An investigation of anthraquinone dye biodegradation by immobilized Aspergillus flavus in fluidized bed bioreactor

Decolorization of Azo and Anthraquinone Dyes Using Recombinant Horseradish Peroxidase A2A Isoenzyme Produced by Komagataella phaffii

Water pollution is a significant issue due to industrialization and population growth, and one of the main sources of wastewater is synthetic dyes. The textile sector is particularly affected by dyes like azo and anthraquinone dyes, which are difficult to degrade and produce toxic organic waste. Currently, synthetic dyes are processed through physical and chemical methods, which have financial and methodological disadvantages. Horseradish peroxidase (HRP) is a widely studied enzyme for purifying pollutants like dyes and phenols in wastewater. However, their high cost makes them a costly option. Recombinant protein production is suitable for the mass production of stable and resistant enzymes. In this study, the decolorization potential of recombinant HRP A2A (rHRP A2A) isoenzyme secreted by Komagataella phaffii and purified by affinity technique in a single step on Acid blue 113, Alizarin red, and Remazol brilliant blue R was presented for the first time, and the optimal conditions for the highest decolorization rate were determined. Fe2+ and Mn2+ metal ions increased enzyme activity by 158.62% and 79.54%, respectively. Color removal with 0.006 EU/mL rHRP A2A for Acid blue 113, Alizarin red, and Remazol brilliant blue R was observed at 71.27, 62.26, and 31.22%, respectively. ABTS served as a redox mediator, significantly increasing the rate of dye decolorization in a shorter period at the specified concentration.

Recent advances in microbial engineering approaches for wastewater treatment: a review

In the present era of global climate change, the scarcity of potable water is increasing both due to natural and anthropogenic causes. Water is the elixir of life, and its usage has risen significantly due to escalating economic activities, widespread urbanization, and industrialization. The increasing water scarcity and rising contamination have compelled, scientists and researchers, to adopt feasible and sustainable wastewater treatment methods in meeting the growing demand for freshwater. Presently, various waste treatment technologies are adopted across the globe, such as physical, chemical, and biological treatment processes. There is a need to replace these technologies with sustainable and green technology that encourages the use of microorganisms since they have proven to be more effective in water treatment processes. The present review article is focused on demonstrating how effectively various microbes can be used in wastewater treatment to achieve environmental sustainability and economic feasibility. The microbial consortium used for water treatment offers many advantages over pure culture. There is an urgent need to develop hybrid treatment technology for the effective remediation of various organic and inorganic pollutants from wastewater.

Development of multifarious carrier materials and impact conditions of immobilised microbial technology for environmental remediation: A review

Microbial technology is the most sustainable and eco-friendly method of environmental remediation. Immobilised microorganisms were introduced to further advance microbial technology. In immobilisation technology, carrier materials distribute a large number of microorganisms evenly on their surface or inside and protect them from external interference to better treat the targets, thus effectively improving their bioavailability. Although many carrier materials have been developed, there have been relatively few comprehensive reviews. Therefore, this paper summarises the types of carrier materials explored in the last ten years from the perspective of structure, microbial activity, and cost. Among these, carbon materials and biofilms, as environmentally friendly functional materials, have been widely applied for immobilisation because of their abundant sources and favorable growth conditions for microorganisms. The novel covalent organic framework (COF) could also be a new immobilisation material, due to its easy preparation and high performance. Different immobilisation methods were used to determine the relationship between carriers and microorganisms. Co-immobilisation is particularly important because it can compensate for the deficiencies of a single immobilisation method. This paper emphasises that impact conditions also affect the immobilisation effect and function. In addition to temperature and pH, the media conditions during the preparation and reaction of materials also play a role. Additionally, this study mainly reviews the applications and mechanisms of immobilised microorganisms in environmental remediation. Future development of immobilisation technology should focus on the discovery of novel and environmentally friendly carrier materials, as well as the establishment of optimal immobilisation conditions for microorganisms. This review intends to provide references for the development of immobilisation technology in environmental applications and to further the improve understanding of immobilisation technology.

