Studies on the treatment of anaerobically digested sludge by white-rot fungi: evaluation of the effect of Phanerochaete chrysosporium and Trametes versicolor

BACKGROUND

The composition of anaerobically digested sludge is inherently complex, enriched with structurally complex organic compounds and nitrogenous constituents, which are refractory to biodegradation. These characteristics limit the subsequent rational utilization of resources from anaerobically digested sludge. White-rot fungi (WRF) have garnered significant research interest due to their exceptional capacity to degrade complex and recalcitrant organic pollutants. However, the exploration of WRF in the context of sludge treatment remains an under-investigated area within the scientific community. The present investigation explores the application of WRF in the treatment of anaerobically digested sludge, offering a novel approach for the valorization of sludge resources.

RESULTS

In this study, WRF enzymes, manganese peroxidase (MnP) and lignin peroxidase (LiP), exhibited sustained high activities of approximately 102 U/L and 26 U/L, respectively, within the anaerobically digested sludge under a controlled pH of 5.5 within the growth system. These conditions were found to significantly enhance the treatment efficacy of the anaerobic sludge. The removal of soluble chemical oxygen demand (COD) and Total COD by Trametes versicolor powder was better than that of Phanerochaete chrysosporium powder. The treatment of sludge samples with WRF, specifically Phanerochaete chrysosporium powder, resulted in a significant reduction of ultraviolet radiation (UV254). Fourier-transform infrared spectroscopy (FTIR) analysis revealed that the application of Trametes versicolor powder exerted a notably pronounced impact on the functional groups present in sludge samples. Specifically, there was a significant decrease in the peak intensities corresponding to the C-O bonds, indicative of saccharide degradation, alongside an observable increase in the intensities of amide peaks, which is suggestive of protein synthesis enhancement. Microbial community analysis demonstrated that Phanerochaete chrysosporium was the predominant fungal species, exerting a significant regulatory role within the sludge ecosystem.

CONCLUSION

In conclusion, this research furnishes a robust scientific foundation for the utilization of WRF in the treatment of anaerobic digestion sludge. It elucidates the fungi's capacity to ameliorate the physicochemical attributes and microbial community composition within the sludge. Furthermore, the study offers a certain reference for the subsequent use of WRF in the treatment of other types of sludge.

Effects of potential inducers to enhance laccase production and evaluating concomitant enzyme immobilisation

This work investigated non-polar solvent hexane and polar solvents methanol and ethanol as inducers besides a well-known inducer, copper, for laccase production with and without mesoporous silica-covered plastic packing under sterilised and unsterilised conditions. The potential of waste-hexane water, which is generated during the mesoporous silica production process, was also investigated as a laccase inducer. During the study, the free and immobilised laccase activity on the packing was measured. The results showed that the highest total laccase activity, approximately 10,000 Units, was obtained under sterilised conditions with 0.5 mM copper concentration. However, no immobilised laccase activity was detected except in the copper and ethanol sets under unsterilised conditions. The maximum immobilised laccase activity of the sets that used waste hexane as an inducer was 1.25 U/mg packing. According to its significant performance, waste hexane can be an alternative inducer under sterilised conditions. Concomitant immobilised packing showed satisfactory laccase activities and could be a promising method to reduce operation costs and improve the cost-efficiency of enzymatic processes in wastewater treatment plants.

Bioprospecting photosynthetic microorganisms for the removal of endocrine disruptor compounds

Endocrine disruption compounds can be found in various daily products, like pesticides, along with cosmetic and pharmaceutical commodities. Moreover, occurrence of EDCs in the wastewater alarms the urgency for their removal before discharge owing to the harmful effect for the environment and human health. Compared to implementation of physical and chemical strategies, cultivation of photosynthetic microorganisms has been acknowledged for their high efficiency and eco-friendly process in EDCs removal along with accumulation of valuable byproducts. During the process, photosynthetic microorganisms remove EDCs via photodegradation, bio-adsorption, -accumulation, and -degradation. Regarding their high tolerance in extreme environment, photosynthetic microorganisms have high feasibility for implementation in wastewater treatment plant. However, several considerations are critical for their scaling up process. This review discussed the potency of EDCs removal by photosynthetic microorganisms and focused on the efficiency, mechanism, challenge, along with the prospect. Details on the mechanism's pathway, accumulation of valuable byproducts, and recent progress in scaling up and application in real wastewater were also projected in this review.

Levels, distribution, sources and human exposure pathways of alkylphenol and alkylphenol ethoxylates in indoor dust in Turkiye

Environmental phenolic chemicals, due to their widespread occurrence and potent estrogenic properties, pose a risk to human exposure. The phenolic organic contaminants alkylphenols (APs) and alkylphenol polyethoxylates (APEs) are used in various household applications, and they may enter to the environment during production and use, potentially appearing in indoor dust. However, little is known about the levels of environmental phenolics in indoor environments. In this study, five of these compounds namely octylphenol (OP), 4-Octylphenol Monoethoxylate (4-OPME), 4-tert-octylphenol (4-t-OP), 4-n-nonylphenol (4-n-NP) and nonylphenol diethoxylate (di-NPE) were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in household dust samples (n = 148) collected from Ankara, the capital of Turkiye. OP and 4-OPME was not present in any of the analyzed samples. The median concentrations of the 148 settling dust samples were 35, 520, and 1910 ng g-1 dust for 4-t-OP, 4-n-NP, and di-NPE, respectively. An assessment of the human (children and adults) exposure pathway to APs and APEs, which are recognized as endocrine-disrupting chemicals found in residential dust, revealed that it was approximately 3 times higher for children than for adults at both moderate and heavy exposure levels. The association between chemical exposure, house characteristics, and family lifestyle was investigated using a multivariate logistic regression model. According to the results of this model, while the high concentrations measured for 4-t-OP were not found to be associated with any of the household parameters, high levels of 4-n-NP and di-NPE were associated with the frequency of house cleaning, repairs made during the previous year, residential type, the number of occupants, flooring materials, and the purchase of new household items within the past year. This study provides a basis for prioritizing toxicology and exposure studies for EDCs and mixtures and may offer new tools for exposure assessment in health studies.

