Exploring the decolorization efficiency and biodegradation mechanisms of different functional textile azo dyes by Streptomyces albidoflavus 3MGH.

Efficiently mitigating and managing environmental pollution caused by the improper disposal of dyes and effluents from the textile industry is of great importance. This study evaluated the effectiveness of Streptomyces albidoflavus 3MGH in decolorizing and degrading three different azo dyes, namely Reactive Orange 122 (RO 122), Direct Blue 15 (DB 15), and Direct Black 38 (DB 38). Various analytical techniques, such as Fourier Transform Infrared (FTIR) spectroscopy, High-Performance Liquid Chromatography (HPLC), and Gas Chromatography-Mass Spectrometry (GC-MS) were used to analyze the degraded byproducts of the dyes. S. albidoflavus 3MGH demonstrated a strong capability to decolorize RO 122, DB 15, and DB 38, achieving up to 60.74%, 61.38%, and 53.43% decolorization within 5 days at a concentration of 0.3 g/L, respectively. The optimal conditions for the maximum decolorization of these azo dyes were found to be a temperature of 35 °C, a pH of 6, sucrose as a carbon source, and beef extract as a nitrogen source. Additionally, after optimization of the decolorization process, treatment with S. albidoflavus 3MGH resulted in significant reductions of 94.4%, 86.3%, and 68.2% in the total organic carbon of RO 122, DB 15, and DB 38, respectively. After the treatment process, we found the specific activity of the laccase enzyme, one of the mediating enzymes of the degradation mechanism, to be 5.96 U/mg. FT-IR spectroscopy analysis of the degraded metabolites showed specific changes and shifts in peaks compared to the control samples. GC-MS analysis revealed the presence of metabolites such as benzene, biphenyl, and naphthalene derivatives. Overall, this study demonstrated the potential of S. albidoflavus 3MGH for the effective decolorization and degradation of different azo dyes. The findings were validated through various analytical techniques, shedding light on the biodegradation mechanism employed by this strain.

Sequence similarity network analysis of drug- and dye-modifying azoreductase enzymes found in the human gut microbiome.

Drug metabolism by human gut microbes is often exemplified by azo bond reduction in the anticolitic prodrug sulfasalazine. Azoreductase activity is often found in incubations with cell cultures or ex vivo gut microbiome samples and contributes to the xenobiotic metabolism of drugs and food additives. Applying metagenomic studies to personalized medicine requires knowledge of the genes responsible for sulfasalazine and other drug metabolism, and candidate genes and proteins for drug modifications are understudied. A representative gut-abundant azoreductase from Anaerotignum lactatifermentan DSM 14214 efficiently reduces sulfasalazine and another drug, phenazopyridine, but could not reduce all azo-bonded drugs in this class. We used enzyme kinetics to characterize this enzyme for its NADH-dependent reduction of these drugs and food additives and performed computational docking to provide the groundwork for understanding substrate specificity in this family. We performed an analysis of the Flavodoxin-like fold InterPro family (IPR003680) by computing a sequence similarity network to classify distinct subgroups of the family and then performed chemically-guided functional profiling to identify proteins that are abundant in the NIH Human Microbiome Project dataset. This strategy aims to reduce the number of unique azoreductases needed to characterize one protein family in the diverse set of potential drug- and dye-modifying activities found in the human gut microbiome.

Biodecolorization and biodegradation of Reactive Green 12 textile industry dye and their post-degradation phytotoxicity-genotoxicity assessments.

The employment of versatile bacterial strains for the efficient degradation of carcinogenic textile dyes is a sustainable technology of bioremediation for a neat, clean, and evergreen globe. The present study has explored the eco-friendly degradation of complex Reactive Green 12 azo dye to its non-toxic metabolites for safe disposal in an open environment. The bacterial degradation was performed with the variable concentrations (50, 100, 200, 400, and 500 mg/L) of Reactive Green 12 dye. The degradation and toxicity of the dye were validated by high-performance liquid chromatography, Fourier infrared spectroscopy analysis, and phytotoxicity and genotoxicity assay, respectively. The highest 97.8% decolorization was achieved within 12 h. Alternations in the peaks and retentions, thus, along with modifications in the functional groups and chemical bonds, confirmed the degradation of Reactive Green 12. The disappearance of a major peak at 1450 cm-1 corresponding to the -N=N- azo link validated the breaking of azo bonds and degradation of the parent dye. The 100% germination of Triticum aestivum seed and healthy growth of plants verified the lost toxicity of degraded dye. Moreover, the chromosomal aberration of Allium cepa root cell treatment also validated the removal of toxicity through bacterial degradation. Thereafter, for efficient degradation of textile dye, the bacterium is recommended for adaptation to the sustainable degradation of dye and wastewater for further application of degraded metabolites in crop irrigation for sustainable agriculture.

