Decolorization Of Textile Dyes Research Articles

Photopolymerization of L-DOPA-Alginate Immobilized Cell Wall Laccase for Textile Dye Decolorization

Alginate is a naturally occurring polymer derived from brown algae biomass, which has numerous applications in various fields. Chemical modification of alginate is widely used to improve alginate’s physicochemical properties and provide new potential for multiple applications. In this article, we modified alginate with L-DOPA, using periodate oxidation and reductive amination, to obtain more suitable biopolymer for biocatalyst immobilization and hydrogel formation. Obtained modified alginate was used for the immobilization of laccase on cell walls. For this purpose, laccase from Streptomyces cyaneus was expressed on the surface of Saccharomyces cerevisiae EBY100 cells. The obtained cell wall laccase was immobilized within L-DOPA-alginate beads by crosslinking the L-DOPA-alginate with calcium ions and laccase. The effect of additional crosslinking of beads by green light-induced photopolymerization with eosin Y was investigated. The immobilized laccase systems were used for dye decolorization and investigated in multiple treatment processes. Beads with L-DOPA-alginate with a higher degree of modification (5.0 mol%) showed higher enzymatic activity and better decolorization efficiency than those with a lower degree of modification (2.5 mol%). Obtained immobilized biocatalysts are suitable for decolorizing dye Evans Blue due to their high efficiency and reusability.

Horseradish Peroxidase Immobilized onto Mesoporous Magnetic Hybrid Nanoflowers for Enzymatic Decolorization of Textile Dyes: A Highly Robust Bioreactor and Boosted Enzyme Stability.

Recently, hybrid nanoflowers (hNFs), which are accepted as popular carrier supports in the development of enzyme immobilization strategies, have attracted much attention. In this study, the horseradish peroxidase (HRP) was immobilized to mesoporous magnetic Fe3O4-NH2 by forming Schiff base compounds and the HRP@Fe3O4-NH2/hNFs were then synthesized. Under optimal conditions, 95.0% of the available HRP was immobilized on the Fe3O4-NH2/hNFs. Structural morphology and characterization of synthesized HRP@Fe3O4-NH2/hNFs were investigated. The results demonstrated that the average size of HRP@Fe3O4-NH2/hNFs was determined to be around 220 nm. The ζ-potential and magnetic saturation values of HRP@Fe3O4-NH2/hNFs were -33.58 mV and ∼30 emu/g, respectively. Additionally, the optimum pH, optimum temperature, thermal stability, kinetic parameters, reusability, and storage stability were examined. It was observed that the optimum pH value shifted from 5.0 to pH 8.0 after immobilization, while the optimum temperature shifted from 30 to 80 °C. K m values were calculated to be 15.5502 and 7.6707 mM for free HRP and the HRP@Fe3O4-NH2/hNFs, respectively, and V max values were calculated to be 0.0701 and 0.0038 mM min-1. The low K m value observed after immobilization indicated that the affinity of HRP for its substrate increased. The HRP@Fe3O4-NH2/hNFs showed higher thermal stability than free HRP, and its residual activity after six usage cycles was approximately 45%. While free HRP lost all of its activity within 120 min at 65 °C, the HRP@Fe3O4-NH2/hNFs retained almost all of its activity during the 6 h incubation period at 80 °C. Most importantly, the HRP@Fe3O4-NH2/hNFs demonstrated good potential efficiency for the biodegradation of methyl orange, phenol red, and methylene blue dyes. The HRP@Fe3O4-NH2/hNFs were used for a total of 8 cycles to degrade methyl orange, phenol red, and methylene blue, and degradation of around 81, 96, and 56% was obtained in 8 h, respectively. Overall, we believe that the HRP@Fe3O4-NH2/hNFs reported in this work can be potentially used in various industrial and environmental applications, particularly for the biodegradation of recalcitrant compounds, such as textile dyes.

