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1.
Int J Syst Evol Microbiol ; 70(9): 4927-4934, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32735535

RESUMO

Two Gram-stain-negative, Fe(III)-reducing, facultatively anaerobic, motile via a single polar flagellum, rod-shaped bacterial strains, designated IMCC35001T and IMCC35002T, were isolated from tidal flat sediment and seawater, respectively. Results of 16S rRNA gene sequence analysis showed that IMCC35001T and IMCC35002T shared 96.6 % sequence similarity and were most closely related to Ferrimonas futtsuensis FUT3661T (98.6 %) and Ferrimonas kyonanensis Asr22-7T (96.8 %), respectively. Draft genome sequences of IMCC35001T and IMCC35002T revealed 4.0 and 4.8 Mbp of genome size with 61.0 and 51.8 mol% of DNA G+C content, respectively. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 73.1 and 19.8 %, respectively, indicating that they are separate species. The two genomes showed ≤84.4 % ANI and ≤27.8 % dDDH to other species of the genus Ferrimonas, suggesting that the two strains each represent novel species. The two strains contained both menaquinone (MK-7) and ubiquinones (Q-7 and Q-8). Major fatty acids of strain IMCC35001T were iso-C15 : 0, C18 : 1 ω9c, C17 : 1 ω8c and C16 : 0 and those of strain IMCC35002 T were C18 : 1 ω9c, C16 : 0 and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c). Major polar lipids in both strains were phosphatidylethanolamine, phosphatidylglycerol, unidentified phospholipid, unidentified aminophospholipid and unidentified lipids. The two strains reduced Fe(III) citrate, Fe(III) oxyhydroxide, Mn(IV) oxide and sodium selenate but did not reduce sodium sulfate. They were also differentiated by several phenotypic characteristics. Based on the polyphasic taxonomic data, IMCC35001T and IMCC35002T were considered to represent each novel species in the genus Ferrimonas, for which the names Ferrimonas sediminicola sp. nov. (IMCC35001T=KACC 21161T=NBRC 113699T) and Ferrimonas aestuarii (IMCC35002T=KACC 21162T=NBRC 113700T) sp. nov. are proposed.


Assuntos
Gammaproteobacteria/classificação , Sedimentos Geológicos/microbiologia , Filogenia , Água do Mar/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Compostos Férricos/metabolismo , Gammaproteobacteria/isolamento & purificação , Hibridização de Ácido Nucleico , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Ubiquinona/química , Vitamina K 2/análogos & derivados , Vitamina K 2/química
2.
Int J Syst Evol Microbiol ; 70(8): 4730-4738, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32697189

RESUMO

An obligately alkaliphilic, anaerobic, proteolytic bacterium was isolated from a sample of Tanatar III soda lake sediment (Altai region, Russia) and designated as strain Z-1701T. Cells of strain Z-1701T were short, straight, motile Gram-stain-positive rods. Growth of Z-1701T obligately depended on the presence of sodium carbonate. Strain Z-1701T could utilize various peptides mixtures, such as beef and yeast extracts, peptone, soytone, trypticase and tryptone, as well as such proteins as albumin, gelatin and sodium caseinate. It was able to grow oligotrophically with 0.02 g l-1 yeast extract as the sole energy and carbon source. Carbohydrates did not support the growth of strain Z-1701T. The main products released during the growth of strain Z-1701T on tryptone were formate, acetate and ammonium. Strain Z-1701T was able to reduce ferrihydrite, Fe(III)-EDTA, anthraquinone-2,6-disulfonate and elemental sulfur, using proteinaceous substrates as electron donors. In all cases the presence of the electron acceptor in the medium stimulated growth. The main cellular fatty acids were iso-C15 : 0, iso-C15 : 0 aldehyde, iso-C15 : 1 ω6, C16 : 0, iso-C17 : 0 aldehyde, C16 : 0 aldehyde and C14 : 0. The DNA G+C content of the isolate was 43.9 mol%. Phylogenetic analysis based on the concatenated alignment of 120 protein-marker sequences revealed that strain Z-1701T falls into a cluster with the genus Tindallia, family Clostridiaceae. 16S rRNA gene sequence identity between strain Z-1701T and Tindallia species were 88.3-89.75 %. On the basis of its phenotypic characteristics and phylogenetic position, the novel isolate is considered to be a representative of a novel genus and species for which the name Isachenkonia alkalipeptolytica gen. nov., sp. nov. is proposed, with Z-1701T (=JCM 32929Т=DSM 109060Т=VKM B-3261Т) as its type strain.