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 from 31×107CFUs to 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.

Kinetic studies on optimized extracellular laccase from Trichoderma harzianum PP389612 and its capabilities for azo dye removal.

BACKGROUND: Azo dyes represent a common textile dye preferred for its high stability on fabrics in various harsh conditions. Although these dyes pose high-risk levels for all biological forms, fungal laccase is known as a green catalyst for its ability to oxidize numerous dyes. METHODS: Trichoderma isolates were identified and tested for laccase production. Laccase production was optimized using Plackett-Burman Design. Laccase molecular weight and the kinetic properties of the enzyme, including Km and Vmax, pH, temperature, and ionic strength, were detected. Azo dye removal efficiency by laccase enzyme was detected for Congo red, methylene blue, and methyl orange. RESULTS: Eight out of nine Trichoderma isolates were laccase producers. Laccase production efficiency was optimized by the superior strain T. harzianum PP389612, increasing production from 1.6 to 2.89 U/ml. In SDS-PAGE, purified laccases appear as a single protein band with a molecular weight of 41.00 kDa. Km and Vmax values were 146.12 µmol guaiacol and 3.82 µmol guaiacol/min. Its activity was stable in the pH range of 5-7, with an optimum temperature range of 40 to 50 °C, optimum ionic strength of 50 mM NaCl, and thermostability properties up to 90 °C. The decolorization efficiency of laccase was increased by increasing the time and reached its maximum after 72 h. The highest efficiency was achieved in Congo red decolorization, which reached 99% after 72 h, followed by methylene blue at 72%, while methyl orange decolorization efficiency was 68.5%. CONCLUSION: Trichoderma laccase can be used as an effective natural bio-agent for dye removal because it is stable and removes colors very well.

Two protocols for the detection of oleaginous bacteria using Oil Red O.

The selection of oleaginous bacteria, potentially applicable to biotechnological approaches, is usually carried out by different expensive and time-consuming techniques. In this study, we used Oil Red O (ORO) as an useful dye for staining of neutral lipids (triacylglycerols and wax esters) on thin-layer chromatography plates. ORO could detect minimal quantities of both compounds (detection limit, 0.0025 mg of tripalmitin or 0.005 mg of cetylpalmitate). In addition, we developed a specific, rapid, and inexpensive screening methodology to detect triacylglycerol-accumulating microorganisms grown on the agar plate. This staining methodology detected 9/13 strains with a triacylglycerol content higher than 20% by cellular dry weight. ORO did not stain polyhydroxyalkanoates-producing bacteria. The four oleaginous strains not detected by this screening methodology exhibited a mucoid morphology of their colonies. Apparently, an extracellular polymeric substance produced by these strains hampered the entry of the lipophilic dye into cells. The utilization of the developed screening methodology would allow selecting of oleaginous bacteria in a simpler and faster way than techniques usually used nowadays, based on unspecific staining protocols and spectrophotometric or chromatographic methods. Furthermore, the use of ORO as a staining reagent would easily characterize the neutral lipids accumulated by microorganisms as reserve compounds. KEY POINTS: • Oil Red O staining is specific for triacylglycerols • Oil Red O staining is useful to detect oleaginous bacteria • Fast and inexpensive staining to isolate oleaginous bacteria from the environment.

Biodegradation of commercial textile reactive dye mixtures by industrial effluent adapted bacterial consortium VITPBC6: a potential technique for treating textile effluents.