Exploring fungal-mediated solutions and its molecular mechanistic insights for textile dye decolorization

Decolorization of textile dyes and study of their intermediate compounds is necessary to comprehend the mechanism of dye degradation. In the present study, different fungal mediated solutions were explored to provide an alternative to treat the reactive dyes. Growing biomass of Pleurotus sajor caju showed 83% decolorization (249.99 mg L−1 removal) of Reactive Blue 13 (RB 13) and 63% decolorization (188.83 mg L−1) of Reactive Black 5 (RB 5) at 300 mg L−1 initial concentration on 8 d. Higher laccase activity was positively correlated with increase in decolorization. However, increasing dye concentration has inhibitory effect on fungal biomass due to increase in toxicity. In laccase mediated decolorization, laccase produced from P. sajor caju using carbon rich waste material as substrate showed 89% decolorization (276.36 mg L−1 removal) of RB 13 and 33% decolorization (105.37 mg L−1 removal) of RB 5 at 300 mg L−1 initial dye concentration in 100 min at 30 °C and pH 3.0’. Comparing the two methods, laccase-mediated decolorization shows better decolorization in less time and does not produce sludge. Further, the present work also attempted to study the dye degradation pathway for Reactive blue 13 via laccase mediated process. Fourier-transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography–mass spectrometry (GC-MS) were utilized to identify the degraded products. The GC-MS analysis showed the formation of naphthalene, naphthalene 2-ol, benzene,1–2, dicarboxylic acid, 4, amino, 6,chloro, 1-3-5, triazin-2-ol as the final degraded products after enzymatic degradation of RB 13. These findings provide in-depth study of laccase-mediated textile dye degradation mechanism.

A novel laccase from Trametes polyzona with high performance in the decolorization of textile dyes

Laccases are multicopper oxidases able to oxidize several phenolic compounds and find application in numerous industrial applications. Among laccase producers, white-rot fungi represent a valuable source of multiple isoforms and isoenzymes of these multicopper oxidases. Here we describe the identification, biochemical characterization, and application of laccase 2 from Trametes polyzona (TP-Lac2), a basidiomycete fungus emerged among others that have been screened by plate assay. This enzyme has an optimal temperature of 50 °C and in acidic conditions it is able to oxidize both phenolic and non-phenolic compounds. The ability of TP-Lac2 to decolorize textile dyes was tested in the presence of natural and synthetic mediators at 30 °C and 50 °C. Our results indicate that TP-Lac2 most efficiently decolorizes (decolorization rate > 75%) malachite green oxalate, orange G, amido black10B and bromocresol purple in the presence of acetosyringone and 2,2′-azinobis (3-ethylbenzthiazoline-6-sulfonate)—ABTS. Overall, the laccase mediator system consisting of TP-Lac2 and the natural mediator acetosyringone has potential as an environmentally friendly alternative for wastewater treatment in the textile industry.

Kinetics of Decolorization of Reactive Textile Dye via Heterogeneous Photocatalysis Using Titanium Dioxide

The textile industry is known for its excessive water consumption and environmental impact. One of the major challenges it faces is managing pollution generated by dyes, particularly bifunctional dyes, such as sumireact supra yellow s-hbu, with a red appearance and sumifix supra lemon-yellow e-xf, with a yellow appearance. This study aimed to investigate the decolorization kinetics of synthetic solutions of said bifunctional dyes, which comprise triazine and vinylsulfon. We conducted various tests, including modifications of pH, the addition of TiO2 P-50 nanoparticles, exposure to solar radiation, limited contact with oxygen, and eolic agitation. The initial solutions had a concentration of 1000 ppm of textile dye. The study showed that the reaction order for the “red” solutions in the R6 and R9 reactors and all the yellow solutions was ½. The concentration of nanoparticles and pH had a significant impact on the reaction rate. The yellow solutions with a concentration of 800 ppm and pH levels of 3.15, 4.13, and 2.25 demonstrated 100% color discoloration, followed by solutions with a concentration of 400 ppm and pH levels of 3.15, 2.25, and 4.13. The analysis of variance confirmed the reaction rate constants for the yellow solutions and emphasized the significance of pH in this process.

Unveiling the azo-reductase mechanism in Pseudomonas putida for efficient decolorization of textile Reactive dyes: an in-silico study

