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1.
Ecotoxicol Environ Saf ; 208: 111742, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396068

RESUMO

The indiscriminate disposal of olsalazine in the environment poses a threat to human health and natural ecosystems because of its cytotoxic and genotoxic nature. In the present study, degradation efficiency of olsalazine by the marine-derived fungus, Aspergillus aculeatus (MT492456) was investigated. Optimization of physicochemical parameters (pH. Temperature, Dry weight) and redox mediators {(2,20-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), p-Coumaric acid and 1-hydroxybenzotriazole (HOBT)} was achieved with Response Surface Methodology (RSM)-Box-Behnken Design (BBD) resulting in 89.43% removal of olsalazine on 7th day. The second-order polynomial regression model was found to be statistically significant, adequate and fit with p < 0.0001, F value=41.87 and correlation coefficient (R2=0.9826). Biotransformation was enhanced in the redox mediator-laccase systems resulting in 99.5% degradation of olsalazine. The efficiency of ABTS in the removal of olsalazine was more pronounced than HOBT and p-Coumaric acid in the laccase-mediator system. This is attributed to the potent nature of the electron transfer mechanism deployed during oxidation of olsalazine. The pseudo-second-order kinetics revealed that the average half-life (t1/2) and removal rates (k1) increases with increasing concentrations of olsalazine. Michaelis-Menten kinetics affirmed the interaction between laccase and olsalazine under optimized conditions with maximum removal rate, Vmax=111.11 hr-1 and half-saturation constant, Km=1537 mg L-1. At the highest drug concentration (2 mM); 98%, 95% and 93% laccase was remarkably stabilized in the enzyme-drug degradation system by HOBT, ABTS and p-Coumaric acid respectively. This study further revealed that the deactivation of laccase by the redox mediators is adequately compensated with enhanced removal of olsalazine.


Assuntos
Ácidos Aminossalicílicos/metabolismo , Anti-Inflamatórios não Esteroides/metabolismo , Aspergillus/fisiologia , Biodegradação Ambiental , Ecossistema , Fungos/metabolismo , Humanos , Cinética , Lacase/metabolismo , Oxirredução , Ácidos Sulfônicos/metabolismo , Triazóis
2.
Water Res ; 189: 116667, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33271411

RESUMO

Synthetic or natural mediators (Med) can enhance the transformation of different types of organic pollutants by mild oxidants, which has been extensively studied in literature. This enhancing effect is attributed to the following two steps: (i) mild oxidants react with Med forming Medox with higher reactivity, and then (ii) these organic pollutants are more readily transformed by Medox. The present work reviews the latest findings on the formation of Medox from the reactions of synthetic (i.e., 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS) and 1-hydroxybenzotriazole (HBT)) or natural mediators (i.e., syringaldehyde (SA), acetosyringone (AS), p-coumaric acid, and catechol) with mild oxidants such as laccase, manganese oxidants including permanganate (Mn(VII)) and MnO2, and ferrate (Fe(VI)), as well as the transformation of organic pollutants including phenols, amines, polycyclic aromatic hydrocarbons (PAHs), organic dyes, pulp, and perfluoroalkyl acids (PFAAs) by Medox. First, reaction kinetics and mechanisms of the oxidation of synthetic or natural mediators by these mild oxidants were summarized. Reactivity and pathways of synthetic Medox including ABTS·+, ABTS2+, HBT· or natural Medox including phenoxy radicals and quinone-type compounds reacting with different organic pollutants were then discussed. Finally, the possibilities of engineering applications and new perspectives were assessed on the combinations of different types of mild oxidants with synthetic or natural mediators for the treatment of various organic pollutants.


