol-based ligand system, H3 L (2,6-bis-[{2-(2-hydroxyethylthio)ethylimino}methyl]-4-methylphenol) formed [Co5 ] aggregates [CoII CoIII 4 L2 (µ-OH)2 (µ1,3 -O2 CCH3 )2 ](ClO4 )4 ⋅H2 O (1) and [CoII CoIII 4 L2 (µ-OH)2 (µ1,3 -O2 CC2 H5 )2 ](ClO4 )4 ⋅H2 O (2). The magnetic studies revealed axial zero-field splitting (ZFS) parameter, D/hc=-23.6 and -24.3 cm-1 , and E/D=0.03 and 0.00, respectively for 1 and 2. Dynamic magnetic data confirmed the complexes as SIMs with Ueff /kB =30 K (1) and 33 K (2), and τ0 =9.1×10-8  s (1), and 4.3×10-8  s (2). The larger atomic radius of S compared to N gave rise to less variation in the distortion of tetrahedral geometry around central CoII centers, thus affecting the D and Ueff /kB values. Theoretical studies also support the experimental findings and reveal the origin of the anisotropy parameters. In solutions, both 1 and 2 which produce {CoIII 2 (µ-L)} units, display solvent-dependent catechol oxidation behavior toward 3,5-di-tert-butylcatechol in air. The presence of an adjacent CoIII ion tends to assist the electron transfer from the substrate to the metal ion center, enhancing the catalytic oxidation rate.


Assuntos
Catecol Oxidase/química , Cobalto/química , Complexos de Coordenação/síntese química , Sulfetos/química , Enxofre/química , Catecol Oxidase/metabolismo , Cobalto/metabolismo , Complexos de Coordenação/química , Complexos de Coordenação/metabolismo , Cristalografia por Raios X , Peróxido de Hidrogênio/análise , Cinética , Ligantes , Campos Magnéticos , Modelos Moleculares , Estrutura Molecular , Oxirredução , Sulfetos/metabolismo , Enxofre/metabolismo
6.
Chemosphere ; 236: 124381, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31545190

RESUMO

Biological sulfur reduction is an attractive sulfidogenic technology for the treatment of organics-deficient metal-laden wastewater, because it theoretically reduces the electron donor consumption by 75%, compared to sulfate reduction. However, reducing the external organic substrate dosage may lower the sulfur reduction rate. Supplying with a more biodegradable organic substrate could possibly enhance sulfidogenic activity but also increase the chemical cost. Therefore, the sulfide production performance of a sulfur-reducing bioreactor feeding with varied levels of organic supply, and different types of organic substrates were investigated. The results showed that high-rate sulfide production (12.30 mg S/L/h) in a sulfur-reducing bioreactor can be achieved at the minimal dosage of organic substrate as low as 39 mg C/L of organic carbon in the influent. Changing the type of organic substrate posed a significant effect on the sulfidogenic activity in the sulfur-reducing bioreactor. Sodium acetate was found to be the optimal substrate to achieve the highest sulfide production rate (28.20 mg S/L/h) by sulfur-reducing bacteria (S0RB), followed by ethanol, methanol, glycerol, pyruvic acid, acetic acid, glucose, sucrose, malic acid, sodium formate, formic acid, N-propanol, N-butanol, lactic acid, sodium lactate, propionic acid and sodium propionate (2.87 mg S/L/h as the lowest rate). However, the cost-effectiveness analysis showed that glucose was the most cost-effective organic substrate to realize the sulfur reduction process in high sulfide production rate (20.13 mg S/L/h) and low chemical cost (5.94 kg S/$). The utilization pathway of the different organic substrates in the sulfur-reducing bioreactor was also discussed.


