Bioremediation of Textile Azo Dyes by Trichophyton rubrum LSK-27

Summary The potential of a recently isolated wood-degrading fungus, Trichophyton rubrum LSK-27, for effective decolorization of textile azo dyes was evaluated. Within two days of dye addition, the fungus was able to decolorize 83% of Remazol Tiefschwarz, 86% of Remazol Blue RR and 80% of Supranol Turquoise GGL in liquid cultures. The reactive dyes, Remazol Tiefschwarz and Remazol Blue, were removed by fungal biodegradation, while decolorization of the acid dye, Supranol Turquoise GGL, was accomplished mainly by bioadsorption. Therefore the fungus proved to be efficiently capable of both biodegradation and biosorption as the major dye removal mechanisms. The extent of biodegradation was associated with the levels of the extracellular ligninolytic enzymes such as manganese peroxidase and laccase.     

Decolorization of reactive dyes by mixed cultures isolated from textile effluent under anaerobic conditions

In the present study mixed cultures that could grew in the molasses media were isolated from textile dye effluent and its decolorization activity was studied in a batch system under anaerobic conditions, in order to determine the optimal conditions required for the highest decolorization activity. The optimum pH value for decolorization was determined as 8 for all the dyes tested. In the experiment with pH 8 dye decolorizations by mixed cultures were investigated at about 96.2–1031.3 mg l⁻¹ initial dye concentrations. The highest dye removal rates of mixed cultures were 94.9% for Reactive Red RB, 91.0% for Reactive Black B and 63.6% for Remazol Blue at 953.2, 864.9 and 1031.3 mg l⁻¹ initial dye concentrations respectively within 24 h incubation period. When the Reactive Red RB was used, approximately 82–98% total color removal was obtained at between 96.2 and 953.2 mg l⁻¹ initial dye concentrations after 12 h of incubation at 35 °C. These results show that our enriched mixed cultures have the potential to serve as an excellent biomass for the use in reactive dye removal from wastewaters under anaerobic conditions.     

Production of the Phanerochaete flavido-alba laccase in Aspergillus niger for synthetic dyes decolorization and biotransformation

We investigated the expression of Phanerochaete flavido-alba laccase gene in Aspergillus niger and the physical and biochemical properties of the recombinant enzyme (rLac-LPFA) in order to test it for synthetic dye biotransformation. A. niger was able to produce high levels of active recombinant enzyme (30 mgL^?1), whose identity was further confirmed by immunodetection using Western blot analysis and N-terminal sequencing. Interestingly, rLac-LPFA exhibited an improved stability at pH (2–9) and organic solvents tested. Furthermore, the percentage of decoloration and biotransformation of synthetic textile dyes, Remazol Brilliant Blue R (RBBR) and Acid Red 299 (NY1), was higher than for the native enzyme. Its high production, simple purification, high activity, stability and ability to transform textile dyes make rLac-LPFA a good candidate for industrial applications.     

Decoloration of textile dyes by Trametes versicolor and its effect on dye toxicity

Amaranth, Tropaeolin O, Reactive Blue 15, Congo Red, and Reactive Black 5 were completely decolorized with no dye sorption by Trametes versicolor. Cibacron Brilliant Red 3G-P, Cibacron Brilliant Yellow 3B-A, and Remazol Brilliant Blue R were partially decolorized with some dye sorbed to the biomass. The Microtox assay before decoloration showed that Amaranth and Tropaeolin O were not toxic [the percent concentration to decrease 20% of the luminescence of Vibrio fischeri (EC₂₀) was greater than 100%]; Cibacron Brilliant Yellow 3B-A, Reactive Blue 15 and Cibacron Brilliant Red 3G-P were moderately non-toxic (100% > EC₂₀ > 75%); Remazol Brilliant Blue R was toxic (75% > EC₂₀ > 50%); and Congo Red and Reactive Black 5 were moderately toxic (50% > EC₂₀ > 25%). After decoloration the toxicity of the solutions containing Amaranth, Tropaeolin O and Reactive Black 5 was unchanged; Reactive Blue 15, Remazol Brilliant Blue R and Cibacron Brilliant Red 3G-P decreased to non-toxic levels; and Cibacron Brilliant Yellow 3B-A and Congo Red became very toxic (EC₂₀ < 25%).     

