Dye Decolorization Research Articles

Decolorization of reactive azo dye using novel halotolerant yeast consortium HYC and proposed degradation pathway

The presence of high salinity levels in textile wastewater poses a significant obstacle to the process of decolorizing azo dyes. The present study involved the construction of a yeast consortium HYC, which is halotolerant and was recently isolated from wood-feeding termites. The consortium HYC was mainly comprised of Sterigmatomyces halophilus SSA-1575 and Meyerozyma guilliermondii SSA-1547. The developed consortium demonstrated a decolourization efficiency of 96.1% when exposed to a concentration of 50 mg/l of Reactive Black 5 (RB5). The HYC consortium significantly decolorized RB5 up to concentrations of 400 mg/l and in the presence of NaCl up to 50 g/l. The effects of physicochemical factors and the degradation pathway were systematically investigated. The optimal pH, salinity, temperature, and initial dye concentration were 7.0, 3%, 35 °C and 50 mg/l, respectively. The co-carbon source was found to be essential, and the addition of glucose resulted in a 93% decolorization of 50 mg/l RB5. The enzymatic activity of various oxido-reductases was assessed, revealing that NADH-DCIP reductase and azo reductase exhibited greater activity in comparison to other enzymes. UV-Visible (UV–vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography–mass spectrometry (GC-MS) were utilized to identify the metabolites generated during the degradation of RB5. Subsequently, a metabolic pathway was proposed. The confirmation of degradation was established through alterations in the functional groups and modifications in molecular weight. The findings indicate that this halotolerant yeast consortium exhibits promising potential of degrading dye compounds. The results of this study offer significant theoretical basis and crucial perspectives for the implementation of halotolerant yeast consortia in the bioremediation of textile and hypersaline wastewater. This approach is particularly noteworthy as it does not produce aromatic amines.

Photocatalytic oxidation of Reactive Red 195 by bimetallic Fe–Co catalyst: Statistical modeling and optimization via Box-Behnken design

Response surface methodology (RSM) is an effective tool for process optimization with multi-complex operational factors. The present work aims to model and optimize the photocatalytic oxidation (PCO) parameters of Reactive Red 195 (RR195) dye decoloration with the SiO2-supported Fe–Co catalyst (FCS) derived from a novel catalyst synthesis method, fluidized-bed crystallization (FBC) process, using Box-Behnken design (BBD) as the RSM statistical model. The Fe–Co@SiO2 catalyst was successfully fabricated using the FBC process, and it showed good catalytic activity and performance toward the degradation of RR195. The extent of the effects of pH, H2O2 dosage (HD), catalyst loading (CL), and operating time (t) on the decoloration of RR195 was studied. Hence, the order of variable significance follows the sequence: pH > t > CL > HD. pH has the most significant effect among the variables for RR195 decoloration. The decoloration efficiency predicted by the BBD model was 88.3% under the optimized operation conditions of initial pH of 3.15, 0.76 mM H2O2, 1.18 g L−1 FCS and 59.4 min of operating time. The actual decoloration efficiency was very close to the predicted value indicating that BBD can efficiently be utilized to optimize RR195 degradation with FCS under the PCO system.

Use of Cu(II) catalyst assisted oxidative decolorization of dye by chlorinating species in water: A kinetic and mechanistic study with acid red1 dye

A quick and easy decolorization method has been created in the current study to get rid of the Acid Red 1 (AR1) dye from the wastewater. At 298 K, the kinetics of oxidative decolorization of AR1 dye with Chloramine-B (CAB) in NaOH medium, catalyzed by copper(II) sulphate, have been examined spectrophotometrically (λmax = 506nm). The experimental rate laws found are as follows: d[CAB]/dt = k [CAB]0 [AR1]0 [Cu(II)]x / [OH−]y in an alkaline medium, where x and y are less than unity.Under ideal experimental conditions, 90% dye decolorization is achieved in 30 minutes using concentrations of 0.003M [CAB], 0.0003M [AR1], 0.003M [Cu(II), and 0.003M [OH−].In the current kinetic redox system, the Cu(II) catalyst showed to be an effective homogeneous catalyst. The 4-acetamido-5,6-dioxo-5,6-dihydro naphthalene-2-sulphonic acid is identified as the oxidation product using mass spectrum analysis. The FTIR spectra show the absence of N=N stretching bands at 1489 cm−1 which confirms the oxidative breakdown of the azo group, a fundamental chromophore responsible for color, which induces toxicity in the waste water. The decolorization reaction catalyzed by Cu(II) is approximately six times faster than the uncatalyzed reaction. The catalytic constant (Kc) is calculated at various temperatures, and activation parameters for copper(II) are also evaluated. The observed results are explained by plausible mechanisms, and relative rate laws has been deduced. Chemical oxygen demand (COD) has been significantly reduced by the oxidative decolorization process. Phytotoxicity tests revealed that the treated dye sample is less toxic than the untreated dye sample. An economic analysis is carried out. Notably, with appropriate modifications, the developed oxidative decolorization technique is expected to benefit in the removal of AR1 dye present from industrial wastewater.