Assuntos
Poluentes Ambientais , Compostos de Manganês , Lacase/metabolismo , Oxidantes , Oxirredução , Óxidos
3.
Food Chem ; 338: 127731, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32810811

RESUMO

Pleurotus tuoliensis is a popular edible and medical mushroom, but it is highly perishable during postharvest storage. The quality parameters, chemical composition, malondialdehyde (MDA) concentration, and activity of metabolic enzymes were studied during 12 days of storage at 4 °C and 6 days of storage at 25 °C. Degradation was well described by changes in quality parameters, losses in nutritional value, increased metabolic enzyme activity, the accumulation of MDA concentrations, and the increase of total phenolic (TP) content. The phenylalanine ammonia lyase (PAL) significantly positively correlated with TP, which suggested an underlying mechanism of browning that the increased PAL activity stimulates the biosynthesis of phenols through the phenylalanine pathway. These results suggest that increased activity of laccase, lipoxygenase, PAL, TP and MDA accumulation, together with polysaccharide degradation, are the main factors involved in the deterioration of P. tuoliensis during storage.


Assuntos
Armazenamento de Alimentos , Pleurotus/química , Pleurotus/metabolismo , Aminoácidos/análise , Enzimas/análise , Enzimas/metabolismo , Proteínas Fúngicas/análise , Lacase/análise , Lacase/metabolismo , Malondialdeído/análise , Malondialdeído/metabolismo , Valor Nutritivo , Fenóis/análise , Fenilalanina Amônia-Liase/análise , Fenilalanina Amônia-Liase/metabolismo , Temperatura
4.
Food Chem ; 337: 127996, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32919275

RESUMO

Hydroxytyrosol oligomer prepared by bioenzyme shows stronger health-promoting properties than its monomer. However, the polymerization process carried out by laccase, tyrosinase or horseradish peroxidase is still lacking in term of product characterization, kinetics and thermodynamics. To achieve these aspects, ATR-FT-IR, NMR, the Michaelis-Menten equation and isothermal titration calorimetry were explored. The results showed that the identified polymers presented a CC bond and a degree of polymerization less than six. Laccase showed the greatest affinity to hydroxytyrosol via comparison of Km and Vm. All of these polymerization processes were spontaneous and exothermic behaviuors ranging from 30 to 50 °C, and were driven by hydrogen bonds, van der Waals interactions and hydrophobic interactions. Furthermore, circular dichroism spectroscopy was used to reveal the enzymatic structural changes during the catalysis, which showed that ß-sheet levels for laccase, α-helix levels for tyrosinase, and the α-helix and random coil levels for horseradish peroxidase were dramatically decreased.


Assuntos
Catecol Oxidase/metabolismo , Peroxidase do Rábano Silvestre/metabolismo , Polimerização , Calorimetria/métodos , Catálise , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Cinética , Lacase/metabolismo , Oxirredução , Álcool Feniletílico/análogos & derivados , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica
5.
Environ Pollut ; 268(Pt A): 115827, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33096462

RESUMO

The present study explores the immobilization of ligninolytic enzyme-laccase on the surface of rice straw biochar and evaluates its application for anthracene biodegradation. The rice straw biochar was acid-treated to generate carboxyl functionality on its surface, followed by detailed morphological and chemical characterization. The surface area of functionalized biochar displayed a two-fold increase compared to the untreated biochar. Laccase was immobilized on functionalized biochar, and an immobilization yield of 66% was obtained. The immobilized enzyme demonstrated operational stability up to six cycles while retaining 40% of the initial activity. Laccase immobilization was further investigated by performing adsorption and kinetic studies, which revealed the highest immobilization concentration of 500 U g-1 at 25 °C. The adsorption followed the Langmuir isotherm model at equilibrium, and the kinetic study confirmed pseudo-second-order kinetics. The equilibrium rate constant (K2) at 25 °C and 4 °C were 3.6 × 10-3 g U-1 min-1 and 4 × 10-3 g U-1 min-1 respectively for 100 U g-1 of enzyme loading. This immobilized system was applied for anthracene degradation in the aqueous batch mode, which resulted in complete degradation of 50 mg L-1 anthracene within 24 h of interaction exposure.