Textile industries release major fraction of dyestuffs in effluents leading to a major environmental concern. These effluents often contain more than one dyestuff, which complicates dye degradation. In this study ten reactive dyes (Reactive Yellow 145, Reactive Yellow 160, Reactive Orange 16, Reactive Orange 107, Reactive Red 195, Reactive Blue 21, Reactive Blue 198, Reactive Blue 221, Reactive Blue 250, and Reactive Black 5) that are used in textile industries were subjected to biodegradation by a bacterial consortium VITPBC6, formulated in our previous study. Consortium VITPBC6 caused single dye degradation of all the mentioned dyes except for Reactive Yellow 160. Further, VITPBC6 efficiently degraded a five-dye mixture (Reactive Red 195, Reactive Orange 16, Reactive Black 5, Reactive Blue 221, and Reactive Blue 250). Kinetic studies revealed that the five-dye mixture was decolorized by VITPBC6 following zero order reaction kinetic; Vmax and Km values of the enzyme catalyzed five-dye decolorization were 128.88 mg L-1 day-1 and 1003.226 mg L-1 respectively. VITPBC6 degraded the dye mixture into delta-3,4,5,6-Tetrachlorocyclohexene, sulfuric acid, 1,2-dichloroethane, and hydroxyphenoxyethylaminohydroxypropanol. Phytotoxicity, cytogenotoxicity, microtoxicity, and biotoxicity assays conducted with the biodegraded metabolites revealed that VITPBC6 lowered the toxicity of five-dye mixture significantly after biodegradation.

Efficient degradation and detoxification of structurally different dyes and mixed dyes by LAC-4 laccase purified from white-rot fungi Ganoderma lucidum.

The purpose of this study is to evaluate the decolorization ability and detoxification effect of LAC-4 laccase on various types of single and mixed dyes, and lay a good foundation for better application of laccase in the efficient treatment of dye pollutants. The reaction system of the LAC-4 decolorizing single dyes (azo, anthraquinone, triphenylmethane, and indigo dyes, 17 dyes in total) were established. To explore the decolorization effect of the dye mixture by LAC-4, two dyes of the same type or different types were mixed at the same concentration (100 mg/L) in the reaction system containing 0.5 U laccase, and time-course decolorization were performed on the dye mixture. The combined dye mixtures consisted of azo + azo, azo + anthraquinone, azo + indigo, azo + triphenylmethane, indigo + triphenylmethane, and triphenylmethane + triphenylmethane. The results obtained in this study were as follows. Under optimal conditions of 30 °C and pH 5.0, LAC-4 (0.5 U) can efficiently decolorize four different types of dyes. The 24-hour decolorization efficiencies of LAC-4 for 800 mg/L Orange G and Acid Orange 7 (azo), Remazol Brilliant Blue R (anthraquinone), Bromophenol Blue and Methyl Green (triphenylmethane), and Indigo Carmine (indigo) were 75.94%, 93.30%, 96.56%, 99.94%, 96.37%, and 37.23%, respectively. LAC-4 could also efficiently decolorize mixed dyes with different structures. LAC-4 can achieve a decolorization efficiency of over 80% for various dye mixtures such as Orange G + Indigo Carmine (100 mg/L+100 mg/L), Reactive Orange 16 + Methyl Green (100 mg/L+100 mg/L), and Remazol Brilliant Blue R + Methyl Green (100 mg/L+100 mg/L). During the decolorization process of the mixed dyes by laccase, four different interaction relationships were observed between the dyes. Decolorization efficiencies and rates of the dyes that were difficult to be degraded by laccase could be greatly improved when mixed with other dyes. Degradable dyes could greatly enhance the ability of LAC-4 to decolorize extremely difficult-to-degrade dyes. It was also found that the decolorization efficiencies of the two dyes significantly increased after mixing. The possible mechanisms underlying the different interaction relationships were further discussed. Free, but not immobilized, LAC-4 showed a strong continuous batch decolorization ability for single dyes, two-dye mixtures, and four-dye mixtures with different structures. LAC-4 exhibited high stability, sustainable degradability, and good reusability in the continuous batch decolorization. The LAC-4-catalyzed decolorization markedly reduced or fully abolished the toxic effects of single dyes (azo, anthraquinone, and indigo dye) and mix dyes (nine dye mixtures containing four structural types of dyes) on plants. Our findings indicated that LAC-4 laccase had significant potential for use in bioremediation due to its efficient degradation and detoxification of single and mixed dyes with different structural types.

Nrf2 through Aryl Hydrocarbon Receptor Regulates IL-22 Response in CD4+ T Cells.

