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1.
Ecotoxicol Environ Saf ; 190: 110103, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31887707

RESUMO

Multi-contaminated industrial wastewaters pose serious environmental risks due to high toxicity and non-biodegradability. The work reported here evaluated the ability of Pseudomonas aeruginosa strain Gb30 isolated from desert soil to simultaneously remove cadmium (Cd) and Reactive Black 5 (RB5), both common contaminants in various industrial effluents. The strain was able to grow normally and decolorize 50 mg L-1 RB5 within 24 h of incubation in the presence of 0.629 m mol L-1 of Cd2+. In order to evaluate strain performance in RB5 detoxification, a cytotoxicity test using Human Embryonic Kidney cells (HEK293) was used. Cadmium removal from culture media was determined using atomic adsorption. Even in presence of (0.115 + 0.157 + 0.401 + 0.381) m mol L-1, respectively, of Cr6+, Cd2+, Cu2+ and Zn2+ in the growth medium, strain Gb30 successfully removed 35% of RB5 and 44%, 36%, 59% and 97%, respectively, of introduced Zn2+, Cu2+, Cr6+ and Cd2+, simultaneously. In order to understand the mechanism of Cd removal used by P. aeruginosa strain Gb30, biosorption and bioaccumulation abilities were examined. The strain was preferentially biosorbing Cd on the cell surface, as opposed to intracellular bioaccumulation. Microscopic investigations using AFM, SEM and FTIR analysis of the bacterial biomass confirmed the presence of various structural features, which enabled the strain to interact with metal ions. The study suggests that Pseudomonas aeruginosa Gb30 is a potential candidate for bioremediation of textile effluents in the presence of complex dye-metal contamination.


Assuntos
Biodegradação Ambiental , Cádmio/metabolismo , Naftalenossulfonatos/metabolismo , Poluentes do Solo/metabolismo , Adsorção , Bactérias/metabolismo , Biomassa , Células HEK293 , Humanos , Metais Pesados/análise , Pseudomonas aeruginosa/metabolismo , Solo , Poluentes do Solo/análise , Águas Residuárias/química
2.
Ecotoxicol Environ Saf ; 184: 109613, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31491606

RESUMO

Four sugar sources were used as co-substrates to promote the degradation of a selected refractory dye reactive black 5 (RB5) by the natural bacterial flora DDMZ1. The boosting performance of the four sugar sources on RB5 decolorization ranked as: fructose > sucrose > glucose > glucose + fructose. Kinetic results of these four co-metabolism systems agreed well with a first-order kinetic model. Four sugar sources stimulated the extracellular azoreductase secretion causing enhanced enzyme activity. An increased formation of low molecular weight intermediates was caused by the addition of sugar sources. The toxicity of RB5 degradation products was significantly reduced in the presence of sugar sources. The bacterial community structure differed remarkably as a result of sugar sources addition. For a fructose addition, a considerably enriched population of the functional species Burkholderia-Paraburkholderia and Klebsiella was noted. The results enlarge our knowledge of the microkinetic and microbiological mechanisms of co-metabolic degradation of refractory pollutants.


Assuntos
Corantes/metabolismo , Naftalenossulfonatos/metabolismo , Açúcares/metabolismo , Bactérias/classificação , Bactérias/metabolismo , Biodegradação Ambiental , Corantes/química , Corantes/toxicidade , Cinética , NADH NADPH Oxirredutases/metabolismo , Naftalenossulfonatos/toxicidade
3.
Ecotoxicol Environ Saf ; 183: 109484, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31398583

RESUMO

This work evaluated the degradation of the Acid Blue 161 and Procion Red MX-5B dyes in a binary solution by the filamentous fungus Aspergillus terreus and the yeast Saccharomyces cerevisiae in systems with and without electrochemical oxidation as the pretreatment process. UV-Vis spectrophotometry, high-performance liquid chromatography with (HPLC), Fourier transform infrared (FT-IR) spectroscopy and Salmonella/microsome assay (Ames test) were applied towards the degradation analysis of the dyes. Adsorption tests with white clay immobilized on alginate were also conducted after the discoloration treatments to remove intermediate metabolites formed during the degradation of the dye molecules. The discoloration treatments led to the complete color removal of the solutions in all the systems tested. The clay demonstrated affinity for the metabolites formed after discoloration treatments, the removal rates were variable, but the all systems has proved efficient. The Salmonella/microsome assay (Ames test) with strains TA98 and TA100 in the absence and presence of exogenous metabolism (S9 microsomal system, Moltox) revealed that the initial molecules and by-products of the metabolism of the dyes were direct mutagens. The electrochemical/A. terreus/clay system was able to discolor the solutions and transform the direct mutagens into non-mutagenic compounds in addition to reducing the mutagenic potency of the pro-mutagens to the Salmonella strain TA100/S9, which demonstrates the high efficiency of this system with regard to discoloring and degrading azo dye molecules and their by-products. Therefore, this study showed that although not having standard treatment system for this type of pollutant, the combination of treatments can be considered promising. The use of electrochemical oxidation along with microbiological treatment may lead to the degradation and mineralization of these compounds, reducing or eliminating the environmental impact caused by the improper disposal of these dyes in aquatic environments.