Induction,Purification and Characterization of a Novel Manganese Peroxidase from Irpex lacteus CD2 and Its Application in the Decolorization of Different Types of Dye

Manganese peroxidase (MnP) is the one of the important ligninolytic enzymes produced by lignin-degrading fungi which has the great application value in the field of environmental biotechnology. Searching for new MnP with stronger tolerance to metal ions and organic solvents is important for the maximization of potential of MnP in the biodegradation of recalcitrant xenobiotics. In this study, it was found that oxalic acid, veratryl alcohol and 2,6-Dimehoxyphenol could stimulate the synthesis of MnP in the white-rot fungus Irpex lacteus CD2. A novel manganese peroxidase named as CD2-MnP was purified and characterized from this fungus. CD2-MnP had a strong capability for tolerating different metal ions such as Ca²⁺, Cd²⁺, Co²⁺, Mg²⁺, Ni²⁺ and Zn²⁺ as well as organic solvents such as methanol, ethanol, DMSO, ethylene glycol, isopropyl alcohol, butanediol and glycerin. The different types of dyes including the azo dye (Remazol Brilliant Violet 5R, Direct Red 5B), anthraquinone dye (Remazol Brilliant Blue R), indigo dye (Indigo Carmine) and triphenylmethane dye (Methyl Green) as well as simulated textile wastewater could be efficiently decolorized by CD2-MnP. CD2-MnP also had a strong ability of decolorizing different dyes with the coexistence of metal ions and organic solvents. In summary, CD2-MnP from Irpex lacteus CD2 could effectively degrade a broad range of synthetic dyes and exhibit a great potential for environmental biotechnology.     

Biosorption of anionic textile dyes by nonviable biomass of fungi and yeast

The nonviable biomass of Aspergillus niger, Aspergillus japonica, Rhizopus nigricans, Rhizopus arrhizus, and Saccharomyces cerevisiae were screened for biosorption of textile dyes. The selected anionic reactive dyes were C.I. Reactive Black 8, C.I. Reactive Brown 9, C.I. Reactive Green 19, C.I. Reactive Blue 38, and C.I. Reactive Blue 3. Experiments were conducted at initial dye concentration of 50, 100, 150 and 200mg/L. The effect of initial dye concentration, dose of biosorbent loading, temperature, and pH on adsorption kinetics was studied. S. cerevisiae and R. nigricans were good biosorbents at initial dye concentration of 50mg/L, 1g% (w/v) biomass loading and 29+/-1 degrees C. R. nigricans adsorbed 90-96% dye in 15min, at 20 degrees C and pH 6.0. The data showed an optimal fit to the Langmuir and Freundlich isotherms. The maximum uptake capacity (Q(o)) for the selected dyes was in the range 112-204mg/g biomass.     

Effect of pretreatments of three waste residues,wheat straw,corncobs and barley husks on dye adsorption

The removal of dyes (Cibacron Yellow C-2R, Cibacron Red C-2G, Cibacron Blue C-R, Remazol Black B and Remazol Red RB) from an aqueous solution has been discussed by adsorption which was examined on three different low cost pretreated agricultural residues viz., wheat straw, corncob and barley husk. The pretreatments were carried out in order to delignify, or to increase the surface area of the sorbents, and to study their effect on the rate and effective adsorption of dyes. Steam, alkali, ammonia steeping and milling were the pretreatments employed and compared with the untreated sorbents. A higher percentage of dye removal was achieved at a faster rate by the milled samples proving milling to be a better and more cost effective treatment, except for barley husk which had a higher percentage removal for the control.     

Dye biosorption sites in Aspergillus niger

Aspergillus niger is capable of removing dyes from an aqueous solution. In the study, the roles played by three major functional groups: carboxyl, amino and phosphate, and the lipid fraction in the biomass of A. niger in biosorption of four dyes, Basic Blue 9, Acid Blue 29, Congo Red and Disperse Red 1, were investigated. These functional groups in A. niger were chemically modified individually to determine their contribution to the biosorption of dyes. It was found that biosorption of dyes was influenced by the functional groups in the fungal biomass and the chemical structure of the dyes.     