Assuntos
Bactérias Anaeróbias/classificação , Compostos Férricos/metabolismo , Lagos/microbiologia , Filogenia , Bactérias Redutoras de Enxofre/classificação , Álcalis , Bactérias Anaeróbias/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Bacilos Gram-Positivos/classificação , Bacilos Gram-Positivos/isolamento & purificação , Concentração de Íons de Hidrogênio , RNA Ribossômico 16S/genética , Federação Russa , Análise de Sequência de DNA , Enxofre/metabolismo , Bactérias Redutoras de Enxofre/isolamento & purificação
3.
Chemosphere ; 259: 127445, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32593005

RESUMO

Iron oxide nanoparticles (nFe2O3)-filled materials have been widely employed in various products and their effects on plants have attracted considerable attention because of their potential release into the environment. Currently, numerous studies reporting the influences of iron-bearing nanoparticles on plants are focused on root or seed exposure. However, plants exposed to atmospheric iron-bearing nanoparticles through the leaves and their impacts on plants are still not well understood. This study focused on the uptake, translocation, and effects of foliar exposure of nFe2O3 on wheat seedlings. Wheat seedlings were foliar applied to various concentrations of nFe2O3 (0, 60 and 180 µg per plant) for 1, 7, 14 or 21 d. Our results demonstrated that after exposure for 21 d, the concentrations of Fe in leaves, stems, and roots were 1100, 280 and 160 µg kg-1, respectively. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), as well as the backscattered electron (BSE) images, revealed the stomatal opening was likely the pathway for nFe2O3 uptake. Analysis of the transfer rate, translocation of Fe from leaves to stems and roots, suggested the involvement of plant Fe regulation processes. Particularly, the antioxidant enzymatic activities and malondialdehyde levels in leaves were modified, which was ascribed to the excessive hydroxyl radical (OH) generated via the Fenton-like reaction mediated by nFe2O3. Finally, the OH facilitated the degradation of chlorophyll, posting a negative impact on the photosynthesis, and thus inhibited the biomass production. These findings are meaningful to understand the fate and physiological effects of atmospheric nFe2O3 in crops.


Assuntos
Compostos Férricos/toxicidade , Nanopartículas/toxicidade , Fotossíntese/efeitos dos fármacos , Triticum/efeitos dos fármacos , Antioxidantes/metabolismo , Transporte Biológico , Biomassa , Clorofila/metabolismo , Compostos Férricos/metabolismo , Ferro/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Sementes/metabolismo , Triticum/metabolismo , Triticum/fisiologia
4.
Inorg Chem ; 59(12): 8034-8043, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32452669

RESUMO

Cytochrome (Cyt) P450s are an important class of enzymes with numerous functions in nature. The unique reactivity of these enzymes relates to their heme b active sites with an axially bound, deprotonated cysteine (a "cysteinate") ligand (chemically speaking a thiolate). The heme-thiolate active sites further contain a number of conserved hydrogen-bonds (H-bonds) to the bound cysteinate ligand, which have been proposed to tune and stabilize the Fe-S bond. In this work, we present the low-temperature preparation of five ferric heme-thiolate nitric oxide (NO) model complexes that contain one tunable hydrogen-bond to the bound thiolate ligand. We show that the presence of a H-bond has a dramatic effect in stabilizing the thiolate ligand against direct reaction with NO. This observation reinforces the important protective role of H-bonds in Cyt P450s. We further demonstrate that H-bond strength tunes thiolate donor strength, which, in turn, controls the N-O and Fe-NO stretching frequencies and hence, bond strengths. We observe a direct correlation between the Fe-NO and N-O stretching frequencies, indicative of a thiolate σ-trans effect (interaction). Here, very small changes in H-bond strength lead to a surprisingly large effect on the FeNO unit. This result implies that subtle changes in the Cys-pocket of a Cyt P450 can strongly affect reactivity. Importantly, using the Fe-NO/N-O correlation established here, the thiolate donor strength in heme-thiolate enzyme active sites and model complexes can be quantified in a straightforward way, using NO as a probe. This spectroscopic correlation provides a quantitative measure of the thiolate's "push" effect, which is important in O2-activation (Compound I formation) in Cyt P450s in general.


Assuntos
Sistema Enzimático do Citocromo P-450/química , Compostos Férricos/química , Modelos Químicos , Compostos de Sulfidrila/química , Sistema Enzimático do Citocromo P-450/metabolismo , Teoria da Densidade Funcional , Compostos Férricos/metabolismo , Ligação de Hidrogênio , Compostos de Sulfidrila/metabolismo
5.
Biochem J ; 477(7): 1227-1240, 2020 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-32271881