IL-17A and IL-22 derived from Th17 cells play a significant role in mucosal immunity and inflammation. TGF-ß and IL-6 promote Th17 differentiation; however, these cytokines have multiple targets. The identification and screening of additional molecules that regulate IL-17A and IL-22 responses in certain inflammatory conditions is of great clinical significance. In this study, we show that CDDO-Im, a specific Nrf2 activator, promotes IL-17A and IL-22 responses in murine Th17 cells. In contrast, CDDO-Im inhibits IL-17A response in multiple sclerosis patient-derived PBMCs. However, Nrf2 specifically regulates IL-22 response in vivo. Nrf2 acts through the regulation of antioxidant response element (ARE) binding motifs in target genes to induce or repress transcription. Promoter analysis revealed that Il17a, Rorc, and Ahr genes have several ARE motifs. We showed that Nrf2 bound to ARE repressor (ARE-R2) of Rorc and inhibited Rorc-dependent IL-17A transactivation. The luciferase reporter assay data showed that CDDO-Im regulated Ahr promoter activity. Chromatin immunoprecipitation quantitative PCR data showed that Nrf2 bound to ARE of AhR. Finally, we confirmed that the CDDO-Im-mediated induction of IL-22 production in CD4+ T cells was abrogated in CD4-specific Ahr knockout mice (AhrCD4 ). CH-223191, a specific AhR antagonist, inhibits CDDO-Im-induced IL-22 production in CD4+ T cells, which further confirmed the AhR-dependent regulation. Collectively, our data showed that Nrf2 via AhR pathways regulated IL-22 response in CD4+ T cells.

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

BACKGROUND: 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. METHODS AND RESULTS: 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. CONCLUSION: 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.

A sustainable approach to the degradation of dyes by fungal species isolated from industrial wastewaters: Performance, parametric optimization, kinetics and degradation mechanism.

Fungal abetted processes are among the finest approaches for the transformation or degradation and decolorization of dyes in effluents. In this piece of research; biodegradation and metabolic pathways of two toxic dyes Congo Red (CR) and Reactive black 5 (RB5) by two strains of Aspergillus sp. fungus in batch experiments has been investigated. Morphological characteristics of the isolates were observed with both light and electron microscopies. Based on molecular characterization the isolates were identified as Aspergillus flavus and Aspergillus niger. The degradation was also optimized via. operational parameters such as pH, temperature, incubation time, inoculums size, dye concentration, carbon sources and nitrogen sources. Degradation measurements revealed that the isolates effectively degraded 90% and 96% of CR and RB5 respectively. Metabolites were identified with Liquid chromatography-mass spectrometry (LCMS) and degradation pathways of the dyes were proposed. Toxicity assay Phaseolus mungo seeds showed that pure CR and RB5 dyes exhibits significant toxicity whereas fungal treated dye solution resulted in an abatement of the toxicity and cell viability was increased. The results stipulated in this article clearly showed the effectiveness of the isolates on detoxification of CR and RB5 dyes.

Application of Salvinia sps. in remediation of reactive mixed azo dyes and Cr (VI) - Its pathway elucidation.

The emerging industrialization has resulted in the rapid growth of textile industries across the globe. The presence of xenobiotic pollutants in textile wastewater threatens the ecosystem. Applying different microbes (bacteria, fungi & algae) has paved the way for phytoremediation - the eco-friendly, cost-effective method. The present study focuses on the phytoremediation of reactive dyes - Reactive red, Reactive Brown & Reactive Black and Cr (VI) in synthetic textile wastewater using Salvinia sps. The mixed azo dyes of each 100 mg/L showed decolourization of 75 ± 0.5% and 82 ± 0.5% of removal of 20 mg/L of Cr (VI) after eight days of incubation in a phytoreactor setup. Chlorophyll analysis revealed the gradual decrease in the photosynthetic pigments during the remediation. The degraded metabolites were analyzed using FT-IR and showed the presence of aromatic amines on day zero, which were converted to aliphatic amines on day four. The GC-MS analysis revealed the disruption of -NN- bond, rupture of -CN- bond, scission of -N-N-bond, and loss of -SO3H from the Reactive Black dye leading to the formation of an intermediate p-Hydroxy phenylhydrazinyl. The rupture of Reactive red dye resulted in the formation of p-Hydrazinyl toluene sulphonic acid, Naphthyl amine -3,6-disulphonic acid and 8-Hydroxy Naphthyl amine -3,6-disulphonic acid. Decarboxylation, desulphonation, deoxygenation and deamination of Reactive Brown dye showed the presence of different metabolites and metabolic pathways were proposed for the reactive azo dyes which were phytoremediated.

Light-driven biodegradation of azo dyes by Shewanella decolorationis-CdS biohybrid in wastewater lacking electron donors.