Decolorization of industrial dyes by a Brazilian strain of Pleurotus pulmonarius producing laccase as the sole phenol-oxidizing enzyme

The ability of a Brazilian strain ofPleurotus pulmonarius to decolorize structurally different synthetic dyes (including azo, triphenylmethane, heterocyclic and polymeric dyes) was investigated in solid and submerged cultures. Both were able to decolorize completely or partially 8 of 10 dyes (Amido Black, Congo Red, Trypan Blue, Methyl Green, Remazol Brilliant Blue R, Methyl Violet, Ethyl Violet, Brilliant Cresyl Blue). No decolorization of Methylene Blue and Poly R 478 was observed. Of the four phenol-oxidizing enzymes tested in culture filtrates (lignin peroxidase, manganese peroxidase, aryl alcohol oxidase, laccase),P. pulmonarius produced only laccase. Both laccase activity and dye decolorization were related to glucose and ammonium starvation or to induction by ferulic acid. The decolorizationin vivo was tested using three dyes — Remazol Brilliant Blue R, Trypan Blue and Methyl Green. All of them were completely decolorized by crude extracellular extracts. Decolorization and laccase activity were equally affected by pH and temperature. Laccase can thus be considered to be the major enzyme involved in the ability ofP. pulmonarius to decolorize industrial dyes.     

Overexpression of a Novel Thermostable and Chloride-Tolerant Laccase from Thermus thermophilus SG0.5JP17-16 in Pichia pastoris and Its Application in Synthetic Dye Decolorization

Laccases have been used for the decolorization and detoxification of synthetic dyes due to their ability to oxidize a wide variety of dyes with water as the sole byproduct. A putative laccase gene (LacTT) from Thermus thermophilus SG0.5JP17-16 was screened using the genome mining approach, and it was highly expressed in Pichia pastoris, yielding a high laccase activity of 6130 U/L in a 10-L fermentor. The LacTT open reading frame encoded a protein of 466 amino acid residues with four putative Cu-binding regions. The optimal pH of the recombinant LacTT was 4.5, 6.0, 7.5 and 8.0 with 2,2''-azino-bis(3-ethylbenzothazoline-6-sulfonic acid) (ABTS), syringaldazine (SGZ), guaiacol, and 2,6-dimethoxyphenol (2,6-DMP) as the substrate, respectively. The optimal temperature of LacTT was 90°C with guaiacol as the substrate. LacTT was highly stable at pH 4.0–11.0 and thermostable at 40°C–90°C, confirming that it is a pH-stable and thermostable laccase. Furthermore, LacTT also exhibited high tolerance to halides such as NaCl, NaBr and NaF, and decolorized 100%, 94%, 94% and 73% of Congo Red, Reactive Black B and Reactive Black WNN, and Remazol Brilliant Blue R, respectively. Interestingly, addition of high concentration of NaCl increased the RBBR decolorization efficiency of LacTT. These results suggest that LacTT is a good candidate for industrial applications such as dyestuff processing and degradation of dyes in textile wastewaters.     

Bioinformatics aided microbial approach for bioremediation of wastewater containing textile dyes

Four textile azo dyes, Joyfix Red, Remazol Red, Reactive Red and Reactive Yellow, were studied for decolorization. Of nineteen soil bacterial isolates, two novel strains were found to highly decolorize Joyfix Red and were identified as Lysinibacillus sphaericus (KF032717) and Aeromonas hydrophila (KF032718) through 16S rDNA analysis. Laccase and Azoreductase enzyme modeling and enzyme–dye interaction performed using Schrödinger Suite imitated decolorization percentage. Results based on cumulative Glide score (Dry laboratory) and decolorization percentage of the other three dyes based on ultraviolet–visible (UV–vis) spectroscopy (Wet laboratory) were reliable. Biodegradation of Joyfix Red was confirmed by high-performance liquid chromatography (HPTLC) elution profile which showed four peaks at 1.522, 1.800, 3.068 and 3.804 min with that of parent dye which showed single peak at 1.472 min. Fourier transform infrared spectroscopy (FT-IR) analysis supported the biotransformation of Joyfix Red. Gas chromatography–mass spectroscopy (GC–MS) analysis showed sodium (3E,5Z)-4-amino-6-hydroxyhexa-13,5-triene-2-sulfonate was formed as end product during biodegradation. From these findings, it can be inferred that enzyme and dye interaction studies can assist in examining decolorization efficiency of bacteria and its enzyme, thereby enhancing the bioremediation process by reducing preliminary lengthy wet laboratory screening. This is the first report of a combinatorial in silico cum in vitro approach and its validation for the bioremediation of wastewater containing these textile azo dyes.     

