Biochemical and molecular assessment of oxidative stress in fruit fly exposed to azo dye Brilliant Black PN.

BACKGROUND: Azo dyes are widely used in the food industry to prevent color loss during processing and storage of products. This study aimed to investigate the effect of a diazo dye Brilliant Black PN (E151) on oxidative stress-related parameters in fruit flies (Drosophila melanogaster) at biochemical and molecular levels. METHODS AND RESULTS: Third instar larvae were transferred to a medium containing the dye at different doses (1, 2.5, and 5 mg/mL). Gene expression and activity of superoxide dismutase, catalase (CAT), glutathione peroxidase (GPX), and acetylcholinesterase (AChE) enzymes were determined in the heads of adult flies obtained from these larvae. In addition, the glutathione (GSH) and malondialdehyde levels were measured using spectrophotometric analysis. Mitochondrial DNA (mtDNA) copy number was also detected by real-time PCR. The results showed that treatment with 5 mg/mL of the dye caused a decrease in both gene expression and enzyme activity of CAT and GPx. Moreover, the same dose of dye treatment decreased AChE activity, GSH level, and mtDNA copy number. CONCLUSIONS: As a result, Brilliant Black PN dye can trigger toxicity by altering the level and activity of oxidative stress-related biomarkers in a dose-dependent manner. Therefore, more comprehensive studies are needed to elucidate the side effect mechanism and toxicity of this dye.

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.

Understanding the biodegradation pathways of azo dyes by immobilized white-rot fungus, Trametes hirsuta D7, using UPLC-PDA-FTICR MS supported by in silico simulations and toxicity assessment.

No biodegradation methods are absolute in the treatment of all textile dyes, which leads to structure-dependent degradation. In this study, biodegradation of three azo dyes, reactive black 5 (RB5), acid blue 113 (AB113), and acid orange 7 (AO7), was investigated using an immobilized fungus, Trametes hirsuta D7. The degraded metabolites were identified using UPLC-PDA-FTICR MS and the biodegradation pathway followed was proposed. RB5 (92%) and AB113 (97%) were effectively degraded, whereas only 30% of AO7 was degraded. Molecular docking simulations were performed to determine the reason behind the poor degradation of AO7. Weak binding affinity, deficiency in H-bonding interactions, and the absence of interactions between the azo (-NN-) group and active residues of the model laccase enzyme were responsible for the low degradation efficiency of AO7. Furthermore, cytotoxicity and genotoxicity assays confirmed that the fungus-treated dye produced non-toxic metabolites. The observations of this study will be useful for understanding and further improving enzymatic dye biodegradation.

Assessment of hepatotoxicity and nephrotoxicity in Cirrhinus mrigala induced by trypan blue - An azo dye.

Cytotoxicity in freshwater fishes induced by industrial effluents and dyes is a global issue. Trypan blue dye has many applications in different sectors, including laboratories and industries. This study determines to detect the cytotoxic effects of trypan blue dye in vivo. The objective of this study was to estimate the sub-lethal effects of azodye in fish. Cirrhinus mrigala, a freshwater fish, was exposed to three different grading concentrations of dye 5 mg/L, 10 mg/L, and 20 mg/L in a glass aquarium. Significant (p < 0.05) decrease in the weight of fish was observed as 0.728 ± 0.14 g and 2.232 ± 0.24 g, respectively, in the trial groups exposed to 10 and 20 mg/L of dye in a week. After exposure to trypan blue dye, fishes were dissected to remove liver and kidney tissues. Histopathological assessments determined hepatotoxicity and nephrotoxicity induced by trypan blue through the paraffin wax method. This dye induces mild alterations in the liver such as congestion, hemolysis, dilated sinusoids, ruptured hepatocytes, vacuolization, edema of hepatocytes, necrosis, degeneration, aggregation, and inflammation. This dye not only alters liver tissue, also induces an acute level of tissue alterations in the kidneys, such as degeneration of epithelial cells of renal tubules, shrinkage of the glomerulus, congestion, reduced lumen, degeneration of glomerulus, absence of space of bowmen, glomerulonephritis, necrosis in hematopoietic interstitial tissues and glomerulus, reduced lumen, vacuolar degeneration of renal tubules, increased per tubular space. The current study concludes that trypan blue dye released even in small amounts is found to be associated with a high incidence of cytotoxicity. Such tissue alterations in this species could be used as biomarkers for azo dyes.