RESUMO

The extracellular transporter, lipocalin-type prostaglandin D synthase (L-PGDS) binds to heme and heme metabolites with high affinity. It has been reported that L-PGDS protects neuronal cells against apoptosis induced by exposure to hydrogen peroxide. Our study demonstrates that when human WT L-PGDS is in complex with heme, it exhibits a strong peroxidase activity thus behaving as a pseudo-peroxidase. Electron paramagnetic resonance studies confirm that heme in the L-PGDS-heme complex is hexacoordinated with high-spin Fe(III). NMR titration of heme in L-PGDS points to hydrophobic interaction between heme and several residues within the ß-barrel cavity of L-PGDS. In addition to the transporter function, L-PGDS is a key amyloid ß chaperone in human cerebrospinal fluid. The presence of high levels of bilirubin and its derivatives, implicated in Alzheimer's disease, by binding to L-PGDS may reduce its chaperone activity. Nevertheless, our ThT binding assay establishes that heme and heme metabolites do not significantly alter the neuroprotective chaperone function of L-PGDS. Guided by NMR data we reconstructed the heme L-PGDS complex using extensive molecular dynamics simulations providing a platform for mechanistic interpretation of the catalytic and transporting functions and their modulation by secondary ligands like Aß peptides and heme metabolites.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Heme/metabolismo , Oxirredutases Intramoleculares/metabolismo , Lipocalinas/metabolismo , Chaperonas Moleculares/metabolismo , Peroxidase/metabolismo , Doença de Alzheimer/metabolismo , Benzotiazóis/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Compostos Férricos/metabolismo , Corantes Fluorescentes/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Simulação de Dinâmica Molecular , Ligação Proteica , Conformação Proteica
6.
J Microbiol ; 58(4): 260-267, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32239454

RESUMO

A strictly anaerobic, dissimilatory Fe(III)-reducing hyperthermophilic archaeon, designated as strain IOH1T, was isolated from a new deep-sea hydrothermal vent (Onnuri Vent Field) area in the Central Indian Ocean ridge. Strain IOH1T showed > 99% 16S rRNA gene sequence similarity with Thermococcus celericrescens TS2T (99.4%) and T. siculi DSM 12349T (99.2%). Additional three species T. barossii SHCK-94T (99.0%), T. celer Vu13T (98.8%), and T. piezophilus (98.6%) showed > 98.6% of 16S rRNA gene sequence similarity, however, the maximum OrthoANI value is 89.8% for the genome of T. celericrescens TS2T. Strain IOH1T cells are coccoid, 1.2-1.8 µm in diameter, and motile by flagella. Growth was at 70-82°C (optimum 80°C), pH 5.4-8.0 (optimum pH 6.0) with 2-4% (optimum 3%) NaCl. Growth of strain IOH1T was enhanced by starch, pyruvate, D(+)-maltose and maltodextrin as a carbon sources, and elemental sulfur as an electron acceptor; clearly different from those of related species T. celecrescens DSM 17994T and T. siculi DSM 12349T. Strain IOH1T, T. celercrescence DSM 17994T, and T. siculi DSM 12349T reduced soluble Fe(III)-citrate present in the medium, whereas the amount of total cellular proteins increased with the concomitant accumulation of Fe(II). We determined a circular chromosome of 2,234 kb with an extra-chromosomal archaeal plasmid, pTI1, of 7.7 kb and predicted 2,425 genes. The DNA G + C content was 54.9 mol%. Based on physiological properties, phylogenetic, and genome analysis, we proposed that strain IOH1T (= KCTC 15844T = JCM 39077T) is assigned to a new species in the genus Thermococcus and named Thermococcus indicus sp. nov.


Assuntos
Sedimentos Geológicos/microbiologia , Filogenia , Água do Mar/microbiologia , Thermococcus/classificação , Composição de Bases , DNA Arqueal/genética , Compostos Férricos/metabolismo , Oceano Índico , RNA Ribossômico 16S/genética , Thermococcus/isolamento & purificação
7.
Appl Environ Microbiol ; 86(11)2020 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-32245756

RESUMO

Acidophiles play a dominant role in driving elemental cycling in natural acid mine drainage (AMD) habitats and exhibit important application value in bioleaching and bioremediation. Acidity is an inevitable environmental stress and a key factor that affects the survival of acidophiles in their acidified natural habitats; however, the regulatory strategies applied by acidophilic bacteria to withstand low pH are unclear. We identified the significance of the ferric uptake regulator (Fur) in acidophiles adapting to acidic environments and discovered that Fur is ubiquitous as well as highly conserved in acidophilic bacteria. Mutagenesis of the fur gene of Acidithiobacillus caldus, a prototypical acidophilic sulfur-oxidizing bacterium found in AMD, revealed that Fur is required for the acid resistance of this acidophilic bacterium. Phenotypic characterization, transcriptome sequencing (RNA-seq), mutagenesis, and biochemical assays indicated that the Acidithiobacillus caldus ferric uptake regulator (AcFur) is involved in extreme acid resistance by regulating the expression of several key genes of certain cellular activities, such as iron transport, biofilm formation, sulfur metabolism, chemotaxis, and flagellar biosynthesis. Finally, a Fur-dependent acid resistance regulatory strategy in A. caldus was proposed to illustrate the ecological behavior of acidophilic bacteria under low pH. This study provides new insights into the adaptation strategies of acidophiles to AMD ecosystems and will promote the design and development of engineered biological systems for the environmental adaptation of acidophiles.IMPORTANCE This study advances our understanding of the acid tolerance mechanism of A. caldus, identifies the key fur gene responsible for acid resistance, and elucidates the correlation between fur and acid resistance, thus contributing to an understanding of the ecological behavior of acidophilic bacteria. These findings provide new insights into the acid resistance process in Acidithiobacillus species, thereby promoting the study of the environmental adaptation of acidophilic bacteria and the design of engineered biological systems.