Induction of Extracellular Hydroxyl Radicals Production in the White-Rot Fungus Pleurotus eryngii for Dyes Degradation: An Advanced Bio-oxidation Process

Among pollution remediation technologies, advanced oxidation processes (AOPs) are genuinely efficient since they are based on the production of strong, non-selective oxidants, mainly hydroxyl radicals (·OH), by a set of physicochemical methods. The biological counterparts of AOPs, which may be referred to as advanced bio-oxidation processes (ABOPs), have begun to be investigated since the mechanisms of induction of ·OH production in fungi are known. To contribute to the development of ABOPs, advanced oxidation of a wide number of dyes by the white-rot fungus Pleurotus eryngii, via a quinone redox cycling (QRC) process based on Fenton's reagent formation, has been described for the first time. The fungus was incubated with 2,6-dimethoxy-1,4-benzoquinone (DBQ) and Fe3+-oxalate, with and without Mn2+, leading to different ·OH production rates, around twice higher with Mn2+. Thanks to this process, the degradative capacity of the fungus increased, not only oxidising dyes it was not otherwise able to, but also increasing the decolorization rate of 20 dyes by more than 7 times in Mn2+ incubations. In terms of process efficacy, it is noteworthy that with Mn2+ the degradation of the dyes reached values of 90-100% in 2-4 h, which are like those described in some AOPs based on the Fenton reaction.

Characterization of laccases from Trametes hirsuta in the context of bioremediation of wastewater treatment plant effluent

The bioremediation of pharmaceutical compounds contained in wastewater, in an ecological and sustainable way, is possible via the oxidative action of fungal laccases. The discovery of new fungal laccases with unique physico-chemical characteristics pushes researchers to identify suitable laccases for specific applications. The aim of this study is to purify and characterize laccase isoenzymes produced from the Trametes hirsuta IBB450 strain for the bioremediation of pharmaceutical compounds. Two main laccases mixtures were observed and purified in the extracts and were called Yn and Yg. Peptide fingerprinting analysis suggested that Yn was constituted mainly of laccase Q02497 and Yg of laccase A0A6M5CX58, respectively. Robustness tests, based on tolerance and stability, showed that both laccases were affected in a relatively similar way by salts (KCl, NaCl), organic solvents (ACN, MeOH), denaturing compounds (urea, trypsin, copper) and were virtually unaffected and stable in wastewater. Determination of kinetic constants (Michaelis (KM), catalytic constant (kcat) and kinetic efficiency (K=kcat/KM)) for the transformation of synthetic hormone 17α-ethynylestradiol and the anti-inflammatory agent diclofenac indicates a lower KM and kcat for laccase Yn but relative similar K constant compared to Yg. Synergistic effects were observed for the transformation of diclofenac, unlike 17α-ethynylestradiol. Transformation studies of 17α-ethynylestradiol at different temperatures (4 and 21 °C) indicate a transformation rate reduction of approximately 75-80% at 4 °C against 25% for diclofenac in less than an hour. Finally, the classification of laccases Yg and Yn into one of eight groups (group A-H) suggests that laccase Yg belongs to group A (constitutive laccase) and laccase Yn belongs to group B (inducible laccase).

Structural insights, biocatalytic characteristics, and application prospects of lignin-modifying enzymes for sustainable biotechnology

Lignin modifying enzymes (LMEs) have gained widespread recognition in depolymerization of lignin polymers by oxidative cleavage. LMEs are a robust class of biocatalysts that include lignin peroxidase (LiP), manganese peroxidase (MnP), versatile peroxidase (VP), laccase (LAC), and dye-decolorizing peroxidase (DyP). Members of the LMEs family act on phenolic, non-phenolic substrates and have been widely researched for valorization of lignin, oxidative cleavage of xenobiotics and phenolics. LMEs implementation in the biotechnological and industrial sectors has sparked significant attention, although its potential future applications remain underexploited. To understand the mechanism of LMEs in sustainable pollution mitigation, several studies have been undertaken to assess the feasibility of LMEs in correlating to diverse pollutants for binding and intermolecular interactions at the molecular level. However, further investigation is required to fully comprehend the underlying mechanism. In this review we presented the key structural and functional features of LMEs, including the computational aspects, as well as the advanced applications in biotechnology and industrial research. Furthermore, concluding remarks and a look ahead, the use of LMEs coupled with computational framework, built upon artificial intelligence (AI) and machine learning (ML), has been emphasized as a recent milestone in environmental research.

Ligninolytic enzyme activity and removal efficiency of pharmaceuticals in a water matrix by fungus Rhizopus sp. Isolated from cassava

Residual amounts of pharmaceutical compounds (PhCs) and by-products are continually released into surface water with effluents from conventional wastewater treatment plants (WWTPs). This study evaluated the ability of fungal isolate to remove selected PhCs [carbamazepine (CBZ), diclofenac (DCF) and ibuprofen (IBP)] from wastewater. The fungus used was Rhizopus sp. which was isolated from tuberous roots of cassava (Manihot esculenta). The isolate exhibited an important removal efficiency up to 100% and this was linked to ligninolytic enzymatic activity for lignin peroxidase (15.29 ± 2.69U/L) and manganese peroxidase (85.22 ± 4.26U/L), except laccase. This activity was optimum on day 9 of treatment. PhC metabolites were identified during the experiment revealing the existence of a biotransformation process catalysed by the isolated fungus. The disappearance of PhCs was attributed to their biosorption and biotransformation. However, it was not possible to establish a relationship between the ligninolytic enzymatic activity and the removal efficiency, which leads to the conclusion that there are other fungal metabolites which also play an important role in the biotransformation and biodegradation of the selected PhCs.

Hierarchically-structured laccase@Ni3(PO4)2 hybrid nanoflowers for antibiotic degradation: Application in real wastewater effluent and toxicity evaluation

Laccase@Ni₃(PO₄)₂ hybrid nanoflowers (HNFs) were prepared by the anisotropic growth of biomineralized nickel phosphate. The immobilization yield was 77.5 ± 3.6 %, and the immobilized enzyme retained 50 % of its initial activity after 18 reusability cycles. The immobilized and free enzymes lost 80 % of their activity after 18 and 6 h incubation in municipal wastewater effluent (MWWE), respectively. The increase in α-helix content (8 %) following immobilization led to a more rigid enzyme structure, potentially contributing to its improved stability. The removal of ciprofloxacin from MWWE by laccase@Ni₃(PO₄)₂·HNFs/p-coumaric acid oxidation system was optimized using a Box-Behnken design. Under the optimized conditions [initial laccase activity (0.05 U mL^-1), the concentration of p-coumaric acid (2.9 mM), and treatment time (4.9 h)], the biocatalyst removed 90 % of ciprofloxacin (10 mg L^-1) from MWWE. The toxicity of ciprofloxacin against some G⁺ and G^- bacteria was reduced by 35-70 %, depending on their strain. The EC₅₀ of ciprofloxacin for the alga Raphidocelis subcapitata reduced from 3.08 to 1.07 mg L^-1 (p-value <0.05) after the bioremoval. Also, the acute and chronic toxicity of identified biodegradation products was lower than ciprofloxacin at three trophic levels, as predicted by ECOSAR software.

