Biodegradation Of Dyes Research Articles

Physicochemical Investigations of Textile Wastewater and Process Parameter Optimization for Bio-decolorization of Congo Red Dye by Pseudomonas aeruginosa MT-2 Strain

Pollution caused by dyes is a major environmental threat, posing adverse impacts on humans, animals, and plants. Therefore, the remediation of such pollutants is essential to protect the environment. This study aimed to conduct physicochemical and bacteriological analyses of textile wastewater to isolate and identify potential native bacterial strains for the decolorization of Congo red dye. Physical and nutritional process parameters were optimized to achieve maximum decolorization. The biological and chemical oxygen demands of the analyzed textile waste water were found to be above the recommended limits. In this study, 19 Congo red -decolorizing bacteria were isolated, with one bacterial culture capable of growing at a higher dye concentration of 300 mg/L. This bacterium was characterized biochemically and genetically (using 16S rRNA sequencing) and identified as the Pseudomonas aeruginosa MT-2 strain. A maximum decolorization of 94.0% was achieved at an initial dye concentration of 150 mg/L, 35°C, and pH 8.0 under static conditions. The bacterial culture also showed resistance to heavy metals such as arsenic, lead, and chromium. The biodegradation of Congo red dye was confirmed through UV-vis spectral analysis and Fourier transform infrared spectrophotometry. The findings of this study demonstrate the high remediation potential of the MT-2 strain, making it suitable for possible use in dye biodecolorization at contaminated sites.

Native microorganisms for sustainable dye biodegradation in wastewaters from jeans finishing.

The textile mill is one of the most water-consuming industries. Wastewater production is very high, and among the main generated pollutants are dyes. In particular, jeans finishing, which is performed all over the world, generates wastewater with indigo dye that has to be eliminated before discharge. This work studies the biological treatment of this type of wastewater using native microorganisms, i.e., without the need for external seed sludge to start-up the process. Two strategies for starting up the biological treatment using laboratory sequencing batch reactors have been compared: the addition of seed sludge from a biological reactor of a wastewater treatment plant and the non-addition of seed sludge, which means that native microorganisms (those in wastewater coming from the industry facilities) are responsible for COD and color degradation. Special attention is paid to biomass shift in both reactors, analyzing both bacterial and fungal populations. Results yielded more than 90% of COD and color removal after 25days in both reactors. MLSS increased in both reactors during the operation, reaching very similar values (around 1840mg/L). Rozellomycota was the predominant phylum in the reactors. Concerning bacteria, Planctomycetota abundance increased considerably in both reactors, which shows the important role of these bacteria in the treatment. It can be concluded that the lower bacterial diversity in the native population in comparison with the seeded sludge was shifting to a higher microbial diversity during the process, achieving a similar microbial population in reactors. It implies that it is not necessary to either work with isolated cultures or seeded sludge, which leads to a simpler and more sustainable solution for textile wastewater treatment in areas all over the world.

Performance study of the bioreactor for the biodegradation of methyl orange dye by luffa immobilized Stenotrophomonas maltophilia and kinetic studies: A sustainable approach

The biodegradation of methyl orange dye was examined in a biofilm reactor with luffa immobilized Stenotrophomonas maltophilia ((HE963840.1), low-cost packing material. The bacteria were isolated from the sludge collected from a common effluent treatment plant at IOCL refinery Mathura, Uttar Pradesh. The bacteria were characterized using 16rRNA. The reactor performance was studied at 30 ± 5 oC temperatures over a period of thirty days. The reactor was operated with the flow rates of 60 mL/h, 90 mL/h, 240 mL/h, 360 mL/h and 432 mL/h. The pollutant load ranges from 151.6 mg/(L-day) to 1091 mg/(L-day) and the pH of the dye solution was maintained at 7.0 ± 0.4 during the study. The maximum removal efficiency (RE) and elimination capacity (EC) at steady state were determined as 90.2 % and 658.1 mg/(L-day) respectively. The rate of utilization of the methyl orange dye is described by modified stover-kincannon model with kinetic parameters- maximum utilization rate (Umax) and saturation constant (KB) to be 2.70 g/(L-day) and 2.34 g/(L-day) respectively. The toxicity studies confirm the non-toxic nature of the biodegraded products.