Oxidative degradation of Remazol Turquoise Blue G 133 by soybean peroxidase

Reactive dyes are widely employed in textile industries and their removal from wastewaters is a relevant environmental problem. In addition to chemical and physical methods, several bioremediation approaches, involving intact micro-organisms or isolated enzymes, have been proposed to decolorize dye solutions. In this paper, we report the complete and fast decolourization of a Cu(II)-phthalocyanine based reactive dye (Remazol Turquoise Blue G 133) by means of the soybean peroxidase/H₂O₂ system. The oxidative degradation of the dye in aqueous solution at 25 °C was studied as function of pH, revealing a quantitative decolourization yield at acidic pH values with a maximum of activity at pH 3.3. The reaction products were identified and characterized by HPLC-diode array detector (DAD)-mass spectrometry (MS), ionic chromatography and EPR techniques. This analysis showed that the enzyme catalyses the breaking of the phthalocyanine ring producing sulfophthalimide as the main degradation product, and the release of stoichiometric amount of ammonium and Cu(II) ions.     

Decolorization of simulated textile dye baths by crude laccases from Trametes hirsuta and Cerrena unicolor

In this study crude laccases from the white‐rot fungi Cerrena unicolor and Trametes hirsuta were tested for their ability to decolorize simulated textile dye baths. The dyes used were Remazol Brilliant Blue R (RBBR) (100 mg/L), Congo Red (12.5 mg/L), Lanaset Grey (75 mg/L) and Poly R‐478 (50 mg/L). The effect of redox mediators on dye decolorization by laccases was also assessed. C. unicolor laccase was able to decolorize all the dyes tested. It was especially effective towards Congo Red and RBBR with 91 and 80% of color removal in 19.5 h despite the fact that simulated textile dye baths were used. Also Poly R‐478 and Lanaset Grey were partially decolorized (69 and 48%, respectively). C. unicolor laccase did not need any mediators for removing the dyes. However, T. hirsuta laccase was only able to decolorize simulated Congo Red and RBBR dye baths (91 and 45%, respectively) in 19.5 h without mediators. When using mediators the decolorization capability was enhanced substantially, e.g. Poly R‐478 was decolorized by 78% in 25.5 h. On the whole, both laccases showed potential to be used in industrial applications.     

Remediation of complex remazol effluent using biochar derived from green seaweed biomass

Abstract

The unique property of biochar, synthesized from a green seaweed (Ulva lactuca), to remediate complex Remazol dye bearing wastewater was investigated. Preliminary trials were targeted to explore the remediation capacity of biochar towards each of Remazol dyes (Remazol brilliant blue R (RBBR), Remazol brilliant orange 3R (RBO3R), Remazol brilliant violet 5R (RBV5R), and Remazol Black B (RBB)) in single-solute system. The results show that equilibrium pH played a vital part with maximum sorption observed at pH 2.0. The isotherm experiments confirmed that biochar exhibited high uptakes of 0.301, 0.292, 0.265, and 0.224?mmol/g for RBO3R, RBBR, RBV5R, and RBB, respectively. Due to the presence of multiple dyes as well as high concentration of auxiliary chemicals, the performance of biochar to remediate Remazol effluent was inhibited markedly compared to single solute systems. Nevertheless, the dye removal efficiency was above 77.5% and the decolorization rate was high with more than 95% of total dye decolorization completed within 240?min. Our results provide novel insights into the potential of biochar to remove Remazol dyes from complex dye wastewaters.     

Biosorption of three textile dyes from contaminated water by filamentous green algal Spirogyra sp.: Kinetic,isotherm and thermodynamic studies

A freshwater filamentous green alga Spirogyra sp. was used as an inexpensive and efficient biosorbent for the removal of C.I. Acid Orange 7 (AO7), C.I. Basic Red 46 (BR46) and C.I. Basic Blue 3 (BB3) dyes from contaminated water. The effects of various physico–chemical parameters on dye removal efficiency were investigated, e.g. contact time, pH, initial dyes concentration, the amount of alga, temperature and biosorbent particle size. Dyes biosorption was a quick process and reactions reached to equilibrium conditions within 60 min. The biosorption capacity of three dyes onto alga was found in the following order: BR46 > BB3> AO7. The values of thermodynamic parameters, including ΔG, ΔH and ΔS, indicated that the biosorption of the dyes on the dried Spirogyra sp. biomass was feasible, spontaneous and endothermic. The pseudo-first order, pseudo-second order and the intraparticle diffusion models were applied to the experimental data in order to kinetically describe the removal mechanism of dyes, with the second one showing the best fit with the experimental kinetic biosorption data (R² = 0.99). It was also found that the adsorption process followed the Freundlich isotherm model with the highest value of correlation coefficients (0.99) and the biosorption capacity being estimated to be 13.2, 12.2 and 6.2 mg g⁻¹ for BR46, BB3 and AO7, respectively.     