In-vitro toxicity assessment of a textile dye Eriochrome Black T and its nano-photocatalytic degradation through an innovative approach using Mf-NGr-CNTs-SnO2 heterostructures.

The present study aimed to assess the in-vitro toxicity of a popular azodye, Eriochrome Black T (EBT) which may be an environmental hazard causing water pollution if released by textile industries as waste effluents to nearby water ponds. We explored the toxic potential of EBT at 200, 400 and 800 µg/ml concentrations, which were selected based on quantification of EBT present in the pond water near carpet industries. We investigated the permeability of EBT across the organ barriers and found it to be 6.48 ± 0.44% at the highest concentration. EBT also showed up to 26.46 ± 0.533% hemolytic potential on human RBCs. MTT assay revealed toxicity of up to 64.9 ± 10.12%. A dose-dependent increase in intracellular ROS levels and Caspase 3/7 activity was observed and confocal microscopy also demonstrated a similar trend of cellular apoptosis indicating ROS mediated induction of apoptosis as a mechanism of EBT induced cytotoxicity. After establishing the toxicity of EBT, an innovative nano-photocatalytic approach for dye remediation was applied by using as synthesized Mf-NGr-CNTs-SnO2 heterostructures. This catalyst showed dye degradation potential of up to 82% in 2 h in the presence of sun light. The degraded dye products were tested to have up to 30% reduced cellular toxicity as compared to the parent compound. This work successfully establishes the toxicity of EBT along with devising an innovative approach towards dye degradation where the catalyst is adhered on melamine foam and not being mixed in the effluents directly, thereby, reducing the possibility of catalyst being leached out into the river water.

Synthetic azo dye bio-decolorization by Priestia sp. RA1: process optimization and phytotoxicity assessment.

Azo compounds represent the most diverse group of colorants widely employed in industrial sectors. Being highly toxic and recalcitrant compound, azo dyes pose a threat to plants, animals, and humans. In the present report, bio-decolorization of azo dye, reactive black 5, was evaluated by newly isolated Priestia sp. RA1. Strain RA1 was able to decolorize 97% of 100 ppm reactive black 5 in 60 h. Specific activity of dye decolorization was found to be 0.233 µmol min-1 g-1 dry cells. Successful decolorization over a broad range of pH, salinity, temperature, and initial dye concentration was observed. Phytotoxicity assay on agriculturally important crops showed considerable difference in percentage seed germination and growth when treated with original and bio-decolorized dye samples. Bio-decolorization at high dye concentrations, promising decolorization rate, and non-toxic nature of treated products suggest the potential of strain RA1 for bioremediation of dye-contaminated water and its re-use in the industries.

Biodecolourisation of Reactive Red 120 as a Sole Carbon Source by a Bacterial Consortium-Toxicity Assessment and Statistical Optimisation.

The application of microorganisms in azo dye remediation has gained significant attention, leading to various published studies reporting different methods for obtaining the best dye decolouriser. This paper investigates and compares the role of methods and media used in obtaining a bacterial consortium capable of decolourising azo dye as the sole carbon source, which is extremely rare to find. It was demonstrated that a prolonged acclimation under low substrate availability successfully isolated a novel consortium capable of utilising Reactive Red 120 dye as a sole carbon source in aerobic conditions. This consortium, known as JR3, consists of Pseudomonas aeruginosa strain MM01, Enterobacter sp. strain MM05 and Serratia marcescens strain MM06. Decolourised metabolites of consortium JR3 showed an improvement in mung bean's seed germination and shoot and root length. One-factor-at-time optimisation characterisation showed maximal of 82.9% decolourisation at 0.7 g/L ammonium sulphate, pH 8, 35 °C, and RR120 concentrations of 200 ppm. Decolourisation modelling utilising response surface methodology (RSM) successfully improved decolourisation even more. RSM resulted in maximal decolourisation of 92.79% using 0.645 g/L ammonium sulphate, pH 8.29, 34.5 °C and 200 ppm RR120.