Assuntos
Lacase , Oryza , Adsorção , Antracenos , Carvão Vegetal , Concentração de Íons de Hidrogênio , Cinética , Lacase/metabolismo , Oryza/metabolismo
6.
J Environ Manage ; 276: 111326, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32891981

RESUMO

This study was focused on creating a new and effective immobilization method for Trametes versicolor laccase (Lc) by using chitosan (CS) microspheres activated with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride. The activation of the support alternated with immobilization of the enzyme, in repetitive procedures, led to obtaining three different products. Also, the physicochemical properties of the new products were investigated and compared with those of free laccase. The discoloration and reusability properties of the immobilized Lc were evaluated using indigo carmine (IC) as a model micropollutant. The ESEM and FT-IR methods demonstrated that the Lc was successfully immobilized. The relative reaction rate and the total amount of immobilized Lc were tripled using the iterative protocol as proved by specific and Bradford assays. The maximum amount of immobilized Lc was 8.4 mg Lc/g CS corresponding to the third immobilization procedure. Compared to the free Lc, the operational stability of the immobilized Lc was significantly improved, presenting a maximum activity plateau over a pH range of 3-5 and a temperature range of 25-50 °C. The thermal inactivation study at 55 °C proved that the immobilized enzyme is three times more stable than the free Lc. The isoconversional and Michaelis-Menten methods showed that the immobilization did not affect the enzyme catalytic properties. After 32 days of storage, the residual activities are 85% for the immobilized laccase and 40% for the free one. In similar conditions, the free and immobilized Lc (2.12 x 10-6 M) completely decolorized IC (7.15 x 10-5 M) within 14 min. The immobilized Lc activity remained almost constant (80%) during 10 reusability cycles. All these results highlight the substantial advantages of the new immobilization protocol and demonstrate that immobilized Lc can be used as a promising micropollutant removal from real wastewater.


Assuntos
Quitosana , Lacase , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Lacase/metabolismo , Microesferas , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Trametes
7.
PLoS One ; 15(9): e0239005, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32946485

RESUMO

The two-domain bacterial laccases oxidize substrates at alkaline pH. The role of natural phenolic compounds in the oxidation of substrates by the enzyme is poorly understood. We have studied the role of ferulic and caffeic acids in the transformation of low molecular weight substrates and of soil humic acid (HA) by two-domain laccase of Streptomyces puniceus (SpSL, previously undescribed). A gene encoding a two-domain laccase was cloned from S. puniceus and over-expressed in Escherichia coli. The recombinant protein was purified by affinity chromatography to an electrophoretically homogeneous state. The enzyme showed high thermal stability, alkaline pH optimum for the oxidation of phenolic substrates and an acidic pH optimum for the oxidation of K4[Fe(CN)6] (potassium ferrocyanide) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt). Phenolic compounds were oxidized with lower efficiency than K4[Fe(CN)6] and ABTS. The SpSL did not oxidize 3.4-dimethoxybenzoic alcohol and p-hydroxybenzoic acid neither in the absence of phenolic acids nor in their presence. The enzyme polymerized HA-the amount of its high molecular weight fraction (>80 kDa) increased at the expense of low MW fraction (10 kDa). The addition of phenolic acids as potential mediators did not cause the destruction of HA by SpSL. In the absence of the HA, the enzyme polymerized caffeic and ferulic acids to macromolecular fractions (>80 kDa and 10-12 kDa). The interaction of SpSL with HA in the presence of phenolic acids caused an increase in the amount of HA high MW fraction and a two-fold increase in the molecular weight of its low MW fraction (from 10 to 20 kDa), suggesting a cross-coupling reaction. Infrared and solution-state 1H-NMR spectroscopy revealed an increase in the aromaticity of HA after its interaction with phenolic acids. The results of the study expand our knowledge on the transformation of natural substrates by two-domain bacterial laccases and indicate a potentially important role of the enzyme in the formation of soil organic matter (SOM) at alkaline pH values.