Assuntos
Compostos Azo/metabolismo , Compostos Azo/toxicidade , Corantes/metabolismo , Corantes/toxicidade , Mutagênicos/metabolismo , Mutagênicos/toxicidade , Aspergillus/metabolismo , Cromatografia Líquida de Alta Pressão , Complexos de Coordenação/metabolismo , Complexos de Coordenação/toxicidade , Naftalenossulfonatos/metabolismo , Naftalenossulfonatos/toxicidade , Oxirredução , Estresse Oxidativo , Saccharomyces cerevisiae/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier
4.
J Appl Microbiol ; 126(6): 1761-1771, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30916880

RESUMO

AIM: The effect of heavy metals presence on the decolourization of Reactive Black 5 by Pseudomonas aeruginosa was evaluated. METHODS AND RESULTS: In the current study, a newly isolated strain identified as P. aeruginosa strain Gb 30 was selected for its ability to remove high concentration of Reactive Black 5 and resistance to several heavy metals (Cu2+ >Zn2+ >Cd2+ >Cr6+ ). Strain Gb30 was used to assess the effect of heavy metals presence on RB5 decolourization. The strain growth exhibited different responses at a fixed concentration of EC50 (10 h) for each heavy metal. The addition of Zn2+ and Cd2+ had no effect on decolourization yield after 24 h of incubation, whereas Cr6+ and Cu2+ ions reduced decolourization up to 17%. In order to understand the relationship between heavy metals contamination and decolourization, experimental data relating the initial decolourization rate of RB5 to the concentrations of single and associated heavy metals were fitted to three different inhibition kinetic models. CONCLUSIONS: In this study, we showed that P. aeruginosa strain Gb30 could be used for dye removal even at high concentrations of heavy metals. The developed models could provide basic information that may help for the best management of the bacteria-mediated decolourization process at the industrial scale. SIGNIFICANCE AND IMPACT OF THE STUDY: This study opens new directions for the management of textile industry wastewaters containing dyes and heavy metals using bioaugmentation by P. aeruginosa strain Gb30.


Assuntos
Corantes/metabolismo , Metais Pesados/metabolismo , Modelos Químicos , Naftalenossulfonatos/metabolismo , Pseudomonas aeruginosa/metabolismo , Eliminação de Resíduos Líquidos/métodos , Biodegradação Ambiental , Farmacorresistência Bacteriana , Metais Pesados/química , Modelos Teóricos , Indústria Têxtil , Águas Residuárias/química
5.
Bioresour Technol ; 280: 430-440, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30784993

RESUMO

In this work, the performance and mechanism for the boosting effects of fructose as an additional co-metabolite towards the biological treatment of reactive black 5 were systematically investigated. A decolorization efficiency of 98% was obtained in sample FRU200 (with 3 g/L fructose added based on 3 g/L yeast extract), which was 21% higher than that without fructose. Several intermediates with low molecular weight generated in sample FRU200 and different metabolic pathways were deduced. The bacterial community structure significantly changed due to fructose addition. Label-free quantitative proteomic approach suggested that several up-regulated proteins in sample FRU200 might play essential roles during the degradation. Furthermore, the mechanisms of RB5 degradation by proteins/enzymes of the dominant species in flora DDMZ1 were proposed. This work deepens our understanding of the molecular and ecological mechanism of fructose as co-metabolite enhancing the biodegradation of refractory organic pollutants by a natural bacterial flora.


