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

Trichoderma harzianum AKH-5: A novel fungal isolate with antimicrobial efficacy for phytopathogen management and environmental remediation

Trichoderma harzianum isolate AKH-5 is recognized as a biological control agent, effective in managing harmful phytopathogens while promoting plant growth and enhancing resistance to various stresses. In this study, a total of 140 morphological different fungal isolates were isolated and in primary screening isolate AKH-5 exhibited significant antifungal activity in vitro. Trichoderma harzianum isolate AKH-5 proved to be effective and was characterized morphologically, physiologically and through 18S rRNA gene sequencing and identified as Trichoderma harzianum. GC-MS profiling of the ethyl acetate extract identified 22 distinct bioactive compounds, including phenylethyl alcohol, dibutyl phthalate, and N-carbobenzyloxy-L-tyrosyl-L-valine, which possess antibacterial, antifungal and antioxidant properties. Further, in antibacterial assessment, AKH-5 extract exhibited significant antibacterial activity on microbial pathogens in a dose-dependent manner. The lowest MIC value against Escherichia coli was 8 μg/mL, indicating strong antibacterial activity. MBC values (32, 64 μg/mL) were higher than MIC values, indicating the need for higher concentrations for bactericidal effects and significant antioxidant activity with an IC50 value of 90.78 μg/mL. The extract exhibited significant inhibition efficacy on Fusarium oxysporum, and Colletotrichum capsici, further moderate activity on Curvularia lunata, Alternaria alternata, and Rhizoctonia solani. The isolate AKH-5 showed good azo-dye degradation capacity and Triticum aestivum L. (wheat) seeds treated with dyes degraded with the isolate AKH-5 broth extract exhibited a germination rate of 98 %, compared to the untreated and control seeds which showed germination of 50 and 94 %, respectively. This study highlights the unexplored habitats as rich sources of diverse antifungal metabolite-producing fungi, which can be promising candidates for developing novel antifungal strains. Overall, the results demonstrate the beneficial role of AKH-5 in controlling phytopathogens and minimizing phytotoxicity through biodegradation of dyes for environmental remediation purposes.

An overview of recent advances in treatment of complex dye-containing wastewater and its techno-economic assessment

Industries such as textiles, polymers, pharmaceuticals, papers, and tanneries are the key contributors to the global economy. These industries utilize various types of synthetic dyes in their processes, leading to discharge of dyes-contaminated wastewater. The wastewater generally contains various types of dyes (such as methyl orange, congo red, malachite green, etc.), which have a detrimental impact on the ecosystem and human health due to their toxic, carcinogenic, and mutagenic nature. As the result, it is crucial to treat the dyes-contaminated wastewater to protect the environment and render it suitable for reuse, mitigating the escalating global demand for clean water. This review provides a comprehensive overview of dyes and their treatment technologies (i.e., physical, chemical, and biological treatment). Among various treatment methods, the biological treatment is widely employed due to its energy efficiency and eco-friendliness. However, biological treatment faces challenges such as slow processing rates and limited effectiveness in handling low-biodegradability pollutants (BOD5/COD <0.2). This review also highlighted recent advancements in treatment technologies and explored the emerging integrated treatment method that aims to achieve higher removal efficiency for a low biodegradability index dye-contaminated wastewater. Additionally, a techno-economic assessment is presented, analyzing the cost-effectiveness of the emerging technologies in real-world applications. Further, the critical research gaps and future outlooks are also discussed. Overall, the review aims to contribute to the ongoing efforts to improve wastewater treatment processes and promote sustainable water management practices.

Sustainable approach for the treatment of dye-containing wastewater – a critical review

In the world’s rapidly expanding economy, textile industries are recognized as a substantial contributor to economic growth, but they are one of the most significant polluting industrial sectors. Dye-contaminated water sources can pose serious public health concerns, including toxicity, mutagenicity, and carcinogenicity among other adverse health effects. Despite a limited understanding of efficacious decolorization methodologies, the pursuit of a sustainable strategy for the treatment of a wide spectrum of dyes remains a formidable challenge. This article conducted an exhaustive review of extant literature pertaining to diverse physical, chemical, biological, and hybrid processes with the aim of ascertaining their efficacy. It also elucidates the advantages and disadvantages, cost considerations, as well as scalability impediments of the treatment methodologies, thereby facilitating the identification of optimal strategies for establishing techno-economically efficient processes in the sustainable handling of these effluents. The hybrid configuration exhibited superior efficiency and was documented to surmount the limitations and constraints inherent to individual techniques. The study also revealed that most of the proven and established dye removal techniques share a common limitation viz., the generation of secondary pollution (i.e., sludge generation, toxic intermediates, etc.) to the ecosystem.

