Distinct laccase expression and activity profiles of Trametes versicolor facilitate degradation of benzo[a]pyrene

Transcriptome analysis reveals the mechanism of tolerance to copper toxicity in the white rot fungus Trametes hirsuta AH28-2

Heavy metals, such as copper (Cu), are prevalent in the environment and pose a substantial threat to human health. White rot fungi, especially Trametes spp., display prominent Cu tolerance and removal capacity. However, how Trametes responds to environmental Cu stress remains poorly understood. Here, we found that Trametes hirsuta AH28-2 exhibits Cu removal efficiencies varying from 80.8 % at 1.25 mg/L to 57.6 % at 37 mg/L. Comparative transcriptome analysis identified 812, 1898, and 2110 differentially expressed genes (DEGs) at the Cu concentrations of 1.25, 12.5, and 25 mg/L, respectively. Some DEGs were associated with antioxidant defense systems, secondary metabolite biosynthesis (terpenoids and polyketides), transmembrane transport, and glutathione metabolism, potentially enhancing Cu tolerance. The activities of antioxidant enzymes such as superoxide dismutase, catalase, and laccase were increased under Cu stress. qRT-PCR confirmed the alterations in gene expression and demonstrated that glutathione S-transferases, catalases, cytochrome P450s, and laccases were involved in counteracting Cu-induced stress. Gene silencing experiments further confirmed the crucial roles of laccases in this process. Many transcription factors were enriched under Cu stress, including the Zn2Cys6 family transcription factor GME8421_g (TH8421), which was significantly upregulated at the Cu concentration of 12.5 mg/L. ChIP-seq identified five antioxidant enzyme-encoding genes as direct targets of TH8421, forming a regulatory network that protects against Cu stress. These findings offer insights into the molecular mechanisms driving Cu toxicity tolerance in Trametes fungi.

From nature to applications: Laccase immobilization onto bio-based materials for eco-conscious environmental remediation

Biodegradable and sustainable materials utilized for laccase immobilization have garnered substantial scholarly interest owing to their capacity to enhance enzyme stability and reusability, which are paramount for effective bioremediation methodologies. Laccase, a versatile oxidase, possesses the ability to degrade a broad spectrum of environmental contaminants, thus rendering it an invaluable asset in bioremediation endeavours. The immobilization of laccase onto biodegradable substrates not only augments its operational stability but also resonates with sustainable environmental strategies. This article systematically investigates recent advancements in sustainable and eco-conscious methodologies aimed at immobilizing laccase. By integrating biodegradable and non-toxic components, we elucidated how these materials not only proficiently enhanced the operational stability of laccases, but also improved their biodegradation effectiveness. A comprehensive analysis revealed that these sustainable materials facilitate immobilized laccase-mediated efficient removal of hazardous chemicals. Furthermore, we highlight the challenges that persist despite the encouraging characteristics of sustainable and eco-friendly approaches to laccase immobilization and pollutant elimination, and engage in discourse regarding potential pathways for their broader application and scalable solutions. This review highlights the significance of incorporating green technologies into environmental remediation efforts, thereby fostering the development of more effective and ecologically sound solutions for sustainable laccase immobilization to mitigate environmental contaminants efficiently.

Enzymatic bioremediation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil: a study on the recombinant laccase TVL

Polycyclic aromatic hydrocarbons (PAHs) are pervasive and persistent pollutants in contaminated soil, posing a severe health and environmental threat. Enzymatic bioremediation presents a viable solution for the remediation of PAH-contaminated soil. In this study, a recombinant laccase with the encoding gene originating from Trametes villosa and recombinantly expressed in Aspergillus oryzae, designated as TVL, was discovered to possess strong PAH reduction capabilities. The specific enzyme activity of TVL was 73485 and 5102 LAMU/g enzyme protein at pH 5.0/7.0 and 37°C. Furthermore, it exhibited significant benzo[a]pyrene degradation, with 100% and 90.48% degradation at pH 5.0/7.0 after 24 h in the liquid phase. The degradation process of benzo[a]pyrene in soil was thoroughly investigated. Optimal conditions were identified as 15 mg/g NK-BSoil-3 and 1.35 mg/g HBT, resulting in a removal rate of 37.54% within 7 days when 0.01 U/g of TVL was applied. The potential mechanisms were investigated using molecular docking simulation. The binding energy between benzo[a]pyrene and TVL protein is notably robust, suggesting a higher propensity for enzyme binding. The TVL protein pocket contains nine amino acids that can interact most strongly with benzo[a]pyrene. Consequently, the recombinant laccase TVL holds considerable practical significance in bioremediation.