Assuntos
Corantes/metabolismo , Frutose/metabolismo , Naftalenossulfonatos/metabolismo , Corantes/química , Microbiota , Proteômica
6.
World J Microbiol Biotechnol ; 35(3): 38, 2019 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-30739299

RESUMO

The present study investigated biodegradation and removal of Reactive Red 198 (RR198) dye from aqueous environments using a new bacterial consortium isolated from textile wastewater sludge on laboratory scale via batch study. Two bacterial species, Enterococcus faecalis (EF) and Klebsiella variicola (KV), were identified after isolation, through biochemical assays, Polymerase chain reaction (PCR), and 16S rRNA gene sequencing. To determine their ability to biodegrade RR198 dye, physicochemical parameters, including bacterial concentration, time, pH, and temperature, were tested; the results showed that the best conditions included a bacterial concentration of 3.5 mL × 105 cells/mL and incubation time of 72 h. Under such conditions, the removal efficiency of RR198 dye at an initial concentration of 10-25 mg/L was more than 98%; however, for concentrations of 50, 75, and 100 mg/L, removal efficiency was reduced to 55.62%, 25.82%, and 15.42%, respectively (p = 0.005). The highest removal efficiency occurred at pH 8.0, reaching 99.26% after 72 h of incubation. With increasing the incubation temperature from 25 °C to 37 °C, removal efficiency increased from 71.71 to 99.26% after 72 h of incubation, and increasing the temperature from 37 to 45 °C, the removal efficiency was reduced (p ≤ 0.001). Therefore, the EF-KV bacterial consortium can be used for efficient removal of RR198 dye from textile effluent.


Assuntos
Compostos Azo/metabolismo , Enterococcus faecalis/metabolismo , Klebsiella/metabolismo , Consórcios Microbianos , Naftalenossulfonatos/metabolismo , Esgotos/microbiologia , Têxteis/microbiologia , Triazinas/metabolismo , Águas Residuárias/microbiologia , Bactérias/isolamento & purificação , Bactérias/metabolismo , Biodegradação Ambiental , Corantes/metabolismo , DNA Bacteriano/análise , DNA Bacteriano/genética , Enterococcus faecalis/genética , Enterococcus faecalis/isolamento & purificação , Concentração de Íons de Hidrogênio , Resíduos Industriais , Klebsiella/genética , Klebsiella/isolamento & purificação , RNA Ribossômico 16S/genética , Esgotos/química , Temperatura , Indústria Têxtil , Fatores de Tempo , Águas Residuárias/química , Poluentes Químicos da Água/metabolismo
7.
Bioresour Technol ; 273: 49-55, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30408643

RESUMO

Treatment of metal complex dye wastewater has attracted growing attention due to the degradation-resistant, high cost and potential hazards of current techniques. This study reported a marine bacterium (Pseudoalteromonas sp CF10-13) with potential performance in decolorization and degradation of a metal complex dye-Naphthol Green B (NGB) at wide ranges of salinity, dye concentration and alkalinity under anaerobic conditions. It was inferred that the secretion of electron mediators in soluble extracellular metabolites by P. sp CF10-13 played important roles in NGB decolorization and degradation through extracellular electron transfer. Naphthalenesulfonate, the major structure in NGB molecule, was further degraded into low-toxic benzamide. Black stable iron-sulfur nanoparticles were formed endogenously avoiding H2S releasing, exogenous sulfur addition and metal sludge in accumulation. Accordingly, this study provided a cost-effective and eco-friendly biodegradation method to refractory NGB, further promoting the understanding of dye resources recovery.


Assuntos
Compostos Férricos/metabolismo , Ferro/metabolismo , Nanopartículas Metálicas , Naftalenossulfonatos/metabolismo , Pseudoalteromonas/metabolismo , Enxofre/metabolismo , Biodegradação Ambiental , Complexos de Coordenação/metabolismo
8.
Appl Microbiol Biotechnol ; 102(24): 10579-10588, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30302519

