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1.
Ecotoxicol Environ Saf ; 214: 112084, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33640726

RESUMO

Direct Black G (DBG) is a highly toxic synthetic azo dye which is difficult to degrade. Biological treatment seems to be a promising option for the treatment of azo dye containing effluent. A thermophilic bacterial strain (Anoxybacillus sp. PDR2) previously isolated from the soil can effectively remove DBG. However, the molecular underpinnings of DBG degradation and the microbial detoxification ability remains unknown. In the present study, the genetic background of PDR2 for the efficient degradation of DBG and its adaptation to azo dye-contaminated environments was revealed by bioinformatics. Moreover, the possible biodegradation pathways were speculated based on the UV-vis spectral analysis, FTIR, and intermediates identified by LC-MS. Additionally, phytotoxicity and the comet experiment studies clearly indicated that PDR2 converts toxic azo dye (DBG) into low toxicity metabolites. The combination of biodegradation pathways and detoxification analysis were utilized to explore the molecular degradation mechanism and bioremediation of azo dye for future applications. These findings will provide a valuable theoretical basis for the practical treatment of azo dye wastewater.


Assuntos
Anoxybacillus/metabolismo , Compostos Azo/metabolismo , Biodegradação Ambiental , Anoxybacillus/genética , Bactérias/metabolismo , Cor , Corantes/metabolismo , Humanos , Solo , Águas Residuárias
2.
Phys Chem Chem Phys ; 23(5): 3552-3564, 2021 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-33514952

RESUMO

The activity of voltage-gated ion channels can be controlled by the binding of photoswitches inside their internal cavity and subsequent light irradiation. We investigated the binding of azobenzene and p-diaminoazobenzene to the human Nav1.4 channel in the inactivated state by means of Gaussian accelerated molecular dynamics simulations and free-energy computations. Three stable binding pockets were identified for each of the two photoswitches. In all the cases, the binding is controlled by the balance between the favorable hydrophobic interactions of the ligands with the nonpolar residues of the protein and the unfavorable polar solvation energy. In addition, electrostatic interactions between the ligand and the polar aminoacids are also relevant for p-diaminoazobenzene due to the presence of the amino groups on the benzene moieties. These groups participate in hydrogen bonding in the most favorable binding pocket and in long-range electrostatic interactions in the other pockets. The thermodinamically preferred binding sites found for both photoswitches are close to the selectivity filter of the channel. Therefore, it is very likely that the binding of these ligands will induce alterations in the ion conduction through the channel.


Assuntos
Compostos Azo/metabolismo , Canal de Sódio Disparado por Voltagem NAV1.4/metabolismo , p-Aminoazobenzeno/análogos & derivados , Compostos Azo/química , Sítios de Ligação , Humanos , Ligação de Hidrogênio , Simulação de Dinâmica Molecular , Canal de Sódio Disparado por Voltagem NAV1.4/química , Ligação Proteica , Eletricidade Estática , Termodinâmica , p-Aminoazobenzeno/química , p-Aminoazobenzeno/metabolismo
3.
Ecotoxicol Environ Saf ; 209: 111791, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33360211

RESUMO

A recently isolated osmo-tolerant yeast Candida tropicalis A1, which could decolorize various azo dyes under high-salinity conditions, was systematically characterized in the present study. Stimulating dye-decolorization effectiveness and osmo-tolerance of the yeast by static magnetic field (SMF) was investigated and transcriptomic responses of the yeast to SMF was analyzed to propose possible mechanisms. The results demonstrated that the yeast A1 effectively decolorized (≥ 97.50% within 12 h) and detoxified (from high toxicity to low toxicity within 24 h) 70 mg/L Acid Red B (ARB) under the optimized conditions through a series of steps including naphthalene-amidine bond cleavage, reductive or oxidative deamination/desulfurization, open-loop of hydroxy-substituted naphthalene or benzene and TCA cycle. Moreover, dye decolorization performance and osmo-tolerance of the yeast A1 were further improved by 24.6 mT SMF. Genes encoding high-affinity hexose/glucose transporter proteins and NADH-ubiquinone oxidoreductase were up-regulated by 24.6 mT SMF, which might be responsible for the increase of dye decolorization. Significant up-regulation of glycerol-3-phosphate dehydrogenase and cell wall protein RHD3 suggested that osmo-tolerance was enhanced by 24.6 mT SMF through promoting production and intracellular accumulation of glycerol as compatible solute, as well as regulation of cell wall component. In conclusion, 24.6 mT SMF led to the up-regulation of related genes resulting in enhanced dye biodegradation efficiency and osmo-tolerance of the yeast A1.