Transcriptomic analysis of lipid metabolism in zebrafish offspring of parental long-term exposure to bisphenol A

Bisphenol A (BPA) is one of the most common environmental endocrine disruptor chemicals (EDCs) and exhibits reproductive, cardiovascular, immune, and neurodevelopmental toxic effects. The development of the offspring was examined in the present investigation to determine the cross-generational effects of long-term exposure of parental zebrafish to environmental concentrations of BPA (15 and 225 µg/L). Parents were exposed to BPA for 120 days, and their offspring were evaluated at 7 days after fertilization in BPA-free water. The offspring exhibited higher mortality, deformity, and heart rates, and showed significant fat accumulation in abdominal region. RNA-Seq data showed that more lipid metabolism-related KEGG pathways, such as the PPAR signaling pathway, adipocytokine signaling pathway, and ether lipid metabolism pathway were enriched in the 225 µg/L BPA-treated offspring compared to 15 µg/L BPA-treated offspring, indicating greater effects of high dose BPA on offspring lipid metabolism. Lipid metabolism-related genes implied that BPA is responsible for disrupting lipid metabolic processes in the offspring through increased lipid production, abnormal transport, and disruption of lipid catabolism. The present study will be helpful for further evaluation of the reproductive toxicity of environmental BPA to organisms and the subsequent parent-mediated intergenerational toxicity.

The Relationship between Typical Environmental Endocrine Disruptors and Kidney Disease

Endocrine disrupting chemicals (EDCs) are exogenous substances that alter the endocrine function of an organism, to result in adverse effects on growth and development, metabolism, and reproductive function. The kidney is one of the most important organs in the urinary system and an accumulation point. Studies have shown that EDCs can cause proteinuria, affect glomeruli and renal tubules, and even lead to diabetes and renal fibrosis in animal and human studies. In this review, we discuss renal accumulation of select EDCs such as dioxins, per- and polyfluoroalkyl substances (PFAS), bisphenol A (BPA), and phthalates, and delineate how exposures to such EDCs cause renal lesions and diseases, including cancer. The regulation of typical EDCs with specific target genes and the activation of related pathways are summarized.

Bibliometric analysis of global research on white rot fungi biotechnology for environmental application

In recent years, white rot fungi (WRFs) have received tremendous attention as a biotechnological tool for environmental pollution control. In order to systematically and comprehensively describe the progress, trends, and hotspots of WRF biotechnology in the field of environmental pollution control, the 3967 related publications from 2003 to 2020 were collected from Web of Science Core Collection database, and the bibliometric characteristics including publication output, country, institution, journal, author, citation frequency, h-index, and research focus were evaluated by using Excel 2007, CiteSpace V, and VOSviewer. The results indicated that the number of research publications increased rapidly before 2009, but after that, the number of publications fluctuated in a certain range. China and USA were the most productive countries and the most active country in international cooperation. In this field, most authors tend to cooperate within a small group. The journal and subject category with the largest number of publications are "International Biodeterioration & Biodegradation" and "Biotechnology Applied Microbiology", respectively. The analysis of high-frequency keywords revealed that "laccase", "biodegradation", "decolorization", and "Phanerochaete chrysosporium" were the most cited terms among all publications. The pretreatment of biomass waste, decolorization of dye wastewater, and bioremediation of polluted environment are the key research directions of WRF biotechnology. Finally, the frontier topics and active authors in this research field were identified using burst detection. We believe that this bibliometric study provides a comprehensive and systematic overview and promoted the future cooperative research and knowledge exchange in this field of WRF biotechnology for environmental applications.

Occurrence, spatial distribution and risk assessment of high concern endocrine-disrupting chemicals in Jiangsu Province, China

Endocrine-disrupting chemicals (EDCs) have attracted much concern because of the environmental and health risks they pose. Here we used liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry to quantify 10 types of EDCs at 118 sampling sites in Jiangsu Province, China, and then evaluated their respective environmental risk using a conservative risk quotient method. The results show that, in surface water, the targeted nonylphenol (NP), 4-tert-octylphenol (4-t-OP), and (2-ethylhexyl)phthalate (DEHP) were ranked highest, having mean concentrations above 300 ng/L. In comparison, both 4-t-OP and DEHP were also ranked highest, with mean concentrations above 100 ng/g, in the sediment samples. Moreover, the ∑₁₀EDCs concentration in the Huai River Basin was similar to that in the Yangtze River Basin. Notably, Huai'an city had the maximum mean concentration for EDCs in the Huai River Basin, followed by Xuzhou city and Suqian city, while Yangzhou city ranked highest in the Yangtze River Basin. Furthermore, the corresponding risk distribution revealed that (1) NP, bisphenol A (BPA), and 4-t-OP are of medium to high risk in 70%, 100% and 95% of the surface water samples, and likewise in 45%, 88% and 100% of the sediment samples, respectively; the maximum RQ value for NP in surface water samples reached 74.9; (2) DEHP belongs to the high-risk category in all samples (100%), whose maximum RQ reached 54.7. To our best knowledge, this is the first study to report on the occurrence, spatial distribution, and risk assessment of EDCs of high concern in Jiangsu Province, China.

Molecular Decoration of Ceramic Supports for Highly Effective Enzyme Immobilization-Material Approach

A highly effective method was developed to functionalize ceramic supports (Al₂O₃ powders and membranes) using newly synthesized spacer molecules. The functionalized materials were subsequently utilized for Candida antarctica lipase B enzyme immobilization. The objective is to systematically evaluate the impact of various spacer molecules grafted onto the alumina materials will affect both the immobilization of the enzymes and specific material surface properties, critical to enzymatic reactors performance. The enzyme loading was significantly improved for the supports modified with shorter spacer molecules, which possessed higher grafting effectiveness on the order of 90%. The specific enzyme activity was found to be much higher for samples functionalized with longer modifiers yielding excellent enantioselectivity >97%. However, the enantiomeric ratio of the immobilized lipase was slightly lower in the case of shorter spacer molecules.