Research on the treatment mechanism of anthraquinone dye wastewater by algal-bacterial symbiotic system

This study analyzed the role of algae and bacteria in algal-bacterial symbiotic systems for the treatment of dyeing wastewater. The mechanism was investigated by constructing an algae-bacteria tandem system (A system) and a bacteria-algae tandem system (B system). The results showed that the chemical oxygen demand (COD) removal and decolorization rates of A system reached 91% and 90%, respectively, under optimal conditions, which were higher than that of B system. The degradation pathways of A and B systems differed according the degradation product analysis. High-throughput sequencing analysis revealed that Proteobacteria were the dominant bacteria in A and B systems. Armatimonadetes increased considerably in A system. These results show that algae mainly contributed to the preliminary degradation of anthraquinone dye, and resulting products were easily degraded by bacteria. This study provides guidance on the optimization of the system. It can be better adapted to the actual needs of wastewater treatment plants.

The mechanism of degradation of alizarin red by a white-rot fungus Trametes gibbosa

Background

Alizarin red (AR) is a typical anthraquinone dye, and the resulting wastewater is toxic and difficult to remove. A study showed that the white rot fungus Trametes gibbosa (T. gibbosa) can degrade dye wastewater by decolorization and has its own enzyme-producing traits.

Methods

In this study, transcriptome sequencing was performed after alizarin red treatment for 0, 3, 7, 10, and 14 h. The key pathways and key enzymes involved in alizarin red degradation were found to be through the analysis of KEGG and GO. The Glutathione S-transferase (GST), manganese peroxidase (MnP) and laccase activities of T. gibbosa treated with alizarin red for 0–14 h were detected. LC–MS and GC–MS analyses of alizarin red decomposition products after 7 h and 14 h were performed.

Results

The glutathione metabolic pathway ko00480, and the key enzymes GST, MnP, laccase and CYP450 were selected. Most of the genes encoding these enzymes were upregulated under alizarin red conditions. The GST activity increased 1.8 times from 117.55 U/mg prot at 0 h to 217.03 U/mg prot at 14 h. The MnP activity increased 2.9 times from 6.45 to 18.55 U/L. The laccase activity increased 3.7 times from 7.22 to 27.28 U/L. Analysis of the alizarin red decolourization rate showed that the decolourization rate at 14 h reached 20.21%. The main degradation intermediates were found to be 1,4-butene diacid, phthalic acid, 1,1-diphenylethylene, 9,10-dihydroanthracene, 1,2-naphthalene dicarboxylic acid, bisphenol, benzophenol-5,2-butene, acrylaldehyde, and 1-butylene, and the degradation process of AR was inferred. Overall, 1,4-butene diacid is the most important intermediate product produced by AR degradation.

Conclusions

The glutathione metabolic pathway was the key pathway for AR degradation. GST, MnP, laccase and CYP450 were the key enzymes for AR degradation. 1,4-butene diacid is the most important intermediate product. This study explored the process of AR biodegradation at the molecular and biochemical levels and provided a theoretical basis for its application in practical production.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12896-021-00720-8.

Transformation of Reactive Blue 19 by a recombinant peroxidase DyP

Wastewater containing recalcitrant dyes causes environmental problems. A new superfamily of heme-containing peroxidases, dye-decolorizing peroxidases (DyPs), has been found to decolorize different kinds of dyes, especial anthraquinone dyes efficiently. However, the mechanism of dyes degradation by DyPs has not been fully understood and the toxicity of dye degradation intermediates by DyPs catalysis to microbes is unclear. In this study, a purified recombinant Thermobifida fusca DyP (TfuDyP) in E. coli BL21(DE3) was used to treat Reactive Blue 19 (RB19), an anthraquinone dye. The reaction intermediates analyzed by ultra performance liquid chromatography/mass spectroscopy (UPLC-MS) indicated the initial site of TfuDyP attack on RB19. In addition, it was found that both RB19 and its incomplete degradation products inhibited the growth of Bacillus subtilis. These findings provided a novel understanding of DyPs catalysis to anthraquinone dyes.