Toxicity Assessment of 4 Azo Dyes in Zebrafish Embryos.

Azo dyes are used widely as color additives in food, drugs, and cosmetics; hence, there is an increasing concern about their safety and possible health hazards. In the present study, we chose 4 azo dyes tartrazine, Sunset Yellow, amaranth, and Allura red and evaluated their developmental toxicity on zebrafish embryos. At concentration levels of 5 to 50 mM, we found that azo dyes can induce hatching difficulty and developmental abnormalities such as cardiac edema, decreased heart rate, yolk sac edema, and spinal defects including spinal curvature and tail distortion. Exposure to 100 mM of each azo dye was completely embryolethal. The median lethal concentration (LC50), median effective concentration (EC50), and teratogenic index (TI) were calculated for each azo dye at 72 hours postfertilization. For tartrazine, the LC50 was 47.10 mM and EC50 value was at 42.66 mM with TI ratio of 1.10. For Sunset Yellow, the LC50 was 38.93 mM and EC50 value was at 29.81 mM with TI ratio of 1.31. For amaranth, the LC50 was 39.86 mM and EC50 value was at 31.94 mM with TI ratio of 1.25. For Allura red, the LC50 was 47.42 mM and EC50 value was 40.05 mM with TI ratio of 1.18. This study reports the developmental toxicity of azo dyes in zebrafish embryos at concentrations higher than the expected human exposures from consuming food and drugs containing azo dyes.

In vivo genotoxicity assessment of sunset yellow and sodium benzoate in female rats.

The use of additives in different food products is growing up. It has attracted the attention towards the relation between the mutagenic potential of human diseases and food additives. Sunset yellow (SY) and sodium benzoate (NaB) are used as colorant and food additives worldwide. In the present study, genotoxic effects of different combinations of SY and NaB were assessed in vivo in female rats. Different combinations of SY and NaB were dissolved in water and administered daily to six animals groups for 12 weeks. Group 1 (control) received water, Group 2 received 5 mg/kg body weight (bw) SY plus 10 mg/kg bw NaB, group 3 received 5 mg/kg SY plus 100 mg/kg NaB, group 4 received 50 mg SY plus 100 mg/kg NaB, group 5 received 50 mg/kg SY plus 10 mg/kg NaB, group 6 received 200 mg/kg SY plus 750 mg/kg NaB, and group 7 received 20 mg/kg SY plus 75 mg/kg NaB. Genotoxicity investigations (Chromosomal aberration of bone marrow cells, Comet assay and DNA profile of liver cells) were carried out at the end of the experiment. Administration of 200 mg/kg SY plus 750 mg/kg NaB (group 6) induced the highest abnormalities percentage (1.5%) and showed structural abnormalities including end-to-end association, fragmentation, chromatid break, ring chromosome, and centric fusion break of chromosomes. Different combinations of SY and NaB induced an increase in the frequency of tailed nuclei (DNA damage) in liver cells. A concentration-dependent distinct DNA smear pattern was observed in the DNA isolated from liver cells of animals administered SY and NaB. In addition, administration of SY plus NaB resulted in an abnormal distribution of serum proteins. The results showed that the SY plus NaB could have genotoxic potential. With the increase applications of food additives, this study reported important data about screening the potential impacts.

Assessment of FD&C Yellow No. 6 (Sunset Yellow FCF) effects on sperm count, motility and viability in the rat in a 28-day toxicity study.