Enhanced bioremediation of organically combined contaminated soil by white rot fungal agent: physiological characteristics and contaminants degradation

Microbial remediation of organically combined contaminated sites is currently facing technical challenges. White rot fungi possess broad-spectrum degradation capabilities, but most of the studies are conducted on polluted water bodies, and few research focus on the degradation of combined organically contaminated soils. This study aimed to investigate the physiological changes in Trametes versicolor to enhance its simultaneous degradation ability towards benzo(a)pyrene (BaP) and TPH. The results demonstrated that Trametes versicolor, when subjected to liquid fermentation, achieved an 88.08% degradation of individual BaP within 7 days. However, under the combined contamination conditions of BaP and TPH, the BaP degradation rate decreased to 69.25%, while the TPH degradation rate was only 16.95%. Furthermore, the degradation rate of BaP exhibited a significant correlation with the extracellular protein concentration and laccase activities. Conversely, the TPH degradation rate exhibited a significant and positive correlation with the intracellular protein concentration. Solid-state fermentation utilizing fungal agents proved to be the most effective method for removing BaP and TPH, yielding degradation rates of 56.16% and 15.73% respectively within 60 days. Overall, Trametes versicolor demonstrated a commendable capability for degrading combined PAHs-TPH pollutants, thereby providing theoretical insights and technical support for the remediation of organically combined contaminated sites.

Removal of benzo[a]pyrene from the soil by adsorption coupled with degradation on saponin-modified bentonite immobilized crude enzymes

Bentonite is a non-metallic mineral with montmorillonite as the main component. It is an environmentally friendly mineral material with large reserves, wide distribution, and low price. Bentonite can be easily modified organically using the surfactant saponin to obtain saponin-modified bentonite (Sap-BT). This study investigates the immobilization of crude enzymes obtained from Trametes versicolor by physical adsorption with Sap-BT. Thus, saponin-modified bentonite immobilized crude enzymes (CE-Sap-BT) were developed to remove benzo[a]pyrene. Immobilization improves the stability of free enzymes. CE-Sap-BT can maintain more than 80% of activity at 45 °C and after storage for 15 d. Additionally, CE-Sap-BT exhibited a high removal rate of benzo[a]pyrene in soil, with 65.69% after 7 d in highly contaminated allotment soil and 52.90% after 6 d in actual soil contaminated with a low concentration of benzo[a]pyrene at a very low laccase dosage (0.1 U/3 g soil). The high catalytic and removal performance of CE-Sap-BT in contaminated sites showed more excellent practical application value.

Biocatalytic degradation of environmental endocrine disruptor chlorobenzene via surfactant-optimized laccase-mediator system

The emergence of environmental endocrine disruptor chlorobenzene (CB) in surface water and its potential environmental impacts have attracted serious global attention. It is still very difficult to achieve effective degradation of it by catalytic oxidation process under mild conditions. Here, an optimized method for degrading CB in aqueous solution using Trametes versicolor laccase and surfactant-assisted laccase-mediator (SALM) system was investigated. The use of a Tween 80 surfactant enhanced the solubility of CB and promoted its efficient degradation. Under favorable conditions, the SALM system yielded a degradation efficiency of 43.5% and a dechlorination efficiency of 41.55% for CB (25 mg/L) within 24 h. The possible degradation pathway of CB by this system was speculated by detecting the intermediates produced during the reaction. The outcome of the proliferation assays on MCF-7 human breast cancer cells demonstrated a reduction in the estrogenic activity of the CB solution following treatment with the SALM system. Furthermore, the influence of the quantity and positional variation of chlorine substituents on the degradation process was methodically investigated. Moreover, molecular analyses were employed to study the detailed interaction mechanism between laccase and CB, which revealed that the hydrophobic interaction contributed dominantly to binding process. These findings provide an efficient and environmentally friendly degradation system for the development of purification strategies for halogenated pollutants.