Production, Purification, and Characterization of Recombinant Bhargavaea beijingensis Laccase for Potential Lignin Degradation and Dyes Decolorization

Production, Purification, and Characterization of Recombinant Bhargavaea beijingensis Laccase for Potential Lignin Degradation and Dyes Decolorization

Visible light driven photocatalytic and competent antioxidant properties of phyto-fabricated zinc oxide nanoparticles (ZnO-NPs) from Borreria hispida

Zinc oxide nanoparticles (ZnO-NPs) have gained considerable interest in biological and photocatalytic applications due to their distinctive physico-chemical characteristics. The study aimed to synthesize ZnO-NPs using the leaf extract of Borreria hispida, a medicinally important plant for its antioxidant and photocatalytic efficacy. The B. hispida mediated ZnO-NPs (Bh-ZnO-NPs) illustrated a characteristic peak at 304 nm with 3.45 eV bandgap energy during the spectral analysis. The Bh-ZnO-NPs XRD studies revealed stiff and narrow peaks with ∼21.87 nm in size. The SEM analysis revealed that the obtained Bh-ZnO-NPs were agglomerated and ZnO elemental purity of 98.23% was confirmed through EDS. The spectral results of Bh-ZnO-NPs obtained by the FT-IR affirmed that phyto-constituents participated in the reduction, capping and stabilization of the particles during the synthesis of nanoparticles. The BET surface area analysis of the Bh-ZnO-NPs confirmed that the particles exhibit a similar Type – IV isotherm curve as per IUPAC classification with 11.681 m2g-1 and a surface roughness (Ra) value of 6.25 nm. The Bh-ZnO-NPs offered significant (p ≤ 0.05) radical scavenging activity, which was dose-dependent with IC50 value falling between 0.6 to 0.8 mg mL−1 among the evaluated test methods. Methyl red (MR) dye degradation tests employing phyto-fabricated Bh-ZnO-NPs resulted in dye degradation up to 94.22% after 40 min of solar irradiation and the decolorization of MR dye followed pseudo-first-order kinetics. In addition to those mentioned above, the fifth cycle of the photocatalyst's stability and reusability studies showed 84.8% dye degradation ability. The findings demonstrate that the phyto-fabricated ZnO-NPs from B. hispida have potent antioxidant and dye-degrading properties that can be investigated at an industrial scale.

Dye Decolorization by a Miniaturized Peroxidase Fe-MimochromeVI*a.

Oxidases and peroxidases have found application in the field of chlorine-free organic dye degradation in the paper, toothpaste, and detergent industries. Nevertheless, their widespread use is somehow hindered because of their cost, availability, and batch-to-batch reproducibility. Here, we report the catalytic proficiency of a miniaturized synthetic peroxidase, Fe-Mimochrome VI*a, in the decolorization of four organic dyes, as representatives of either the heterocyclic or triarylmethane class of dyes. Fe-Mimochrome VI*a performed over 130 turnovers in less than five minutes in an aqueous buffer at a neutral pH under mild conditions.

Physicochemical parameters optimization and peroxidase characterization from Aspergillus niger native strain by solid-state fermentation for improved dye decolorization

The hyper yield of peroxidase (POX) was investigated for a novel native Aspergillus niger strain identified by 18S RNA analysis. A. niger strains sequences were submitted to GenBank; IDs allotted were MN611114.1 (BMB 17) and MN559756.1 (BMB-18). The identified Aspergillus strains in combination showed enhanced (POX) activity (601.5 U/mL) by solid-state fermentation in comparison to their individual activities. POX was purified by ammonium sulfate, and size exclusion gel chromatography exhibited a 7.83-fold increase in POX concentration (13.3 U/mg) in comparison to BMB17 and BMB 18 (11.8 & 7.6 U/mg respectively). The best POX activity was obtained with pH 6.5, 37 °C, and 5 days of incubation. Using guaiacol as substrate, POX showed maximum activity (Vmax) of 537 U/mL with a corresponding Michaelis constant (Km) value of 126 µM. Calcium chloride worked as a POX activator at 300 & 400 mM. Zinc sulfate (500 mM), EDTA (5 mM); ethanol, propanol, and acetonitrile (50%) inhibited (18-30%) POX. Urea (1M), and copper sulfate (500 mM) strongly inhibited POX up to 40%. Polysorbate-80 (1%) slightly reduced the POX by 10% to 15%. BMB17+18-induced promising dye decolorization (88-98%) against all vat dyes, methylene blue, and phenol red.