Sunset Yellow FCF was tested for 28-days in male Hsd:SD® rats for its potential effect on sperm quality parameters at dietary concentrations of 6,000, 12,000 and 18,000 ppm, corresponding to target doses of 500, 1000, and 1500 mg/kg bw/day. The measured average daily intake was 490, 944, and 1,475 mg/kg bw/day, based on feed consumption and stability of Sunset Yellow FCF in the diet. The animals fed diets with Sunset Yellow FCF presented no clinical signs of toxicity and no differences in feed consumption, body weights, organ weights, ophthalmology, hematology, clinical chemistry, urinalysis, or coagulation parameters that were considered adverse. No mortality or abnormalities were observed at necropsy, and no microscopic changes were observed in histopathology. Increased testes weights relative to body weight in animals of the middle and high intake groups were not associated with any abnormal findings in histopathology. Sperm quality evaluation presented no adverse effects on sperm motility, epididymal sperm count, homogenization-resistant spermatid count, or sperm morphological development. Therefore, in the absence of any adverse effects under the conditions of this study, the NOAEL for Sunset Yellow FCF was 1,475 mg/kg bw/day in male rats, corresponding to 18,000 ppm in the diet.

Influence of auxochrome group in disperse dyes bearing azo groups as chromophore center in the biotransformation and molecular docking prediction by reductase enzyme: Implications and assessment for environmental toxicity of xenobiotics.

Synthetic azo dyes have increasingly become a matter of great concern as a result of the genotoxic and mutagenic potential of the products derived from azo dye biotransformation. This work evaluates the manner in which reducing enzymes produced by Escherichia coli (E. coli) act on three disperse dyes bearing azo groups, namely Disperse Red 73 (DR 73), Disperse Red 78 (DR 78), and Disperse Red 167 (DR 167). UV-Vis spectrophotometry, high-performance liquid chromatography with diode array detector (HPLC-DAD), and liquid chromatography mass spectrometry (LC-MS/MS) were applied towards the identification of the main products. Seven days of incubation of the azo dyes with the tested enzymes yielded a completely bleached solution. 3-4-Aminophenyl-ethyl-amino-propanitrile was detected following the biotransformation of both DR 73 and DR 78. 4-Nitroaniline and 2-chloro-4-nitroaniline were detected upon the biotransformation of DR 73 and DR 78, respectively. The main products derived from the biotransformation of DR 167 were dimethyl 3,3'-3-acetamido-4-aminophenyl-azanedyl-dipropanoate and 2-chloro-4-nitroaniline. The results imply that DR 73 lost the CN- substituent during the biotransformation. Furthermore, theoretical calculations were also carried out aiming at evaluating the interaction and reactivity of these compounds with DNA. Taken together, the results indicate that DR 73, DR 78, and DR 167 pose health risks and serious threats to both human beings and the environment at large as their biotransformation produces harmful compounds such as amines, which have been widely condemned by the International Agency for Research on Cancer.

Functional cardiotoxicity assessment of cosmetic compounds using human-induced pluripotent stem cell-derived cardiomyocytes.