Assuntos
Reatores Biológicos/microbiologia , Compostos Orgânicos/análise , Bactérias Redutoras de Enxofre/metabolismo , Enxofre/metabolismo , Purificação da Água/métodos , Reatores Biológicos/economia , Análise Custo-Benefício , Metais/metabolismo , Compostos Orgânicos/economia , Compostos Orgânicos/metabolismo , Oxirredução , Sulfatos/metabolismo , Sulfetos/metabolismo , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/microbiologia , Purificação da Água/economia
7.
Int. microbiol ; 22(3): 305-316, sept. 2019. ilus, graf, tab
Artigo em Inglês | IBECS | ID: ibc-184837

RESUMO

Effluents from petroleum refineries contain a toxic mixture of sulfide, nitrogen, and phenolic compounds that require adequate treatment for their removal. Biological denitrification processes are a cost-effective option for the treatment of these effluents, but the knowledge on the microbial interactions in simultaneous sulfide and phenol oxidation in denitrifying reactors is still very limited. In this work, microbial community structure and macrostructure of granular biomass were studied in three denitrifying reactors treating a mixture of inorganic (sulfide) and organic (p-cresol) electron donors for their simultaneous removal. The differences in the available substrates resulted in different community assemblies that supported high removal efficiencies, indicating the community adaptation capacity to the fluctuating compositions of industrial effluents. The three reactors were dominated by nitrate reducing and denitrifying bacteria where Thiobacillus spp. were the prevalent denitrifying organisms. The toxicity and lack of adequate substrates caused the endogenous decay of the biomass, leading to release of organic matter that maintained a diverse although not very abundant group of heterotrophs. The endogenous digestion of the granules caused the degradation of its macrostructure, which should be considered to further develop the denitrification process in sulfur-based granular reactors for treatment of industrial wastewater with toxic compounds


No disponible


Assuntos
Águas Residuárias/microbiologia , Desnitrificação , Microbiota , Sulfetos/metabolismo , Cresóis/química , Bactérias/metabolismo , Indústria de Petróleo e Gás , Ciclo do Nitrogênio , Sulfetos/química , Nitratos/química , Thiobacillus/isolamento & purificação , Biomassa
8.
Microbes Environ ; 34(3): 304-309, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31391357

RESUMO

Chloroflexus aggregans is a thermophilic filamentous anoxygenic phototrophic bacterium frequently found in microbial mats in natural hot springs. C. aggregans often thrives with cyanobacteria that engage in photosynthesis to provide it with an organic substrate; however, it sometimes appears as the dominant phototroph in microbial mats without cyanobacteria. This suggests that C. aggregans has the ability to grow photoautotrophically. However, photoautotrophic growth has not been observed in any cultured strains of C. aggregans. We herein attempted to isolate a photoautotrophic strain from C. aggregansdominated microbial mats in Nakabusa hot spring in Japan. Using an inorganic medium, we succeeded in isolating a new strain that we designated "ACA-12". A phylogenetic analysis based on 16S rRNA gene and 16S-23S rRNA gene internal transcribed spacer (ITS) region sequences revealed that strain ACA-12 was closely related to known C. aggregans strains. Strain ACA-12 showed sulfide consumption along with autotrophic growth under anaerobic light conditions. The deposited elemental sulfur particles observed by microscopy indicated that sulfide oxidation occurred, similar to that in photoautotrophic strains in the related species, C. aurantiacus. Moreover, we found that other strains of C. aggregans, including the type strain, also exhibited a slight photoautotrophic growing ability, whereas strain ACA-12 showed the fastest growth rate. This is the first demonstration of photoautotrophic growth with sulfide in C. aggregans. The present results strongly indicate that C. aggregans is associated with inorganic carbon incorporation using sulfide as an electron donor in hot spring microbial mats.


Assuntos
Chloroflexus/metabolismo , Processos Fototróficos , Sulfetos/metabolismo , Proteínas de Bactérias/genética , Chloroflexus/classificação , Chloroflexus/genética , Chloroflexus/efeitos da radiação , Meios de Cultura/química , DNA Bacteriano/genética , DNA Espaçador Ribossômico/genética , Fontes Termais/microbiologia , Japão , Luz , Oxirredução , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Sulfetos/análise , Enxofre/metabolismo
9.
Nat Commun ; 10(1): 3566, 2019 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-31395877

RESUMO

Iron-sulfur (Fe-S) clusters are essential protein cofactors whose biosynthetic defects lead to severe diseases among which is Friedreich's ataxia caused by impaired expression of frataxin (FXN). Fe-S clusters are biosynthesized on the scaffold protein ISCU, with cysteine desulfurase NFS1 providing sulfur as persulfide and ferredoxin FDX2 supplying electrons, in a process stimulated by FXN but not clearly understood. Here, we report the breakdown of this process, made possible by removing a zinc ion in ISCU that hinders iron insertion and promotes non-physiological Fe-S cluster synthesis from free sulfide in vitro. By binding zinc-free ISCU, iron drives persulfide uptake from NFS1 and allows persulfide reduction into sulfide by FDX2, thereby coordinating sulfide production with its availability to generate Fe-S clusters. FXN stimulates the whole process by accelerating persulfide transfer. We propose that this reconstitution recapitulates physiological conditions which provides a model for Fe-S cluster biosynthesis, clarifies the roles of FDX2 and FXN and may help develop Friedreich's ataxia therapies.