Assuntos
Compostos Azo/metabolismo , Biodegradação Ambiental , Candida tropicalis/fisiologia , Antagonistas de Receptores de Angiotensina/metabolismo , Inibidores da Enzima Conversora de Angiotensina/metabolismo , Compostos Azo/química , Candida tropicalis/metabolismo , Corantes/química , Naftalenossulfonatos , Transcriptoma
4.
Biochemistry ; 60(1): 31-40, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33350810

RESUMO

The flavin reductase (FRED) and isobutylamine N-hydroxylase (IBAH) from Streptomyces viridifaciens constitute a two-component, flavin-dependent monooxygenase system that catalyzes the first step in valanimycin biosynthesis. FRED is an oxidoreductase that provides the reduced flavin to IBAH, which then catalyzes the hydroxylation of isobutylamine (IBA) to isobutylhydroxylamine (IBHA). In this work, we used several complementary methods to investigate FAD binding, steady-state and rapid reaction kinetics, and enzyme-enzyme interactions in the FRED:IBAH system. The affinity of FRED for FADox is higher than its affinity for FADred, consistent with its function as a flavin reductase. Conversely, IBAH binds FADred more tightly than FADox, consistent with its role as a monooxygenase. FRED exhibits a strong preference (28-fold) for NADPH over NADH as the electron source for FAD reduction. Isothermal titration calorimetry was used to study the association of FRED and IBAH. In the presence of FAD, either oxidized or reduced, FRED and IBAH associate with a dissociation constant of 7-8 µM. No interaction was observed in the absence of FAD. These results are consistent with the formation of a protein-protein complex for direct transfer of reduced flavin from the reductase to the monooxygenase in this two-component system.


Assuntos
Proteínas de Bactérias/metabolismo , FMN Redutase/metabolismo , Flavina-Adenina Dinucleotídeo/metabolismo , Oxigenases de Função Mista/metabolismo , Streptomyces/enzimologia , Compostos Azo/metabolismo , Hidroxilação , Cinética , NADPH Oxidases/metabolismo , Consumo de Oxigênio
5.
Ecotoxicol Environ Saf ; 203: 111047, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888598

RESUMO

Understanding azo dye degrading enzymes and the encoding of their functional genes is crucial for the elucidation of their molecular mechanisms. In this study, a thermophilic strain capable of degrading azo dye was isolated from the soil near a textile dye manufacturing factory. Based on its morphological, physiological and biochemical properties, as well as 16S rRNA gene sequence analysis, the strain was identified as Anoxybacillus sp. PDR2. The decolorization ratios of 100-600 mg/L Direct Black G (DBG) by strain PDR2 reached 82.12-98.39% within 48 h of dyes. Genome analysis revealed that strain PDR2 contains a circular chromosome of 3791144 bp with a G + C content of 42.48%. The genetic basis of azo dye degradation by strain PDR2 and its capacity to adapt to harsh environments, were further elucidated through bioinformatics analysis. RNA-Seq and qRT-PCR technology confirmed that NAD(P)H-flavin reductase, 2Fe-2S ferredoxin and NAD(P)-dependent ethanol dehydrogenase genes expressed by strain PDR2, were the key genes involved in DBG degradation. The combination of genome and transcriptome analysis was utilized to explore the key genes of strain PDR2 involved in azo dye biodegradation, with these findings providing a valuable theoretical basis for the practical treatment of azo dye wastewater.