RESUMO

Peroxidases are well-known biocatalysts produced by all organisms, especially microorganisms, and used in a number of biotechnological applications. The enzyme DypB from the lignin-degrading bacterium Rhodococcus jostii was recently shown to degrade solvent-obtained fractions of a Kraft lignin. In order to promote the practical use, the N246A variant of DypB, named Rh_DypB, was overexpressed in E. coli using a designed synthetic gene: by employing optimized conditions, the enzyme was fully produced as folded holoenzyme, thus avoiding the need for a further time-consuming and expensive reconstitution step. By a single chromatographic purification step, > 100 mg enzyme/L fermentation broth with a > 90% purity was produced. Rh_DypB shows a classical peroxidase activity which is significantly increased by adding Mn2+ ions: kinetic parameters for H2O2, Mn2+, ABTS, and 2,6-DMP were determined. The recombinant enzyme shows a good thermostability (melting temperature of 63-65 °C), is stable at pH 6-7, and maintains a large part of the starting activity following incubation for 24 h at 25-37 °C. Rh_DypB activity is not affected by 1 M NaCl, 10% DMSO, and 5% Tween-80, i.e., compounds used for dye decolorization or lignin-solubilization processes. The enzyme shows broad dye-decolorization activity, especially in the presence of Mn2+, oxidizes various aromatic monomers from lignin, and cleaves the guaiacylglycerol-ß-guaiacyl ether (GGE), i.e., the Cα-Cß bond of the dimeric lignin model molecule of ß-O-4 linkages. Under optimized conditions, 2 mM GGE was fully cleaved by recombinant Rh_DypB, generating guaiacol in only 10 min, at a rate of 12.5 µmol/min mg enzyme.


Assuntos
Proteínas de Bactérias/metabolismo , Corantes/química , Guaifenesina/análogos & derivados , Manganês/metabolismo , Peroxidases/metabolismo , Antraquinonas/química , Antraquinonas/metabolismo , Corantes Azur/química , Corantes Azur/metabolismo , Proteínas de Bactérias/genética , Corantes/metabolismo , Dimetil Sulfóxido/química , Escherichia coli/genética , Guaifenesina/metabolismo , Peróxido de Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Naftalenossulfonatos/química , Naftalenossulfonatos/metabolismo , Oxirredução , Peroxidases/genética , Polissorbatos/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Rhodococcus/genética , Temperatura
9.
World J Microbiol Biotechnol ; 34(9): 131, 2018 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-30105649

RESUMO

A new yeast strain which was capable of degrading various azo dyes under high-salt conditions was identified in this study. The results showed that the yeast named S4 was identified as Cyberlindnera samutprakarnensis through 26S rDNA sequence analysis and could decolorize more than 97% of Acid Red B (ARB) within 18 h under the optimal conditions. The acute toxicity of ARB sharply decreased after degradation. NADH-DCIP reductase and lignin peroxidase were determined as the key reductase and oxidase of the yeast S4, respectively. Furthermore, it was proposed that ARB was degraded by strain S4 successively through reduction of azo bonds, hydroxylation, deamination, desulfonation and finally to the TCA cycle.


Assuntos
Adaptação Fisiológica , Compostos Azo/metabolismo , Biodegradação Ambiental , Saccharomycetales/metabolismo , Aliivibrio fischeri/efeitos dos fármacos , Compostos Azo/química , Compostos Azo/toxicidade , Corantes/química , Corantes/metabolismo , Corantes/toxicidade , DNA Ribossômico/genética , Inativação Metabólica , Naftalenossulfonatos/química , Naftalenossulfonatos/metabolismo , Peroxidases/metabolismo , Filogenia , Quinona Redutases/metabolismo , Saccharomycetales/enzimologia , Saccharomycetales/genética , Saccharomycetales/isolamento & purificação , Análise de Sequência , Cloreto de Sódio/metabolismo , Águas Residuárias , Purificação da Água
10.
J Hazard Mater ; 357: 226-234, 2018 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-29890419

RESUMO

Effect of dosing ferroferric oxide (Fe3O4) on the anaerobic treatment of azo dye Reactive Red 2 (RR2) was investigated in two anaerobic sequencing batch reactors (ASBRs). System performance, dye degradation pathways, and microbial activities and structure were examined. The addition of Fe3O4 significantly improved treatment efficiency, with the removal efficiency of RR2 increased by 116%, the maximum methane (CH4) yield potential and the peak CH4 production rate improved by 7.7% and 22.3%, and the lag phase shortened by 39.6%, respectively. The activity of the electron transport system was significantly enhanced by dosing Fe3O4, with the maximum value increased by 77% and conductivity of the anaerobic sludge increased by 178%. According to the proposed pathway for the degradation of RR2, the degradation products from complete cleavage of the NN bond in RR2 were obtained at the presence of Fe3O4, while were absent without Fe3O4. At high initial dye concentrations, the dosage of Fe3O4 alleviated the inhibition to microbes by RR2, and high degradation rate and removal efficiency were maintained. The microbial community structure changed during the long-term acclimation with the dosage of Fe3O4. Paludibacter, Trichococcus and Methanosarcina were predominant and their relative abundances increased with the addition of Fe3O4.