Successful cultivation of edible fungi on textile waste offers a new avenue for bioremediation and potential food production

Textile waste contains both natural fibres such as cotton and bamboo viscose, and synthetic fibres such as elastane and polyester. As a complex mixture, textiles present a challenging pollution issue as breakdown in landfill results in microplastics entering water and soil environments, and incineration results in particulate air pollution. Here the use of edible fungi as bioremediation agents of waste textiles is described for the first time. Three species of filamentous fungi were shown to colonise and grow on mixed fibre textile waste (underpants made from 28% cotton: 68% bamboo viscose: 4% elastane). All three fungi were able to metabolise the common textile dye Reactive Black 5 to some extent. The metabolome was captured to elucidate the dye remediation pathway utilized and to characterise the volatiles released during bioremediation with a view to assessing the safety profile of this process for future industrial applications. The results suggest that edible fungi may be cultivated on textiles, and that some interesting and useful compounds may be produced in the process. This has great biotechnological potential. No mushrooms were produced in this study, suggesting that further work will be needed to optimise conditions for crop production from waste textiles.

Biotransformation of the azo dye reactive orange 16 by Aspergillus flavus A5P1: Performance, genetic background, pathway, and mechanism

This study reports the strain Aspergillus flavus A5P1 (A5P1), which is with the capable of degrading the azo dye reactive orange 16 (RO16). The mechanism of RO16 degradation by A5P1 was elucidated through genomic analysis, enzymatic analysis, degradation pathway analysis and oxidative stress analysis. Strain A5P1 exhibited aerobic degradation of RO16, with optimal degradation at an initial pH of 3.0. Genomic analysis indicates that strain A5P1 possesses the potential for acid tolerance and degradation of azo dye. Enzymatic analysis, combined with degradation product analysis, demonstrated that extracellular laccase, intracellular lignin peroxidase, and intracellular quinone reductase were likely key enzymes in the RO16 degradation process. Oxidative stress analysis revealed that cell stress responses may participate in the RO16 biotransformation process. The results indicated that the biotransformation of RO16 may involves biological processes such as transmembrane transport of RO16, cometabolism of the strain with RO16, and cell stress responses. These findings shed light on the biodegradation of RO16 by A5P1, indicating A5P1's potential for environmental remediation.

Fungal bioremediation approaches for the removal of toxic pollutants: Mechanistic understanding for biorefinery applications

Pollution is a global menace that poses harmful effects on all the living ecosystems and to the Earth. As years pass by, the available and the looming rate of pollutants increases at a faster rate. Although many treatments and processing strategies are waged for treating such pollutants, the by-products and the wastes or drain off generated by these treatments further engages in the emission of hazardous waste. Innovative and long-lasting solutions are required to address the urgent global issue of hazardous pollutant remediation from contaminated environments. Myco-remediation is a top-down green and eco-friendly tool for pollution management. It is a cost-effective and safer practice of converting pernicious substances into non-toxic forms by the use of fungi. But these pollutants can be transformed into useable products along with multiple benefits for the environment such as sequestration of carbon emissions and also to generate high valuable bioactive materials that fits as a sustainable economic model. The current study has examined the possible applications of fungi in biorefineries and their critical role in the transformation and detoxification of pollutants. The paper offers important insights into using fungal bioremediation for both economically and environmentally sound solutions in the domain of biorefinery applications by combining recent research findings.

Biomass waste-derived carbon materials for sustainable remediation of polluted environment: A comprehensive review

In response to the growing global concern over environmental pollution, the exploration of sustainable and eco-friendly materials derived from biomass waste has gained significant traction. This comprehensive review seeks to provide a holistic perspective on the utilization of biomass waste as a renewable carbon source, offering insights into the production of environmentally benign and cost-effective carbon-based materials. These materials, including biochar, carbon nanotubes, and graphene, have shown immense promise in the remediation of polluted soils, industrial wastewater, and contaminated groundwater. The review commences by elucidating the intricate processes involved in the synthesis and functionalization of biomass-derived carbon materials, emphasizing their scalability and economic viability. With their distinctive structural attributes, such as high surface areas, porous architectures, and tunable surface functionalities, these materials emerge as versatile tools in addressing environmental challenges. One of the central themes explored in this review is the pivotal role that carbon materials play in adsorption processes, which represent a green and sustainable technology for the removal of a diverse array of pollutants. These encompass noxious organic compounds, heavy metals, and organic matter, encompassing pollutants found in soils, groundwater, and industrial wastewater. The discussion extends to the underlying mechanisms governing adsorption, shedding light on the efficacy and selectivity of carbon-based materials in different environmental contexts. Furthermore, this review delves into multifaceted considerations, spanning the spectrum from biomass and biowaste resources to the properties and applications of carbon materials. This holistic approach aims to equip researchers and practitioners with a comprehensive understanding of the synergistic utilization of these materials, ultimately facilitating effective and affordable strategies for combatting industrial wastewater pollution, soil contamination, and groundwater impurities.