Oxidative ligninolytic enzymes and their role in textile dye biodegradation: a comprehensive review

ABSTRACT Dye degradation mediated by oxidoreductive enzymes has been well explored in textile wastewater treatment. Ligninolytic enzymes (LEs) play key roles in the biodegradation of textile dyes. This paper aimed to provide a comprehensive review of the potentiality of LEs in textile dye biodegradation. The sources, biodegradation mechanisms, and dye removal efficiencies of LEs were discussed. Moreover, factors affecting dye biodegradation efficiency, and applications and limitations of LEs were highlighted. LEs are extracellular protein complexes that have a synergetic effect on dye biodegradation and can remove up to 99% of the dye using one or more LEs over wide pH and temperature ranges. Laccase is a highly explored and examined enzyme compared to lignin peroxidase (LiP) and manganese peroxidase (MnP) for dye biodegradation. Although extensive research has been conducted on fungal laccases, it is worth noting that bacterial laccases exhibit unique properties, such as stability at elevated temperatures and alkaline pH, which are not typically observed in fungal laccases, making them an ideal candidate for the treatment of textile wastewater. Further research on the optimization of experimental conditions is required to improve the dye biodegradation efficiency of these enzymes. It is also crucial for improving biodegradation capabilities using recombinant DNA technology.

Kinetics studies and effect of the process parameters on the biodegradation of methyl orange dye

The biodegradation of methyl orange dye using Stenotrophomonas maltophilia (HE963840.1) bacteria was studied. The optimization of the biodegradation process has been performed using central composite design (CCD) of response surface methodology (RSM) with respect to three parameters namely temperature, initial dye concentration and inoculum dose. The response is best described by the second order polynomial with R2 value of 0.99. The optimized values of the process parameters were empirically checked and the model equation of the RSM was found statistically significant. The errors between experimental and model predicted results were found to be less than 8 %. The maximum dye removal efficiency was found as 86.5 ± 0.1 %. The growth kinetics of the bacteria was also studied and it is best described by Andrew-Haldane model. The values of kinetic parameters maximum specific growth rate (μmax), inhibition constant (KI) and saturation constant (KS) were found as 0.032 h−1, 156 mg/L and 78 mg/L respectively.

New insights into the mechanism of azo dye biodegradation by Lactococcus lactis

Azo dye reduction by syntrophic microbial communities is still unclear, with conflicting observations reported in the literature. In this study, the biodegradation mechanism of a model azo dye by Lactococcus lactis strain LLSP-01 isolated from an acidogenic reactor system was investigated. Proteomics and RT-PCR analysis results showed that LLSP-01 azoreductase (AzoL) was not expressed by the isolate during exposure to Direct Black 22. In contrast, the mechanism appears to involve biosorption by glycoconjugates, particularly exopolysaccharides (EPS) and rhamnolipids, as proteins from the LPS O-antigen metabolism were statistically higher expressed in cells challenged with the target compound. Based on the proteomic observations, it is hypothesized that Direct Black 22 is adsorbed into the biofilm matrix and indirectly reduced by an SDR family oxidoreductase, in a mechanism mediated by riboflavin carriers. Induction of a ring-cleaving dioxygenase in the presence of azo dye indicates further degradation of the resulting aromatic amines. The collected results show that azo dye reduction by L. lactis is mediated by enzymes with broad range specificity, and not the typical azoreductases. This information can assist in the design of new strategies for the bioremediation of textile azo dyes.

Omics-Based Approaches in Research on Textile Dye Microbial Decolorization.