Assuntos
Anoxybacillus/isolamento & purificação , Compostos Azo/análise , Corantes/análise , Genes Bacterianos , Microbiologia do Solo , Anoxybacillus/genética , Anoxybacillus/metabolismo , Compostos Azo/metabolismo , Biodegradação Ambiental , China , Corantes/metabolismo , Perfilação da Expressão Gênica , Genômica , RNA Ribossômico 16S/genética , Solo/química , Indústria Têxtil
6.
Ecotoxicol Environ Saf ; 204: 111073, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32755736

RESUMO

The high pH and salinity of textile wastewater is a major hindrance to azo dye decolorization. In this study, a mixed bacterial consortium ZW1 was enriched under saline (10% salinity) and alkaline (pH 10.0) conditions to decolorize Methanil Yellow G (MY-G). Consortium ZW1 was mainly composed of Halomonas (49.8%), Marinobacter (30.7%) and Clostridiisalibacter (19.2%). The effects of physicochemical factors were systematically investigated, along with the degradation pathway and metagenome analysis. The co-carbon source was found to be necessary, and the addition of yeast extract led to 93.3% decolorization of 100 mg/L MY-G within 16 h (compared with 1.12% for control). The optimum pH, salinity, temperature and initial dye concentration were 8.0, 5-10%, 40 °C and 100 mg/L, respectively. The typical dye-related degradation enzymes were most effective at 10% salinity. Consortium ZW1 was also able to differentially decolorize five other direct and acidic dyes in a short period. Phototoxicity tests revealed the detoxification of MY-G degradation products. Combining UV-vis, FTIR and GC-MS detection, the MY-G degradation pathway by consortium ZW1 was proposed. Furthermore, metagenomic approach was used to elucidate the functional potential of genes in MY-G biodegradation. These results signify the broad potential application of halo-alkaliphilic consortia in the bioremediation of dyeing wastewater.


Assuntos
Compostos Azo/toxicidade , Corantes/toxicidade , Metagenoma , Microbiota/efeitos dos fármacos , Águas Residuárias , Poluentes Químicos da Água/toxicidade , Purificação da Água/métodos , Compostos Azo/metabolismo , Biodegradação Ambiental , Carbono/metabolismo , Corantes/metabolismo , Microbiota/genética , Salinidade , Temperatura , Indústria Têxtil , Águas Residuárias/química , Águas Residuárias/microbiologia , Poluentes Químicos da Água/metabolismo
7.
Chemosphere ; 259: 127470, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32603967

RESUMO

Zero-valent iron (ZVI) pre-treatment in sequential strategy for removal of non-biodegradable azo-dye Orange II by activated-sludge was quantitatively examined. The decolorization and TOC (total organic carbon) removal of Orange II by ZVI pre-treatment were examined in the ranges of pH from 3 to 11 and ZVI dosage from 500 to 2000 mgL-1. While the decolorization was enhanced with decreasing pH and the optimal pH for decolorization was found at pH 3, the TOC removal rate at pH 3 remained at 22.2% and the maximum TOC removal rate of 78.2% was obtained at pH 4. The decolorization and TOC removal of Orange II were monotonously increased with increasing ZVI dosage. To quantify the ZVI pre-treatment, the contributions of redox degradation, complexation/precipitation and adsorption to TOC removal by ZVI were defined. Novel kinetic models for the ZVI pre-treatment and activated-sludge post-treatment were developed. The proposed kinetic models satisfactorily predicted the transitional behaviors of the ZVI pre-treatment and activated-sludge post-treatment and the contributions of redox degradation, complexation/precipitation and adsorption to TOC removal by the ZVI pre-treatment. The complete removal of non-biodegradable azo-dye Orange II of 300 mgL-1 was accomplished by 78.2% removal after 360 min ZVI pre-treatment with the ZVI dosage of 1000 mgL-1 at pH 4 and subsequently 21.8% removal after 480 min activated-sludge post-treatment. The ZVI pre-treatment integrated with activated-sludge post-treatment was proved to be an effective strategy for treating non-biodegradable pollutants.