Assuntos
Lacase/metabolismo , Solo/química , Streptomyces/metabolismo , Ácidos Cafeicos/metabolismo , Clonagem Molecular/métodos , Ácidos Cumáricos/metabolismo , Substâncias Húmicas , Concentração de Íons de Hidrogênio , Cinética , Peso Molecular , Oxirredução , Proteínas Recombinantes/genética , Microbiologia do Solo , Streptomyces/genética , Especificidade por Substrato/genética
8.
J Biosci Bioeng ; 130(6): 630-636, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32958392

RESUMO

To achieve the high-level stable expression of chlorothalonil hydrolytic dehalogenase (Chd), the gene chd was first integrated into the chromosome of Bacillus subtilis WB800. High generation stability was achieved by almost no gene lost after six generations but Chd activity decreased. aprE promoter alteration, translation initiation region modification and multi-copy chromosome integration were studied and these modifications could increase Chd activity by 270%, 2304% and 25%. Chlorothalonil residual exhibited inhibition on bioconversion of lignocellulosic biomass. The addition of Chd crude enzyme (60 µL per g wheat straw) could increase glucose production by 36.10% and 39.65% in synergistic hydrolysis and separate hydrolysis by laccase and cellulase with 120 mg/L residual chlorothalonil. Filter paper activity and carboxymethyl cellulase activity were enhanced by 12.84% and 23.95%, and biomass of Trichoderma reesei was increased by 76.67% under 50 µg chlorothalonil/g dry straw in solid-state fermentation. Thus, the high-level stable expressed Chd effectively eliminated chlorothalonil inhibition on enzymatic hydrolysis and solid-state fermentation. It showed promising potential for bioremediation of chlorothalonil pollution and improving conversion efficiency of lignocellulose.


Assuntos
Bacillus subtilis/enzimologia , Biomassa , Enzimas/genética , Enzimas/metabolismo , Lignina/metabolismo , Nitrilos/metabolismo , Celulase/metabolismo , Fermentação , Expressão Gênica , Hidrólise , Hypocreales/metabolismo , Lacase/metabolismo
9.
Mol Biol (Mosk) ; 54(4): 680-687, 2020.
Artigo em Russo | MEDLINE | ID: mdl-32799230

RESUMO

Bacterial laccases are very stable at high temperature and high pH values, and have many biotechnological and industrial applications. Here we describe how we cloned, expressed and purified the laccase from Bacillus subtilis (B. subtilis). The enzyme molecular weight has been determined as 34 kDa in SDS-PAGE analysis. The activity of the recombinant enzyme has been proved by guaiacol oxidation. The KM and Vmax values of the enzyme were at 1.1077 mM and at 19.3 µmol/min/mg, respectively. The recombinant laccase was effective in the decolorization of Turquoise blue HF6, Remazol red 106, Remazol brilliant orange 3R, and Brilliant blue, thus, possessing the characteristics necessary for its possible application in textile and environmental industries.


Assuntos
Bacillus subtilis/enzimologia , Proteínas de Bactérias/metabolismo , Lacase/metabolismo , Bacillus subtilis/genética , Proteínas de Bactérias/genética , Clonagem Molecular , Corantes/metabolismo , Concentração de Íons de Hidrogênio , Lacase/genética , Temperatura
10.
Ecotoxicol Environ Saf ; 205: 111134, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32829208

RESUMO

The recalcitrant azo dyes combined with heavy metals constitute a major challenge for the bioremediation of industrial effluents. This study aimed to investigate the effect and mechanism of action of a white-rot fungus Trametes hirsuta TH315 on the simultaneous removal of hexavalent chromium [Cr(VI)] and azo dye (Reactive Black 5, RB5). Here, this study discovered that toxic Cr(VI) (1 mM) greatly promoted RB5 decolorization (from 57.15% to 83.65%) by white-rot fungus Trametes hirsuta with high Cr(VI)-reducing ability (>96%), resulting in the simultaneous removal of co-contaminants. On the basis of transcriptomic and biochemical analysis, our study revealed that the oxidative stress in co-contaminants mainly caused by Cr(VI), and a number of dehydrogenases and oxidases showed up-regulation in response to Cr(VI) stress. It was noteworthy that the oxidative stress caused by Cr(VI) in co-contaminants can both significantly induce glutathione S-transferase and laccase expression. Glutathione S-transferase potentially involved in antioxidation against Cr(VI) stress. Laccase was found to play a key role in RB5 decolorization by T. hirsuta. These results suggested that the simultaneous removal of co-contaminants by T. hirsuta could be achieved with Cr(VI) exposure. Overall, the elucidation of the molecular basis in details will help to advance the general knowledge about the fungus by facing harsh environments, and put forward a further possible application of fungi on environmental remediation.