The textile industry utilizing affordable azo dyes is a high threat to aquatic life and causes environmental problems due to their toxicity. Biodegradation of azo dyes employing microbes and enzymes has proved to be an efficient method for treating industrial effluent. This study used the novel microbial consortium to decolorize reactive azo dyes (Reactive Red 120; Reactive Black 5 and Reactive Blue 13), and its azo-reductase activity was evaluated. The metagenomic analysis of the consortium identified azo-reductase-producing bacterial species. The molecular docking revealed that PpAzoR from Pseudomonas putida had the highest binding affinities for all the three dyes such as Reactive Black 5 (−9.3 kcal/mol), Reactive Blue 13 (−9.8 kcal/mol) and Reactive Red 120 (−10.7 kcal/mol). The structural rigidity and stability of the docked complex were confirmed through MD simulations evaluated across multiple descriptors from the simulation trajectories. Further, MMPBSA analysis validated the results that binding of the ligands, i.e. dye molecules Reactive Black (RB5), Reactive Blue (RB13) and Reactive Red (RR120) binding with the Azoreductase (PpAzoR) to the screened Azo-dyes was spontaneous. Based on molecular dynamics simulations for 100 ns, RR 120 showed the highest binding affinity (−411.336 ± 46.799 KJ/mol), followed by RB5 (−288.012 ± 33.371 KJ/mol). The dyes (RR120 and RB5) exhibited stable interactions with the target azoreductase (PpAzoR). The present study provides insights that PpAzoR shows the highest decolorization potency, which could be interpreted as a potential dye-degrading protein based on dye-degrading assay findings. Communicated by Ramaswamy H. Sarma

Isolation of Indigenous Bacillus Spp. From Garden Soil To Decolorize Synthetic Textile Dyes

Textile and clothing industries are major contributor to the economic growth in Bangladesh. Establishment of a number of such industries are imparting huge amount of industrial waste containing different types of chemicals including dyes. Pollutants generated from textile industries creates a huge burden on the environment. Textile industries discharge effluents containing various harmful chemicals including synthetic dyes that are very stable and a threat to living organisms. Bacillus spp. are remarkable bacteria which demonstrated potential to produce diverse kinds of metabolites for different uses. This study focuses on the potential use of Bacillus spp. isolated from the garden soil of Stamford University Bangladesh for decolorization of BemacronBlue RS (BB) and BemacronRed RS 01 (BR) dyes. Four Bacillus isolates were screened out from garden soil and named as 1B, 3A, 2C and 4B. Isolates were subjected to decolorization assay with 0.002 gm/l of BB and BR dyes. Bacillus spp. showed great potential in decolorizing BB and BR dyes, which was initiated after 2 days of incubation. Following 8 days of incubation, decolorization of BB was, 79%, 80%, 75%, 77% and BR was, 75%, 73%, 69%, 89% by the isolates 1B, 3A, 2C and 4B, respectively. This study shed some light on the potential use of indigenous garden bacteria for decolorization of textile dyes to control environmental pollution. Stamford Journal of Microbiology, 2023. Vol. 13, Issue 1, p. 1-5

Decolorization of Textile Azo Dye via Solid-State Fermented Wheat Bran by Lasiodiplodia sp. YZH1.

Textile dyes are one of the major water pollutants released into water in various ways, posing serious hazards for both aquatic organisms and human beings. Bioremediation is a significantly promising technique for dye decolorization. In the present study, the fungal strain Lasiodiplodia sp. was isolated from the fruiting bodies of Schizophyllum for the first time. The isolated fungal strain was examined for laccase enzyme production under solid-state fermentation conditions with wheat bran (WB) using ABTS and 2,6-Dimethoxyphenol (DMP) as substrates, then the fermented wheat bran (FWB) was evaluated as a biosorbent for Congo red dye adsorption from aqueous solutions in comparison with unfermented wheat bran. A Box-Behnken design was used to optimize the dye removal by FWB and to analyze the interaction effects between three factors: fermentation duration, pH, and dye concentration. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were applied to study the changes in the physical and chemical characteristics of wheat bran before and after fermentation. An additional experiment was conducted to investigate the ability of the Lasiodiplodia sp. YZH1 to remove Congo red in the dye-containing liquid culture. The results showed that laccase was produced throughout the cultivation, reaching peak activities of ∼6.2 and 22.3 U/mL for ABTS and DMP, respectively, on the fourth day of cultivation. FWB removed 89.8% of the dye (100 mg L-1) from the aqueous solution after 12 h of contact, whereas WB removed only 77.5%. Based on the Box-Behnken design results, FWB achieved 93.08% dye removal percentage under the conditions of 6 days of fermentation, pH 8.5, and 150 mg L-1 of the dye concentration after 24 h. The fungal strain removed 95.3% of 150 mg L-1 of the dye concentration after 8 days of inoculation in the dye-containing liquid culture. These findings indicate that this strain is a worthy candidate for dye removal from environmental effluents.

Degradation and decolorization of textile azo dyes by effective fungal-bacterial consortium.