Assuntos
Compostos Azo/metabolismo , Benzenossulfonatos/metabolismo , Biodegradação Ambiental , Poluentes Químicos da Água/metabolismo , Adsorção , Concentração de Íons de Hidrogênio , Ferro , Cinética , Oxirredução , Esgotos
8.
Ecotoxicol Environ Saf ; 202: 110859, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32574861

RESUMO

The effects of quinoid compounds on azo dyes decolorization were studied. Compared with other quinones, menadione was the most effective at aiding azo dye decolorization. Sodium formate was a suitable carbon source for the anaerobic decolorization system. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis indicated that the microbial structure changed in response to varying carbon sources. Phylogenetic analysis showed that the anaerobic sludge was consisted mainly of nine genera. The mechanism studies showed that the biotransformation of menadione to its hydroquinone form was the rate-limiting step in the dye decolorization process. Moreover, study of the electron transfer mechanism of quinone-mediated reduction showed that azo dye decolorization is not a specific reaction. The NADH chain was involved in the decolorization process. The methane production test indicated that azo dyes had an inhibitory effect on methane production. However, supplementation with a redox mediator could recover the inhibited methanogenesis. High-throughput sequencing analysis revealed that the methanogenic archaeal community was altered in the anaerobic sludge with or without azo dyes and the redox mediator.


Assuntos
Compostos Azo/metabolismo , Quinonas/metabolismo , Eliminação de Resíduos Líquidos , Anaerobiose , Compostos Azo/química , Benzoquinonas , Biotransformação , Catálise , Corantes/química , Metano/metabolismo , Oxirredução , Filogenia , Quinonas/química , Esgotos
9.
Arch Microbiol ; 202(8): 2135-2145, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32519019

RESUMO

In Pakistan, 55% of textile exports are contributed by textile-units of Faisalabad. The effluents of these textile units, being discharged without any treatment, contain the contamination of a huge amount of synthetic azo dyes. The objective of the current research was to evaluate the contribution of an azoreductase-encoding gene (azrS) from a pre-characterized azo dye decolorizing bacterial strain Bacillus sp. MR-1/2 in a high copy number host system (pUC19-T7-Top-T) of Escherichia coli strain DH5α followed by in-silico prediction of azoreductase enzyme (AzrS) function. The recombinant cells that contained azrS had a significantly higher rate of color removal in congo red and reactive black-5 dyes when compared to wild-type MR-1/2 and E. coli DH5α after 72 h of incubation. Moreover, we were able to show that the recombinant strain significantly reduced the values of all tested parameters (pH, EC, turbidity, TSS, and COD) in actual wastewater. In support of our results, it was also predicted through bioinformatics analysis that the deduced azoreductase protein of strain MR-1/2 is linked with the dye decolorization ability of the strain through NAD(P)H-ubiquinone: oxidoreductase activity. Furthermore, we also found that the deduced protein resembled closely related proteins of protein databank in many features, yet some unique features were predicted in the enzyme activity of strain MR-1/2. It was concluded that the recombinant strain could be examined in pilot-scale experiments for textile wastewater treatment.


Assuntos
Compostos Azo/metabolismo , Bacillus/enzimologia , Bacillus/genética , NADH NADPH Oxirredutases/genética , NADH NADPH Oxirredutases/metabolismo , Águas Residuárias/microbiologia , Purificação da Água , Compostos Azo/química , Biodegradação Ambiental , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica/genética , Paquistão
10.
Sci Rep ; 10(1): 7881, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32398650

RESUMO

A facile green route has been employed for the synthesis of ZnO and Ag-doped ZnO using Cannabis sativa as a reducing and stabilizing agent. The as-synthesized nanoparticles were characterized and tested for photocatalytic dye degradation and antimicrobial activity. The results suggested that nanoparticles have shown antimicrobial activity against different human pathogenic bacteria (Escherichia coli, Klebsiella pneumonia, MRSA, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus) and fungal strains (Fusarium spp. and Rosellinia necatrix). Ag-doped nanoparticles comparatively have shown better removal Congo red and methyl orange under visible light. Therefore, green synthesized nanoparticles could have beneficial applications in environmental science and biological field.