Oxidation and removal of industrial textile dyes by a novel peroxidase extracted from post-harvest lentil (Lens culinaris L.) stubble

The degradation and removal of a series of dyes used in the textile industry for polyester/wool (PES/WO) blends and present in effluents, such as Green, Ash-Grey, Black, Navy Blue, Red and Yellow Domalan, and Orange and Red Bemacid, by catalytic action, in the presence of H₂O₂, of extracts of a novel peroxidase from postharvest lentil stubble was investigated. The extracts of this peroxidase (LSP) were effective in degrading these lastgeneration textile dyes, especially Green Domalan, Orange Bemacid, Grey and Black Domalan. A sensitivity study was carried out for Green Domalan biodegradation to determine the effects of process parameters such as pH, H₂O₂, enzyme and dye concentrations, contact and centrifugation times, and temperature. Standard ecotoxicity studies performed with Vibrio fischeri revealed that the dye solutions treated with peroxidase and H₂O₂ were less ecotoxic than the untreated ones.     

Degradation of Remazol Red dye by <Emphasis Type="Italic">Galactomyces geotrichum</Emphasis> MTCC 1360 leading to increased iron uptake in <Emphasis Type="Italic">Sorghum vulgare</Emphasis> and <Emphasis Type="Italic">Phaseolus mungo</Emphasis> from soil

Removal of azo dyes from the effluent generated by textile industries is rather difficult. Azo dyes represent a major class of synthetic colorants that are both mutagenic and carcinogenic. Galactomyces geotrichum MTCC 1360, a yeast species, showed more than 96% decolorization of the azo dye Remazol Red (50 mg/L) within 36 h at 30°C and pH 11.0 under static condition with a significant reduction in the chemical oxygen demand (62%) and total organic carbon (41%). Peptone (5.0 g/L), rice husk (10 g/L extract), and ammonium chloride (5.0 g/L) were found to be more significant among the carbon and nitrogen sources used. The presence of tyrosinase, NADH-DCIP reductase, riboflavin reductase and induction in azo reductase and laccase activity during decolorization indicated their role in degradation. High performance thin layer chromatography analysis revealed the degradation of Remazol Red into different metabolites. Fourier transform infrared spectroscopy and high performance liquid chromatography analysis of samples before and after decolorization confirmed the biotransformation of dye. Atomic absorption spectroscopy analysis revealed a less toxic effect of the metabolites on iron uptake by Sorghum vulgare and Phaseolus mungo than Remazol Red dye. Remazol Red showed an inhibitory effect on iron uptake by chelation and an immobilization of iron, whereas its metabolites showed no chelation as well as immobilization of iron. Phytotoxicity study indicated the conversion of complex dye molecules into simpler oxidizable products which had a less toxic nature.     

Reactive azo dye reduction by Shewanella strain J18 143

A bacterial isolate designated strain J18 143, originally isolated from soil contaminated with textile wastewater, was shown to reduce intensely coloured solutions of the reactive azo dye, Remazol Black B to colourless solutions. Phylogenetic placement based on 16S rRNA gene sequence homology identified the bacterium as a Shewanella species. Based on results from analyses of the end products of dye decoloration of Remazol Black B and the simpler molecule, Acid Orange 7, using capillary electrophoresis, UV-visible spectrophotometry and liquid chromatography-mass spectrometry, we suggest that colour removal by this organism was a result of microbially mediated reduction of the chromophore in the dye molecules. Anaerobic dye reduction by Shewanella strain J18 143 was 30 times more efficient than the reduction carried out by aerated cultures. Whole cells used a range of electron donors for dye reduction, including acetate, formate, lactate, and nicotinamide adenine dinucleotide (NADH), with formate being the optimal electron donor. The impact of a range of process variables was assessed (including nitrate, pH, temperature, substrate concentration, presence of an extracellular mediator) and results suggest that whole cells of Shewanella J18 143 offer several advantages over other biocatalysts with the potential to treat azo dyes.