Synthetic dyes are one of the main pollutants in the textile industry and bioremediation is considered as an environmentally friendly method to degrade them. Soil microbial consortia (MCs) are reported having the potential of decolorizing most of textile dyes. This study aimed at evaluating dye-degrading ability of MCs developed from fungi and bacteria. Fungi and bacteria were isolated from the soil samples obtained from textile waste dumping site at Horana industrial zone, Sri Lanka and were screened for crystal violet (CV) and congo red (CR) dyes to develop MCs. Decolorization assay was performed for MCs along with individual isolates under variable pH levels. Metabolized products were characterized to confirm the biodegradation. A. tamari (F5) and P. putida (B3) significantly (P < 0.05) decolorized both dyes. All the MCs showed higher decolorization percentages over the individual microorganisms. Neutral pH (pH 7) was the optimum pH for the decolorization of both dyes by individual isolates and the percentages were significantly changed under the acidic and basic pH levels. However, decolorization ability by all MCs was not significantly changed with pH. Consortium with A. tamari - P. putida significantly (P < 0.05) decolourized both dyes under optimum pH 7. All MCs showed better pH tolerance in degrading CV and CR. Thus, it can be concluded that the selected MC with A. tamari - P. putida can degrade CV and CR textile dyes efficiently into non-toxic compounds against plants under neutral pH. Degradation and decolorization of textile azo dyes by effective fungal-bacterial consortium.

Dye Decolorization of Textile Dyes by Using Aspergillus fumigatus Isolated from Marine Soil

Dye Decolorization of Textile Dyes by Using Aspergillus fumigatus Isolated from Marine Soil

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.

Removing color while lowering toxicity: the case for decolorization of textile dyes and simulated effluents with yeasts

Removing color while lowering toxicity: the case for decolorization of textile dyes and simulated effluents with yeasts

Laccase immobilization on bacterial cellulose produced in a mulberry pomace waste extract medium: Characterization and use for dye decolorization

AbstractThe present study aimed to immobilize laccase on dry bacterial cellulose (BC) produced by Komagataeibacter xylinus B759 in mulberry pomace waste extract as a low‐cost and natural waste by‐product and to determine the effectiveness of the obtained laccase immobilized BC (Lac/BC) for textile dye decolorization. The highest BC yield obtained after optimization studies was as 1.70 g/L in pH 8.0 medium at 32°C after 15 days. BC and Lac/BC structures were characterized by different instrumental techniques. A transition to more amorphous character was observed with the binding of the enzyme structure. The morphological properties and fiber structure of the BC and enzyme‐linked cellulose structures were examined by SEM and AFM analyses. Obtained Lac/BC pieces were used for the decolorization of Reactive Blue 171 (RB 171) and Reactive Blue 198 (RB 198) diazo dyes during the repeated‐batch process. As a result of using 12 pieces of Lac/BC, 93% and 98% decolorization values were obtained for the RB 171 and RB 198 dyes in the first use, while the color removal was still 83% and 51% at the 8th use, respectively. The results showed that BC produced in a mulberry pomace waste extract can be used for laccase immobilization and Lac/BC is an effective and promising system for textile dye decolorization.

Activity of laccase enzyme extracted from Malva parviflora and its potential for degradation of reactive dyes in aqueous solution

The use of enzymes, particularly laccase as a dye-degrading biogenic agent, is a significantly low carbon footprint, bio-inspired approach towards dye wastewater remediation, which not only decomposes and decolorizes the dyes but has also been reported to transmute dyes into less toxic by-products. The work presented herein utilizes both original and purified laccase extracted from Malva parviflora for decomposing pigments that adversely affect ecosystems. Extractions of enzymes from plants were designed by changing one variable at one time and by using response surface methodology (RSM). The optimum enzyme-specific activity of 420 units/mg protein from this flora occurred with extraction for 16.1 min at pH 5.0 with an extraction ratio of 0.17 in 0.42 M sodium acetate buffer. Sephadex G-150 was utilized to filter and purify the enzymes. An ultimate purity of 42% was thus achievable, which constituted a fourfold increase over that of the original extract. The extent to which both natural and purified laccases eliminated textile dyes was assessed under optimal conditions, which were considered to be 180 min at 37 °C. The enzyme extracted from Malva parviflora exhibited high removal efficiency and was able to transmute dyes into less toxic by-products. The extraction process was optimized using response surface methodology, resulting in an optimum enzyme-specific activity. The study found that unpurified enzymes exhibited a greater removal efficiency of dyes compared to purified enzymes. Overall, the findings suggest that laccase enzyme from Malva parviflora could serve as a practical biocatalyst for continuous decolorization of textile dyes with low carbon footprint.