Assuntos
Reatores Biológicos , Corantes/metabolismo , Óxido Ferroso-Férrico/farmacologia , Naftalenossulfonatos/metabolismo , Triazinas/metabolismo , Poluentes Químicos da Água/metabolismo , Anaerobiose/efeitos dos fármacos , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Biodegradação Ambiental , Condutividade Elétrica
11.
J Hazard Mater ; 352: 70-79, 2018 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-29573731

RESUMO

The biotreatment of recalcitrant wastes in microbial fuel cells (MFCs) rather than chemical, physical, and advanced oxidation processes is a low-cost and eco-friendly process. In this study, sulfate-reducing mixed communities in MFC anodic chamber were employed for simultaneous electricity generation, dye degradation, and sulfate reduction. A power generation of 258 ±â€¯10 mW/m2 was achieved under stable operating conditions in the presence of electroactive sulfate-reducing bacteria (SRB). The SRBs dominant anodic chambers result in dye, chemical oxygen demand (COD), and sulfate removal of greater than 85% at an initial COD (as lactate)/SO42- mass ratio of 2.0 and dye concentration of 100 mg/L. The effects of the COD/SO42- ratio (5.0:1.0-0.5:1.0) and initial diazo dye concentration (100-1000 mg/L) were studied to evaluate and optimize the MFC performance. Illumina Miseq technology for bacterial community analysis showed that Proteobacteria (89.4%), Deltaproteobacteria (52.7%), and Desulfovibrio (48.2%) were most dominant at phylum, class, and genus levels, respectively, at the MFC anode. Integration of anaerobic SRB culture in MFC bioanode for recalcitrant chemical removal and bioenergy generation may lead to feasible option than the currently used technologies in terms of overall pollutant treatment.


Assuntos
Compostos Azo/metabolismo , Fontes de Energia Bioelétrica , Corantes/metabolismo , Naftalenossulfonatos/metabolismo , Poluentes Químicos da Água/metabolismo , Bactérias/genética , Bactérias/metabolismo , Eletricidade , Resíduos Industriais , Oxirredução , Sulfatos/metabolismo , Têxteis , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias
12.
Colloids Surf B Biointerfaces ; 161: 169-176, 2018 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-29078166

RESUMO

Cyclodextrins (CD) are cyclic oligosaccharides produced from the enzymatic degradation of starch as a white powder form; on the other hand, they can be transformed into ultrathin electrospun fiber form by electrospinning technique. The electrospun cyclodextrin fibers (CD-F) can be quite attractive materials to encapsulate bacteria for bioremediation purposes. For instance, CD-F not only serve as a carrier matrix but also it serves as a feeding source for the encapsulated bacteria. In the present study, we demonstrate a facile approach by encapsulation of bacteria into CD-F matrix for wastewater treatment application. The natural and non-toxic properties of CD-F render a better bacterial viability for fibrous biocomposite. The encapsulated bacteria in CD-F exhibit cell viability for more than 7days at 4°C storage condition. Furthermore, we have tested the bioremediation capability of bacteria/CD-F biocomposite for the treatment of heavy metals (Nickel(II) and Chromium(VI)) and textile dye (Reactive Black 5, RB5). The bacteria/CD-F biocomposite has shown removal efficiency of Ni(II), Cr(VI) and RB5 as 70±0.2%, 58±1.4% and 82±0.8, respectively. As anticipated, the pollutants removal capabilities of the bacteria/CD-F was higher compare to free bacteria since bacteria can use CD as an extra carbon source which promotes their growth rate. This study demonstrates that CD-F are suitable platforms for the encapsulation of bacterial cells to develop novel biocomposites that have bioremediation capabilities for wastewater treatment.