Assuntos
Biodegradação Ambiental , Cromo/toxicidade , Naftalenossulfonatos/química , Trametes/fisiologia , Compostos Azo/análise , Recuperação e Remediação Ambiental , Lacase/metabolismo , Metais Pesados/análise , Trametes/metabolismo
11.
PLoS One ; 15(7): e0227529, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32730337

RESUMO

The pretreatment of biomass remains a critical requirement for bio-renewable fuel production from lignocellulose. Although current processes primarily involve chemical and physical approaches, the biological breakdown of lignin using enzymes and microorganisms is quickly becoming an interesting eco-friendly alternative to classical processes. As a result, bioprospection of wild fungi from naturally occurring lignin-rich sources remains a suitable method to uncover and isolate new species exhibiting ligninolytic activity. In this study, wild species of white rot fungi were collected from Colombian forests based on their natural wood decay ability and high capacity to secrete oxidoreductases with high affinity for phenolic polymers such as lignin. Based on high activity obtained from solid-state fermentation using a lignocellulose source from oil palm as matrix, we describe the isolation and whole-genome sequencing of Dictyopanus pusillus, a wild basidiomycete fungus exhibiting ABTS oxidation as an indication of laccase activity. Functional characterization of a crude enzymatic extract identified laccase activity as the main enzymatic contributor to fungal extracts, an observation supported by the identification of 13 putative genes encoding for homologous laccases in the genome. To the best of our knowledge, this represents the first report of an enzymatic extract exhibiting laccase activity in the Dictyopanus genera, offering means to exploit this species and its enzymes for the delignification process of lignocellulosic by-products from oil palm.


Assuntos
Agaricales/genética , Genoma Fúngico , Lignina/metabolismo , Óleo de Palmeira/metabolismo , Agaricales/classificação , Agaricales/enzimologia , Biomassa , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Concentração de Íons de Hidrogênio , Lacase/genética , Lacase/metabolismo , Oxirredução , Filogenia , Temperatura , Sequenciamento Completo do Genoma
12.
Sci Rep ; 10(1): 11013, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620925

RESUMO

Saprobic soil fungi drive many important ecosystem processes, including decomposition, and many of their effects are related to growth rate and enzymatic ability. In mycology, there has long been the implicit assumption of a trade-off between growth and enzymatic investment, which we test here using a set of filamentous fungi from the same soil. For these fungi we measured growth rate (as colony radial extension) and enzymatic repertoire (activities of four enzymes: laccase, cellobiohydrolase, leucine aminopeptidase and acid phosphatase), and explored the interaction between the traits based on phylogenetically corrected methods. Our results support the existence of a trade-off, however only for the enzymes presumably representing a larger metabolic cost (laccase and cellobiohydrolase). Our study offers new insights into potential functional complementarity within the soil fungal community in ecosystem processes, and experimentally supports an enzymatic investment/growth rate trade-off underpinning phenomena including substrate succession.


Assuntos
Proteínas Fúngicas/metabolismo , Fungos/crescimento & desenvolvimento , Fosfatase Ácida/metabolismo , Celulose 1,4-beta-Celobiosidase/metabolismo , Ecossistema , Fungos/enzimologia , Lacase/metabolismo , Leucil Aminopeptidase/metabolismo , Filogenia , Microbiologia do Solo
13.
PLoS One ; 15(6): e0229968, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497077