Assuntos
Acidithiobacillus/fisiologia , Adaptação Biológica/genética , Proteínas de Bactérias/genética , Ecossistema , Concentração de Íons de Hidrogênio , Proteínas Repressoras/genética , Acidithiobacillus/genética , Ácidos , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Compostos Férricos/metabolismo , Mineração , Proteínas Repressoras/química , Proteínas Repressoras/metabolismo , Alinhamento de Sequência
8.
Chemosphere ; 251: 126427, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32171940

RESUMO

Schwertmannite (Sch) is known to be an effective scavenger of arsenic (As) due to its strong binding affinity for toxic As species. However, the evolution of As-bearing schwertmannite under extreme pH conditions is poorly understood. In this study, we investigated the effects of extremely acidic and alkaline conditions on the stability of schwertmannite with structurally incorporated As(V) (CO-Sch) and schwertmannite with adsorbed As(V) (AD-Sch). The results show that both extremely acidic and alkaline conditions have significant effects on the evolution of minerals and liberation of iron and sulfate. At extremely acidic pH, the maximal release of ferric iron (Fe(III)) and sulfate from CO-Sch were greater than that from AD-Sch, whereas 6.2% and 0.3% of total As released from AD-Sch and CO-Sch, respectively. At extremely alkaline pH, aqueous Fe(III) was not observed, and Fe(III) was retained in As-bearing schwertmannite due to the chemical equilibrium between the dissolution of schwertmannite and re-precipitation of goethite; structurally incorporated As(V) promoted the liberation of sulfate. In addition, the adsorbed As on schwertmannite is more stable, which led to a minor release of As (0.8%) over a 30-d period, however, the liberated As(V) from CO-Sch accounts for up to 3.2%. Under extremely acidic and alkaline conditions, portions of AD-Sch and CO-Sch transformed from schwertmannite to goethite after 30 d, while schwertmannite was still the dominant mineral. Adsorbed As(V) inhibited the transformation of As-bearing schwertmannite to goethite more significantly than structurally incorporated As(V).


Assuntos
Arsênico/química , Compostos de Ferro/química , Adsorção , Compostos Férricos/metabolismo , Concentração de Íons de Hidrogênio , Ferro , Minerais , Oxirredução , Sulfatos , Água
9.
Chem Commun (Camb) ; 56(20): 3089-3092, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32052805

RESUMO

Reaction of FeIII(O2˙-)(TPP) with 2,3-dimethylindole at -40 °C gives the ring-opened, dioxygenated N-(2-acetyl-phenyl)-acetamide product. The reaction was monitored in situ by low-temperature UV-vis and 1H NMR spectroscopies. This work demonstrates that a discrete iron(iii)(superoxo) porphyrin is competent to carry out indole oxidation, as proposed for the tryptophan and indoleamine 2,3-dioxygenases.


Assuntos
Compostos Férricos/química , Indolamina-Pirrol 2,3,-Dioxigenase/química , Indóis/química , Metaloporfirinas/química , Superóxidos/química , Triptofano Oxigenase/química , Compostos Férricos/metabolismo , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Indóis/metabolismo , Metaloporfirinas/metabolismo , Estrutura Molecular , Oxirredução , Superóxidos/metabolismo , Triptofano Oxigenase/metabolismo
10.
Chemosphere ; 250: 126263, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32088616

RESUMO

The coupling between ferrous iron and methane production has important global implications, with iron ions acting as electron acceptors for anaerobic oxidation of methane (AOM) and inhibitors of methanogenesis in different environments, including floodplain soils. In this sense, we analyzed the relationship between Fe(II) concentration and methane production in soil layers collected at 0-15 cm and 15-30 cm from flooded-forest and -agroforestry in Amazonian clear water floodplain incubated in anaerobic batch reactors using acetate, formate and glucose as organic sources. High throughput sequencing of archaeal and bacterial 16S rRNA genes was employed to assess the abundance and composition of the active methanogenic and methanotrophic microbial groups potentially involved in Fe(III)-dependent AOM in the soil used as inoculum. Positive correlation was revealed between Fe(II) concentration and methane production, with higher accumulation of Fe(II) in incubated soil layer collected at 0-15 cm in both forest and agroforestry sites for all the three organic sources. The accumulation of Fe(II) in the incubated soil evidenced the oxidation of Fe(III) potentially by Methanobacterium, Desulfobulbus and 'Candidatus methanoperedens nitroreducens' living in anaerobic condition at this soil layer. The results point out to the microbial ferric iron reduction as an important potential pathway for anaerobic organic matter decomposition in Amazonian floodplain, evidencing methanogenesis suppression by Fe(III) reduction in flooded-forest and -agroforestry in Amazonian clear water river floodplain.