Assuntos
Antibacterianos/toxicidade , Compostos Azo/metabolismo , Nanopartículas Metálicas/toxicidade , Extratos Vegetais/química , Óxido de Zinco/química , Antibacterianos/química , Compostos Azo/química , Cannabis/química , Catálise/efeitos da radiação , Escherichia coli/efeitos dos fármacos , Fusarium/efeitos dos fármacos , Química Verde/métodos , Humanos , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana/métodos , Microscopia Eletrônica , Estrutura Molecular , Oxirredução , Folhas de Planta/química , Pseudomonas aeruginosa/efeitos dos fármacos , Espectrometria por Raios X , Staphylococcus aureus/efeitos dos fármacos , Difração de Raios X
11.
Sci Rep ; 10(1): 6894, 2020 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-32327683

RESUMO

Early interstitial fibrosis (IF) correlates with long-term renal graft dysfunction, highlighting the need for accurate quantification of IF. However, the currently used Banff classification exhibits some limitations. The aim of our study was to precisely describe the progression of IF after renal transplantation using a new morphometric image analysis method relying of Sirius Red staining. The morphometric analysis we developed showed high inter-observer and intra-observer reproducibility, with ICC [95% IC] of respectively 0.75 [0.67-0.81] (n = 151) and 0.88 [0.72-0.95] (n = 21). We used this method to assess IF (mIF) during the first year after the kidney transplantation from 66 uncontrolled donors after circulatory death (uDCD). Both mIF and interstitial fibrosis (ci) according to the Banff classification significantly increased the first three months after transplantation. From M3 to M12, mIF significantly increased whereas Banff classification failed to highlight increase of ci. Moreover, mIF at M12 (p = 0.005) correlated with mean time to graft function recovery and was significantly associated with increase of creatininemia at M12 and at last follow-up. To conclude, the new morphometric image analysis method we developed, using a routine and cheap staining, may provide valuable tool to assess IF and thus to evaluate new sources of grafts.


Assuntos
Compostos Azo/metabolismo , Circulação Sanguínea , Processamento de Imagem Assistida por Computador , Transplante de Rim/efeitos adversos , Doadores de Tecidos , Adulto , Biópsia , Feminino , Fibrose , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Resultado do Tratamento , Adulto Jovem
12.
Enzyme Microb Technol ; 136: 109509, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32331716

RESUMO

Azo dyes are toxic and carcinogenic synthetic pigments that accumulate as pollutants in aquatic bodies near textile factories. The pigments are structurally diverse, and bioremediation is mostly limited to single dye compounds or related groups. Versatile peroxidase (VP) from Pleurotus eryngii is a heme-containing peroxidase with a broad substrate spectrum that can break down many structurally distinct pollutants, including azo dyes. The utilization of this enzyme could be facilitated by engineering to modify its catalytic activity and substrate range. We used saturation mutagenesis to alter two amino acids in the catalytic tryptophan environment of VP (V160 and A260). Library screening with three azo dyes revealed that these two positions had a significant influence on substrate specificity. We were able to isolate and sequence VP variants with up to 16-fold higher catalytic efficiency for different azo dyes. The same approach could be used to select for VP variants that catalyze the degradation of many other types of pollutants. To allow multiple cycles of dye degradation, we immobilized VP on the surface of yeast cells and used washed cell wall fragments after lysis. VP embedded in the cell wall retained ∼70 % of its initial activity after 10 cycles of dye degradation each lasting 12 h, making this platform ideal for the bioremediation of environments contaminated with azo dyes.


Assuntos
Compostos Azo/metabolismo , Parede Celular/metabolismo , Mutagênese Sítio-Dirigida/métodos , Peroxidases/metabolismo , Saccharomyces cerevisiae/metabolismo , Biocatálise , Biodegradação Ambiental , Corantes/metabolismo , Oxirredução , Oxirredutases/genética , Oxirredutases/metabolismo , Peroxidases/genética , Especificidade por Substrato
13.
Enzyme Microb Technol ; 135: 109507, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32146934

RESUMO

The azo dye Congo red is heavily used in textile industries and is actively present in the wastewater run-offs. Its structural complexity and physical characteristics make it resistant to the physicochemical treatments employed by the industry. Over time, application of the enzyme laccase has proved to be quite useful due to its ability to oxidize and eventually decolorize the dye. Moreover, the use of ABTS as the electron mediator also helps in enhancing the oxidizing capability of the enzyme with congo red. The present study involves establishing the role of the individual components i.e. laccase, ABTS and the dye, in the LMS electrochemically. Congo red doesn't have any form of electrochemical activity by itself, but the enzyme brings about a substantial change by increasing the rate of reduction. The effect of ABTS, though same, is concentration-dependent. For LMS, laccase helps in bringing about the rate of reduction much faster in the presence of the mediator, initiating the decolorization of the dye.