Biological Treatment of Real Textile Effluent Using Aspergillus flavus and Fusarium oxysporium and Their Consortium along with the Evaluation of Their Phytotoxicity

Twenty-one fungal strains were isolated from dye-contaminated soil; out of them, two fungal strains A2 and G2-1 showed the highest decolorization capacity for real textile effluent and were, hence, identified as Aspergillus flavus and Fusarium oxysporium based on morphological and molecular methods. The highest decolorization percentage of 78.12 ± 2.1% was attained in the biotreatment with fungal consortium followed by A. flavus and F. oxysporium separately with removal percentages of 54.68 ± 1.2% and 52.41 ± 1.0%, respectively. Additionally, ultraviolet-visible spectroscopy of the treated effluent showed that a maximum peak (λ_max) of 415 nm was reduced as compared with the control. The indicators of wastewater treatment efficacy, namely total dissolved solids, total suspended solids, conductivity, biological oxygen demand, and chemical oxygen demand with removal percentages of 78.2, 78.4, 58.2, 78.1, and 77.6%, respectively, demonstrated a considerable decrease in values due to fungal consortium treatment. The reduction in peak and mass area along with the appearance of new peaks in GC-MS confirms a successful biodegradation process. The toxicity of treated textile effluents on the seed germination of Vicia faba was decreased as compared with the control. The shoot length after irrigation with effluents treated by the fungal consortium was 15.12 ± 1.01 cm as compared with that treated by tap-water, which was 17.8 ± 0.7 cm. Finally, we recommended the decrease of excessive uses of synthetic dyes and utilized biological approaches for the treatment of real textile effluents to reuse in irrigation of uneaten plants especially with water scarcity worldwide.

Biodegradation and metabolic pathway of anthraquinone dyes by Trametes hirsuta D7 immobilized in light expanded clay aggregate and cytotoxicity assessment

Biodegradation and metabolic pathways of three anthraquinone dyes, Reactive Blue 4 (RB4), Remazol Brilliant Blue - R (RBBR), and Acid Blue 129 (AB129) by Trametes hirsuta D7 fungus immobilized in light expanded clay aggregate (LECA) were investigated. Morphological characteristics observed with scanning electron microscope (SEM) showed successful immobilization of the fungus in LECA. Based on UV absorbance measurement, immobilized T. hirsuta D7 effectively degraded 90%, 95%, and 96% of RB4, RBBR and AB129, respectively. Metabolites were identified with high-resolution mass spectrometry (HRMS) and degradation pathway of the dyes by T. hirsuta D7 was proposed. Toxicity assay on human dermal fibroblast (HDF) showed that anthraquinone dyes exhibits significant toxicity of 35%, 40%, and 34% reduction of cell viability by RB4, RBBR, and AB129, respectively. Fungal treatment resulted in an abatement of the toxicity and cell viability was increased up to 94%. The data clearly showed the effectiveness of immobilized T. hirsuta D7 in LECA on detoxification of anthraquinone dyes. This study provides potential and fundamental understanding of wastewater treatment using the newly isolated fungus T. hirsuta D7.

Degradation of Anthraquinone Dyes from Effluents: A Review Focusing on Enzymatic Dye Degradation with Industrial Potential

Up to 84 000 tons of dye can be lost in water, and 90 million tons of water are attributed annually to dye production and their application, mainly in the textile and leather industry, making the dyestuff industry responsible for up to 20% of the industrial water pollution. The majority of dyes industrially used today are aromatic compounds with complex, reinforced structures, with anthraquinone dyes being the second largest produced in terms of volume. Despite the progress on decolorization and degradation of azo dyes, very little attention has been given to anthraquinone dyes. Anthraquinone dyes pose a serious environmental problem as their reinforced structure makes them difficult to degrade naturally. Existing methods of decolorization might be effective but are neither efficient nor practical due to extended time, space, and cost requirements. Attention should be given to the emerging routes for dye decolorization via the enzymatic action of oxidoreductases, which have already a strong presence in various other bioremediation applications. This review will discusses the presence of anthraquinone dyes in the effluents and ways for their remediation from dyehouse effluents, focusing on enzymatic processes.

Bacterial degradation of anthraquinone dyes

Anthraquinone dyes, which contain anthraquinone chromophore groups, are the second largest class of dyes after azo dyes and are used extensively in textile industries. The majority of these dyes are resistant to degradation because of their complex and stable structures; consequently, a large number of anthraquinone dyes find their way into the environment causing serious pollution. At present, the microbiological approach to treating printing and dyeing wastewater is considered to be an economical and feasible method, and reports regarding the bacterial degradation of anthraquinone dyes are increasing. This paper reviews the classification and structures of anthraquinone dyes, summarizes the types of degradative bacteria, and explores the possible mechanisms and influencing factors of bacterial anthraquinone dye degradation. Present research progress and existing problems are further discussed. Finally, future research directions and key points are presented.