The development of the textile industry has negative effects on the natural environment. Cotton cultivation, dyeing fabrics, washing, and finishing require a lot of water and energy and use many chemicals. One of the most dangerous pollutants generated by the textile industry is dyes. Most of them are characterized by a complex chemical structure and an unfavorable impact on the environment. Especially azo dyes, whose decomposition by bacteria may lead to the formation of carcinogenic aromatic amines and raise a lot of concern. Using the metabolic potential of microorganisms that biodegrade dyes seems to be a promising solution for their elimination from contaminated environments. The development of omics sciences such as genomics, transcriptomics, proteomics, and metabolomics has allowed for a comprehensive approach to the processes occurring in cells. Especially multi-omics, which combines data from different biomolecular levels, providing an integrative understanding of the whole biodegradation process. Thanks to this, it is possible to elucidate the molecular basis of the mechanisms of dye biodegradation and to develop effective methods of bioremediation of dye-contaminated environments.

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.

Biodegradation of aniline blue dye by salt-tolerant Bacillus thuringiensis DHC4 isolated from soil-feeding termite guts

The existence of aniline blue in aquatic environments poses a large threat to aquatic organisms. Microbial degradation of aniline blue has been frequently used in remediation because of its effectiveness, low cost, and environmental friendliness. However, the mechanisms by which the dye can be biodegraded are not well understood. In this study, Bacillus thuringiensis DHC4 was isolated from the gut of a soil-feeding termite, and its ability to degrade aniline blue was investigated. The results showed that DHC4 was highly resistant to both aniline blue and salt, with the decolorization rate reaching 78% and 67% after 96 h of incubation at initial dye concentrations of 1 g/L and 7% salinity, respectively. Aniline blue degradation products were identified based on UV–vis, FTIR, and GC–MS analyses, and genome analysis confirmed that DHC4 contained many potential dye-degrading genes. Transcriptome analysis revealed significant up-regulation of methyltransferase, nitroreductase, arylamine N-acetyltransferase and oxidoreductase genes on exposure to aniline blue, indicating their active role in its biodegradation. A new degradation pathway of aniline blue by DHC4 is proposed, based on analysis of metabolites and differentially expressed genes. This mechanism involves cleavage of aniline blue by oxidoreductases into mono- and diphenyl ring molecules, followed by further methylation and alkylation through methyltransferases. The phytotoxicity results showed that aniline blue was degraded by DHC4 into less toxic metabolites. These results provide new insights into the mechanism of biodegradation of aniline blue by microorganisms.

Microalgal and activated sludge processing for biodegradation of textile dyes

The textile industry contributes substantially to water pollution. To investigate bioremediation of dye-containing wastewater, the decolorization and biotransformation of three textile azo dyes, Red HE8B, Reactive Green 27, and Acid Blue 29, were considered using an integrated remediation approach involving the microalga Chlamydomonas mexicana and activated sludge (ACS). At a 5 mg L−1 dye concentration, using C. mexicana and ACS alone, decolorization percentages of 39%–64% and 52%–54%, respectively, were obtained. In comparison, decolorization percentages of 75%–79% were obtained using a consortium of C. mexicana and ACS. The same trend was observed for the decolorization of dyes at higher concentrations, but the potential for decolorization was low. The toxic azo dyes adversely affect the growth of microalgae and at high concentration 50 mg L−1 the growth rate inhibited to 50–60% as compared to the control. The natural textile wastewater was also treated with the same pattern and got promising results of decolorization (90%). Moreover, the removal of BOD (82%), COD (72%), TN (64%), and TP (63%) was observed with the consortium. The HPLC and GC-MS confirm dye biotransformation, revealing the emergence of new peaks and the generation of multiple metabolites with more superficial structures, such as N-hydroxy-aniline, naphthalene-1-ol, and sodium hydroxy naphthalene. This analysis demonstrates the potential of the C. mexicana and ACS consortium for efficient, eco-friendly bioremediation of textile azo dyes.