Endocrine-disruptive chemicals as contaminants of emerging concern in wastewater and surface water: A review

Population growth followed by rapid development of industrialisation has caused serious environmental pollution with contaminants of emerging concern found in wastewater and surface water. As one of the most important resources for human survival, water is daily polluted by endocrine-disruptive chemicals (EDCs) including pharmaceuticals and personal care products, organic pollutants and heavy metals. Even at low concentrations in water bodies, chronic exposure to EDCs can cause adverse effects on human and environment health. The main concern with EDCs is the diseases they can generate in humans or wildlife by affecting the function of hormones in the body. Problems in the reproductive system, thyroid problems, Alzheimer's, cancer and obesity are some of the major effects of EDCs in humans. In wildlife, the reproductive system may be affected, including its levels of hatchability and vitellogenin. The efforts of the present review are on emphasising on the environmental concern on the occurrence and risk assessment of EDCs, their harmful effects in the ecosystem, human life, and wildlife, as a result of their incomplete removal from wastewater treatment plants. The review focuses on studies conducted in South Africa highlights the use of fungal bioreactors as a low-cost and eco-effective environmentally friendly wastewater treatment processes.

White rot fungi can be a promising tool for removal of bisphenol A, bisphenol S, and nonylphenol from wastewater

Endocrine-disrupting chemicals (EDC) are a wide group of chemicals that interfere with the endocrine system. Their similarity to natural steroid hormones makes them able to attach to hormone receptors, thereby causing unfavorable health effects. Among EDC, bisphenol A (BPA), bisphenol S (BPS), and nonylphenol (NP) seem to be particularly harmful. As the industry is experiencing rapid expansion, BPA, BPS, and NP are being produced in growing amounts, generating considerable environmental pollution. White rot fungi (WRF) are an economical, ecologically friendly, and socially acceptable way to remove EDC contamination from ecosystems. WRF secrete extracellular ligninolytic enzymes such as laccase, manganese peroxidase, lignin peroxidase, and versatile peroxidase, involved in lignin deterioration. Owing to the broad substrate specificity of these enzymes, they are able to remove numerous xenobiotics, including EDC. Therefore, WRF seem to be a promising tool in the abovementioned EDC elimination during wastewater treatment processes. Here, we review WRF application for this EDC removal from wastewater and indicate several strengths and limitations of such methods.

Genetic Diversity and Dye-Decolorizing Spectrum of Schizophyllum commune Population

Synthetic dyes are widely used in various industries and their wastage causes severe environmental problems while being hazardous to human health, leading to the need for eco-friendly degradation techniques. The split-gill fungus Schizophyllum commune, which is found worldwide, has the potential to degrade all components of the lignocellulosic biomass and is a candidate for the treatment of synthetic dyes. A systematic molecular analysis of 75 Korean and 6 foreign S. commune strains has revealed the high genetic diversity of this population and its important contribution to the total diversity of S. commune. We examined the dye decolorization ability of this population and revealed 5 excellent strains that strongly decolorized 3 dyes: Crystal Violet, Congo Red and Methylene Blue. Finally, comparison of dye decolorization ability and the phylogenetic identification of these strains generalized their genetic and physiological diversity. This study provides an initial resource for physiological and genetic research projects as well as the bioremediation of textile dyes.

Persistence, ecological risks, and oxidoreductases-assisted biocatalytic removal of triclosan from the aquatic environment

Triclosan (TCS) has been immensely employed in health care products and consumer items, as an active agent with fungicidal and bactericidal potentialities, such as soaps, sanitizers, tubes of toothpaste, deodorants, skin creams, and so on for over last five decades. The ultimate excretory route of TCS ends in our water matrices, thus has been frequently detected with ecological and human-health related matters and hazards. Bioactive residues of TCS reach into the key atmosphere compartment through numerous routes, such as (1) scarce or ineffective elimination or degradation throughout the treatment practices, (2) abandoned landfill leachates, (3) leakage from the discarded TCS-containing materials, and so on. Such persistence and occurrence of TCS or its degraded but bioactive residues have growing attentions. Its complete removal and/or effective prevention are still challenging tasks for safeguarding the environment. Owing to the highly effective catalytic and stability potential, enzyme-based bio-degradation approaches are considered an evocative substitute for TCS mitigation from environmental matrices. As compared to enzymes in their pristine form, immobilized enzymes, with unique catalytic, stability, selectivity, and reusability profile, are of supreme and strategic interest in environmental biotechnology. Herein, an effort has been made to signify the novel bio-catalytic and bio-degradation potentialities of various oxidoreductases, including laccases, and peroxidases including soybean peroxidase, versatile manganese peroxidase, and horseradish peroxidase with suitable examples. Following a brief introduction, the focus is given to the presence of TCS in the key atmosphere compartments. Potential sources, acquaintance, and hazardous influence of TCS are also discussed with recent and relevant examples. The second half shows the TCS removal/degradation potentialities of soluble enzyme-based catalytic systems and immobilized-enzyme-based catalytic systems. Finally, the concluding remarks, along with possible future directions are given in this significant research arena.

From Laboratory Tests to the Ecoremedial System: The Importance of Microorganisms in the Recovery of PPCPs-Disturbed Ecosystems

The presence of a wide variety of emerging pollutants in natural water resources is an important global water quality challenge. Pharmaceuticals and personal care products (PPCPs) are known as emerging contaminants, widely used by modern society. This objective ensures availability and sustainable management of water and sanitation for all, according to the 2030 Agenda. Wastewater treatment plants (WWTP) do not always mitigate the presence of these emerging contaminants in effluents discharged into the environment, although the removal efficiency of WWTP varies based on the techniques used. This main subject is framed within a broader environmental paradigm, such as the transition to a circular economy. The research and innovation within the WWTP will play a key role in improving the water resource management and its surrounding industrial and natural ecosystems. Even though bioremediation is a green technology, its integration into the bio-economy strategy, which improves the quality of the environment, is surprisingly rare if we compare to other corrective techniques (physical and chemical). This work carries out a bibliographic review, since the beginning of the 21st century, on the biological remediation of some PPCPs, focusing on organisms (or their by-products) used at the scale of laboratory or scale-up. PPCPs have been selected on the basics of their occurrence in water resources. The data reveal that, despite the advantages that are associated with bioremediation, it is not the first option in the case of the recovery of systems contaminated with PPCPs. The results also show that fungi and bacteria are the most frequently studied microorganisms, with the latter being more easily implanted in complex biotechnological systems (78% of bacterial manuscripts vs. 40% fungi). A total of 52 works has been published while using microalgae and only in 7% of them, these organisms were used on a large scale. Special emphasis is made on the advantages that are provided by biotechnological systems in series, as well as on the need for eco-toxicological control that is associated with any process of recovery of contaminated systems.