Computer-aided discovery of a novel thermophilic laccase for low-density polyethylene degradation

Polyethylene (PE) and industrial dyes are recalcitrant pollutants calling for the development of sustainable solutions for their degradation. Laccases have been explored for removal of contaminants and pollutants, including dye decolorization and plastic degradation. Here, a novel thermophilic laccase from PE-degrading Lysinibaccillus fusiformis (LfLAC3) was identified through a computer-aided and activity-based screening. Biochemical studies of LfLAC3 indicated its high robustness and catalytic promiscuity. Dye decolorization experiments showed that LfLAC3 was able to degrade all the tested dyes with decolorization percentage from 39% to 70% without the use of a mediator. LfLAC3 was also demonstrated to degrade low-density polyethylene (LDPE) films after eight weeks of incubation with either crude cell lysate or purified enzyme. The formation of a variety of functional groups was detected using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Damage on the surfaces of PE films was observed via scanning electron microscopy (SEM). The potential catalytic mechanism of LfLAC3 was disclosed by structure and substrate-binding modes analysis. These findings demonstrated that LfLAC3 is a promiscuous enzyme that has promising potential for dye decolorization and PE degradation.

An Inferred Ancestral CotA Laccase with Improved Expression and Kinetic Efficiency.

Laccases are widely used in industrial production due to their broad substrate availability and environmentally friendly nature. However, the pursuit of laccases with superior stability and increased heterogeneous expression to meet industry demands appears to be an ongoing challenge. To address this challenge, we resurrected five ancestral sequences of laccase BsCotA and their homologues. All five variants were successfully expressed in soluble and functional forms with improved expression levels in Escherichia coli. Among the five variants, three exhibited higher catalytic rates, thermal stabilities, and acidic stabilities. Notably, AncCotA2, the best-performing variant, displayed a kcat/KM of 7.5 × 105 M-1·s-1, 5.2-fold higher than that of the wild-type BsCotA, an improved thermo- and acidic stability, and better dye decolorization ability. This study provides a laccase variant with high application potential and presents a new starting point for future enzyme engineering.

In-situ encapsulation and construction of Lac@HOFs/hydrogel composite for enhancing laccase stability and azo dyes decolorization efficiency

Enzymes with high catalytic activity and stability have been used for the sustainable development of green chemical applications, such as water remediation. Immobilized laccase can be used to construct a synergistic system for adsorption and degradation, which has great potential for water remediation. Herein, a hydrogen-bonded organic framework was installed onto laccase in-situ to form a net-carboxylate-arranged defective cage, which enhanced its catalytic stability. Thereafter, the CMC/PVA/Lac@HOF-101 hydrogel was fabricated by freeze–thaw cycles using sodium carboxymethylcellulose and polyvinyl alcohol as carriers and copper (II) as a cross-linker. Notably, the MOFs/hydrogel as a protective carrier of laccase maintain long-term recyclability and catalytic stability. After the fifth catalytic cycle, approximately 66.7 % activity of the CP-Lac@HOF-101 was retained. When both free laccase and CP-Lac@HOF-101 were used for decolorization of Acid Orange 7 (AO), the removal rates were 10.9 % and 82.5 % after 5 h, respectively. Furthermore, even in the presence of metal cations, almost 60.0 % of the AO removal efficiency was achieved. The relationship between the structure of the azo dyes and decolorization efficiency of the synergistic system was further investigated. This study offers a method for constructing enzyme@HOF-based composite hydrogels and provides a promising water remediation strategy.