RESUMO

Although laccase has been recognized as a wonder molecule and green enzyme, the use of low yielding fungal strains, poor production, purification, and low enzyme kinetics have hampered its large-scale application. Thus,this study aims to select high yielding fungal strains and optimize the production, purification, and kinetics of laccase of Aspergillus sp. HB_RZ4. The results obtained indicated that Aspergillus sp. HB_RZ4 produced a significantly large amount of laccase under meso-acidophilic shaking conditions in a medium containing glucose and yeast extract. A 25 µM CuSO4 was observed to enhance the enzyme yield. The enzyme was best purified on a Sephadex G-100 column. The purified enzyme resembled laccase of A. flavus. The kinetics of the purified enzyme revealed high substrate specificity and good velocity of reaction,using ABTS as a substrate. The enzyme was observed to be stable over various pH values and temperatures. The peptide structure of the purified enzyme was found to resemble laccase of A. kawachii IFO 4308. The fungus was observed to decolorize various dyes independent of the requirement of a laccase mediator system.Aspergillus sp. HB_RZ4 was observed to be a potent natural producer of laccase, and it decolorized the dyes even in the absence of a laccase mediator system. Thus, it can be used for bioremediation of effluent that contains non-textile dyes.


Assuntos
Aspergillus/enzimologia , Biotecnologia/métodos , Corantes/metabolismo , Lacase/metabolismo , Casca de Planta/microbiologia , Biodegradação Ambiental , Corantes/isolamento & purificação , Ativação Enzimática , Inibidores Enzimáticos/farmacologia , Estabilidade Enzimática , Enzimas Imobilizadas/antagonistas & inibidores , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Lacase/antagonistas & inibidores , Lacase/química
14.
J Environ Sci Health B ; 55(8): 704-711, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32500809

RESUMO

In order to solve the problem of heavy metal-organic compound soil pollution, in this paper, we developed a highly efficient electro kinetic-laccase combined remediation (EKLCR) system. The results showed that the EKLCR system had an obvious migration effect on heavy metals (copper and cadmium) and good migration-degradation effect on phenanthrene. The migration rates of copper and cadmium were 48.3% and 40.3%, respectively. Especially, with the presence of laccase, the removal rate of phenanthrene on Cu2+-contaminated soil was higher than that of Cd2+-contaminated soil due to the significant effect of heavy metals on the enzymatic activity of laccase. The average migration-degradation rate of phenanthrene by EKLCR system was 45.4%. Finally, gas chromatography-mass spectrometry (GC/MS) was used to analyze the degradation intermediates of phenanthrene in the soil, which included 9,10-Phenanthrenequinone, phthalic acid, and 2,2-Biphenyldicarboxylic Acid. In addition, we give the possible degradation pathways of phenanthrene, 2,2-Biphenyldicarboxylic Acid is further degraded to produce phthalic acid. The products of the phthalic acid metabolic pathway are protocatechuic acid, pyruvic acid or succinic acid, the final products of these organic acids are carbon dioxide and water.


Assuntos
Recuperação e Remediação Ambiental/métodos , Metais Pesados/análise , Fenantrenos/análise , Poluentes do Solo/análise , Biodegradação Ambiental , Desenho de Equipamento , Cromatografia Gasosa-Espectrometria de Massas , Cinética , Lacase/metabolismo , Metais Pesados/química , Fenantrenos/química , Fenantrenos/metabolismo , Solo/química , Poluentes do Solo/química
15.
Chemosphere ; 259: 127462, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32590177

RESUMO

Spent mushroom substrate (SMS) is an agricultural waste with a high potential for polycyclic aromatic hydrocarbons (PAH) removal in aged contaminated soils. In this study, fresh and air-dried Pleurotus ostreatus, Pleurotus eryngii, and Auricularia auricular SMSs were used to remove PAHs in agricultural soil under 60-day incubation. The potential of SMS in PAH dissipation was studied by detecting the dissipation rate and the soil physicochemical index, enzyme activity, PAH-degradation bacterial biomass, and microbial diversity. Results showed that SMS significantly enhanced the dissipation of PAHs and fresh SMS had a better effect than air-dried SMS. The highest dissipation rate of 16 PAHs was 34.5%, which was observed in soil amended with fresh P. eryngii SMS, and the PAH dissipation rates with low and high molecular weights were 41.3% and 19.4%, respectively. By comparison, fresh P. eryngii SMS presented high nutrient contents, which promoted the development of PAH-degrading bacteria and changed the soil bacterial community involved in degradation, thereby promoting the PAH dissipation. The lignin-degrading enzymes in fresh SMS were abundant, and the laccase and manganese peroxidase activities in the treatment of fresh P. eryngii SMS was higher than those in other treatments. Fresh P. eryngii SMS improved the relative abundance of Microbacterium, Rhizobium, and Pseudomonas in soil, which were all related to PAH degradation. Consequently, adding fresh P. eryngii SMS was an effective method for remediating aged PAH-contaminated agricultural soils.