Влияние ингибиторов фенолоксидаз на эффективность деколоризации малахитового зеленого бактериями рода Azo spirillum

Synthetic dyes are widely used in various branches of light industry. Due to the insufficient efficiency of industrial painting processes, a large percentage of dyes end up in the wastewater of enterprises in an unmodified form, which creates a huge risk of environmental pollution with these compounds. Triphenylmethane dyes, in particular malachite green, are toxic, allergenic and carcinogenic compounds. To date, biodegradability of triphenylmethane dyes has been shown for some bacteria and fungi producing phenol oxidase complex enzymes, including soil associative bacteria of the genus Azospirillum. Many factors are capable of inducing and inhibiting the biodegradation efficiency, in particular the enzymatic systems that are involved in bleaching processes. In the present work we studied the effects of typical deactivating agents of phenol oxidases, such as H2O2, EDTA, SDS-Na, β-mercaptoethanol, dithiothreitol, Tween, and sodium azide, on the azospirilla’s phenol oxidases activity and the ability to decolorize malachite green. It was found that Tween and sodium azide do not have an inhibitory effect on azospirillum enzymes and exhibit a total stabilizing effect on the entire complex. An inhibitory effect from 60 to 100% was noted for laccase and Mn-peroxidase activity under the action of β-mercaptoethanol, dithiothreitol and EDTA, which is directly proportional to the decolorization rate of malachite green. Compared with the latest issues on classical phenol-oxidizing enzymes, our data revealed non-typical properties of the phenol oxidase complex enzymes of azospirillum.

Identification of novel microbial isolate with efficiency of biodegradation of plastic and synthetic dyes

Identification of novel microbial isolate with efficiency of biodegradation of plastic and synthetic dyes

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

Eco-friendly natural dyeing of submicron cotton fabrics

To explore the color diversity and performance of functional submicron cotton fabric dyed with ecological natural dyes, three types of natural dyes sappanwood, madder, and gardenia and orchid, were used to dye the fabric. The optimal dyeing conditions for sappanwood were found to be an insulation temperature of 95°C, a dyeing bath pH of 5.5, and a dyeing time of 60 min, resulting in the highest apparent color value ( K/S). For madder, the optimal conditions were an insulation temperature of 90°C, a dyeing bath pH value of 6, and a dyeing time of 60 min. Similarly, for gardenia and orchid, the optimal conditions were an insulation temperature of 90°C, a dyeing bath pH value of 5, and a dyeing time of 60 min. Based on these preferred dyeing processes, the K/S value, color characteristic value, color fastness, and biodegradability of the three natural dyes were compared and analyzed with synthetic dyes. The results showed that natural dyeing resulted in higher brightness ( L* values), lower color depth ( C* values), lower red-green ( a*) and yellow-blue ( b*) values, similar hues, and lower K/S values compared to synthetic dyeing. The color fastness of the natural dyes was slightly lower than that of chemical dyes by 0.5 grade. Additionally, the average breaking strength, elongation at break, tearing strength, and bursting strength of the fabric increased by 9.34%, 5.69%, 9.75%, and 7.31%, respectively. Furthermore, the biodegradability of the natural dyes was over 93%, significantly higher than that of synthetic dyes. These findings provide a theoretical basis for the production of eco-friendly dyeing of functional submicron cotton fabrics and their textile color applicability.

Efficient Decolorization of the Poly-Azo Dye Sirius Grey by Coriolopsis gallica Laccase-Mediator System: Process Optimization and Toxicity Assessment.

The textile industry produces high volumes of colored effluents that require multiple treatments to remove non-adsorbed dyes, which could be recalcitrant due to their complex chemical structure. Most of the studies have dealt with the biodegradation of mono or diazo dyes but rarely with poly-azo dyes. Therefore, the aim of this paper was to study the biodegradation of a four azo-bond dye (Sirius grey) and to optimize its decolorization conditions. Laccase-containing cell-free supernatant from the culture of a newly isolated fungal strain, Coriolopsis gallica strain BS9 was used in the presence of 1-hydroxybenzotriazol (HBT) to optimize the dye decolorization conditions. A Box-Benken design with four factors, namely pH, enzyme concentration, HBT concentration, and dye concentration, was performed to determine optimal conditions for the decolorization of Sirius grey. The optimal conditions were pH 5, 1 U/mL of laccase, 1 mM of HBT, and 50 mg/L of initial dye concentration, ensuring a decolorization yield and rate of 87.56% and 2.95%/min, respectively. The decolorized dye solution showed a decrease in its phytotoxicity (Germination index GI = 80%) compared to the non-treated solution (GI = 29%). This study suggests that the laccase-mediator system could be a promising alternative for dye removal from textile wastewater.