Assuntos
Ferredoxinas/metabolismo , Proteínas de Ligação ao Ferro/metabolismo , Proteínas com Ferro-Enxofre/metabolismo , Sulfetos/metabolismo , Liases de Carbono-Enxofre/metabolismo , Ferredoxinas/isolamento & purificação , Ataxia de Friedreich/patologia , Ferro/metabolismo , Proteínas de Ligação ao Ferro/isolamento & purificação , Proteínas com Ferro-Enxofre/química , Proteínas com Ferro-Enxofre/genética , Mutagênese Sítio-Dirigida , Ressonância Magnética Nuclear Biomolecular , Oxirredução , Espectroscopia de Prótons por Ressonância Magnética , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Zinco/metabolismo
10.
Microbes Environ ; 34(3): 293-303, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31378759

RESUMO

Candidatus Hydrothermarchaeota, formally called Marine Benthic Group E, has often been detected in iron- and sulfur-rich marine environments, such as hydrothermal vents and cold seeps. However, their ecology and physiology remain unclear. Cultivated representatives of this group are still lacking and only several metagenome-assembled genomes (MAGs) and single-amplified genomes (SAGs) are available from two deep-sea hydrothermal areas, the Juan de Fuca Ridge (JdFR) and Guaymas Basin (GB), in the north-east Pacific. We herein report four MAGs of Ca. Hydrothermarchaeota recovered from hydrothermally-inactive metal sulfide deposits at the Southern Mariana Trough (SMT) in the north-west Pacific. A phylogenetic analysis indicated that the MAGs of the SMT were distinct from those of the JdFR and GB at the genus or potentially family level. Ca. Hydrothermarchaeota MAGs from the SMT commonly possessed putative genes for carboxydotrophic and hydrogenotrophic respiration using oxidized chemical species of sulfur as electron acceptors and also for carbon fixation, as reported previously in MAGs/SAGs from the JdFR and GB. This result strongly supports Ca. Hydrothermarchaeota containing anaerobic chemolithoautotrophs using carbon monoxide and/or hydrogen as electron donors. A comparative genome analysis highlighted differences in the capability of nitrogen fixation between MAGs from the SMT and the other fields, which are consistent with environmental differences in the availability of nitrogen sources for assimilation between the fields. Based on the wide distribution in various areas, abundance, and metabolic potential of Ca. Hydrothermarchaeota, they may play a role in the biogeochemical cycling of carbon, nitrogen, sulfur, and iron in marine environments, particularly in deep-sea hydrothermal fields.


Assuntos
Archaea/classificação , Archaea/metabolismo , Sedimentos Geológicos/microbiologia , Filogenia , Água do Mar/microbiologia , Archaea/genética , Archaea/isolamento & purificação , Proteínas Arqueais/genética , Monóxido de Carbono/metabolismo , DNA Arqueal/genética , Sedimentos Geológicos/química , Hidrogênio/metabolismo , Fontes Hidrotermais/química , Fontes Hidrotermais/microbiologia , Metagenoma , Metais/análise , Metais/metabolismo , Nitratos/metabolismo , Oxirredução , Oceano Pacífico , RNA Ribossômico 16S/genética , Água do Mar/química , Sulfetos/análise , Sulfetos/metabolismo
11.
J Sci Food Agric ; 99(15): 6944-6953, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31414495