Assuntos
Poluentes Atmosféricos/metabolismo , Inundações , Metano/metabolismo , Microbiologia do Solo , Anaerobiose , Archaea/metabolismo , Brasil , Compostos Férricos/metabolismo , Florestas , Água Doce , Ferro/metabolismo , Methanosarcinales/metabolismo , Oxirredução , RNA Ribossômico 16S/genética , Solo
11.
Proc Natl Acad Sci U S A ; 117(9): 4842-4849, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32071221

RESUMO

Iron is the limiting factor for biological production over a large fraction of the surface ocean because free iron is rapidly scavenged or precipitated under aerobic conditions. Standing stocks of dissolved iron are maintained by association with organic molecules (ligands) produced by biological processes. We hypothesize a positive feedback between iron cycling, microbial activity, and ligand abundance: External iron input fuels microbial production, creating organic ligands that support more iron in seawater, leading to further macronutrient consumption until other microbial requirements such as macronutrients or light become limiting, and additional iron no longer increases productivity. This feedback emerges in numerical simulations of the coupled marine cycles of macronutrients and iron that resolve the dynamic microbial production and loss of iron-chelating ligands. The model solutions resemble modern nutrient distributions only over a finite range of prescribed ligand source/sink ratios where the model ocean is driven to global-scale colimitation by micronutrients and macronutrients and global production is maximized. We hypothesize that a global-scale selection for microbial ligand cycling may have occurred to maintain "just enough" iron in the ocean.


Assuntos
Retroalimentação , Ferro/metabolismo , Oceanos e Mares , Água do Mar/química , Água do Mar/microbiologia , Bactérias/metabolismo , Simulação por Computador , Cianobactérias/metabolismo , Compostos Férricos/metabolismo , Ferro/análise , Quelantes de Ferro , Ligantes , Micronutrientes , Modelos Biológicos , Nutrientes , Fotoquímica , Sideróforos/metabolismo , Microbiologia da Água
12.
PLoS One ; 15(1): e0215341, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31945063

RESUMO

Geobacter sulfurreducens was originally considered a strict anaerobe. However, this bacterium was later shown to not only tolerate exposure to oxygen but also to use it as terminal electron acceptor. Research performed has so far only revealed the general ability of G. sulfurreducens to reduce oxygen, but the oxygen uptake rate has not been quantified yet, nor has evidence been provided as to how the bacterium achieves oxygen reduction. Therefore, microaerobic growth of G. sulfurreducens was investigated here with better defined operating conditions as previously performed and a transcriptome analysis was performed to elucidate possible metabolic mechanisms important for oxygen reduction in G. sulfurreducens. The investigations revealed that cell growth with oxygen is possible to the same extent as with fumarate if the maximum specific oxygen uptake rate (sOUR) of 95 mgO2 gCDW-1 h-1 is not surpassed. Hereby, the entire amount of introduced oxygen is reduced. When oxygen concentrations are too high, cell growth is completely inhibited and there is no partial oxygen consumption. Transcriptome analysis suggests a menaquinol oxidase to be the enzyme responsible for oxygen reduction. Transcriptome analysis has further revealed three different survival strategies, depending on the oxygen concentration present. When prompted with small amounts of oxygen, G. sulfurreducens will try to escape the microaerobic area; if oxygen concentrations are higher, cells will focus on rapid and complete oxygen reduction coupled to cell growth; and ultimately cells will form protective layers if a complete reduction becomes impossible. The results presented here have important implications for understanding how G. sulfurreducens survives exposure to oxygen.


Assuntos
Bactérias Aeróbias/genética , Proteínas de Bactérias/genética , Geobacter/genética , Transcriptoma/genética , Bactérias Aeróbias/crescimento & desenvolvimento , Bactérias Anaeróbias/genética , Compostos Férricos/metabolismo , Fumaratos/metabolismo , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica/genética , Geobacter/crescimento & desenvolvimento , Oxirredução , Oxigênio/metabolismo
13.
Chemosphere ; 247: 125900, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31951957

RESUMO

We assessed the toxicity of iron oxide nanoparticles compared with iron salts in the blackfish (Capoeta fusca). After an acute toxicity assessment, we conducted a chronic exposure to a sub-lethal concentration of Fe3O4 NPs, and iron salts (ferric nitrate (Fe(NO3)3), ferric chloride (FeCl3), ferrous sulfate (FeSO4)) to measure iron uptake over a period of 28 days and then subsequent clearance of the iron uptake in the exposed fish that were transferred to clean water for 28 days. Fe(NO3)3 was the most acutely toxic compound followed by FeCl3, FeSO4, and Fe3O4 NPs. Exposure to Fe3O4 NPs and iron salts induced histopathology anomalies in both gills and intestine that included aneurism, hyperplasia, oedema, fusion of lamellae, lamellar synechiae, and clear signs of necrosis (in the gills) and increases in the number of goblet cells, blood cell counts, and higher numbers of lymphocyte (in the intestine). Fe3O4 NPs showed a higher level of uptake in the body tissues compared with iron salts (p < 0.05) with levels of Fe in the gill > intestine > liver > kidney. Fe was shown to be eliminated most efficiently from the gills, followed by the kidney, then liver and finally the intestine. The highest tissue bioconcentration factors (BCF) occurred in the liver for FeCl3, Fe3O4 NPs, and FeSO4 and in the gills for Fe(NO3)3. We thus show differences in the patterns of tissue accumulation, clearance and toxicological responses for exposures to Fe3O4 NPs and iron salts in blackfish with implications for different susceptibilities for biological effects.