Revealing the degrading-possibility of methyl red by two azoreductases of Anoxybacillus sp. PDR2 based on molecular docking

Azo dyes, as the most widely used synthetic dyes, are considered to be one of the culprits of water resources and environmental pollution. Anoxybacillus sp. PDR2 is a thermophilic bacterium with the ability to degrade azo dyes, whose genome contains two genes encoding azoreductases (named AzoPDR2-1 and AzoPDR2-2). In this study, through response surface methodology (RSM), when the initial pH, inoculation volume and Mg2+ addition amount were 7.18, 10.72% and 0.1 g/L respectively, the decolorization rate of methyl red (MR) (200 mg/L) could reach its maximum (98.8%). The metabolites after biodegradation were detected by UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and liquid chromatography mass spectrometry (LC-MS/MS), indicating that MR was successfully decomposed into 4-aminobenzoic acid and other small substrates. In homologous modeling, it was found that both azoreductases were flavin-dependent azoreductases, and belonged to the α/β structure, using the Rossmann fold. In their docking results with the cofactor flavin mononucleotide (FMN), FMN bound to the surface of the protein dimer. Nicotinamide adenine dinucleotide (NADH) was superimposed on the plane of the pyrazine ring between FMN and the activity pocket of protein. Besides, both azoreductase complexes (azoreductase-FMN-NADH) exhibited a substrate preference for MR. Asn104 and Tyr74 played an important role in the combination of the azoreductase AzoPDR2-1 complex and the azoreductase AzoPDR2-2 complex with MR, respectively. This provided assistance for studying the mechanism of azoreductase biodegradation of azo dyes in thermophilic bacteria.

Plant and yeast consortium for efficient remediation of dyes and effluents: a biochemical and toxicological study.

Textile effluent carries a range of dyes that may be recalcitrant and resistant to biodegradation. A unique consortium of the Fimbristylis dichotoma and Saccharomyces cerevisiae is exploited for the biodegradation of an azo dye Rubine GFL and actual textile effluent. This consortium enhances the rate of biodegradation of Rubine GFL and actual textile effluent with an excellent rate of biodegradation of 92% for Rubine GFL and 68% for actual textile effluent when compared to the individual one within 96 h. Speedy decolorization of Rubine GFL and actual textile effluent was observed due to the induction of oxido-reductive enzymes of the FD-SC consortium. Along with the significant reduction in the values of COD, BOD, ADMI, TSS, and TDS with 70, 64, 65, 41, and 52%, respectively, in experimental sets treated with FD-SC consortium. The biodegradation of Rubine GFL was confirmed with UV-Vis spectroscopy at the preliminary level, and then, metabolites formed after degradation were detected and identified by FTIR, HPLC, and GC-MS techniques. Also, decolorization of the dye was observed in the sections of the root cortex of Fimbristylis dichotoma. The toxicity of dye and metabolites formed after degradation was assessed by seed germination and bacterial count assay, where increased germination % and bacterial count from31×107CFUsto 92 × 107 CFUs reflect the nontoxic nature of metabolites. Furthermore, the nontoxic nature of metabolites was confirmed by fish toxicity on Cirrhinus mrigala showed normal structures of fish gills and liver in the groups treated with FD-SC consortium proving the better tactic for biodegradation of dyes and textile effluent.

Sustainable approach for the degradation of Contrast dye Evans blue by Enterobacter cloacae strain SD4-1