There is a large demand of a human relevant in vitro test system suitable for assessing the cardiotoxic potential of cosmetic ingredients and other chemicals. Using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), we have already established an in vitro cardiotoxicity assay and identified genomic biomarkers of anthracycline-induced cardiotoxicity in our previous work. Here, five cosmetic ingredients were studied by the new hiPSC-CMs test; kojic acid (KJA), triclosan (TS), triclocarban (TCC), 2,7-naphthalenediol (NPT), and basic red 51 (BR51) based on cytotoxicity as well as ATP assays, beating rate, and genomic biomarkers to determine the lowest observed effect concentration (LOEC) and no observed effect concentration (NOEC). The LOEC for beating rate were 400, 10, 3, >400, and 3 µM for KJA, TS, TCC, NPT, and BR51, respectively. The corresponding concentrations for cytotoxicity or ATP depletion were similar, with the exception of TS and TCC, where the cardiomyocyte-beating assay showed positive results at non-cytotoxic concentrations. Functional analysis also showed that the individual compounds caused different effects on hiPSC-CMs. While exposure to KJA, TS, TCC, and BR51 induced significant arrhythmic beating, NPT slightly decreased cell viability, but did not influence beating. Gene expression studies showed that TS and NPT caused down-regulation of cytoskeletal and cardiac ion homeostasis genes. Moreover, TS and NPT deregulated genomic biomarkers known to be affected also by anthracyclines. The present study demonstrates that hiPSC-CMs can be used to determine LOECs and NOECs in vitro, which can be compared to human blood concentrations to determine margins of exposure. Our in vitro assay, which so far has been tested with several anthracyclines and cosmetics, still requires validation by larger numbers of positive and negative controls, before it can be recommended for routine analysis.

A new approach for risk assessment of aggregate dermal exposure to banned azo dyes in textiles.

A semi-quantitative risk assessment of banned azo dyes in textiles was performed to assess the health risk when consumers have direct dermal contact with these products. A novel model, which includes three exposure scenarios, was proposed to estimate the absorption of leachable azo dyes from twenty textiles samples. The effective daily uptakes of benzidine from sample 1 and sample 19 in chronic exposure model were 0.318 ng/kg-day and 0.011 ng/kg-day, respectively. Compared to virtually safe dose (VSD), the corresponding cancer risks were 7.42 × 10-5 (Sample 1) and 2.56 × 10-6 (Sample 19). As noted by nomograph assessment, the health risk induced by long-term exposure of banned azo dyes from textiles was at the range of "very low" to "low". In short-term exposure cases, the risks were acceptable though the amount of detected aromatic amines was relatively high in particular samples. The amount of exposure and the risk level might be overestimated as a series of assumptions were made under extreme conditions.

Degradation of Direct Red 81 mediated by Fenton reactions: multivariate optimization, effect of chloride and sulfate, and acute ecotoxicity assessment.

The role of different operational parameters related to Fenton reactions (pH, concentration of Fe2+ and H2O2, and reaction time) and of Cl- and SO 4- was investigated in the degradation of the azo dye Direct Red 81, expressed in terms of its decolorization. The factorial design and Pareto's charts showed that only Fe2+ concentration and pH influence the decolorization under the conditions evaluated. So, only these parameters were optimized using the response surface model. Under the best experimental conditions (initial pH 2.5, 11 mg L-1 Fe2+, 78 mg L-1 H2O2, and 20 min of reaction), 94 % of decolorization was achieved. However, even under the these conditions, but in the presence of Cl- and SO 4- , a striking loss of efficiency was observed as the concentration of these ions was increased, due the formation of chloride- and sulfate-iron complexes and less reactive inorganic radicals (Cl2•- and SO4•-). The results show that the presence of Cl- is more deleterious, since sulfate-iron complexes are more reactive towards H2O2, and the SO4•- turns out to favor the degradation. On the other hand, the  negative effect of Cl- can be compensated by increasing the chloride concentration up to 300 mmol L-1. In addition, although a high degradation level has been obtained by monitoring the dye absorbance and by HPLC-UV, a low mineralization occurred, being generated degradation products of higher ecotoxicity to Vibrio fischeri, showing the need of subsequent studies to identify these compounds as well as the application of additional treatments aiming the complete mineralization of the dye.

Ecotoxicological risk assessment of the "Acid Black 210" dye.