Assuntos
Cyprinidae/fisiologia , Compostos Férricos/toxicidade , Nanopartículas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Bioacumulação , Cloretos , Compostos Férricos/metabolismo , Brânquias/efeitos dos fármacos , Ferro/metabolismo , Fígado/metabolismo , Nanopartículas/metabolismo , Nitratos , Sais/metabolismo , Sais/toxicidade , Testes de Toxicidade Aguda , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
14.
Plant Mol Biol ; 102(4-5): 431-445, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31907707

RESUMO

KEY MESSAGE: Iron deficiency conditions as well as iron supplied as a Fe(III)-mimosine complex induced a number of strategy I and strategy II genes for iron uptake in leucaena. Leucaena leucocephala (leucaena) is a tree-legume that can grow in alkaline soils, where metal-cofactors like Fe(III) are sparingly available. Mimosine, a known chelator of Fe(III), may facilitate Fe(III) uptake in leucaena by serving as a phytosiderophore. To test if mimosine can serve as a phytosiderophore, three sets of experiments were carried out. First, the binding properties and solubility of metal-mimosine complexes were assessed through spectrophotometry. Second, to study mimosine uptake in plants, pole bean, common bean, and tomato plants were supplied with mimosine alone and metal-mimosine complexes. Third, the expression of strategy I (S1) and strategy II (S2) genes for iron uptake from the soil was studied in leucaena plants exposed to different Fe(III) complexes. The results of this study show that (i) mimosine has high binding affinity for metallic cations at alkaline pH, Fe(III)-mimosine complexes are water soluble at alkaline pH, and that mimosine can bind soil iron under alkaline pH; (ii) pole bean, common bean, and tomato plants can uptake mimosine and transport it throughout the plant; and (iii) a number of S1 and S2 genes were upregulated in leucaena under iron-deficiency condition or when Fe(III) was supplied as a Fe(III)-mimosine complex. These findings suggest that leucaena may utilize both S1 and S2 strategies for iron uptake; and mimosine may play an important role in both strategies.


Assuntos
Fabaceae/efeitos dos fármacos , Fabaceae/metabolismo , Mimosina/farmacocinética , Transporte Biológico , Tampões (Química) , Cátions , Compostos Férricos/metabolismo , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Ferro/metabolismo , Metais/metabolismo , Nitrogênio , Phaseolus/efeitos dos fármacos , Phaseolus/metabolismo , Folhas de Planta/metabolismo , Caules de Planta/metabolismo , Ligação Proteica , Sideróforos/metabolismo , Solo , Solanum/efeitos dos fármacos , Solanum/metabolismo , Solubilidade
15.
Sci Total Environ ; 703: 135515, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31761354

RESUMO

Microbial Fe(III) reduction plays an important role for biogeochemical carbon and iron cycling in sediments and soils. Biochar is used as a soil amendment to increase fertility and lower N2O/CO2 emissions. It is redox-active and can stimulate microbial Fe(III) mineral reduction. It is currently unknown, however, how the aggregation of cells and Fe(III) minerals with biochar particles influence microbial Fe(III) reduction. Therefore, we determined rates and extent of ferrihydrite (Fh) reduction in S. oneidensis MR-1 cell suspensions with different particles sizes of wood-derived Swiss biochar and KonTiki biochar at different biochar/Fh ratios. We found that at small biochar particle size and high biochar/Fh ratios, the biochar, MR-1 cells and Fh closely aggregated, therefore addition of biochar stimulated electron transfer and microbial Fh reduction. In contrast, large biochar particles and low biochar/Fh ratios inhibited the electron transfer and Fe(III) reduction due to the lack of effective aggregation. These results suggest that for stimulating Fh reduction, a certain biochar particle size and biochar/Fh ratio is necessary leading to a close aggregation of all phases. This aggregation favors electron transfer from cells to Fh via redox cycling of the electron donating and accepting functional groups of biochar and via direct electron transfer through conductive biochar carbon matrices. These findings improve our understanding of electron transfer between microorganisms and Fe(III) minerals via redox-active biochar and help to evaluate the impact of biochar on electron transfer processes in the environment.