Biodegradation and toxicity reduction of nonylphenol, 4-tert-octylphenol and 2,4-dichlorophenol by the ascomycetous fungus Thielavia sp HJ22: Identification of fungal metabolites and proposal of a putative pathway

Research on the biodegradation of emerging pollutants is gained great focus regarding their detrimental effects on the environment and humans. The objective of the present study was to evaluate the ability of the ascomycetes Thielavia sp HJ22 to remove the phenolic xenobiotics nonylphenol (NP), 4-tert-octylphenol (4-tert-OP) and 2,4-dichlorophenol (2,4-DCP). The strain showed efficient degradation of NP and 4-tert-OP with 95% and 100% removal within 8 h of incubation, respectively. A removal rate of 80% was observed with 2,4-DCP within the same time. Under experimental conditions, the degradation of the tested pollutants concomitantly increased with the laccase production and cytochrome P450 monooxygenases inhibition. This study showed the involvement of laccase in pollutants removal together with biosorption mechanisms. Additionally, results demonstrated the participation of cytochrome P450 monooxygenase in the elimination of 2,4-DCP. Liquid chromatography-mass spectrometry analysis revealed several intermediates, mainly hydroxylated and oxidized compounds with less harmful effects compared to the parent compounds. A decrease in the toxicity of the identified metabolites was observed using Aliivibrio fischeri as bioindicator. The metabolic pathways of degradation were proposed based on the identified metabolites. The results point out the potential of Thielavia strains in the degradation and detoxification of phenolic xenobiotics.

Ecofriendly laccases treatment to challenge micropollutants issue in municipal wastewaters

In this study, a multidisciplinary approach investigated the enzymatic degradation of micropollutants in real, not modified, municipal wastewaters of a plant located in Italy. Stir Bar Sorptive Extraction combined to Gas Chromatography-Mass Spectrometric detection (SBSE-GC-MS) was applied to profile targeted pollutants in wastewaters collected after the primary sedimentation (W1) and the final effluent (W2). Fifteen compounds were detected at ng/L - μg/L, including pesticides, personal care products (PCPs) and drugs. The most abundant micropollutants were bis(2-ethylhexyl) phthalate, diethyl phthalate and ketoprofen. Laccases of Trametes pubescens MUT 2400 were very active against all the target micropollutants: except few cases, their concentration was reduced more than 60%. Chemical analysis and environmental risk do not always come together. To verify whether the treated wastewaters can represent a stressor for the aquatic ecosystem, toxicity was also evaluated. Raphidocelis subcapitata and Lepidium sativum tests showed a clear ecotoxicity reduction, even though they did not evenly respond. Two in vitro tests (E-screen test and MELN assay) were used to evaluate the estrogenic activity. Treatments already operating in the plant (e.g. activated sludge) partially reduced the estradiol equivalent concentration, and it was almost negligible after the laccases treatment. The results of this study suggest that laccases of T. pubescens are promising biocatalysts for the micropollutants transformation in wastewaters and surface waters.

Immobilization of laccase onto meso-MIL-53(Al) via physical adsorption for the catalytic conversion of triclosan

Due to the abundant binding sites and high stability, a synthesized meso-MIL-53(Al) was selected as the backbone and used for immobilizing laccase (Lac-MIL-53(Al)) to catalytically degrade of TCS. XRD, BET and FTIR analyses proved that the carboxyl groups on PTA of meso-MIL-53(Al) could provide sufficient adsorption sites for physically immobilizing laccase through hydrogen bonds and electrostatic interactions. Although the catalytic efficiency of V_max/K_m slightly decreased from 785 to 607 min^-1 due to the mass transfer limitation upon immobilized, Lac-MIL-53(Al) showed high activity recovery (93.8%) and stability. The conformational analysis indicated the laccase could partially enter into the MOF by conformational changes without impairing laccase, although the laccase molecular (6.5 nm × 5.5 nm × 4.5 nm) was larger than the mesopore sizes of the MOF (4 nm). The kinetics indicated that Lac-MIL-53(Al) could remove 99.24% of TCS within 120 min due to the synergy effect of the adsorption of meso-MIL-53(Al) and catalytic degradation of laccase. Meanwhile, Lac-MIL-53(Al) could remain approximately 60% of activity for up to 8 times reuse without desorption. The GC/MS and LC/MS/MS analyses further confirmed that TCS could be transformed to 2, 4-DCP by laccase via the breakage of the ether bond, or to passivated dimers, trimers and tetramers by the self-coupling and oxidization of the phenoxyl radicals, and finally removed by precipitation. In summary, enzyme-MOF composite might be a potential strategy to control the micropollutants in the wastewater.

Mitigation of bisphenol A using an array of laccase-based robust bio-catalytic cues - A review

Bisphenol A (BPA) is a known endocrine disruptor that poses concerning environmental and human-health related issues and ecological risks. It has been largely used as an intermediate in the manufacture of epoxy resins and polycarbonate plastics. Traces of BPA can reach into the environment through inadequate or inefficient removal during wastewater treatment, uncontrolled landfill leachates, and leaching out from the discarded BPA-based materials. Several physicochemical treatment methods including adsorption, Fenton, ozonation, electrochemical and photochemical degradation, and membrane filtration, have been applied for BPA elimination. However, these methods are not adequate for large-scale treatment due to some inherent limitations. Benefiting from high catalytic efficiency and specificity, enzyme-based bio-catalytic degradation strategies are considered quite meaningful alternative for efficient and effective BPA removal from different routes. Among various oxidoreductases, i.e., laccases exhibited a superior potential for the remediation of BPA-containing wastewater. Enzymatic oxidation of BPA can be boosted by using various natural or synthetic redox mediators. Immobilized enzymes can expand their applicability to continuous bioprocessing and facilitates process intensification. Therefore, optimized formulations of insolubilized biocatalysts are of strategic interest in the environmental biotechnology. In this review, recent research studies dealing with BPA removal by the laccase-catalyzed system are presented. At first, the presence of BPA in the ecosystem, sources, exposure, and its impact on the living organisms and human beings is summarized. Then, we highlighted the use of crude as well as immobilized laccases for the degradation of BPA. In addition to toxicity and estrogenicity removal studies, the unresolved challenges, concluding remarks, and possible future direction is proposed in this important research area. It is palpable from the literature reviewed that free as well as immobilized forms of laccases have displayed noteworthy potential for BPA removal from wastewater.