RESUMO

BACKGROUND: Dimethyl sulfide (DMS) is a small sulfur-containing impact odorant, imparting distinctive positive and / or negative characters to food and beverages. In white wine, the presence of DMS at perception threshold is considered to be a fault, contributing strong odors reminiscent of asparagus, cooked cabbage, and creamed corn. The source of DMS in wine has long been associated with S-methyl-l-methionine (SMM), a derivative of the amino acid methionine, which is thought to break down into DMS through chemical degradation, particularly during wine ageing. RESULTS: We developed and validated a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with a stable isotope dilution assay (SIDA) to measure SMM in grape juice and wine. The application of this new method for quantitating SMM, followed by the quantitation of DMS using headspace-solid phase micro-extraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS), confirmed that DMS can be produced in wine via the chemical breakdown of SMM to DMS, with greater degradation observed at 28 °C than at 14 °C. Further investigation into the role of grape juice and yeast strain on DMS formation revealed that the DMS produced from three different Sauvignon blanc grape juices, either from the SMM naturally present or SMM spiked at 50 mmol L-1 , was modulated depending on each of the four strains of Saccharomyces cerevisiae wine yeast used for fermentation. CONCLUSION: This study confirms the existence of a chemical pathway to the formation of DMS and reveals a yeast-mediated mechanism towards the formation of DMS from SMM during alcoholic fermentation. © 2019 Society of Chemical Industry.


Assuntos
Cromatografia Líquida/métodos , Sucos de Frutas e Vegetais/análise , Saccharomyces cerevisiae/metabolismo , Sulfetos/metabolismo , Espectrometria de Massas em Tandem/métodos , Vitamina U/análise , Vitis/química , Fermentação , Frutas/química , Frutas/metabolismo , Frutas/microbiologia , Sucos de Frutas e Vegetais/microbiologia , Odorantes/análise , Sulfetos/análise , Vitamina U/metabolismo , Vitis/metabolismo , Vitis/microbiologia , Vinho/análise
12.
Biomater Sci ; 7(8): 3450-3459, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31268067

RESUMO

Bismuth-containing nanoparticles (BNPs) are potential enhancers for tumor radiotherapy. Improving the bioavailability and developing synergistic therapeutic regimens benefit the drug transformation of BNPs. In the present study, we prepare a mesoporous silica-coated bismuth nanorod (BMSNR) camouflaged by a platelet membrane (PM). This biomimetic material is termed BMSNR@PM. The PM camouflage enhances the immune escape of the BMSNRs by lowering endocytosis by macrophages in the reticuloendothelial system. Additionally, the PM camouflage strengthens the material tumor-targeting capacity and leads to better radiotherapeutic efficacy compared with bare BMSNRs. Owing to the photothermal effect, BMSNR@PMs alters the cell cycle of 4T1 cancer cells post-treatment with 808 nm near-infrared irradiation (NIR). The proportions of S phase and G2/M phase cells decrease and increase, respectively, which explains the synergistic effect of NIR on BMSNR@PM-based radiotherapy. BMSNR@PMs efficiently eradicates cancer cells by the combined action of photothermal therapy (PTT) and radiotherapy in vivo and markedly improves the survival of 4T1-tumor-bearing mice. The synergistic therapeutic effect is superior to the outcomes of PTT and radiotherapy performed alone. Our study demonstrates a versatile bismuth-containing nanoplatform with tumor-targeting, immune escape, and radiosensitizing functionalities using an autologous cell membrane biomimetic concept that may promote the development of radiotherapy enhancers.


Assuntos
Bismuto/química , Bismuto/farmacologia , Plaquetas/citologia , Neoplasias da Mama/terapia , Membrana Celular/metabolismo , Nanotubos/química , Fototerapia , Sulfetos/química , Sulfetos/farmacologia , Animais , Bismuto/metabolismo , Neoplasias da Mama/patologia , Neoplasias da Mama/radioterapia , Linhagem Celular Tumoral , Terapia Combinada , Endocitose , Feminino , Humanos , Macrófagos/metabolismo , Camundongos , Nanocompostos/química , Porosidade , Células RAW 264.7 , Radiossensibilizantes/química , Radiossensibilizantes/metabolismo , Radiossensibilizantes/farmacologia , Dióxido de Silício/química , Sulfetos/metabolismo
13.
Chemosphere ; 234: 568-578, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31229718