Assuntos
Agaricales/química , Biodegradação Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes do Solo/análise , Agricultura , Bactérias/metabolismo , Biomassa , Lacase/metabolismo , Pleurotus/metabolismo , Solo/química , Microbiologia do Solo
16.
Proc Natl Acad Sci U S A ; 117(27): 15400-15402, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571955

RESUMO

The Casparian strip (CS) is a tight junction-like structure formed by lignin impregnation on the walls of endodermal cells in plant roots. The CS membrane domain (CSDM), demarked by the CASP proteins, is important for orienting lignification enzymes. Here, we report that an endodermis-expressed multicopper oxidase, LACCASE3 (LAC3) in Arabidopsis, locates to the interface between lignin domains and the cell wall during early CS development prior to CASP1 localizing to CSDM and eventually flanks the mature CS. Pharmacological perturbation of LAC3 causes dispersed localization of CASP1 and compensatory ectopic lignification. These results support the existence of a LAC3-based CS wall domain which coordinates with CSDM to provide bidirectional positional information that guides precise CS lignification.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Lacase/metabolismo , Proteínas de Membrana/metabolismo , Raízes de Plantas/metabolismo , Arabidopsis/citologia , Parede Celular/metabolismo , Lacase/genética , Lignina/metabolismo , Proteínas de Membrana/genética , Raízes de Plantas/citologia , Plantas Geneticamente Modificadas , Domínios Proteicos
17.
J Biosci Bioeng ; 130(4): 347-351, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32536566

RESUMO

Triphenylmethane dyes are commonly used in dyeing and printing, but such dyes are recalcitrant to degradation and thus biodegradation of dye compounds has received increasing attention. Here, a recombinant bacterial laccase, CotA, from Bacillus amyloliquefaciens MN-13 was expressed in Escherichia coli BL21(DE3) and used as a biocatalyst to degrade crystal violet (CV). The recombinant CotA remained stable at temperatures in the range 30-40 °C and retained 44-100% enzyme activity at pH 4.5-8.0. The CotA exhibited high activities for decolorization of CV and, after 72 h of incubation, CotA decolorized 70.98% of CV at pH 5.0 and 30 °C. In the UV-visible spectra of CV solution treated by CotA, the full wavelength scan indicated that the chromophore of the triphenylmethane structure of CV was destroyed and CV was degraded into small-molecule aromatic compounds. The main degradation compounds of CV were identified as bis[4-(dimethylamino) phenyl] methanone and its N-demethylation derivative by HPLC/MS/MS. Based on these data, a hypothetical degradation pathway of CV by CotA, including N-demethylation and cleavage of the chromophore structure initiated by radicals, is proposed.


Assuntos
Bacillus amyloliquefaciens/enzimologia , Violeta Genciana/metabolismo , Lacase/metabolismo , Biodegradação Ambiental , Corantes/metabolismo , Concentração de Íons de Hidrogênio , Lacase/química , Temperatura
18.
J Appl Microbiol ; 129(6): 1633-1643, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32491245