Assuntos
Vermelho Congo/metabolismo , Proteínas Fúngicas/metabolismo , Lacase/metabolismo , Trametes/metabolismo , Compostos Azo/química , Compostos Azo/metabolismo , Benzotiazóis/metabolismo , Biodegradação Ambiental , Proteínas Fúngicas/química , Cinética , Lacase/química , Ácidos Sulfônicos/metabolismo , Trametes/química , Trametes/enzimologia
14.
Nat Nanotechnol ; 15(4): 296-306, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32015505

RESUMO

Optical technologies allowing modulation of neuronal activity at high spatio-temporal resolution are becoming paramount in neuroscience. In this respect, azobenzene-based photoswitches are promising nanoscale tools for neuronal photostimulation. Here we engineered a light-sensitive azobenzene compound (Ziapin2) that stably partitions into the plasma membrane and causes its thinning through trans-dimerization in the dark, resulting in an increased membrane capacitance at steady state. We demonstrated that in neurons loaded with the compound, millisecond pulses of visible light induce a transient hyperpolarization followed by a delayed depolarization that triggers action potential firing. These effects are persistent and can be evoked in vivo up to 7 days, proving the potential of Ziapin2 for the modulation of membrane capacitance in the millisecond timescale, without directly affecting ion channels or local temperature.


Assuntos
Potenciais de Ação , Compostos Azo/metabolismo , Membrana Celular/metabolismo , Hipocampo/metabolismo , Neurônios/metabolismo , Animais , Compostos Azo/síntese química , Compostos Azo/química , Compostos Azo/farmacologia , Camundongos
15.
Ecotoxicol Environ Saf ; 191: 110228, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31982684

RESUMO

An efficient MnCeOx composite was successfully synthesized for activation of persulfate to degrade acid orange 7 (AO7) and ofloxacin. Pollutants degradation efficiencies with different catalytic systems were investigated. Results showed the performance of MnCeOx was better than MnOx, CeO2 and MnOx + CeO2. Thus, there was a clear synergistic effect (Se) between Mn and Ce in the composite, and the Se was 73.8% for AO7 and 39.6% for ofloxacin. In addition, AO7 removal fitted 1st order reaction while ofloxacin removal fitted 2nd order reaction in MnCeOx/persulfate system. Moreover, MnCeOx/persulfate system showed high efficiency in pH range of 5-9. Mechanism analysis showed that SO4- and OH on the surface of the catalyst were the main active species, and O2- also played an important role in pollutants degradation. Furthermore, MnCeOx showed high activity in actual water. Finally, the possible degradation pathway of ofloxacin was proposed according to the high performance liquid chromatography-mass spectrometry result. Overall, this study provides an efficient and stable catalyst to activate persulfate to degrade refractory pollutants.


Assuntos
Compostos Azo/metabolismo , Benzenossulfonatos/metabolismo , Cério/química , Compostos de Manganês/química , Ofloxacino/metabolismo , Óxidos/química , Sulfatos/química , Poluentes Químicos da Água/metabolismo , Catálise , Oxirredução
16.
Chemosphere ; 246: 125753, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31901528

RESUMO

Granules which could efficiently mineralize azo dyes were cultivated through immobilization of aerobic degradation strains in a core composed of anaerobic decolorization cultures. The core was obtained in a up-flow anaerobic sludge blanket (UASB) reactor incubated with anaerobic decolorization bacteria. Aerobic degradation strains were then grown on the surface of the anaerobic core in a sequencing batch reactor (SBR). Three of the granules' surface layers demonstrated the occurrence of immobilization. The granulation process was monitored with 16S rDNA high throughput sequencing. Anaerobic decolorization cultures belonging to the genera of unclassified, Levilinea, and Petrimonas and the aerobic degradation genera of Thauera, unclassified, Thermomonas, and Ottowia were successfully fixed in the granules. The obtained granules were capable of decolorizing azo dyes under anaerobic situation, and the generated aromatic amines were then completely mineralized in aerated environment. Comparative studies on the relationship between removed contaminates and typical components concentrations in low to high strength azo dye wastewater showed that the granules have great potentials in treating wastewater with different complexity. The removal efficiency of COD and TOC was not restricted by loading concentrations.