RESUMO

The pathways and intermediates of continuous sulfur biotransformation in an anaerobic and anoxic sequential batch reactor (AA-SBR) involving sulfate reduction (SR) and denitrifying sulfide oxidization (DSO) were investigated. In the anoxic phase, DSO occurred in two sequential steps, the oxidation of sulfide (S2-) to elemental sulfur (S0) and the oxidation of S0 to sulfate (SO42-). The oxidation rate of S2- to S0 was 3.31 times faster than that of S0 to SO42-, resulting in the accumulation of S0 as a desired intermediate under S2--S/NO3--N ratio (molar ratio) of 0.9:1. Although, approximately 60% of generated S0 suspended in the effluent, about 40% of S0 retained in the sludge, which could be further oxidized or reduced in anoxic or anaerobic phase. In anoxic, S0 was subsequently oxidized to SO42- under S2--S/NO3--N ratio of 0.5:1. In anaerobic, S0 coexist with SO42- (in fresh wastewater) were simultaneously reduced to S2-, and the reduction rate of SO42- to S2- was 3.17 times faster than that of S0 to S2-, resulting in a higher production of S0 in subsequent anoxic phase. Microbial community analysis indicated that SO42-/S0-reducing bacteria (e.g. Desulfomicrobium and Desulfuromonas) and S2-/S0-oxidizing bacteria (e.g. Paracoccus and Thermothrix) co-participated in continuous sulfur biotransformation in the AA-SBR. A conceptual model was established to describe these main processes and key intermediates. The research offers a new insight into the reaction processes optimization for S0 recovery and simultaneous removal of SO42- and NO3- in an AA-SBR.


Assuntos
Anaerobiose , Reatores Biológicos/microbiologia , Biotransformação , Desnitrificação , Enxofre/metabolismo , Bactérias/metabolismo , Oxirredução , Esgotos/microbiologia , Sulfatos/metabolismo , Sulfetos/metabolismo , Águas Residuárias/microbiologia
14.
Chem Commun (Camb) ; 55(60): 8868-8871, 2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31240288

RESUMO

New evidence on the role of H2S as a gasotransmitter suggests that the true signalling effectors are polysulfides. Both oxidized polysulfides and hydropolysulfides were synthesized and their presence in S. cerevisiae was observed for the first time. A single gene-deletant approach allowed observation of the modulation of polysulfide species and levels.


Assuntos
Gasotransmissores/análise , Saccharomyces cerevisiae/química , Sulfetos/análise , Proteínas de Transporte/genética , Cistationina beta-Sintase/genética , Cistationina gama-Liase/genética , Gasotransmissores/síntese química , Gasotransmissores/metabolismo , Deleção de Genes , Metabolômica/métodos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Sulfetos/síntese química , Sulfetos/metabolismo
15.
J Ind Microbiol Biotechnol ; 46(8): 1113-1127, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31165968

RESUMO

Extremely thermoacidophilic Crenarchaeota belonging to the order Sulfolobales, such as Metallosphaera sedula, are metabolically versatile and of great relevance in bioleaching. However, the impacts of extreme thermoacidophiles propagated with different energy substrates on subsequent bioleaching of refractory chalcopyrite remain unknown. Transcriptional responses underlying their different bioleaching potentials are still elusive. Here, it was first showed that M. sedula inocula propagated with typical energy substrates have different chalcopyrite bioleaching capabilities. Inoculum propagated heterotrophically with yeast extract was deficient in bioleaching; however, inoculum propagated mixotrophically with chalcopyrite, pyrite or sulfur recovered 79%, 78% and 62% copper, respectively, in 12 days. Compared with heterotrophically propagated inoculum, 937, 859 and 683 differentially expressed genes (DEGs) were identified in inoculum cultured with chalcopyrite, pyrite or sulfur, respectively, including upregulation of genes involved in bioleaching-associated metabolism, e.g., Fe2+ and sulfur oxidation, CO2 fixation. Inoculum propagated with pyrite or sulfur, respectively, shared 480 and 411 DEGs with chalcopyrite-cultured inoculum. Discrepancies on repertories of DEGs that involved in Fe2+ and sulfur oxidation in inocula greatly affected subsequent chalcopyrite bioleaching rates. Novel genes (e.g., Msed_1156, Msed_0549) probably involved in sulfur oxidation were first identified. This study highlights that mixotrophically propagated extreme thermoacidophiles especially with chalcopyrite should be inoculated into chalcopyrite heaps at industrial scale.