Decolorization of mordant yellow 1 using Aspergillus sp. TS-A CGMCC 12964 by biosorption and biodegradation

In this report, the decolorization features of extracellular enzymes and mycelia separately prepared from Aspergillus sp. TS-A CGMCC 12,964 (120 h) were investigated. The fermentation broth of TS-A degraded 98.6% of Mordant Yellow 1 (50 mg/L) at an initial pH 6 within 1 h with over 70% of the dye (50 mg/L) degraded by extracellular enzymes and 18.8% removed by live mycelia. The degradation products of the dye were analyzed by UV-Vis and FTIR spectra. The decolorization rates of extracellular enzymes and mycelia were examined under different contact periods, dye concentrations and pH values. The extracellular enzymes exhibited excellent degradation activity under weak acidic conditions. In addition, biosorption models of mycelia fitted well the Langmuir isotherm model and the pseudo-second-order kinetic equation. Although the decolorization process was achieved through the synergistic effects of mycelia and extracellular enzymes, decolorization was dominated by the biodegradation activity of the extracellular enzymes from TS-A.

Bioreactors based on immobilized fungi: bioremediation under non-sterile conditions

White-rot fungi are renowned for their remarkable potential to degrade a wide range of organic pollutants. They are applicable in standard bioreactors offering both the use of the continuous mode of action and easy upscaling of the biodegradation process. The recent advance in this field consisted in the use of various fungi and different types of reactors in the treatment of real wastewaters. Most degradation studies involving white-rot fungi carried out so far used controlled, aseptic conditions. However, during bioremediation of real wastewaters, the degradation capacity of the fungi would be significantly affected by autochthonous microorganisms. Consequently, for the development of sustainable bioremediation technologies, it is important to understand the mechanisms involved in the intermicrobial interactions occurring during the bioremediation process. This review summarizes recent applications of white-rot fungi to biodegradation of recalcitrant organopollutants under non-sterile conditions describing the invading microorganism(s) and the way how they affect the stability and degradation efficiency of the fungal bioreactor cultures. In addition, studies where fungal cultures were exposed to defined microbial stress are also reported documenting the effect and mechanisms of microbial interactions. Advanced OMICs techniques, specifically the genomics and metabolomics analyses, are suggested to help in identification of the invading microorganisms and in discovery of mechanisms taking part in the interspecific interactions.

Decolorization of textile dyes in an air-lift bioreactor inoculated with Bjerkandera adusta OBR105

A new decolorizing white-rot fungus, OBR105, was isolated from Mount Odae in South Korea and identified by the morphological characterization of its fruit body and spores and partial 18s rDNA sequences. The ligninolytic enzyme activity of OBR105 was studied to characterize their decolorizing mechanism using a spectrophotometric enzyme assay. For the evaluation of the decolorization capacity of OBR105, the isolate was incubated in an erlenmeyer flask and in an airlifte bioreator with potato dextrose broth (PDB) medium supplemented with each dye. In addition, the decolorization efficiency of real textile wastewater was evaluated in an airlift bioreactor inoculated with the isolate. The isolate was identified as Bjerkandera adusta and had ligninolytic enzymes such as laccase, lignin peroxidase (LiP), and Mn-dependent peroxidase (MnP). Its LiP activity was higher than its MnP and laccase activities. B. adusta OBR105 successfully decolorized reactive dyes (red 120, blue 4, orange 16, and black 5) and acid dyes (red 114, blue 62, orange 7, and black 172). B. adusta OBR105 decolorized 91-99% of 200 mg L^-1 of each dye (except acid orange 7) within 3 days in a PDB medium at 28°C, pH 5, and 150 rpm. This fungus decolorized only 45% of 200 mg L^-1 acid orange 7 (single azo-type dye) within 3 days, and the decolorization efficiency did not increase by prolonging the cultivation time. In the air-lift bioreactor, B. adusta OBR105 displayed a high decolorization capacity, greater than 90%, for 3 acid dyes (red 114, blue 62, and black 172) and 1 reactive dye (blue 4) within 10-15 h of treatment. B. adusta OBR105 could decolorize real textile wastewater in the air-lift bioreactor. This result suggests that an air-lift reactor employing B. adusta OBR105 is a promising bioreactor for the treatment of dye wastewater.