Assuntos
Carvão Vegetal/química , Compostos Férricos/metabolismo , Microbiologia do Solo , Elétrons , Ferro , Minerais , Oxirredução , Solo
16.
ISME J ; 14(2): 425-436, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31641279

RESUMO

Redox-active iron minerals can act as energy sources or electron-transferring mediators in microbial syntrophic associations, being important means of interspecies metabolic cooperation in sedimentary environments. Alkaline conditions alter the thermodynamic stability of iron minerals, influencing their availability for interspecies syntrophic interactions. We have modeled anaerobic alkaliphilic microbial associations in ethanol-oxidizing co-culture of an obligate syntroph Candidatus "Contubernalis alkalaceticum" and a facultative lithotroph Geoalkalibacter ferrihydriticus, which is capable of dissimilatory Fe(III) reduction and homoacetogenic oxidation of Fe(II) with CO2. The co-cultures were cultivated with thermodynamically metastable ferric-containing ferrihydrite, or ferrous-containing siderite, or without minerals. Mössbauer spectral analysis revealed the transformation of both minerals to the stable magnetite. In the presence of ferrihydrite, G. ferrihydriticus firstly reduced Fe(III) with ethanol and then switched to syntrophic homoacetogenesis, providing the growth of obligate syntroph on ethanol. The ability of G. ferrihydriticus to accept hydrogen from its syntrophic partner and produce extra acetate from carbonate during ethanol oxidation was confirmed by co-culture growth without minerals. In the presence of siderite, G. ferrihydriticus performed homoacetogenesis using two electron donors simultaneously- siderite and hydrogen. Pieces of evidence for direct and indirect hydrogen-mediated electron exchange between partner organisms were obtained. Relative abundancies of partner organisms and the rate of acetate production by their co-cultures were strongly determined by thermodynamic benefits, which G. ferrihydriticus got from redox transformations of iron minerals. Even the minor growth of G. ferrihydriticus sustained the growth of the syntroph. Accordingly, microbe-to-mineral interactions could represent underestimated drivers of syntrophic interactions in alkaline sedimentary environments.


Assuntos
Acetatos/metabolismo , Deltaproteobacteria/metabolismo , Compostos Férricos/metabolismo , Compostos Ferrosos/metabolismo , Firmicutes/metabolismo , Interações Microbianas , Minerais/metabolismo , Anaerobiose , Carbonatos/metabolismo , Deltaproteobacteria/crescimento & desenvolvimento , Etanol/metabolismo , Óxido Ferroso-Férrico/metabolismo , Firmicutes/crescimento & desenvolvimento , Oxirredução , Simbiose
17.
J Basic Microbiol ; 60(1): 37-46, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31696958

RESUMO

Geobacter metallireducens GS15, a model of dissimilatory iron-reducing bacteria, is the key regulator in biogeochemical iron cycling. How the emerging contaminant microplastics involved in the iron cycling are driven by microbes on the microscale remains unknown. Hence, the influences of two typical microplastics, polybutylene terephthalate-hexane acid (PBAT) and polyvinyl chloride (PVC), were explored on the activity of G. metallireducens GS15 with ferrihydrite or ferric citrate as the respective electron acceptors. The results showed that the iron (II) contents in PBAT- and PVC-treatment groups were 16.79 and 6.81 mM, respectively, at the end of the experiment. Compared with the PBAT-treatment group, scanning electron microscopy and energy dispersive spectrometery revealed that merely a small amount of iron-containing products covered the surface of PVC. Moreover, PBAT and PVC could both retard the electroactivity of G. metallireducens GS15 at the beginning of microbial fuel cell operation. On the basis of the results above, microplastic PVC might exhibit potential inhibition of the iron cycling process driven by G. metallireducens GS15 with ferrihydrite as the terminal electron acceptor. This study extended our understanding of the influence of the microplastics PBAT and PVC on microbially mediated biogeochemical iron cycling. The findings might have an important implication on the biogeochemical elements cycling in the ecosystem with the involvement of emerging contaminant microplastics.


Assuntos
Poluentes Ambientais/toxicidade , Compostos Férricos/metabolismo , Geobacter/efeitos dos fármacos , Microplásticos/toxicidade , Cloreto de Polivinila/toxicidade , Eletroquímica , Geobacter/metabolismo , Oxirredução , Poliésteres/toxicidade
18.
Environ Pollut ; 259: 113852, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31887592

RESUMO

The widespread use of nanoparticles (NPs) has drawn considerable attention because of their potential toxicity and the environmental consequences thereof. However, the effects of the exposure route and life stage of an organism on the bioaccumulation and toxicity of NPs are largely unknown. In the present study, we investigated the accumulation kinetics (uptake, assimilation, and efflux) and tissue distribution of waterborne and dietary hematite NPs (HemNPs) during three life stages (embryo, larva, and adult) of the zebrafish Danio rerio. For all zebrafish life stages, the waterborne accumulation of well-dispersed HemNPs increased linearly with exposure time but decreased after reaching a maximum. The increase in HemNPs accumulation followed the order embryo > larva > adult. Compared with the waterborne route, the dietary accumulation of HemNPs in larval and adult zebrafish fluctuated, reaching a maximum after each food refreshment and then decreasing until the next food addition. Similar to waterborne exposure, adult fish accumulated less dietary HemNPs than did larvae. Nevertheless, dietary HemNPs mostly accumulated in the intestinal tract, with smaller amounts in the truncus, head, and gills, as compared with their waterborne counterparts. Moreover, in the gonad no dietary HemNPs were detected whereas accumulation via waterborne HemNPs was significant. Despite the low assimilation efficiency of dietary HemNPs, biodynamic modeling showed that the diet was the main source of particle accumulation in zebrafish. Thus, both the life stage and the exposure route should be considered in evaluations of the environmental risks of NPs.