Assuntos
Cobre/metabolismo , Sulfolobaceae/metabolismo , Processos Heterotróficos , Ferro/metabolismo , Oxirredução , Sulfetos/metabolismo , Sulfolobaceae/genética , Enxofre/metabolismo
16.
Ecotoxicol Environ Saf ; 181: 336-344, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31202934

RESUMO

The present study focused on the bioaccumulation and cytotoxicities of Cd2+, CdSe quantum dots (QDs) and CdSe/ZnS QDs in Escherichia coli (E. coli, represents prokaryotic system) and Phanerochaete chrysosporium (P. chrysosporium, represents eukaryotic system), respectively. Two types of QDs were characterized by transmission electron microscopy (TEM) and dynamic light scattering. The inductively coupled plasma optical emission spectrometer results showed that the bioaccumulation amounts of CdSe QDs by E. coli and P. chrysosporium were larger than those of CdSe/ZnS QDs due to the smaller particle size and less negative surface charges of CdSe QDs. Confocal microscopy and TEM results showed that there was an interaction between QDs and cells, and QDs have entered into the cells eventually, leading to the change of cell morphology. Plasma membrane fluidities and membrane H+-ATPase activities of E. coli and P. chrysosporium decreased gradually with the increasing concentrations of Cd2+, CdSe and CdSe/ZnS QDs. Results of the cell viabilities and intracellular reactive oxygen species levels indicated that the induced cytotoxicities were decreased as follows: CdSe QDs > CdSe/ZnS QDs > Cd2+. These findings suggested that the cytotoxicity of QDs was not only attributed to their heavy metal components, but also related to their nanosize effects which could induce particle-specific toxicity. The above results offer valuable information for exploring the cytotoxicity mechanism of QDs in prokaryote and eukaryote.


Assuntos
Compostos de Cádmio/toxicidade , Cádmio/toxicidade , Pontos Quânticos/toxicidade , Compostos de Selênio/toxicidade , Sulfetos/toxicidade , Compostos de Zinco/toxicidade , Citotoxinas/metabolismo , Citotoxinas/toxicidade , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Escherichia coli/ultraestrutura , Íons , Fluidez de Membrana/efeitos dos fármacos , Viabilidade Microbiana/efeitos dos fármacos , Phanerochaete/efeitos dos fármacos , Phanerochaete/ultraestrutura , Pontos Quânticos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sulfetos/metabolismo , Compostos de Zinco/metabolismo
17.
Chemosphere ; 233: 252-260, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31176126

RESUMO

Although 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane (DDT) was banned in the United States in 1972, it is still often detected in sediments where pyrogenic carbonaceous matter (PCM) and sulfate-reducing bacteria (SRB) co-exist. In this study, we found that 70.2 ±â€¯0.2% of DDT disappeared in the presence of SRB and graphite powder, a model PCM, after 21 days at pH 7. Our results suggest that the observed DDT decay was due to the reaction between graphite powder and the reduced sulfur species that were produced by SRB. No biofilm formation was observed on the surface of graphite powder. Rather, the activity of SRB was inhibited by the presence of graphite powder. To understand the involvement of PCM in DDT decay, electrochemical cells and batch reactor experiments with sulfur-pretreated PCM as well as direct electrochemical reduction by a potentiostat were employed. Our results suggest that polysulfide, sulfide, sulfite, and thiosulfate could all react with PCM, forming surface-bound intermediates that subsequently led to DDT decay. The reactivity of reduced sulfur species was the highest for polysulfide, followed by sulfide, sulfite, and thiosulfate.


Assuntos
DDT/química , DDT/metabolismo , Desulfovibrio/metabolismo , Biodegradação Ambiental , Poluentes Ambientais/química , Poluentes Ambientais/metabolismo , Grafite , Sulfetos/química , Sulfetos/metabolismo , Sulfitos/química , Sulfitos/metabolismo , Tiossulfatos/química , Tiossulfatos/metabolismo
18.
Environ Pollut ; 251: 738-745, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31112928