RESUMO

AIM: The aim of the study is to investigate the efficiency of Geotrichum candidum in the decolourization and mineralization of synthetic azo dyes. METHODS AND RESULTS: It includes screening of enzymes from G. candidum and its optimization, followed by decolourization and mineralization studies. Decolourization was observed to be maximum in methyl orange (94·6%) followed by Congo red (85%), trypan blue (70·4%) and Eriochrome Black T (55·6%) in 48 h, suggesting the plausible degradation of the azo dyes by G. candidum. The enzyme activity study showed that DyP-type peroxidase has highest activity of 900 mU ml-1 compared to that of laccase (405 mU ml-1 ) and lignin peroxidase (LiP) (324 mU ml-1 ) at optimized pH (6) and temperature (35°C). Moreover, the rate of decolourization was found to be directly proportional to the production of laccase and LiP, unlike DyP-type peroxidase. Furthermore, mineralization study demonstrated reduction in aromatic amines, showing 20% mineralization of methyl orange. CONCLUSION: Geotrichum candidum with its enzyme system is able to efficiently decolourize and mineralize the experimental azo dyes. SIGNIFICANCE AND IMPACT OF THE STUDY: The efficient decolourization and mineralization of azo dyes makes G. candidum a promising alternative in the treatment of textile effluent contaminated with azo dyes.


Assuntos
Compostos Azo/metabolismo , Corantes/metabolismo , Proteínas Fúngicas/metabolismo , Geotrichum/enzimologia , Descoloração da Água/métodos , Biodegradação Ambiental , Geotrichum/metabolismo , Lacase/metabolismo , Peroxidase/metabolismo , Peroxidases/metabolismo , Têxteis
19.
Chemosphere ; 252: 126619, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32443277

RESUMO

Laccase, a unique class of multicopper oxidase, presents promising potential as a biocatalyst in many industrial and biotechnological applications. Recently, it has been significantly applied in many metal-polluted sites due to its Manganese (Mn)-oxidation ability. Here, we demonstrate the Mn(II)-oxidase activity of laccase obtained from Bacillus sp. GZB. The CotA gene of GZB was transformed in E. coli BL21 and overexpressed. The purified laccase (LACREC3-laccase) displayed the absence of a peak at 610 nm that is usually found in blue-laccase. Further, the LACREC3-laccase exhibited high activity and stability at different pH and temperatures with substrates 2, 2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonate) and syringaldazine, respectively. It also functioned in the presence of various metals and enzyme inhibitors. Most notably, LACREC3-laccase formed insoluble brown Mn(III)/Mn(IV)-oxide particles from Mn(II) mineral, exhibiting its Mn(II)-oxidase activity. In addition to native polyacrylamide gel electrophoresis and buffer test, we developed an 'agarose gel plate' assay to evaluate Mn(II) oxidation activity of laccase. Furthermore, using the leucoberbelin blue assay, a total of 44.45 ± 0.45% Mn(IV)-oxides were quantified, in which 5.87 ± 0.61% autoxidized after 24 h. The Mn(II) oxidation mechanisms were further predicted by trapping Mn(III) using pyrophosphate during Mn(II) to Mn(IV) conversion by LACREC3-laccase. Overall, the laccase of GZB has excellent activity and stability plus an ability to oxidize Mn(II). This study is the first report on a non-blue laccase, exhibiting Mn(II)-oxidase activity. Thus, it offers a novel finding of the Mn(II) oxidation processes that can be a valuable way of Mn(II)-mineralization in various metal-polluted environments.


Assuntos
Bacillus/fisiologia , Lacase/metabolismo , Manganês/metabolismo , Bacillus/metabolismo , Difosfatos , Escherichia coli/metabolismo , Manganês/química , Compostos de Manganês , Oxirredução , Óxidos
20.
J Biotechnol ; 318: 45-50, 2020 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-32447128

RESUMO

The aim of this study was to optimize the laccase immobilization on a silica/chitosan composite support. The innovative method proposed is based on the use of Ca(II) as a linker of the support precursors. In addition for the laccase immobilization the glycosidic part of enzyme is oxidized by periodate in order to form aldehydes reactive towards the NH2 groups of chitosan. The immobilized laccase presents a good storage stability (7 months 40% residual activity) and a good affinity towards ABTS substrate (Kmapp 0.008 mM, Vmaxapp = 0.0034 µmol/min). Furthermore, the biocatalyst showed optimum pH 3 and optimum incubation temperature of 50 °C.


Assuntos
Quitosana/química , Enzimas Imobilizadas/química , Lacase/química , Dióxido de Silício/química , Biocatálise , Cálcio/química , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Lacase/metabolismo , Temperatura
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