Methacrylic Acid-Acrylamide based ZnO Hydrogel Nanocomposite Assisted Photocatalytic Decolorization of Methylene Blue Dye

In this research, preparation of methacrylic acid-acrylamide based ZnO hydrogel nanocomposite (MAA-AM)/ZnO hydrogel nanocomposite by way of co-polymerization via used acrylate acid (AA) (or acrylate salt) (AA) or methacrylic acid (MAA)) and acrylamide (AM). Nanocomposites based on acrylate are characterized via being hydrophilic and able to retain water. Nanocomposite properties were studied using different techniques (FE-SEM, TEM, and EDX). The photocatalytic degradation of methylene blue MB dye under different conditions was studied using nanocomposite like time of irradiation, mass of catalyst (MAA- AM)/ZnO hydrogel nanocomposite, initial MB dye concentration onto photocatalytic degradation and reactivation were studied. The result increases the photocatalytic degradation with the rise weight of catalyst (MAA- AM)/ZnO hydrogel nanocomposite range (0.1–0.25 g). Too, a decrease in photocatalytic degradation was observed with an increase in MB. Observed that after reuse, ((MAA- AM)/ZnO) nanocomposite hydrogel appear photocatalytic efficiency from of the use 1 to 6 cycle 87.88 to 58.87%, showing that ((MAA- AM)/ZnO hydrogel nanocomposite surface appear good stability.

Solar-light-sensitive applications of recycled iron oxyhydroxide as photoelectrolytic heterostructure by encapsulating in reduced graphene oxide and titanium oxide nanotube array (FeOxrGO/TiNTA)

FeOxrGO/Ti photoanodes by decorating TiO2 nanotube array (TiNTA) with waste iron oxide and reduced graphene oxide (rGO) were synthesized via wet impregnation and calcination. Photoelectrocatalytic (PEC) degradation of azo dye pollutants, accompanied by hydrogen gas evolution, was demonstrated in a dual-chamber divided cell. Characterization showed that the iron oxide recovered from the wastewater treatment plant were crystalline clusters consisting of mineral goethite nanoparticles (αFeOOH NPs) with a visible-light responsive bandgap. Furthermore, the incorporation of rGO led to an enhancement in the electrochemical surface area (ECSA, cm2) of the anode due to its larger capacitive current compared to TiNTA. This improvement facilitated the transport of charge carriers (e- and h+) within a type-II heterostructure of αFeOOH and TiO2. The applied bias photon-to-current conversion efficiency and transient photocurrent density, depending on the composition of iron oxide in FeOxrGO/Ti, substantially increased. 2%wt of iron oxide in FeO2.0rGO/Ti has been optimized in terms of azo dye decolorization, TOC removal, and H2 generation rates (on Pt/G cathode) in 0.1 M Na2SO4 at a working potential of +1.0 V (vs. Ag/AgCl). This study explored the reusability and valorization of Fenton fluidized-bed waste iron oxide with TiO2 for PEC applications.

Effect of noble bacteria Ochrobactrum intermedium (Alhpa-22) on decolorization of methyl orange dye in a bioreactor

Abstract In this study Ochrobactrum intermedium (Alhpa-22) was isolated from petroleum refinery sludge and characterized by using 16rRNA. In experimentation, for decolrization of methyl orange dye an indigenous noble bacterial ochrobactrum intermedium (Alhpa-22) at 35 °C has been used in a bioreactor. The ochrobactrum bacterial decolorized methyl orange dye having the concentration of 50 mgL−1 by 87 % within 9 days, which is a very encouraging result. decolorization of methyl orange dye by the isolated bacteria was elucidated using a UV–Vis spectrophotometer. The experimental data were fitted first and zero order kinetics models which show degradation of dye follows first order kinetics in presence of Lysinibacillus fusiformis KLm1, bacterial ochrobactrum intermedium (Alhpa-22) and mix consortia of Lysinibacillus fusiformis KLm1 and ochrobactrum intermedium (Alhpa-22). The rate constant were estimated to be 0.017 h−1, 0.020 h−1 and 0.014 h−1 respectively. Due to its higher decolorizing capability these may be used for the bioremediation of methyl orange dye (azo dye).

Effects of agro-waste resources on characteristics of Fe/nanocellulose hybrids and their applications as novel Fenton-like catalysts in dye removal from wastewater