Assuntos
Dieta , Compostos Férricos , Nanopartículas , Poluentes Químicos da Água , Peixe-Zebra , Animais , Compostos Férricos/metabolismo , Nanopartículas/metabolismo , Poluentes Químicos da Água/metabolismo , Peixe-Zebra/crescimento & desenvolvimento , Peixe-Zebra/metabolismo
19.
Mater Sci Eng C Mater Biol Appl ; 107: 110318, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31761250

RESUMO

Cobalt ferrite nanoparticles were successfully synthesized using the fungus Monascus purpureus ATCC16436 as a potentially low-cost, eco-friendly and easy to produce method. Fourier transform infrared spectroscopy confirmed the functional groups present in the prepared samples. X-ray diffraction pattern of the synthesized nanoparticles revealed a single-phase crystalline structure. Transmission electron microscope studies showed the spherical shape with a mean particle size of 6.50 nm. Vibrating sample magnetometer analyses revealed that the synthesized nanoparticles have a superparamagnetic behavior. In addition, the antioxidant, anticancer and antimicrobial activities of the synthesized nanoparticles were evaluated. The synthesized nanoparticles exhibited antioxidant potential as compared by ascorbic acid with 50% inhibitory concentration of 100.25 µg mL-1. Based on the MTT assay, the synthesized nanoparticles significantly inhibited the proliferation of two different human cancer cell lines (breast and liver) and normal human melanocytes. The recorded 50% inhibitory concentrations of the respective cell lines were 45.21, 61.86 and 200.15 µg mL-1. The synthesized nanoparticles showed potent antibacterial and antifungal activities against all the tested plant and human microbial pathogens with minimal inhibitory concentration range 250-500 µg mL-1. Moreover, the feasibility of production enhancement of the synthesized nanoparticles using the fungal culture as affected by gamma irradiation was also adopted. Gamma irradiation at 1000 Gy dramatically intensified the yield of nanoparticles to 24.87 g L-1. Accordingly, these findings suggest a new and alternate approach with the excellent biotechnological potentiality for the nanoparticles production that will open up the way for the industrial manufacture of nanomaterials.


Assuntos
Anti-Infecciosos/farmacologia , Antineoplásicos/farmacologia , Antioxidantes/farmacologia , Cobalto/química , Compostos Férricos/química , Nanopartículas Metálicas/química , Monascus/metabolismo , Anti-Infecciosos/química , Antineoplásicos/química , Antioxidantes/química , Linhagem Celular Tumoral , Cobalto/metabolismo , Compostos Férricos/metabolismo , Raios gama , Humanos , Células MCF-7 , Melanócitos/efeitos dos fármacos , Nanopartículas Metálicas/uso terapêutico , Testes de Sensibilidade Microbiana , Monascus/efeitos da radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
20.
Redox Biol ; 28: 101337, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31622846

RESUMO

Cellular senescence may contribute to aging and age-related diseases and senolytic drugs that selectively kill senescent cells may delay aging and promote healthspan. More recently, several categories of senolytics have been established, namely HSP90 inhibitors, Bcl-2 family inhibitors and natural compounds such as quercetin and fisetin. However, senolytic and senostatic potential of nanoparticles and surface-modified nanoparticles has never been addressed. In the present study, quercetin surface functionalized Fe3O4 nanoparticles (MNPQ) were synthesized and their senolytic and senostatic activity was evaluated during oxidative stress-induced senescence in human fibroblasts in vitro. MNPQ promoted AMPK activity that was accompanied by non-apoptotic cell death and decreased number of stress-induced senescent cells (senolytic action) and the suppression of senescence-associated proinflammatory response (decreased levels of secreted IL-8 and IFN-ß, senostatic action). In summary, we have shown for the first time that MNPQ may be considered as promising candidates for senolytic- and senostatic-based anti-aging therapies.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Compostos Férricos , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Nanopartículas , Oxidantes/farmacologia , Quercetina/metabolismo , Apoptose , Biomarcadores , Células Cultivadas , Senescência Celular , Espaço Extracelular/metabolismo , Compostos Férricos/química , Compostos Férricos/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Imunofenotipagem , Modelos Biológicos , Nanopartículas/química , Nanopartículas/metabolismo , Estresse Oxidativo , Quercetina/química
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