RESUMO

Pyrite weathering often occurs in nature and causes heavy metal ion pollution and acid mine drainage during the process. Humic acid (HA) is a critical natural organic material that can bind metal ions, thus affecting metal transfer and transformation. In this work, in situ electrochemical techniques combined with spectroscopic analysis were adopted to investigate the interfacial processes involved in pyrite weathering with/without HA. The results showed that the pyrite weathering mechanism with/without HA is FeS2 → Fe2+ + 2S0 + 2e-. The presence of HA did not change the pyrite weathering mechanism, but HA adsorbs on the pyrite surface and inhibits the further transformation of sulfur. Furthermore, HA and Fe(II) ions can form complex at 45.0 °C. Increased concentration of HA, decreased HA solution acidity or decreased environmental temperature would all weaken the pyrite weathering, for the above conditions cause pyrite weathering to have a larger resistance of the double layer and a larger passive film resistance. Pyrite will release 73.7 g m-2·y-1 Fe2+ to solution at pH 4.5, and the amount decreases to 36.8 g m-2·y-1 in the presence of 100 mg/L HA. This study provides an in situ electrochemical method for the assessment of pyrite weathering.


Assuntos
Técnicas Eletroquímicas , Meio Ambiente , Substâncias Húmicas/análise , Ferro/análise , Ferro/metabolismo , Sulfetos/análise , Sulfetos/metabolismo , Adsorção , Mineração , Enxofre/análise
19.
ISME J ; 13(9): 2264-2279, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31073213

RESUMO

There are many unknowns regarding the distribution, activity, community composition, and metabolic repertoire of microbial communities in the subseafloor of deep-sea hydrothermal vents. Here we provide the first characterization of subseafloor microbial communities from venting fluids along the central Mariana back-arc basin (15.5-18°N), where the slow-spreading rate, depth, and variable geochemistry along the back-arc distinguish it from other spreading centers. Results indicated that diverse Epsilonbacteraeota were abundant across all sites, with a population of high temperature Aquificae restricted to the northern segment. This suggests that differences in subseafloor populations along the back-arc are associated with local geologic setting and resultant geochemistry. Metatranscriptomics coupled to stable isotope probing revealed bacterial carbon fixation linked to hydrogen oxidation, denitrification, and sulfide or thiosulfate oxidation at all sites, regardless of community composition. NanoSIMS (nanoscale secondary ion mass spectrometry) incubations at 80 °C show only a small portion of the microbial community took up bicarbonate, but those autotrophs had the highest overall rates of activity detected across all experiments. By comparison, acetate was more universally utilized to sustain growth, but within a smaller range of activity. Together, results indicate that microbial communities in venting fluids from the Mariana back-arc contain active subseafloor communities reflective of their local conditions with metabolisms commonly shared across geologically disparate spreading centers throughout the ocean.


Assuntos
Bactérias/isolamento & purificação , Bactérias/metabolismo , Fontes Hidrotermais/microbiologia , Bactérias/classificação , Bactérias/genética , Ciclo do Carbono , Crescimento Quimioautotrófico , Hidrogênio/metabolismo , Fontes Hidrotermais/química , Microbiota , Filogenia , RNA Ribossômico 16S/metabolismo , Sulfetos/metabolismo
20.
Artigo em Inglês | MEDLINE | ID: mdl-31094279

RESUMO

Two types of solid bacterial agents for the simultaneous removal of methane and odor were designed using humic soil (De-MO-1) and the mixture of humic soil and tobermolite (De-MO-2) as biocarriers. The bacterial consortium, having the removability of methane and dimethyl sulfide (DMS), was immobilized in the biocarriers, and then stored at room temperature for 375 days without additional treatment. Although the lag period, of which the incubation time required for removing methane and DMS, tended to increase over the storage period, the removability of methane and DMS was maintained during 375 days in both bacterial agents. Key bacteria associated with the removal of methane and odors (Streptomyces, Promicromonospora, Paracoccus, Lysobacter, Sphingopyxis and Methylosystis) could keep their abundance during the storage period. The richness and evenness values of the bacterial communities in De-MO-1 and De-MO-2 ranged 4.89 ∼ 6.50 and 0.89 ∼ 0.98, respectively, indicating that high bacterial diversity was maintained during the storage period. The results suggest that De-MO-1 and De-MO-2, designed for the simultaneous removal of methane and odors, had shelf stabilities over one year.


Assuntos
Bactérias/metabolismo , Metano/metabolismo , Odorantes , Microbiologia do Solo , Bactérias/classificação , Bactérias/isolamento & purificação , Biodegradação Ambiental , Microbiota , Solo/química , Sulfetos/metabolismo
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