Effect of Various Carbon and Nitrogen Sources on Decolorization of Textile Dyes by Pseudomonas taiwanensis Strain TNZ3

The co-substrate is a crucial component in the bio-decolorization process that helps bacteria to grow and carry out their fundamental functions. Different types of textile dyes with diverse chemical structures are frequently employed in the textile industry, and the most of them are resistant to biodegradation because of their xenobiotic nature. Due to the low carbon content of textile dyes, particularly of azo dyes, co-metabolic conditions are required for decolorization process. Hence, the current study was aimed to determine which striking carbon and nitrogen sources are preferred for generating co-metabolic conditions to decolorize the following dyes: Disperse Yellow-3, Malachite Green, Basic Red-18, and Reactive Blue-4. Different carbon and nitrogen sources were used to isolate, screen, and evaluate different bacterial strains for dye degradation. A potential bacterial strain Pseudomonas taiwanensis strain TNZ3 was identified based on 16s rDNA sequence and selected for further study. It was found that the presence of yeast, peptone, NH4Cl, sucrose, glucose, fructose, maltose, galactose, lactose, and starch in dye contaminated media effectively enhanced azo dye degradation rate by Pseudomonas taiwanensis strain TNZ3. In the medium inoculated with Pseudomonas taiwanensis strain TNZ3, sucrose and yeast with peptone extracts induced the greatest decolorization among diverse carbon and nitrogen sources. In all dyes, the maximum decolorization occurs at 1.5% yeast extract supplementation. The results made it abundantly clear that various carbon and nitrogen sources used as co-substrates played effective role on dye decolorization process.

Immobilization of Trametes trogii laccase on polyvinylpyrrolidone-coated magnetic nanoparticles for biocatalytic degradation of textile dyes

High cost and low operational stability are the most important challenges limiting the possible use of laccase in the removal of textile dyes. To overcome these challenges, in this study, polyvinylpyrrolidone (PVP)-coated magnetic nanoparticles (MNPs) were produced and characterized. To our knowledge, this is the first study to explore the feasibility of immobilizing a Trametes trogii laccase enzyme on Fe3O4/PVP MNPs. The characterization of samples and the successful immobilization of laccase were verified by characterization methods. Besides, the biochemical properties and stability of the Fe3O4/PVP/Lac were evaluated in terms of optimum pH, optimum temperature, thermostability, thermodynamic and kinetic parameters, storage stability, operational stability, and decolorization efficiency of two different textile dyes. The optimum activities were recorded at pH 2.5 °C and 30 °C. The Fe3O4/PVP/Lac displayed remarkable thermal stability and activation energy for denaturation, enthalpy, Gibbs free energy, and entropy results confirmed the enhanced stability of Fe3O4/PVP/Lac against high temperatures. Meanwhile, the Fe3O4/PVP/Lac retained about 58% of its original activity after seven consecutive reuses, while it retained up to 25% of its original activity after 28 d of storage at room temperature. Km and V max for the Fe3O4/PVP/Lac were calculated to be 126 µM and 211 µmol/min, respectively. Finally, after 8 and 6 cycles of repeated use, the Fe3O4/PVP/Lac still decolorized 32.34% and 32.23% of Remazol Brilliant Blue R (RBBR) and Indigo Carmine (IC), respectively. As envisioned, this study suggests a promising way to solve the problems of high price and poor operational stability of the enzyme during biocatalytic decolorization of textile dyes in wastewaters.

Deciphering the alkaline stable mechanism of bacterial laccase from Bacillus pumilus by molecular dynamics simulation can improve the decolorization of textile dyes.