High-Throughput, Rapid Quantification of Phthalic Acid Esters and Alkylphenols in Fish Using a Coated Direct Inlet Probe Coupled with Atmospheric Pressure Chemical Ionization

Intake of endocrine-disrupting chemicals (EDCs) by humans could disturb the metabolism of hormones, induce cancer, and damage the liver and other organs. Phthalate acid esters (PAEs) and alkylphenols (APs) are important EDCs and environmental contaminants. With the increasing use of plastics and nonionic surfactants worldwide, PAEs and APs have entered environmental water and accumulated in edible fish, which are finally consumed by humans. In this study, a coated direct inlet probe (CDIP) based on an atmospheric solid analysis probe, which can rapidly and simultaneously extract both PAEs and APs in fish, was developed. Twelve PAEs and APs were quantified by using a stable-isotope-labeled internal standard. Standard curves of the PAEs and APs having correlation coefficients of R² ≥ 0.9837 were obtained. The limit of detection of the PAEs and APs was distributed from 0.01 to 40 ng g^-1. The relative recovery of the method was 78-120% between low, medium, and high spiked levels. Combined with principal component analysis, PAE- and AP-contaminated Carassius auratus from different habitats could be identified. Multiple sample analysis mode allowed the extraction of up to 12 samples at once, and the total analysis time (including sample pretreatment, extraction, and analysis time) was less than 10 min per sample, which indicates that CDIP is useful for rapid quantitative analysis.

4-n-nonylphenol degradation by the genus Metarhizium with cytochrome P450 involvement

In this study, the ability of 4-n-nonylphenol (4-n-NP) elimination by fungal species belonging to the genus Metarhizium was investigated. The occurrence of 35 metabolites from 4-n-NP degradation was confirmed. For the first time, based on the obtained results, the 4-n-NP biodegradation pathway distinctive for the genus Metarhizium was proposed. Principal Component Analysis (PCA) indicated that despite the similar elimination pathway in all the examined Metarhizium species, there are significant differences in the kinetics of degradation of 4-n-NP. Oxidation of the terminal methyl group of the aliphatic chain leading to the formation of carboxylic acids coupled with the removal of terminal carbon is characteristic of M. robertsii and M. guizhouense, whereas metabolites with a hydroxyl group in the distal part of the nonyl chain distinguish M. lepidiotae and M. majus. Additionally, this study verified the participation of cytochrome P450 in the elimination of the xenobiotic by Metarhizium as experimentally proven for M. robertsii.

Peroxidases-assisted removal of environmentally-related hazardous pollutants with reference to the reaction mechanisms of industrial dyes

Environmental protection is one of the most important challenges for the humankind. Increasing number of emerging pollutants resulting from industrial/human-made activities represents a serious menace to the ecological and environmental equilibrium. Industrial dyes, endocrine disrupters, pesticides, phenols and halogenated phenols, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and other xenobiotics are among the top priority environmental pollutants. Some classical remediation approaches including physical, chemical and biological are being employed, but are ineffective in cleaning the environment. Enzyme-catalyzed transformation reactions are gearing accelerating attention in this context as potential alternatives to classical chemical methods. Peroxidases are catalysts able to decontaminate an array of toxic compounds by a free radical mechanism resulting in oxidized or depolymerized products along with a significant toxicity reduction. Admittedly, enzymatic catalysis offers the hallmark of high chemo-, regio-, and enantioselectivity and superior catalytic efficiency under given reaction environment. Moreover, enzymes are considered more benign, socially acceptable and greener production routes since derived from the renewable and sustainable feedstock. Regardless of their versatility and potential use in environmental processes, several limitations, such as heterologous production, catalytic stability, and redox potential should be overcome to implement peroxidases at large-scale transformation and bio-elimination of recalcitrant pollutants. In this article, a critical review of the transformation of different types of hazardous pollutants by peroxidases, with special reference to the proposed reaction mechanisms of several dyes is presented. Following that major challenges for industrial and environmental applications of peroxidases are also discussed. Towards the end, the information is also given on miscellaneous applications of peroxidases, concluding remarks and outlook.

Microfluidic System for Rapid Detection of Airborne Pathogenic Fungal Spores

Airborne fungi, including Aspergillus species, are the major causes of human asthma. Direct capture and analysis of pathogenic fungi in indoor air is important for disease prevention and control. In this paper, we demonstrated an integrated microfluidic system capable of enrichment and high-throughput detection for airborne fungal spores of Aspergillus niger, a well-known allergenic harmful species. The microfluidic system allowed semiquantitative detection of Aspergillus niger spores based on immunofluorescence analysis. To assess its contaminated level, the whole analysis time could be completed in 2-3 h including ∼1 h of enrichment and ∼1 h of target detection. The detection limit was ∼20 spores, equivalent to ∼300 spores·m^-3 of the concerned targets in air. In addition, the microfluidic system has integrated sampling and sample analysis to avoid additional sample concentration step, showing the potential for point-of-care detection for other pathogenic fungal spores.

Ligninolytic enzymes: Versatile biocatalysts for the elimination of endocrine-disrupting chemicals in wastewater

Direct municipal wastewater effluent discharge from treatment plants has been identified as the major source of endocrine‐disrupting chemicals (EDC) in freshwaters. Consequently, efficient elimination of EDC in wastewater is significant to good water quality. However, conventional wastewater treatment approaches have been deficient in the complete removal of these contaminants. Hence, the exploration of new and more efficient methods for elimination of EDC in wastewater is imperative. Enzymatic treatment approach has been suggested as a suitable option. Nonetheless, ligninolytic enzymes seem to be the most promising group of enzymes for EDC elimination, perhaps, owing to their unique catalytic properties and characteristic high redox potentials for oxidation of a wide spectrum of organic compounds. Therefore, this paper discusses the potential of some ligninolytic enzymes (laccase, manganese peroxidase, and versatile peroxidase) in the elimination of EDC in wastewater and proposes a new scheme of wastewater treatment process for EDC removal.

Removal of pharmaceutical compounds in water and wastewater using fungal oxidoreductase enzymes

Due to recalcitrance of some pharmaceutically active compounds (PhACs), conventional wastewater treatment is not able to remove them effectively. Therefore, their occurrence in surface water and potential environmental impact has raised serious global concern. Biological transformation of these contaminants using white-rot fungi (WRF) and their oxidoreductase enzymes has been proposed as a low cost and environmentally friendly solution for water treatment. The removal performance of PhACs by a fungal culture is dependent on several factors, such as fungal species, the secreted enzymes, molecular structure of target compounds, culture medium composition, etc. In recent 20 years, numerous researchers tried to elucidate the removal mechanisms and the effects of important operational parameters such as temperature and pH on the enzymatic treatment of PhACs. This review summarizes and analyzes the studies performed on PhACs removal from spiked pure water and real wastewaters using oxidoreductase enzymes and the data related to degradation efficiencies of the most studied compounds. The review also offers an insight into enzymes immobilization, fungal reactors, mediators, degradation mechanisms and transformation products (TPs) of PhACs. In brief, higher hydrophobicity and having electron-donating groups, such as amine and hydroxyl in molecular structure leads to more effective degradation of PhACs by fungal cultures. For recalcitrant compounds, using redox mediators, such as syringaldehyde increases the degradation efficiency, however they may cause toxicity in the effluent and deactivate the enzyme. Immobilization of enzymes on supports can enhance the performance of enzyme in terms of reusability and stability. However, the immobilization strategy should be carefully selected to reduce the cost and enable regeneration. Still, further studies are needed to elucidate the mechanisms involved in enzymatic degradation and the toxicity levels of TPs and also to optimize the whole treatment strategy to have economical and technical competitiveness.