The lack of electron donors prevents the effective degradation of azo dyes by bacteria, which severely limits the practical application of conventional biological treatment. Herein, we innovatively designed a bio-photoelectric reduction degradation system composed of CdS and Shewanella decolorationis, which could effectively degrade amaranth in anaerobic conditions driven by light when electron donors were unavailable. Compared with bare S. decolorationis and S. decolorationis (heat-killed)-CdS biohybrid, S. decolorationis-CdS biohybrid had 39.36-fold and 3.82-fold higher first-order kinetic constants, respectively. The morphology, particle size, elemental composition, crystalline type, photovoltaic properties, and band structure of the nanoparticles synthesized by S. decolorationis were carefully examined and analyzed. Light-driven biodegradation experiments showed that amaranth was degraded by the synergy of CdS and S. decolorationis. Reductive degradation of amaranth by electrons was demonstrated by electron and hole trapping. The effect of potential coexisting contaminants, which might serve as hole scavengers, on the degradation of amaranth was evaluated. Membrane protein inhibition experiments also suggested that NADH dehydrogenase, menaquinone, and cytochrome P450 played an important role in electron transfer between CdS and Shewanella decolorationis. The cyclic conversion of NAD+/NADH was probably the most critical rate-limiting step. Electrochemical measurements suggested that faster electron transfer might facilitate the degradation of amaranth. Our findings might contribute to the degradation of azo dyes in wastewater lacking electron donors and deepen our recognition of the microbe-material interface. KEY POINTS: • A BPRDS was constructed with Shewanella decolorationis and CdS. • Amaranth was effectively degraded by BPRDS in anaerobic conditions driven by light. • NDH, MQ, and CYP450 were involved in electron transfer.

Enhanced Biodegradation of Methyl Orange Through Immobilization of Shewanella oneidensis MR-1 by Polyvinyl Alcohol and Sodium Alginate.

Shewanella oneidensis MR-1 has great potential for use in remediating azo dye pollution. Here, a new high-efficiency biodegradation method was developed utilizing S. oneidensis MR-1 immobilized by polyvinyl alcohol (PVA) and sodium alginate (SA). After determining the optimal immobilization conditions, the effects of various environmental factors on methyl orange (MO) degradation were analyzed. The biodegradation activity of the immobilized pellets was evaluated by analyzing the MO removal efficiency, and characterization was performed using scanning electron microscopy. The MO adsorption kinetics can be described using pseudo-second-order kinetics. Compared with free bacteria, the MO degradation rate of the immobilized S. oneidensis MR-1 increased from 41% to 92.6% after 21 days, suggesting that the immobilized bacteria performed substantially better and had more stable removal rates. These factors indicate the superiority of bacteria entrapment in addition to its easy application. This study demonstrates that the application of immobilized S. oneidensis MR-1 entrapped by PVA-SA can be used to establish a reactor with stable and high MO removal rates.

A small-molecule fluorescence probe ANP77 for sensing RNA internal loop of C, U and A/CC motifs and their binding molecules.

Small-molecules interacting with particular RNAs and modulating their functions are vital tools for RNA-targeting drug discovery. Considering the substantial distribution of the internal loops involving two contiguous cytosines opposite to a single-nucleotide base (Y/CC; Y = C, U or A) within the biologically significant functional RNAs, developing small-molecule probes targeting Y/CC sites should provide profound insight into their functions and roles in biochemical processes. Herein, we report ANP77 as the small-molecule probe for sensing RNA internal loop of Y/CC motifs and molecules binding to the motifs. The Y/CC motifs interact with ANP77 via the formation of a 1:1 complex and quench the fluorescence of ANP77. The flanking sequence-dependent binding to C/CC and U/CC sites was assessed by fluorometric screening, provided the binding heat maps. The quenching phenomena of ANP77 fluorescence was confirmed with intrinsic potential drug target pre-miR-1908. Finally, the binding-dependent fluorescence quenching of ANP77 was utilized in the fluorescence indicator displacement assay to demonstrate the potential of ANP77 as an indicator by using the RNA-binding drugs, risdiplam and branaplam.

Recognition of single-stranded nucleic acids by small-molecule splicing modulators.