Assuntos
Bactérias/metabolismo , Ciclodextrinas/metabolismo , Metais Pesados/metabolismo , Nanofibras/microbiologia , Naftalenossulfonatos/metabolismo , Águas Residuárias/microbiologia , Bactérias/isolamento & purificação , Biodegradação Ambiental , Ciclodextrinas/química , Técnicas Eletroquímicas , Concentração de Íons de Hidrogênio , Metais Pesados/isolamento & purificação , Microscopia Eletrônica de Varredura , Nanofibras/química , Nanofibras/ultraestrutura , Naftalenossulfonatos/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/metabolismo
13.
Water Sci Technol ; 76(11-12): 2979-2987, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29210685

RESUMO

Continuous treatment of Acid Red B (ARB) with activated sludge (AS) bioaugmented by an azo-degrading yeast Candida tropicalis TL-F1 under aerobic conditions was investigated in the form of sequencing batch tests. Dynamics of both bacterial and fungal communities were analyzed using polymerase chain reaction followed by denaturing gradient gel electrophoresis (PCR-DGGE) method. The results showed that bioaugmentation with the yeast TL-F1 improved the performance of AS for continuously decolorizing, degrading and detoxifying ARB. Meanwhile, the AS systems bioaugmented by the yeast TL-F1 showed higher sludge concentration and better AS settleability. The result of PCR-DGGE suggested that microbial communities of both bacteria and fungi shifted due to treatment of ARB and bioaugmentation. Some dominant bacteria and fungi were identified as probably efficient degraders of ARB or its decolorization byproducts. Furthermore, the yeast TL-F1 was found as one of the dominant fungi in all the three bioaugmented systems, suggesting that bioaugmentation was successful due to the colonization of the yeast TL-F1 in AS systems.


Assuntos
Compostos Azo/química , Reatores Biológicos , Candida tropicalis/metabolismo , Naftalenossulfonatos/química , Esgotos/microbiologia , Compostos Azo/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Candida tropicalis/classificação , Naftalenossulfonatos/metabolismo , Reação em Cadeia da Polimerase , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo
14.
Water Sci Technol ; 76(7-8): 1754-1769, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28991791

RESUMO

This study aimed to kinetically discover optimal conditions on characteristics of Reactive Black 5 decolorization/degradation via ferrous (Fe2+)-activated potassium persulfate (PS). Monod-like kinetics and interactive model-based response surface methodology (RSM) were applied to fitting and predict optimize treatment. Biodegradability of the intermediates was also tested by shaking culture with two species (Proteus hauseri ZMd44 and Shewanella sp. WLP72). Results showed that the optimal degradation efficiency was predicted (through RSM) as pH 3.72, (PS) = 0.39 mM, and (Fe2+) = 0.29 mM. The transformation products (dl-4-hydroxymandelic acid, benzoic acid, benzene, formic acid, oxalic acid and acetic acid) were less toxic than the original dye solution. According to those results, clean-up of dye pollutants by the Fe2+/S2O82- process is feasible as a pre-processing for the biodegradation, and the predicted optimal conditions are meaningful for further industry utilization.


Assuntos
Biodegradação Ambiental , Naftalenossulfonatos/química , Poluentes Químicos da Água/química , Corantes/química , Corantes/metabolismo , Cinética , Modelos Biológicos , Naftalenossulfonatos/metabolismo , Compostos de Potássio , Proteus/metabolismo , Shewanella/metabolismo , Compostos de Sódio , Sulfatos , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo
15.
Bioresour Technol ; 245(Pt A): 1103-1109, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28950652

RESUMO

A microwave (MW)-assisted-H2O2 technique used to revise 4-amino-5-hydroxynaphthalene-2,7-disulfonic acid (H-acid)-saturated biochars (BCs) was investigated in detail. This method could simultaneously degrade the H-acid adsorbed in the BCs-based BiFeO3 (BFO) nanocomposites (BFO/BCs), in which BFO was used as dopant intercalated into BC, and activate the used BCs. Because H-acid could be decomposed by OH, which was generated in a coexistent system, including MW irradiation, H2O2, and BCs. It's worth noticing the adsorption capacity was (236.8mgg-1) 1.1-fold higher than that of unused BFO/BC (211.7mgg-1). It indicated that the surplus OH exhibited a cooperative effect with MW irradiation to restore H-acid-saturated BCs via the cleavage of CC bond, thereby forming carboxylic groups and the pyrolysis effect. Findings indicated that the one-step degradation-regeneration method could effectively promote the adsorption capacity of H-acid-saturated BCs in a few minutes and could thus be considered a potential technology in water treatment.