Plant Defense Mechanisms against Polycyclic Aromatic Hydrocarbon Contamination: Insights into the Role of Extracellular Vesicles

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants that pose significant environmental and health risks. These compounds originate from both natural phenomena, such as volcanic activity and wildfires, and anthropogenic sources, including vehicular emissions, industrial processes, and fossil fuel combustion. Their classification as carcinogenic, mutagenic, and teratogenic substances link them to various cancers and health disorders. PAHs are categorized into low-molecular-weight (LMW) and high-molecular-weight (HMW) groups, with HMW PAHs exhibiting greater resistance to degradation and a tendency to accumulate in sediments and biological tissues. Soil serves as a primary reservoir for PAHs, particularly in areas of high emissions, creating substantial risks through ingestion, dermal contact, and inhalation. Coastal and aquatic ecosystems are especially vulnerable due to concentrated human activities, with PAH persistence disrupting microbial communities, inhibiting plant growth, and altering ecosystem functions, potentially leading to biodiversity loss. In plants, PAH contamination manifests as a form of abiotic stress, inducing oxidative stress, cellular damage, and growth inhibition. Plants respond by activating antioxidant defenses and stress-related pathways. A notable aspect of plant defense mechanisms involves plant-derived extracellular vesicles (PDEVs), which are membrane-bound nanoparticles released by plant cells. These PDEVs play a crucial role in enhancing plant resistance to PAHs by facilitating intercellular communication and coordinating defense responses. The interaction between PAHs and PDEVs, while not fully elucidated, suggests a complex interplay of cellular defense mechanisms. PDEVs may contribute to PAH detoxification through pollutant sequestration or by delivering enzymes capable of PAH degradation. Studying PDEVs provides valuable insights into plant stress resilience mechanisms and offers potential new strategies for mitigating PAH-induced stress in plants and ecosystems.

Bioremediation of 2,4,6-trichlorophenol by extracellular enzymes of white rot fungi immobilized with sodium alginate/hydroxyapatite/chitosan microspheres

Hydroxyapatite, a calcium phosphate biomass material known for its excellent biocompatibility, holds promising applications in water, soil, and air treatment. Sodium alginate/hydroxyapatite/chitosan (SA-HA-CS) microspheres were synthesized by cross-linking sodium alginate with calcium chloride. These microspheres were carriers for immobilizing extracellular crude enzymes from white rot fungi through adsorption, facilitating the degradation of 2,4,6-trichlorophenol (2,4,6-TCP) in water and soil. At 50 °C, the immobilized enzyme retained 87.2% of its maximum activity, while the free enzyme activity dropped to 68.86%. Furthermore, the immobilized enzyme maintained 68.09% of its maximum activity at pH 7, surpassing the 51.16% observed for the free enzyme. Under optimal conditions (pH 5, 24 h), the immobilized enzymes demonstrated a remarkable 94.7% removal rate for 160 mg/L 2,4,6-TCP, outperforming the 62.1% achieved by free crude enzymes. The degradation of 2,4,6-TCP by immobilized and free enzymes adhered to quasi-first-order degradation kinetics. Based on LC-MS, the plausible biodegradation mechanism and reaction pathway of 2,4,6-TCP were proposed, with the primary degradation product identified as 1,2,4-trihydroxybenzene. The immobilized enzyme effectively removed 72.9% of 2,4,6-TCP from the soil within 24 h. The degradation efficiency of the immobilized enzyme varied among different soil types, exhibiting a negative correlation with soil organic matter content. These findings offer valuable insights for advancing the application of immobilized extracellular crude enzymes in 2,4,6-TCP remediation.

Effects of Orange Peel Extract on Laccase Activity and Gene Expression in Trametes versicolor

The genome of Trametes versicolor encodes multiple laccase isozymes, the expression of which is responsive to various conditions. Here, we set out to investigate the potential of orange peel extract as an inducer of laccase production in this white-rot fungus, in comparison to the previously identified inducing chemical compound, veratryl alcohol. For four geographically distinct T. versicolor strains, a positive correlation has been observed between their oxidative activity and incubation time in liquid cultures. The addition of 20% orange peel extract or 5 mM veratryl alcohol caused a rapid increase in the oxidative potential of T. versicolor M99 after 24 h, with a more pronounced effect observed for the orange peel extract. To elucidate the underlying molecular mechanisms of the induced laccase activity, a transcriptional gene expression analysis was performed for the seven individual laccase genes in T. versicolor, revealing the upregulation of several laccase genes in response to the addition of each inducer. Notably, the gene encoding TvLac5 demonstrated a substantial upregulation in response to the addition of 20% orange peel extract, likely contributing to the observed increase in its oxidative potential. In conclusion, our results demonstrate that orange peels are a promising agro-industrial side stream for implementation as inducing agents in large-scale laccase production with T. versicolor.