Decolorization pathways of anthraquinone dye Disperse Blue 2BLN by Aspergillus sp. XJ-2 CGMCC12963

Anthraquinone dye represents an important group of recalcitrant pollutants in dye wastewater. Aspergillus sp XJ-2 CGMCC12963 showed broad-spectrum decolorization ability, which could efficiently decolorize and degrade various anthraquinone dyes (50 mg L^-1) under microaerophilic condition. And the decolorization rate of 93.3% was achieved at 120 h with Disperse Blue 2BLN (the target dye). Intermediates of degradation were detected by FTIR and GC-MS, which revealed the cleavage of anthraquinone chromophoric group and partial mineralization of target dye. In addition, extracellular manganese peroxidase showed the most closely related to the increasing of decolorization rate and biomass among intracellular and extracellular ligninolytic enzymes. Given these results, 2 possible degraded pathways of target dye by Aspergillus sp XJ-2 CGMCC12963 were proposed first in this work. The degradation of Disperse Blue 2BLN and broad spectrum decolorization ability provided the potential for Aspergillus sp XJ-2 CGMCC12963 in the treatment of wastewater containing anthraquinone dyes.

Decolorization of anthraquinonic dyes from textile effluent using horseradish peroxidase: optimization and kinetic study

Two anthraquinonic dyes, C.I. Acid Blue 225 and C.I. Acid Violet 109, were used as models to explore the feasibility of using the horseradish peroxidase enzyme (HRP) in the practical decolorization of anthraquinonic dyes in wastewater. The influence of process parameters such as enzyme concentration, hydrogen peroxide concentration, temperature, dye concentration, and pH was examined. The pH and temperature activity profiles were similar for decolorization of both dyes. Under the optimal conditions, 94.7% of C.I. Acid Violet 109 from aqueous solution was decolorized (treatment time 15 min, enzyme concentration 0.15 IU/mL, hydrogen peroxide concentration 0.4 mM, dye concentration 30 mg/L, pH 4, and temperature 24°C) and 89.36% of C.I. Acid Blue 225 (32 min, enzyme concentration 0.15 IU/mL, hydrogen peroxide concentration 0.04 mM, dye concentration 30 mg/L, pH 5, and temperature 24°C). The mechanism of both reactions has been proven to follow the two substrate ping-pong mechanism with substrate inhibition, revealing the formation of a nonproductive or dead-end complex between dye and HRP or between H2O2 and the oxidized form of the enzyme. Both chemical oxygen demand and total organic carbon values showed that there was a reduction in toxicity after the enzymatic treatment. This study verifies the viability of use of horseradish peroxidase for the wastewaters treatment of similar anthraquinonic dyes.

Enhanced bio-decolorization of 1-amino-4-bromoanthraquinone-2-sulfonic acid by Sphingomonas xenophaga with nutrient amendment

Bacterial decolorization of anthraquinone dye intermediates is a slow process under aerobic conditions. To speed up the process, in the present study, effects of various nutrients on 1-amino-4-bromoanthraquinone-2-sulfonic acid (ABAS) decolorization by Sphingomonas xenophaga QYY were investigated. The results showed that peptone, yeast extract and casamino acid amendments promoted ABAS bio-decolorization. In particular, the addition of peptone and casamino acids could improve the decolorization activity of strain QYY. Further experiments showed that l-proline had a more significant accelerating effect on ABAS decolorization compared with other amino acids. l-Proline not only supported cell growth, but also significantly increased the decolorization activity of strain QYY. Membrane proteins of strain QYY exhibited ABAS decolorization activities in the presence of l-proline or reduced nicotinamide adenine dinucleotide, while this behavior was not observed in the presence of other amino acids. Moreover, the positive correlation between l-proline concentration and the decolorization activity of membrane proteins was observed, indicating that l-proline plays an important role in ABAS decolorization. The above findings provide us not only a novel insight into bacterial ABAS decolorization, but also an l-proline-supplemented bioaugmentation strategy for enhancing ABAS bio-decolorization.