The "Acid Black 210" dye is one of the most used black dyes by the leather industry. This compound contains three azo groups in its chemical structure, and has been quoted as a non-regulated dye with toxicological concern, since it could generate carcinogenic aromatic amines. The objective of this study was to perform the ecotoxicological risk assessment of this dye through testing its toxicity in vitro and in vivo with the Ames test, the Comet assay, the Daphnia similis test, and the zebrafish embryo acute toxicity test. Moreover, we evaluated the presence of this dye in environmental samples related with a tannery industry. All the tests performed were negative, with the exception of the Ames test with the Salmonella typhimurium TA98 strain, which resulted in a low mutagenic potency. Due to the low concentrations of the "Acid Black 210" dye found in tannery effluents, and the high concentrations where any toxic activity is occasionally described, we concluded that this dye is safe from the ecotoxicological point of view in the areas evaluated and in the light of the current knowledge.

Assessment of the cytotoxic, genotoxic and mutagenic effects of the commercial black dye in Allium cepa cells before and after bacterial biodegradation treatment.

The present study evaluated the cytotoxic, genotoxic and mutagenic actions of different concentrations (50 and 200 µg/L) of BDCP (Black Dye Commercial Product) used by textile industries, before and after bacterial biodegradation, by the conventional staining cytogenetic technique and NOR-banding in Allium cepa cells. Differences in the chromosomal and nuclear aberrations and alterations in the number of nucleoli were observed in cells exposed to BDCP with and without the microbial treatment. The significant frequencies of chromosome and nuclear aberrations noted in the tests with bacterially biodegraded BDCP indicate that the metabolites generated by degradation are more genotoxic than the chemical itself. Losses of genetic material characterize a type of alteration that was mainly associated with the action of the original BDCP, whereas chromosome stickiness, nuclear buds and binucleated cells were the aberrations that were preferentially induced by BDCP metabolites after biodegradation. The significant frequencies of cell death observed in the tests with biodegraded BDCP also show the cytotoxic effects of the BDCP metabolites. The reduction in the total frequency of altered cells after the recovery treatments showed that the test organism A. cepa has the ability to recover from damage induced by BDCP and its metabolites after the exposure conditions are normalized.

An integrated (electro- and bio-oxidation) approach for remediation of industrial wastewater containing azo-dyes: Understanding the degradation mechanism and toxicity assessment.

A hybrid approach for the remediation of recalcitrant dye wastewater is proposed. The chlorine-mediated electrochemical oxidation of real textile effluents and synthetic samples (using Ti/IrO2-RuO2-TiO2 anodes), lead to discoloration by 92% and 89%, respectively, in 100min, without significant mineralization. The remediation was obtained through biodegradation, after removing the residual bio-toxic active chlorine species via sunlight exposition. Results show that the electrochemical discoloration enhances the effluent biodegradability with about 90% COD removal employing acclimatized naphthalene-degrading bacterial consortia, within 144h. Based on results obtained through FT-IR and GC-MS, it is likely that azo group stripping and oxidative cleavage of dyes occur due to the nucleophilic attack of active chlorine species during electro-oxidation. This leads to generation of aromatic intermediates which are further desulfonated, deaminated or oxidized only at their functional groups. These aromatic intermediates were mineralized into simpler organic acids and aldehydes by bacterial consortia. Phyto-toxicity trials on Vigna radiata confirmed the toxic nature of the untreated dye solutions. An increase in root and shoot development was observed with the electrochemically treated solutions, the same was higher in case of bio-treated solutions. Overall, obtained results confirm the capability of the proposed hybrid oxidation scheme for the remediation of textile wastewater.

Occurrence and risk assessment of an azo dye - The case of Disperse Red 1.