The transformation of triclosan by laccase: Effect of humic acid on the reaction kinetics, products and pathway

This study systematically explored the effect of humic acid (HA) (as model of natural organic matter) on the kinetics, products and transformation pathway of triclosan (TCS) by laccase-catalyzed oxidation. It was found that TCS could be effectively transformed by laccase-catalysis, with the apparent second-order rate constant being 0.056 U^-1 mL min^-1. HA inhibited the removal rate of TCS. HA-induced inhibition was negatively correlated with HA concentration in the range of 0-10 mg L^-1 and pH-dependent from 3.5 to 9.5. FT-IR and ¹³C NMR spectra showed a decrease of aromatic hydroxyl (phenolic) groups and an increase of aromatic ether groups, indicating the cross-linking of HA via C-O-C and C-N-C bonds during enzyme-catalyzed oxidation. Ten principle oxidative products, including two quinone-like products (2-chlorohydroquinone, 2-chloro-5-(2,4-dichlodichlorophenoxy)-(1,4)benzoquinone), one chlorinated phenol (2,4-dichlorophenol (2,4-DCP)), three dimers, two trimmers and two tetramers, were detected by gas chromatograghy/mass spectrometry (GC-MS) and high performance liquid chromatography/quadrupole time-of-flight/mass spectrometry (HPLC/Q-TOF/MS). The presence of HA induced significantly lesser generation of self-polymers and enhanced cross-coupling between HA and self-polymers via C-O-C, C-N-C and C-C coupling pathways. A plausible transformation pathway was proposed as follows: TCS was initially oxidized to form reactive phenoxyl radicals, which self-coupled to each other subsequently by C-C and C-O pathway, yielding self-polymers. In addition, the scission of ether bond was also observed. The presence of HA can promote scission of ether bond and further oxidation of phenoxyl radicals, forming hydroxylated or quinone-like TCS. This study shed light on the behavior of TCS in natural environment and engineered processes, as well provided a perspective for the water/wastewater treatment using enzyme-catalyzed oxidation techniques.

The effect of operational parameters on the biodegradation of bisphenols by Trametes versicolor laccase immobilized on Hippospongia communis spongin scaffolds

Due to the rapid growth in quantities of phenolic compounds in wastewater, the development of efficient and environmentally friendly methods for their removal becomes a necessity. Thus, in a presented work, for the first time, a novel material, Hippospongia communis spongin-based scaffold, was used as a biopolymeric support for the immobilization of laccase from Trametes versicolor. The resulting biocatalytic systems were used for the biodegradation of three bisphenols: bisphenol A (BPA), bisphenol F (BPF) and bioremoval-resistant bisphenol S (BPS). Optimization of the immobilization and biodegradation methodologies was performed to increase bisphenols removal. The effect of temperature, pH and initial pollutant concentration was evaluated. It was shown that under optimal conditions, almost 100% of BPA (pH5, 30°C) and BPF (pH5, 40°C), and over 40% of BPS (pH4, 30°C) was removed from the solution at a concentration of 2mg/mL. Furthermore, the immobilized laccase exhibited good reusability and storage stability, retaining over 80% of its initial activity after 50days of storage. In addition, the main biodegradation products of BPA and BPF were identified. It was shown that mainly dimers and trimers were formed following the oxidation of bisphenols by the immobilized laccase.

Laccase-Mediated Treatment of Pharmaceutical Wastes

Laccases are versatile multi-copper enzymes belonging to the superfamily of oxidase enzymes, which have been known since the nineteenth century. Recent discoveries have refined investigators' views of the potential of laccase as a magic tool for remarkable biotechnological purposes. A literature review of the capabilities of laccases, their assorted substrates, and their molecular mechanism of action now indicates the emergence of a new direction for laccase application as part of an arsenal in the fight against the contamination of water supplies by a number of frequently prescribed medications. This chapter provides a critical review of the literature and reveals the pivotal role of laccases in the elimination and detoxification of pharmaceutical contaminants in aquatic environments and wastewaters.

Degradation of 17α-ethinylestradiol by nano zero valent iron under different pH and dissolved oxygen levels

The catalytic properties of nanoparticles (e.g., nano zero valent iron, nZVI) have been used to effectively treat a wide range of environmental contaminants. Emerging contaminants such as endocrine disrupting chemicals (EDCs) are susceptible to degradation by nanoparticles. Despite extensive investigations, questions remain on the transformation mechanism on the nZVI surface under different environmental conditions (redox and pH). Furthermore, in terms of the large-scale requirement for nanomaterials in field applications, the effect of polymer-stabilization used by commercial vendors on the above processes is unclear. To address these factors, we investigated the degradation of a model EDC, the steroidal estrogen 17α-ethinylestradiol (EE₂), by commercially sourced nZVI at pH 3, 5 and 7 under different oxygen conditions. Following the use of radical scavengers, an assessment of the EE₂ transformation products shows that under nitrogen purging direct reduction of EE₂ by nZVI occurred at all pHs. The radicals transforming EE₂ in the absence of purging and upon air purging were similar for a given pH, but the dominant radical varied with pH. Upon air purging, EE₂ was transformed by the same radical species as the non-purged system at the same respective pH, but the degradation rate was lower with more oxygen - most likely due to faster nZVI oxidation upon aeration, coupled with radical scavenging. The dominant radicals were OH at pH 3 and O₂^- at pH 5, and while neither radical was involved at pH 7, no conclusive inferences could be made on the actual radical involved at pH 7. Similar transformation products were observed without purging and upon air purging.