BackgroundDischarge of dye complexes through industrial effluents continues to be a never-ending problem for the environment. Several degradation techniques have been experimented with, of which utilizing biological entities for the effective degradation of these dye molecules is extensively studied and still being explored. The present study focuses on (i) isolation of bacterial strains from the contaminated agricultural lands (ii) screening the isolates for their decolourization efficiency of Evans blue dye (iii) optimization of culture parameters such as temperature, pH, concentration of dye and nitrogen source for effective decolourization (iv) analysing the effect of degradation of diazo dye Evan's blue by the selected strain using GCMS analysis. MethodsThe bacterial strains were isolated from contaminated agricultural lands in Chennai, Tamil Nadu, India. The collected samples were aseptically transferred to the laboratory and stored for further studies. The collected samples were serially diluted, and the colonies with distinct morphology were pure-cultured. The isolated strains were studied for their efficiency to decolourize the dye Evans blue dye. The strain with higher decolourization efficiency was selected and optimized for parameters such as temperature, pH, nitrogen source and concentration of dye. The degradation of dye by the isolate was analysed by GCMS. Significant FindingsThe investigation unveiled that the strain SD4-1 of Enterobacter cloacae effectively decolorizes Evans blue dye at 37°C and pH 6.0, utilizing Sodium nitrate as the nitrogen source. SD4-1 exhibited an impressive dye decolourization efficiency of approximately 75%. The comprehensive GCMS analysis verified the bacterium's capability to fully degrade the azo dye Evans blue. Consequently, this study concludes that the SD4-1 Enterobacter cloacae strain holds promising potential for the efficient biodegradation of Evan's blue dye. Its application as a highly effective biological agent in the practical removal of dyes from textile industries is envisaged. Notably, this organism demonstrates superior performance in comparison to other studies where a mixture of dyes or consortia of microorganisms were employed for dye decolourization.

Ligninolytic enzyme potential of Trametes spp. associated with leaf litter in riparian forest of the Amazônia region.

The present study explored the potential of leaf litter as a source of fungi able to produce ligninolytic enzymes for the biodegradation of anthraquinone dyes. Within the colonies isolated from the leaf litter, only three colonies of two species Trametes were selected based on the detection of oxidation and decolorization halos in Petri dishes with PDA (potato-dextrose-agar) + Guaicol and PDA + RBBR (Remazol Brilliant Blue R). The identification of the colonies was done through sequencing of the ITS region. The enzymatic activity of Lac (lacase), MnP (manganês peroxidase) and LiP (lignina peroxidase) was analyzed by spectrophotometry during fermentation in PD+RBBR imedium. Isolates A1SSI01 and A1SSI02 were identified as Trametes flavida, while A5SS01 was identified as Trametes sp. Laccase showed the highest enzymatic activity, reaching 452.13 IU.L-1 (A1SSI01, 0.05% RBBR) after 96h. Isolate A1SSI02 reached the highest percentage of decolorization, achieving 89.28% in seven days. The results imply that these Trametes isolates can be highly effective in waste treatment systems containing toxic anthraquinone dyes. Keywords: laccase, peroxidases, basidiomycete, litter and biodecolorization.

Decolorization and Degradation of azo dyes in textile wastewater effluent by Aspergillus Niger and Aspergillus ochraceous

In this study, fungi were isolated from contaminated soil collected from textile wool factories in Thi Qar Governorate. The results showed a high potential for removing Methylene Blue dye by Aspergillus niger and Aspergillus ochraceous. The removal process was conducted under optimized conditions, including different concentrations of the azo dye, pH levels, carbon sources, and nitrogen sources. The results indicated that the fungi Aspergillus niger and Aspergillus. Ochraceus were the most common isolates. Both fungi were treated with Methylene Blue dye in solid and liquid media, and both showed the ability to degrade this dye. However, Aspergillus niger demonstrated higher activity in color removal compared to Aspergillus ochraceous, with a diameter of (9) cm in solid medium for Aspergillus niger and (8) cm for Aspergillus. ochraceus. These results were confirmed by statistical analysis, which showed significant differences between these fungi and concentrations. The decolorization percentage was confirmed by Fourier Transform Infrared (FTIR) spectroscopy of which showed complete disappearance of peaks at 500 nm and at 1500 nm, indicates the degradation of dyes due to fungal activity, The technology also confirmed that a pH of 7 was the optimal pH for dye biodegradation compared to pH 4. This was observed through the dry weight of the fungi, with Aspergillus niger reaching to (2.35) and Aspergillus ochraceous reaching to (2.15) at pH 7. Also, in pH 4, the dry weight of Aspergillus niger and Aspergillus. ochraceus reached (2.17) and (2.05) respectively. Furthermore, the study confirmed the potential use of filamentous fungi in treating dye-contaminated water, regardless of their pH values.