Assuntos
Carvão Vegetal , Naftalenossulfonatos/metabolismo , Adsorção , Peróxido de Hidrogênio , Nanocompostos , Regeneração , Temperatura
16.
Chemosphere ; 186: 287-294, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28787684

RESUMO

By combining sequential anaerobic-aerobic reactor and penetrable cathode-anode operation, a novel anaerobic/aerobic sequencing three-dimensional biofilm electrode reactor (3D-BER) was developed to evaluate the degradation of azo dye reactive brilliant red X-3B (RBRX-3B). In the bottom cathodic region, anaerobic reductive conditions and H2 were produced for the bioreduction of azo dyes; in the top anodic region, aerobic oxidative conditions and O2 were produced for the mineralization of dye intermediates. Due to the supply of electrical power, electrons could be mediated via electrolysis of water or directly transfer between electrodes and microbe cells. The biofilm immobilized on the surface of the cathode utilized electrode or H2 as electron donors and accelerated the rate of RBRX-3B reduction, and the decolorization rate was significantly increased 2.6-3.7 fold, reaching at 2.52-3.39 mol/m3/d at an energy consumption of 0.15 kWh/mol RBRX-3B. RBRX-3B was reductively cleaved into aromatic amines at the biocathode and these amines were effectively removed at the bioanode. Acute toxicity tests showed that the intermediates of RBRX-3B were more toxic when compared with the initial influent, and the 3D-BER effluent exhibited much lower toxicity (5% inhibition of bioluminescence of Vibrio fisheri) than the electrochemical and biological effluent (65% and 30% inhibition, respectively). These findings suggest the novel 3D-BER may provide a promising alternative to remove azo dyes in dyeing wastewater.


Assuntos
Compostos Azo/metabolismo , Biofilmes , Corantes/metabolismo , Eliminação de Resíduos Líquidos/métodos , Eletrodos , Eletrólise , Naftalenossulfonatos/metabolismo , Oxirredução , Eliminação de Resíduos Líquidos/instrumentação
17.
J Biosci Bioeng ; 124(6): 668-673, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28803054

RESUMO

Textile wastewater contains high concentrations of organic substances derived from diverse dyes and auxiliary chemicals, some of which are non-biodegradable and/or toxic. Therefore, it is essential that textile wastewater is treated and that these substances are removed before being discharged into the environment. A combination of advanced oxidation processes (AOPs) to obtain partial dye degradation followed by a biological treatment has been suggested as a promising method for cost-effective decolorization of wastewater. The aim of this study was to develop and evaluate a combined method of partial Fenton's oxidation and biological treatment using activated sludge for decolorization of azo dyes, which represent an important group of recalcitrant, toxic textile dyes. Using Reactive Violet 5 (RV5) as a model dye, color removal was significantly higher when the combined Fenton treatment/activated sludge method was used, as opposed to separate application of these treatments. More specifically, pretreatment with Fenton's reagent removed 52.9, 83.9 and 91.3 % of color from a 500 mg l-1 RV5 aqueous solution within 60 min when H2O2 concentrations of 1.0, 1.5, and 2.0 mM were used, respectively. Subsequent biological treatment was found to significantly enhance the chemical treatment, with microbial decolorization removing 70.2 % of the remaining RV5 concentration, on average. Molecular analysis of the microbial community within the activated sludge revealed that exposure to RV5 shifted the community composition from diverse towards a highly-specialized community harboring taxa with azo dye degrading activity, including Trichosporon, Aspergillus and Clostridium species.


Assuntos
Compostos Azo/química , Compostos Azo/metabolismo , Cor , Esgotos/química , Esgotos/microbiologia , Peróxido de Hidrogênio/química , Ferro/química , Naftalenossulfonatos/química , Naftalenossulfonatos/metabolismo , Oxirredução , Têxteis , Águas Residuárias/química
18.
Curr Microbiol ; 74(8): 965-971, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28573341

RESUMO

The aim of this study was to develop a rapid detection assay to identify methicillin-resistant Staphylococcus aureus by simultaneous testing for the mecA, nuc, and femB genes using the loop-mediated isothermal amplification (LAMP) method. LAMP primers were designed using online bio-software ( http://primerexplorer.jp/e/ ), and amplification reactions were performed in an isothermal temperature bath. The products were then examined using 2% agarose gel electrophoresis. MecA, nuc, and femB were confirmed by triplex TaqMan real-time PCR. For better naked-eye inspection of the reaction result, hydroxy naphthol blue (HNB) was added to the amplification system. Within 60 min, LAMP successfully amplified the genes of interest under isothermal conditions at 63 °C. The results of 2% gel electrophoresis indicated that when the Mg2+ concentration in the reaction system was 6 µmol, the amplification of the mecA gene was relatively good, while the amplification of the nuc and femB genes was better at an Mg2+ concentration of 8 µmol. Obvious color differences were observed by adding 1 µL (3.75 mM) of HNB into 25 µL reaction system. The LAMP assay was applied to 128 isolates cases of methicillin-resistant Staphylococcus aureus, which were separated from the daily specimens and identified by Vitek microbial identification instruments. The results were identical for both LAMP and PCR. LAMP offers an alternative detection assay for mecA, nuc, and femB and is faster than other methods.