Assuntos
Compostos Azo/metabolismo , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Aminas/metabolismo , Anaerobiose , Compostos Azo/análise , Bactérias Anaeróbias/metabolismo , Reatores Biológicos , Corantes/metabolismo , Esgotos/microbiologia , Águas Residuárias , Poluentes Químicos da Água/análise
17.
Electron. j. biotechnol ; 43: 1-7, Jan. 2020. tab, graf, ilus
Artigo em Inglês | LILACS | ID: biblio-1087520

RESUMO

Background: Textile industry not only plays a vital role in our daily life but also a prominent factor in improving global economy. One of the environmental concern is it releases huge quantities of toxic dyes in the water leading to severe environmental pollution. Bacterial laccase and azoreductase successfully oxidize complex chemical structure of nitrogen group-containing azo dyes. Additionally, the presence of textile dye infuriates bacterial peroxidase to act as a dye degrading enzyme. Our present study deals with three textile dye degrading enzymes laccase, azoreductase, and peroxidase through analyzing their structural and functional properties using standard computational tools. Result: According to the comparative analysis of physicochemical characteristics, it was clear that laccase was mostly made up of basic amino acids whereas azoreductase and peroxidase both comprised of acidic amino acids. Higher aliphatic index ascertained the thermostability of all these three enzymes. Negative GRAVY value of the enzymes confirmed better water interaction of the enzymes. Instability index depicted that compared to laccase and preoxidase, azoreductase was more stable in nature. It was also observed that the three model proteins had more than 90% of total amino acids in the favored region of Ramachandran plot. Functional analysis revealed laccase as multicopper oxidase type enzyme and azoreductase as FMN dependent enzyme, while peroxidase consisted of α-ß barrel with additional haem group. Conclusion: Present study aims to provide knowledge on industrial dye degrading enzymes, choosing the suitable enzyme for industrial set up and to help in understanding the experimental laboratory requirements as well.


Assuntos
Compostos Azo/metabolismo , Peroxidase/química , Lacase/química , NADH NADPH Oxirredutases/química , Temperatura , Compostos Azo/química , Indústria Têxtil , Biodegradação Ambiental , Simulação por Computador , Estabilidade Enzimática , Peroxidase/metabolismo , Lactase/metabolismo , Corantes/metabolismo , NADH NADPH Oxirredutases/metabolismo
18.
Braz J Microbiol ; 51(1): 99-106, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31776865

RESUMO

White-rot basidiomycetes such as Lentinus crinitus produce laccases with potential use in dye biodegradation. However, high productivity and enzymes with specific properties are required in order to make viable laccase production. We aimed to produce laccase from Lentinus crinitus grown in sugarcane bagasse for dye decolorization. Solid state cultivation medium had sugarcane bagasse added with a nutrient solution of 10 g/L glucose, 1 g/L KH2PO4, 0.5 g/L MgSO4, 0.001 g/L FeSO4, 0.01 g/L ZnSO4, and 0.01 g/L MnSO4. The addition of different nitrogen sources (peptone, urea, or peptone plus urea) and different nitrogen concentrations (0, 0.4, 0.6, 0.8, 1.0, and 1.2 g/L) were evaluated. Enzymatic extract was used in the decolorization of azo dyes, reactive blue 220 (RB220) and reactive black 5 (RB5), and anthraquinone dye, Remazol brilliant blue R (RBBR). The greatest laccase activity (4800 U/g dry mass) occurred when the peptone and urea mixture was added to the solid state cultivation medium. When the nitrogen concentration was 1 g/L, the laccase activity increased to 6555 U/g dry mass. The laccase activity peak occurred on the 10th day, and the maximum decolorization within 24 h was observed with enzymatic extracts obtained on different cultivation days, i.e., 6th day for RB220, 10th day for RB5, and 9th day for RBBR. Manganese and lignin peroxidases were not produced when nitrogen was added to the cultivation medium. The crude enzymatic extract was more effective in the decolorization of azo dyes (RB220 and RB5), more than 90% of decolorization, than anthraquinone dye with 77% decolorization.