Herein, a novel, effective and bio-based Fenton-like catalyst by in situ incorporation of Fe2O3 nanoparticles on the surface of nanocellulose (NCs) was synthesized from sugar beet pulp (SBP) and utilized for efficient removal of three different dyes. Firstly, different NC samples were synthesized by acid hydrolysis of two different biomass (SBP and Q-quinoa husk) at various concentrations of H2SO4. The characterization analyses of samples showed that SBP-based NCs prepared using 60% concentration of H2SO4 (1 h string at 50 °C) showed the highest crystallinity (56.7%), lowest aggregation, highest surface negative charge (−38.5 mV), and largest surface area (13.9 m2/g) compared to the Q-based NCs. Both SBP and Q-based nanocatalyst utilized for degradation of dyes (methylene blue (MB), crystal violet (CV), and congo red (CR)), and SBP-based sample (Fe/NC-S3) displayed the best results in dye removal due to its larger specific surface area (39.8 vs. 9.2 m2/g), and higher content of magnetic nanoparticles (6.7 vs. 3.7 at% of Fe) than Q-based catalyst. At optimum conditions, Fe/NC-S3 nano-catalyst (2 g/L), in the presence of H2O2 (30 mM) removed MB, CV, and CR dyes (30 mg/L), in 30 min, at neutral pH, with 98%, 96%, and 62% removal efficiencies, respectively. Kinetic studies revealed that pseudo-first-order model was appropriate model to explain the decolorization of dyes at these conditions, and the rate constants were 0.0217, 0.018, and 0.0113 min−1 for the degradation of MB, CV, and CR, respectively. Moreover, raising the temperature from 15 ºC to 35 ºC resulted in enhancement of removal performance of nano-catalyst for all dyes. Fe/NC-S3 nano-catalyst showed proper reusability (just around 20% decrease for removal of all three dyes after ten consecutive reuse runs). Treatment of real water effluent (collected from a textile factory) containing mixture of all three dyes by Fe/NC-S3 and H2O2 approved the practical application of nano-catalyst in dye removal from complex matrixes even after nine reusing cycles. The results confirmed that SBP biomass could effectively turn to valuable NC nanocarriers for synthesis of advanced and innovative catalysts with proficient catalytic activity, stability, and recyclability.

Enzymatic degradation of azo dyes methylene blue and congo red with peroxidase purified from cauliflower using affinity chromatography technique: Kinetic study, optimization and metal binding activity

The effective results of the enzymatic decolorization of industrial azo dyes found in wastewater, which cause serious health and environmental problems, with peroxidases have recently increased the interest in these enzyme sources. Redox-mediated decolorization of Methylene Blue and Congo Red azo dyes with cauliflower (Brassica oleracea var. botrytis L.) peroxidase (CPOD) purified in one step using 4-amino 3-bromo 2-methyl benzohydrazide molecule was investigated for the first time. The inhibition effect of this molecule, which is used as a ligand in affinity chromatography, on the CPOD enzyme was investigated. The Ki and IC50 values for this enzyme were calculated as 0.113 ± 0.012mM and 0.196 ± 0.011mM, respectively. With the affinity gel obtained by binding to the Sepharose-4B-l-tyrosine matrix of this molecule, which shows a reversible inhibition effect, the purification values of CPOD enzyme were determined as 562-fold with a specific activity of 50,250 Umg-1. The purity of the enzyme was checked by the SDS-PAGE technique and its molecular weight was determined. A single band at 44kDa was observed for the CPOD enzyme. In dye decolorization studies, the effects of dye, enzyme, and hydrogen peroxide concentrations as well as time, pH, and temperature were investigated. The profiles of the optimum conditions for both dyes were similar, and the percentages of decolorization of Methylene Blue and Congo Red under these conditions were 89% and 83%, respectively, at the end of the 40min reaction time. Again, when examining the effect of metal ions on enzyme activity, it was found that there was no significant negative change in CPOD.

Decolorization of Malachite green dye using seaweed

The potential use of seaweed Sargassum crassifolium to decolorize Malachite Green dye (MG) in a batch process has been investigated in the current study. Adsorbent dosage, contact duration, initial dye concentration, as well as temperature were examined as influencing factors for adsorption. Optimizing the initial pH (2 – 12), temperature (20 – 38°C), initial concentration of dye (10 – 30 mg/L) as well as adsorbent dose (0.4 – 2.4 g) at varying time intervals led to an increase in the decolorization efficiency. The percentage of dye adsorption was calculated using standardized colorimetric procedures. The highest degree of decolorization was observed at an initial pH of 8, dye concentration of 10 mg/L, a biosorbent dosing of 2 g, contact temperature of 35°C, at a contact period of 150 min. The findings have indicated that the research is a useful alternative technique in minimizing damage to the ecosystem.

Evaluating the efficacy of wood decay fungi and synthetic fungal consortia for simultaneous decolorization of multiple textile dyes.