Risdiplam is the first approved small-molecule splicing modulator for the treatment of spinal muscular atrophy (SMA). Previous studies demonstrated that risdiplam analogues have two separate binding sites in exon 7 of the SMN2 pre-mRNA: (i) the 5'-splice site and (ii) an upstream purine (GA)-rich binding site. Importantly, the sequence of this GA-rich binding site significantly enhanced the potency of risdiplam analogues. In this report, we unambiguously determined that a known risdiplam analogue, SMN-C2, binds to single-stranded GA-rich RNA in a sequence-specific manner. The minimum required binding sequence for SMN-C2 was identified as GAAGGAAGG. We performed all-atom simulations using a robust Gaussian accelerated molecular dynamics (GaMD) method, which captured spontaneous binding of a risdiplam analogue to the target nucleic acids. We uncovered, for the first time, a ligand-binding pocket formed by two sequential GAAG loop-like structures. The simulation findings were highly consistent with experimental data obtained from saturation transfer difference (STD) NMR and structure-affinity-relationship studies of the risdiplam analogues. Together, these studies illuminate us to understand the molecular basis of single-stranded purine-rich RNA recognition by small-molecule splicing modulators with an unprecedented binding mode.

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

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

In vitro and in silico analysis of Brilliant Black degradation by Actinobacteria and a Paraburkholderia sp.

The soil bacteria isolated in this study, including three strains of actinobacteria and one Paraburkholderia sp., showed decolorization activity of azo dyes in the resting cell assay and were shown to use methyl red as the sole carbon source to proliferate. Therefore, their ability to degrade, bioabsorb, or a combination of both mechanism was investigated using the substrate brilliant black. The strains DP-A9 and DP-L11, within 24 h of incubation, showed complete biodegradation of 173.54 mg/L brilliant black and the strains DP-D10 and DP-P12 showed partial decolorization of 83.3 mg/L and 36.4 mg/L, respectively, by both biosorption and biodegradation. In addition, the shotgun assembled genome of these strains showed a highly diverse set of genes encoding for candidate dye degrading enzymes, providing avenues to study azo dye metabolism in more detail.

Metabolism of azo food dyes by bacterial members of the human gut microbiome.

OBJECTIVES: We set out to survey the capacities of bacterial isolates from the human gut microbiome to reduce common azo food dyes in vitro. METHODS: A total of 206 strains representative of 124 bacterial species and 6 phyla were screened in vitro using a simple azo dye decolorization assay. Strains which showed azoreductive activity were characterized by studies of azoreduction kinetics and bacterial growth. RESULTS: Several groups of gut bacteria, including ones not previously associated with azoreduction, reduced one or more of the four azo food dyes commonly used in Canada: Allura Red, Amaranth, Sunset Yellow, and Tartrazine. Strains within some species differed in their azoreductive capabilities. Some strains displayed evidence of effects on growth related to the presence of azo dyes and/or the products of their azoreduction. CONCLUSION: The continued widespread use of food azo dyes requires re-evaluation in light of the potential for disturbance of the gut microbial ecosystem resulting from azoreduction and the possibility of consequences for human health.

Impact of immobilized algae and its consortium in biodegradation of the textile dyes.

In biological engineering, cell immobilization is a modern technique for immobilizing free cells in a small space. Disintegration and elimination of azo dyes [Reactive Orange 122 (orange 2RL) and Reactive Red 194 (Reactive Red M-2BF)] were investigated by using Chlorococcum sp. and Chlorococcum sp. mixed with Scenedesmus obliquus, respectively. After 7 days of incubation, the maximum decolorization was spotted at 40 ppm for Reactive Orange 122 and 20 ppm for Reactive Red 194 by Chlorococcum sp. and Chlorococcum sp. mixed with S. obliquus, respectively. The findings revealed that the best decolorization activity was found at pH 11 and 25 °C under aeration conditions. BG11 was considered the best medium for azo dye decolorization with a high decolorization percentage. Additionally, different concentrations of nitrogen and phosphorus show the high activity of decolorization of both dyes. Referring to vitamins (thiamin and Ascorbic acid), all studied concentrations showed high decolorization activity with immobilized Chlorococcum sp. mixed with S. obliquus; however, different concentrations (20, 40, and 60 mg/l) of thiamin showed completely decolorization of Reactive Red 194 after 3 days, and 60 mg/l of ascorbic acid showed completely decolorization of Reactive Orange 122 after 5 days of inoculation. FT-IR and GC-Ms analysis for azo dyes after and before treatment with Immobilization of Chlorococcum sp. and Chlorococcum sp. mixed with Scenedesmus obliquus were detected. Novelty statement: The natural carrier algae and its consortium combined with a suitable immobilization technique were considered in this study, which is non-toxic, enhanced their bioremediation potential for dyes, and allowed multiple uses of biocatalysts. The novel use of the immobilization and its consortium of algae on the degradation efficiency of azo dyes and studying the effect of physicochemical conditions on decolorization and degradation of azo dyes. Application of immobilization techniques using microalgae could be excellent bioremediation of wastewaters.