The mycoremediation potential of the armillarioids: a comparative genomics analysis

Genes involved in mycoremediation were identified by comparative genomics analysis in 10 armillarioid species and selected groups of white-rot Basidiomycota (14) and soft-rot Ascomycota (12) species to confine the distinctive bioremediation capabilities of the armillarioids. The genomes were explored using phylogenetic principal component analysis (pPCA), searching for genes already documented in a biocatalysis/biodegradation database. The results underlined a distinct, increased potential of aromatics-degrading genes/enzymes in armillarioids, with particular emphasis on a high copy number and diverse spectrum of benzoate 4-monooxygenase [EC:1.14.14.92] homologs. In addition, other enzymes involved in the degradation of various monocyclic aromatics were more abundant in the armillarioids than in the other white-rot basidiomycetes, and enzymes involved in the degradation of polycyclic aromatic hydrocarbons (PAHs) were more prevailing in armillarioids and other white-rot species than in soft-rot Ascomycetes. Transcriptome profiling of A. ostoyae and A. borealis isolates confirmed that several genes involved in the degradation of benzoates and other monocyclic aromatics were distinctively expressed in the wood-invading fungal mycelia. Data were consistent with armillarioid species offering a more powerful potential in degrading aromatics. Our results provide a reliable, practical solution for screening the likely fungal candidates for their full biodegradation potential, applicability, and possible specialization based on their genomics data.

Filamentous Fungi Are Potential Bioremediation Agents of Semi-Synthetic Textile Waste

Textile waste contributes to the pollution of both terrestrial and aquatic ecosystems. While natural textile fibres are known to be biodegraded by microbes, the vast majority of textiles now contain a mixture of processed plant-derived polymers and synthetic materials generated from petroleum and are commonly dyed with azo dyes. This presents a complex recycling problem as the separation of threads and removal of dye are challenging and costly. As a result, the majority of textile waste is sent to landfill or incinerated. This project sought to assess the potential of fungal bioremediation of textile-based dye as a step towards sustainable and environmentally-friendly means of disposal of textile waste. Successful development of an agar-independent microcosm enabled the assessment of the ability of two fungal species to grow on a range of textiles containing an increasing percentage of elastane. The white rot fungus Hypholoma fasciculare was shown to grow well on semi-synthetic textiles, and for the first time, bioremediation of dye from textiles was demonstrated. Volatile analysis enabled preliminary assessment of the safety profile of this process and showed that industrial scale-up may require consideration of volatile capture in the design process. This study is the first to address the potential of fungi as bioremediation agents for solid textile waste, and the results suggest this is an avenue worthy of further exploration.

Microbial biodegradation of recalcitrant synthetic dyes from textile-enriched wastewater by Fusarium oxysporum

The present study reported the improvement of biological treatment for the removal of recalcitrant dyes including aniline blue, reactive black 5, orange II, and crystal violet in contaminated water. The biodegradation efficiency of Fusarium oxysporum was significantly enhanced by the addition of mediators and by adjusting the biomass density and nutrient composition. A supplementation of 1% glucose in culture medium improved the biodegradation efficiency of aniline blue, reactive black 5, orange II, and crystal violet by 2.24, 1.51, 4.46, and 2.1 folds, respectively. Meanwhile, the addition of mediators to culture medium significantly increased the percentages of total removal for aniline blue, reactive black 5, orange II, and crystal violet, reaching 86.07%, 68.29%, 76.35%, and 95.3%, respectively. Interestingly, the fungal culture supplemented with 1% remazol brilliant blue R boosted the biodegradation up to 97.06%, 89.86%, 91.38%, and 86.67% for aniline blue, reactive black 5, orange II, and crystal violet, respectively. Under optimal culture conditions, the fungal culture could degrade these synthetic dyes concentration up to 10⁴ mg/L. The present study demonstrated that different recalcitrant dye types can be efficiently degraded using microorganism such as F. oxysporum.

Adsorption of textile dyes from aqueous solutions onto clay: Kinetic modelling and equilibrium isotherm analysis

The commercial activated carbon commonly uses to reduce of dye amount in the textile industry effluents. In this study has focused on the use of a natural clay sample as low cost but potential adsorbent. For this purpose the adsorption of commercial textile dyes, Astrazon Red FBL and Astrazon Blue FGRL, onto clay was investigated. The physicochemical and topographic characteristics of natural clay sample were determined by scanning electron microscopy (SEM), X-Ray fluorescence spectrometry (XRF), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and cation exchange capacity measurements. It was determined that the major clay mineral was smectite with partial impurities. The effects of several operational parameters such as contact time, initial dye concentration, temperature, and adsorbent dosage on the adsorption process were evaluated. The adsorption kinetics was interpreted with pseudo-first order, pseudo-second order, and intra-particle diffusion models. The equilibrium adsorption data were analyzed using Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherm models. It was determined that the adsorption equilibrium was reached in the first 60 min for each dye. The amount of adsorbed dyes onto clay decreased with increasing temperature, similarly, it decreased with increasing sorbent dosage. The kinetic data were well described by pseudo-second order kinetic model, and adsorption equilibrium data was followed both Langmuir and Redlich-Peterson models for each dyes. The adsorption enthalpy and entropy values were calculated as −10.7 kJ.mol−1 and −13.21 J.mol−1.K−1 for astrazon red and those for astrazon blue −11.65 kJ.mol−1 and 37.4 J.mol−1.K−1, respectively. The experimental results support that the physical interactions between clay particles and dye molecules have an important role for the spontaneous adsorption of textile dyes onto the clay. This study revealed that clay could effectively be used as an alternative adsorbent with high removal percentages of astrazon red and astrazon blue.