Wastewater from the textile industry dyeing process containing high loads of synthetic dyes leads to pollution of water with these toxic and genotoxic dyes. Much effort has been put towards developing biological systems to resolve this issue. Mycoremediation is a well-known approach using fungi to remove, degrade, or remediate pollutants and can be applied to decolorize textile dyes in industrial effluent. Fungal strains from four genera of Polyporales, namely Coriolopsis sp. TBRC 2756, Fomitopsis pinicola TBRC-BCC 30881, Rigidoporus vinctus TBRC 6770, and Trametes pocas TBRC-BCC 18705, were studied for decolorization efficiency, and R. vinctus was found to exhibit the greatest activity in removing all seven tested reactive dyes and one acid dye with a decolorization efficiency of 80% or more within 7 days under limited oxygen. This fungus simultaneously degraded multiple dyes in synthetic wastewater as well as industrial effluent from the dyeing process. To enhance the decolorization rate, various fungal consortia were formulated for testing. However, these consortia only trivially improved efficiency compared with using R. vinctus TBRC 6770 alone. Evaluation of R. vinctus TBRC 6770 decolorization ability was further performed in a 15-L bioreactor to test its ability to eliminate multiple dyes from industrial effluent. The fungus took 45 days to adapt to growth in the bioreactor and subsequently reduced dye concentration to less than 10% of the initial concentration. The following six cycles required only 4-7 days to reduce dye concentrations to less than 25%, demonstrating that the system can run efficiently for multiple cycles without the need for extra medium or other carbon sources.

Azo Congo Red Dye Decolorization by Oyster Mushroom (Pleurotus ostreatus) F209

Azo Congo Red Dye Decolorization by Oyster Mushroom (Pleurotus ostreatus) F209

Green synthesis of gold nanoparticles by phycoerythrin extracted from Solieria tenuis as an efficient catalyst for 4-nitrophenol reduction and degradation of dyes in wastewater

Algal blooms and untreated wastewater will destroy the environment and ecosystem on which human beings depend. In this study, Solieria tenuis, a potential bloom in some regions of the sea in China, was used to mediate the composite of phycoerythrin (PE) and gold nanoparticles namely Au@PE NPs via a quick, easy, and effective manner. The physicochemical properties of Au@PE NPs were determined through UV–vis spectroscopy (UV–Vis), fluorescence spectroscopy (FP), fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The composite materials with a fine morphology and size (average size of 16 nm) exhibited superior catalytic abilities for the conversion of 4-nitrophenol(4-NP) to 4-aminophenol (4-AP, k298K = 0.36 × 10−2 s) and the degradation of cationic dyes methylene blue (MB) and safranine O (SO) in wastewater. Additionally, the mechanisms of 4-NP's catalytic reduction and decolorization of dyes by Au@PE NPs were proposed. The results indicated that PE could not only act as capping and reducing agents but also enhance solubility and photocatalytic activity of the synthesized gold nanoparticles. The current study provides clear evidence of a potential economic solution for utilizing organisms that are harmful to the environment to develop novel bioconjugated composites with multiple functions for efficient pollutant removal and environmental remediation.

Expression of a deep-sea bacterial laccase from Halomonas alkaliantartica and its application in dyes decolorization

IntroductionLaccase is a copper-containing polyphenolic oxidase widely found in bacteria, archaea, fungi, animals, and plants. As a green biocatalyst with considerable potential for numerous environmental and industrial applications, the enzyme production efficiency of laccase in nature is low, and the cost is high.PurposeTo examine the characterization and potential applications of laccase in this study, a novel laccase from Halomonas alkaliantartica (LacHa) was cloned and heterologously expressed it in Escherichia coli.ResultsTo achieve heterologous and efficient laccase expression, a bacterial laccase gene designed as LacHa from Halomonas alkaliantartica of deep sea was cloned and expressed in E. coli. The results showed that the optimum temperature and pH of the enzyme reaction were 45 °C and 7.5. The 100 μM Cu2+ and Fe2+ ions had the strongest stimulatory effect on laccase activity, the surface-active agent SDS and organic solvent 5% ethanol had opposite effect. EDTA, and 5% DMSO have no effect on LacHa activity.The activity of LacHa was enhanced 1.5-fold by chloride at concentrations lower than 500 mM, and 57.6% of its initial activity remained in the reaction system containing 1000 mM.NaCl. Furthermore, LacHa showed decolorization rates ranging from 90.28 to 100% for indigo carmine and two azo dyes without mediators, with wide pH (5.0–9.0) and temperature (25–65 °C) ranges.ConclusionsIn this study, LacHa was expressed and showed unusual properties, indicating its great application potential in textile industries or environmental fields.