Interactions of carbon nanotubes and/or graphene with manganese peroxidase during biodegradation of endocrine disruptors and triclosan

Molecular-level biodegradation processes of bisphenol A (BPA), nonylphenol (NP) and triclosan (TCS) mediated by manganese peroxidase (MnP) were investigated with and without single-walled carbon nanotube (SWCNT) and/or graphene (GRA). Although the incorporation of SWCNT, GRA or their combination (SWCNT+GRA) did not break up the complexes composed of manganese peroxidase (MnP) and these substrates, they had different effects on the native contacts between the substrates and MnP. GRA tended to decrease the overall stability of the binding between MnP and its substrates. SWCNT or SWCNT+GRA generally had a minor impact on the mean binding energy between MnP and its substrates. We detected some sensitive residues from MnP that were dramatically disturbed by the GRA, SWCNT or SWCNT+GRA. Nanomaterials changed the number and behavior of water molecules adjacent to both MnP and its substrates, which was not due to the destruction of H-bond network formed by sensitive regions and water molecules. The present results are useful for understanding the molecular basis of pollutant biodegradation affected by the nanomaterials in the environment, and are also helpful in assessing the risks of these materials to the environment.

Laccases: Production, Expression Regulation, and Applications in Pharmaceutical Biodegradation

Laccases are a family of copper-containing oxidases with important applications in bioremediation and other various industrial and biotechnological areas. There have been over two dozen reviews on laccases since 2010 covering various aspects of this group of versatile enzymes, from their occurrence, biochemical properties, and expression to immobilization and applications. This review is not intended to be all-encompassing; instead, we highlighted some of the latest developments in basic and applied laccase research with an emphasis on laccase-mediated bioremediation of pharmaceuticals, especially antibiotics. Pharmaceuticals are a broad class of emerging organic contaminants that are recalcitrant and prevalent. The recent surge in the relevant literature justifies a short review on the topic. Since low laccase yields in natural and genetically modified hosts constitute a bottleneck to industrial-scale applications, we also accentuated a genus of laccase-producing white-rot fungi, Cerrena, and included a discussion with regards to regulation of laccase expression.

From the conventional biological wastewater treatment to hybrid processes, the evaluation of organic micropollutant removal: A review

Because of the recalcitrance of some micropollutants to conventional wastewater treatment systems, the occurrence of organic micropollutants in water has become a worldwide issue, and an increasing environmental concern. Their biodegradation during wastewater treatments could be an interesting and low cost alternative to conventional physical and chemical processes. This paper provides a review of the organic micropollutants removal efficiency from wastewaters. It analyses different biological processes, from conventional ones, to new hybrid ones. Micropollutant removals appear to be compound- and process- dependent, for all investigated processes. The influence of the main physico-chemical parameters is discussed, as well as the removal efficiency of different microorganisms such as bacteria or white rot fungi, and the role of their specific enzymes. Even though some hybrid processes show promising micropollutant removals, further studies are needed to optimize these water treatment processes, in particular in terms of technical and economical competitiveness.

Assessment of methods of detection of water estrogenicity for their use as monitoring tools in a process of estrogenicity removal

Methods of monitoring of estrogenicity in water were gathered, compared, and tested within the context of their practical use as measurement and design tools, in the development of a process of degradation of estrogenic endocrine disruptors. In this work, the focus was put on in vitro assays, with the use of analytical techniques as additional analysis when possible. Practically, from a literature review, four methods that seemed most suitable to practical use required in a process development were tested: the Yeast Estrogen Screen assay, the Lyticase-assisted Yeast Estrogen Screen assay (LYES), the MMV-LUC assay and the HPLC-UV analytical method. Dose-response curves in response to estrogenic standard 17β-estradiol were compared. Bisphenol A estrogenicity was measured by the methods as well. The model for the calculation of estradiol equivalents as measurements units was adapted. The methods were assessed in terms of ranges of detection, time of experiment, cost, ease of the experiment, reproducibility, etc. Based on that assessment, the LYES assay was selected and successfully applied to the monitoring of estrogenicity removal from 17β-estradiol and bisphenol A. More precisely, the bioassay allowed the acquisition of kinetic curves for a laboratory-scaled process of estrogenicity removal by immobilized enzymes in a continuous packed-bed reactor. The LYES assay was found to have a real methodological potential for scale-up and design of a treatment process. The HPLC-UV method showed good complementarity with the LYES assay for the monitoring of bisphenol A concentrations in parallel with estrogenicity, reporting no significant estrogenicity from degradation byproducts, among others.

Green Disposal of Waste Bisphenol A

Bisphenol A (BPA) is an important precursor for polycarbonates and epoxy resins that are used to make products that many would consider essential for modern living. Unfortunately, BPA is an endocrine disrupter and more and more evidence is being uncovered about its negative effects on humans as well as on organisms in the environment. Sustainable chemistry means we take everything into account in designing a chemical process: the risks, the costs, the benefits, and so on. BPA is not likely to be replaced by a less toxic chemical in the foreseeable future, nor is our society willing to give up valuable polycarbonate products. As part of sustainable green chemistry, we want to assure that any toxic chemicals that leave a manufacturing plant pose a minimal risk to the environment. Using a green method to clean up effluent before it is released into the environment would be ideal. In this report, little bluestem seeds are shown to be capable of degrading BPA in aqueous solutions. This gives them the potential to be used in reducing the amount of BPA that may be in effluent. Additionally, an enzyme was isolated that was responsible for degrading BPA and this could also have potential for the treatment of effluent.

Fabrication highly dispersed Fe3O4 nanoparticles on carbon nanotubes and its application as a mimetic enzyme to degrade Orange II

Fe3O4 nanoparticles were grown in situ on carbon nanotubes (CNTs) by a solvothermal method. The Fe3O4/CNTs composites were characterised by the Brunauer-Emmett-Teller method and transmission electron microscopy. The results indicated that the Fe3O4 nanoparticles were uniformly deposited on CNTs, and the average diameter was approximately 7.0 nm. The Fe3O4/CNTs were applied as an enzyme mimetic to decompose Orange II, and the decomposing conditions were optimised. At 500 mg L(-1) of Fe3O4/CNTs in the presence of 15.0 mmol L(-1) of H2O2, at 30°C, it degraded 94.0% of Orange II (0.25 mmol L(-1), pH = 3.5), showing higher catalytic activity than pure Fe3O4 nanoparticles. The high activity was attributed to the uniform Fe3O4 nanoparticles growing on the side walls of the CNTs and the synergetic effect between Fe3O4 and CNTs. The Fe3O4/CNTs maintained their activity at temperatures as high as 65°C. The Fe3O4/CNTs presented high reusability and stability even after eight uses. These data proved that the Fe3O4/CNTs-catalysed degradation is a promising technique for wastewater treatment. Fe3O4 nanoparticles were grown in situ on carbon nanotubes (CNTs) by a solvothermal method. The Fe3O4/CNTs was applied as a mimetic enzyme to decompose Orange II. The Fe3O4/CNTs were collected after the reaction by applying an external magnetic field and can use repeatedly.