Assuntos
Antraquinonas/metabolismo , Compostos Azo/metabolismo , Corantes/metabolismo , Lacase/metabolismo , Lentinula/enzimologia , Biodegradação Ambiental , Celulose , Cor , Meios de Cultura/química , Nitrogênio/metabolismo , Peptonas/farmacologia , Saccharum , Ureia
19.
Prep Biochem Biotechnol ; 50(4): 317-329, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31755822

RESUMO

Azo dyes are recalcitrant compounds used as a colorant in various industries. The pollution caused by their extensive usage has adversely affected the environment for years. The existing physicochemical methods for dye pollution remediation are rather inefficient and hence there is a dearth of low-cost, potential systems capable of dye degradation. The current research studies the biodegradation potential of immobilized bacterial cells against azo dyes Reactive Orange 16 (RO-16) and Reactive Blue 250 (RB-250). Two indigenous dye degrading bacteria Bacillus sp. VITAKB20 and Lysinibacillus sp. KPB6 was isolated from textile sludge sample. Free cells of Bacillus. sp. VITAKB20 degraded 92.38% of RO-16 and that of Lysinibacillus sp. KPB6 degraded 95.36% of RB-250 within 72 h under static conditions. Upon immobilization with calcium alginate, dye degradation occurred rapidly. Bacillus. sp. VITAKB20 degraded 97.5% of RO-16 and Lysinibacillus sp. KPB6 degraded 98.2% of RB-250 within 48 h under shaking conditions. Further, the nature of dye decolorization was biodegradation as evident by high-performance liquid chromatography (HPLC), and Fourier-transform infrared spectroscopy (FTIR) results. Phytotoxicity and biotoxicity assays revealed that the degraded dye products were less toxic in nature than the pure dyes. Thus, immobilization proved to be a highly likely alternative treatment for dye removal.


Assuntos
Compostos Azo/metabolismo , Bacillaceae/metabolismo , Bacillus/metabolismo , Células Imobilizadas/metabolismo , Corantes/metabolismo , Alginatos/química , Animais , Artemia/metabolismo , Bacillaceae/química , Bacillus/química , Biodegradação Ambiental , Resíduos Industriais/prevenção & controle , Vigna/metabolismo
20.
Ann Anat ; 227: 151431, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31634560

RESUMO

Histological analysis is a fundamental and principal method used in biological research and even for disease diagnosis. The result shows the status of cells and tissues in organs and enables us to infer the condition of the whole body. The tissue staining method known as hematoxylin and eosin staining (HE) is one of the most general methods of investigating the status of cells and tissues. Hematoxylin stains the nucleus violet and eosin stains cytosol pink. HE staining shows the unique morphologies of tissues and cells. However, after being stained with HE, tissues are very difficult to use in another histological analysis because hematoxylin is hard to remove from the sections due to its stain stability. Therefore, serial sections of the tissue are used to obtain more information through another staining, including immunohistochemistry. The adjacent tissue section is not the same as the HE-stained section, however, so the results from the adjacent sections can cause confusion or ambiguity. The present study showed that our decolorization solution can decolor the hematoxylin or iron hematoxylin stain from stained structures, including the nucleus, and the decolored section could be stained again in another staining, including immunohistochemistry. This decolorization method is very valuable, in that it can determine the accurate distribution of substances and features in cells and tissues, and thus it can improve the robustness of the resulting data.


Assuntos
Corantes/metabolismo , Corantes Fluorescentes/metabolismo , Animais , Compostos Azo/metabolismo , Ácidos Carboxílicos/química , Quelantes/química , Amarelo de Eosina-(YS)/metabolismo , Hematoxilina/metabolismo , Imuno-Histoquímica , Verde de Metila/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Microscopia de Fluorescência , Ácidos Fosfóricos/química , Nitrato de Prata/metabolismo , Trometamina/química
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