Laccases are considered promising tools for removing synthetic dyes from textile and tannery effluents. However, the alkaline pH in the effluents causes laccase instability, inactivation, and difficulty in its bioremediation. Based on a Bacillus pumilus ZB1 (BpLac) derived alkaline stable laccase, this study aimed to elucidate its alkaline stable mechanism at molecular level using molecular dynamics simulation. The effects of metal ions, organic solvents, and inhibitors on BpLac activity were assessed. BpLac formed more salt bridges and negatively charged surface in alkaline environment. Thereafter, pH-induced conformation changes were analyzed using GROMACS at pH 5.0 and 10.0. Among the identified residues with high fluctuation, the distance between Pro359 and Thr414 was stable at pH 10.0 but highly variable at pH 5.0. DSSP analysis suggested that BpLac formed more β-sheet and less coil at pH 10.0. Principal component analysis and free energy landscape indicated that irregular coils formed at pH 5.0 benefit for activity, while rigid α-helix and β-sheet structures formed at pH 10.0 contributed to alkaline stability. Breaking the α-helix near T1 copper center would not reduce alkaline stability but could improve dye decolorization by BpLac. Overall, these findings would advance the potential application of bacterial laccase in alkaline effluent treatment.

Banana peel as bioremediation agent in textile dyes decolorization for wastewater management

The aim of this study is to investigate the possibility of utilizing enzymatic and adsorbent banana peel extract as a bioremediation agent by evaluating its adsorption capacity on selected reactive dyes commonly used in the textile industry. The effects of polyphenol oxidase and peroxidase enzyme, pH, temperature, dye concentration on adsorption capacity were examined. The polyphenol oxidase enzyme isolated from banana peel extracted with buffer pH 6.5 showed highest decolorization of Methylene blue and Basic fuchsin while the polyphenol oxidase enzyme isolated from banana peel extracted with buffer pH 7.5 had the greatest decolorization. Complete adsorption was observed after 24 h of incubation for all banana peel extract concentrations. At pH 6–11, the adsorption capacity of banana peel was 60%, 70%, and 85%, respectively, and peaked after 24 h (96%). When the temperature was greater than 50 °C, the adsorption capacity increased overtime and reached 98% after 24 h. It can be concluded that banana peel can be utilized as an effective bioremediation agent due to its high adsorption capacity on selected textile dyes.

Decolorization of Textile Dye by Spore Surface Displayed Small Laccase for the Enhanced Thermal Stability and Robust Repeated Reaction.

In this study, we tried to decolorize synthetic dyes using small laccase (SLAC) from Streptomyces coelicolor, which is resistant to pH, temperature change, and traditional inhibitors for the actual industrial applications using spore surface display system. We inserted SLAC-His6 tag at the C-terminal of CotE anchoring motif. The proper surface expression of CotE-SLAC fusion protein on the surface of Bacillus subtilis spore was verified with flow cytometry using FITC labeled anti-His6 tag antibody. After 6 h of reaction, more than 90% of Indigo carmine was decomposed using recombinant SLAC displaying Bacillus spore, whereas less than 10% of Indigo carmine was decomposed with wild type spore. Over 70% of laccase activity was retained with recombinant SLAC displaying spore, which was heat-treated for 3 h at 90°C. For eight rounds of repeated decomposition of Indigo carmine, no significant decrease of enzymatic activity was observed. This showed the robust characteristics of spore display format for repeated and harsh condition reactions.

Evaluation of Congo red dye decolorization and degradation potential of an endophyte Colletotrichum gloeosporioides isolated from Thevetia peruviana (Pers.) K. Schum.

Decolorization and degradation of textile dye by endophytic fungi stand to be a profitable and viable alternative over conventional methods with respect to eco-friendliness, cost-effectiveness, and non-hazardous nature. One of the active fungal endophytes Colletotrichum gloeosporioides isolated from plant Thevetia peruviana (Pers.) K. Schum. was screened for laccase production and Congo red dye decolorization. Various physicochemical parameters like dye concentration, carbon sources, nitrogen sources, temperature, and pH were optimized, and the maximum decolorization (%) was achieved at 100 mg/L of dye concentration (82%), yeast extract (80%), 30 °C temp (80%), glucose (79%), and 7 pH (78%), respectively. SEM image and fungal biomass changes represent that fungus actively participated in the dye decolorization and had less significant effect on biomass. The regenerative ability of fungus C. gloeosporioides after dye decolorization indicated tolerance against the dye and was found to be more advantageous over previous reports of dye decolorization by other endophytic fungi. UV-Vis spectra, TLC, FTIR, and HPLC results confirmed the decolorization and degradation process due to absorption and biodegradation. Phytotoxicity assay depicted that degraded products are less toxic to Phaseolus mungo compared to Congo red. The overall findings showed that C. gloeosporioides possesses a good decolorization and degradation potential against Congo red and this endophyte can be profitably used for dye-containing wastewater treatment.