Assuntos
Proteínas de Bactérias/genética , Técnicas Bacteriológicas/métodos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Nuclease do Micrococo/genética , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Proteínas de Ligação às Penicilinas/genética , Eletroforese em Gel de Ágar , Staphylococcus aureus Resistente à Meticilina/genética , Naftalenossulfonatos/metabolismo , Coloração e Rotulagem , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/microbiologia
19.
Luminescence ; 32(7): 1319-1327, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28524270

RESUMO

In this study, the interaction between human serum albumin (HSA) and a copper complex of carmoisine dye; [Cu(carmoisine)2 (H2 O)2 ], was studied in vitro using multi-spectroscopic methods. It was found that the intrinsic fluorescence of HSA was quenched by the addition of the [Cu(carmoisine)2 (H2 O)2 ] complex and the quenching mechanism was considered as static quenching by formation of a [Cu(carmoisine)2 (H2 O)2 ]-HSA complex. The binding constant was about 104  M-1 at room temperature. The values of the calculated thermodynamic parameters (ΔH < 0 and ΔS > 0) suggested that both hydrogen bonds and the hydrophobic interactions were involved in the binding process. The site marker competitive experiments revealed that the binding of [Cu(carmoisine)2 (H2 O)2 ] to HSA primarily occurred in subdomain IIIA (site II) of HSA. The results of circular dichroism (CD) and UV-vis spectroscopy showed that the micro-environment of amino acid residues and the conformation of HSA were changed after addition of the [Cu(carmoisine)2 (H2 O)2 ] complex. Finally, the binding of the [Cu(carmoisine)2 (H2 O)2 ] complex to HSA was modelled by a molecular docking method. Excellent agreement was obtained between the experimental and theoretical results with respect to the binding forces and binding constant.


Assuntos
Cobre/química , Aditivos Alimentares/química , Naftalenossulfonatos/química , Albumina Sérica Humana/química , Albumina Sérica Humana/metabolismo , Sítios de Ligação , Dicroísmo Circular , DNA/química , DNA/metabolismo , Aditivos Alimentares/metabolismo , Humanos , Ligação de Hidrogênio , Simulação de Acoplamento Molecular , Naftalenossulfonatos/metabolismo , Compostos Organometálicos/química , Compostos Organometálicos/metabolismo , Conformação Proteica , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Termodinâmica
20.
J Environ Sci (China) ; 53: 78-87, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28372763

RESUMO

Azo dyes are extensively used in textile dyeing and other industries. Effluents of dying industries are specially colored and could cause severe damage to the environment. The anaerobic treatment of textile dying effluents is nowadays the preferred option, but it could generate carcinogenic aromatic amines. Recently, yeasts have become a promising alternative, combining unicellular growth with oxidative mechanisms. This work reports the characterization of the first methylotrophic yeast with dye decolorizing ability, Candida boidinii MM 4035 and some insights into its decoloration mechanism. The analysis of two selected media revealed a possible two stages mechanism of Reactive Black 5 decoloration. In glucose poor media, decoloration is incomplete and only the first stage proceeds, leading to the accumulation of a purple compound. In media with higher glucose concentrations, the yeast is able to decolorize totally an initial concentration of 200mg/L. The entire process is co-metabolic, being largely dependent on glucose concentration but being able to proceed with several nitrogen sources. Manganese dependent peroxidase but not laccase activity could be detected during decoloration. Aromatic amines do not accumulate in culture media, supporting an oxidative decoloration mechanism of unknown ecophysiological relevance.


Assuntos
Candida/fisiologia , Naftalenossulfonatos/metabolismo , Indústria Têxtil , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental , Resíduos Industriais , Naftalenossulfonatos/análise , Têxteis , Poluentes Químicos da Água/análise
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