Water quality criteria to protect aquatic life are not available for most disperse dyes which are often used as commercial mixtures in textile coloration. In this study, the acute and chronic toxicity of the commercial dye Disperse Red 1 (DR1) to eight aquatic organisms from four trophic levels was evaluated. A safety threshold, i.e. Predicted No-Effect Concentration (PNEC), was derived based on the toxicity information of the commercial product and the purified dye. This approach was possible because the toxicity of DR1 was accounting for most of the toxicity of the commercial mixture. A long-term PNEC of 60 ng L(-1) was proposed, based on the most sensitive chronic endpoint for Daphnia similis. A short-term PNEC of 1800 ng L(-1) was proposed based on the most sensitive acute endpoint also for Daphnia similis. Both key studies have been evaluated with the new "Criteria for Reporting and Evaluating ecotoxicity Data" (CRED) methodology, applying more objective criteria to assess the quality of toxicity tests, resulting in two reliable and relevant endpoints with only minor restrictions. HPLC-MS/MS was used to quantify the occurrence of DR1 in river waters of three sites, influenced by textile industry discharges, resulting in a concentration range of 50-500 ng L(-1). The risk quotients for DR1 obtained in this work suggest that this dye can pose a potential risk to freshwater biota. To reduce uncertainty of the derived PNEC, a fish partial or full lifecycle study should be performed.

Remediation of textile azo dye acid red 114 by hairy roots of Ipomoea carnea Jacq. and assessment of degraded dye toxicity with human keratinocyte cell line.

Bioremediation has proven to be the most desirable and cost effective method to counter textile dye pollution. Hairy roots (HRs) of Ipomoea carnea J. were tested for decolourization of 25 textile azo dyes, out of which >90% decolourization was observed in 15 dyes. A diazo dye, Acid Red 114 was decolourized to >98% and hence, was chosen as the model dye. A significant increase in the activities of oxidoreductive enzymes was observed during decolourization of AR114. The phytodegradation of AR114 was confirmed by HPLC, UV-vis and FTIR spectroscopy. The possible metabolites were identified by GCMS as 4- aminobenzene sulfonic acid 2-methylaniline and 4- aminophenyl 4-ethyl benzene sulfonate and a probable pathway for the biodegradation of AR114 has been proposed. The nontoxic nature of the metabolites and toxicity of AR114 was confirmed by cytotoxicity tests on human keratinocyte cell line (HaCaT). When HaCaT cells were treated separately with 150 µg mL(-1) of AR114 and metabolites, MTT assay showed 50% and ≈100% viability respectively. Furthermore, flow cytometry data showed that, as compared to control, the cells in G2-M and death phase increased by 2.4 and 3.6 folds respectively on treatment with AR114 but remained unaltered in cells treated with metabolites.

Environmental assessment of the degradation potential of mushroom fruit bodies of Pleurotus ostreatus (Jacq.: Fr.) P. Kumm. towards synthetic azo dyes and contaminating effluents collected from textile industries in Karnataka, India.

Pleurotus ostreatus (Jacq.: Fr.) P. Kumm. is one of the edible mushrooms currently gaining attention as environmental restorer. The present study explores the potential of P. ostreatus (Jacq.: Fr.) P. Kumm. in degradation of textile dyes and effluents. The mushroom cultivation was carried out using paddy bed as substrate. The fully grown mushroom fruit bodies were used as a bioremediation agent against two industrially important azo dyes such as nylon blue and cotton yellow and few effluents collected from various textile industries in Karnataka, India. The ideal growth parameters such as temperature, pH, and dye concentrations for effective degradation were carried out. One of the main enzymes, laccase, responsible for biodegradation, was partially characterized. The degradation was found to be ideal at pH 3.0 and temperature at 26-28 °C. This study demonstrated a percentage degradation of 78.10, 90.81, 82.5, and 64.88 for dye samples such as nylon blue (50 ppm), cotton yellow (350 ppm), KSIC effluents, and Ramanagar effluents at 28 °C within 15th days respectively in comparison with other temperature conditions. Similarly, a percentage degradation of 35.99, 33.33, 76.13 and 25.8 for nylon blue (50 ppm), cotton yellow (350 ppm), Karnataka Silk Industries Corporation (KSIC) effluents and Ramnagar effluents were observed at pH 3.0 within 15 days, respectively (p < 0.05). Thus, the current study concluded that the utilization of P. ostreatus (Jacq.: Fr.) P. Kumm. at ideal environmental conditions is a cost-effective and eco-friendly approach for the degradation of various azo dyes and textile effluents which are harmful to the ecosystem.