Synergistic degradation of Azure B and sulfanilamide antibiotics by the white-rot fungus Trametes versicolor with an activated ligninolytic enzyme system

The treated wastewater enhances the biodegradation of sulfonamide antibiotics in biofilm-sediment downstream of the receiving river outlet

Although the treated wastewater meets the discharge standards, it can still become a potential transmitted stressor that affects aquatic organisms in receiving rivers. Biofilms and sediments as the main solid-phase substances in natural aquatic environments can biodegrade micropollutants. However, most of the current studies have selected a single solid-phase material, and there are relatively few studies that comprehensively consider the effect of treated wastewater on the dissipation of micropollutants in a composite biofilm-sediment system. Therefore, this study investigated the dissipation pathways of six sulfonamide antibiotics (SAs) in biofilm-sediment and the effect of treated wastewater on SAs dissipation. The results showed that biodegradation was the main pathway for SAs dissipation in biofilm-sediment. The input of treated wastewater increased the abundance of dominant degradation bacteria Burkholderiales and Pseudomonadale, thereby improving the biodegradation rate of SAs (approximately 1.5 times higher than upstream degradation rate). These genera could also be further integrated into downstream communities to continuously mediate the biodegradation of SAs. Through mass spectrometry and metagenomic sequencing analysis, it was found that the common degradation pathways of SAs in biofilm-sediment affected by treated wastewater are acetylation, formylation, hydroxylation, and bond cleavage. Acetyltransferase played an important role in the biodegradation of SAs. In addition, the enrichment of antibiotic resistant genes during biodegradation increased the risk of their spread in the aquatic environment. These findings provide new insights into the fate of antibiotics in aquatic environments and the impact of treated wastewater on downstream bacterial communities.

Insights into the Imidaclothiz Biodegradation by the White-Rot Fungus Phanerochaete sordida YK-624 under Ligninolytic Conditions

Imidaclothiz (IMZ), an innovative neonicotinoid insecticide, has attracted significant interest due to its environmental persistence and consequent ecological implications. In this research, the white-rot fungus Phanerochaete sordida YK-624 was used to degrade IMZ, unveiling a novel fungal degradation mechanism. The results demonstrated that IMZ was efficiently degraded by P. sordida YK-624. Transcriptomic analysis revealed that IMZ-induced stress triggered a cascade of enzymatic and cellular defense responses that are instrumental in facilitating its biodegradation. Through inhibitor experiments and enzyme activity profiling, cytochrome P450 and manganese peroxidase (MnP) were identified to play crucial roles in IMZ biodegradation. Additionally, three metabolites were isolated and identified by NMR, and two innovative degradation pathways involving hydroxylation and nitro reduction were proposed. Toxicity assessment suggested the reduced environmental risk of IMZ after its degradation by P. sordida YK-624. These findings provided insights into the IMZ degradation mechanism and highlighted the potential of white-rot fungi in neonicotinoid bioremediation.

Eliminating antibiotics by white-rot-fungi Trametes versicolor from manure solids and synthetic wastewater

Antibiotics have been abused in livestock as veterinary drug and feed additive. Their incomplete metabolization by animals resulted in heavy accumulation in livestock manure, and therefore they can pose a threat to the environment. In this study, the mechanism of three antibiotics (oxytetracycline (OTC), sulfadiazine (SDZ), enrofloxacin (ENR)) removal/biodegradation by Trametes versicolor pellets in air-pulse fluidized-bed reactor was explored, and the effects of wood immobilized T. versicolor on four antibiotics (OTC, SDZ, ENR and chloramphenicol (CAP)) removal in solid cow manures were evaluated. T. versicolor could remove OTC, SDZ, ENR through adsorption and biodegradation, with the removal efficiency at 92% and 98% in 21 hours and 98% after 68 hours, respectively. The removal kinetics of those three antibiotics fitted well with the first-order kinetic model, with the removal constant k at -0.238 h-1, -0.102 h-1 and -0.023 h-1, respectively. T. versicolor could biodegrade those three antibiotics using laccase and cytochrome P450 system with the order SDZ≈OTC>ENR. Furthermore, wood immobilized T. versicolor promoted SDZ, OTC, ENR and chloramphenicol (CAP) antibiotic biodegradation in cow manure, especially in high inoculation ratio (wood immobilized T. versicolor: solid cow manures=1:2). This study revealed the mechanism of simultaneous SDZ, OTC, ENR and CAP antibiotic removal/biodegradation by white-rot fungi T. versicolor even by wood immobilized T. versicolor in solid cow manures, which provide a theoretical basis for future application of biological removal of antibiotics present in wastewater and solid manures.

NADH flavin oxidoreductase and catalase-induced reactive oxygen species and key enzymes synergistically drive oxidative degradation of xanthene dye Rose Bengal in Aspergillus flavus A5P1

This study showed that Aspergillus flavus A5P1 efficiently degrades Rose Bengal dye through the synergistic action of extracellular reactive oxygen species (H₂O₂ and O₂-) and key enzymes (laccase, lignin peroxidase, and quinone reductase), confirmed by quenching and enzyme activity assays. An abnormal 90 % decreased in intracellular catalase activity, increased superoxide dismutase activity, and elevated superoxide anion content were observed under dye stress, but no detectable H₂O₂ accumulation was found, suggesting that intracellularly generated H₂O₂ and O₂- were transported extracellularly via transmembrane mechanisms. Genome and transcriptome analyses reveal a complete ROS generation and transport pathway, with upregulated genes for ROS production (e.g., NADH flavin oxidoreductase) and transmembrane transporters, while catalase genes are downregulated. Based on these findings, this study proposes a novel mechanism of " dye induction - intracellular ROS generation - transmembrane transport - intra- and extracellular synergistic degradation". Specifically, dye stress induces the production of H2O2 and O2- within cells. These ROS are subsequently transported to the extracellular environment via transmembrane systems, where they synergize with extracellular ROS and traditional key decolorization enzymes to achieve efficient dye degradation. This discovery provides a critical theoretical foundation for the development of ROS-enzyme synergistic dye bioremediation processes.

Biodegradation of ciprofloxacin by a manganese-oxidizing fungus Cladosporium sp. XM01: Performance and transcriptome analysis

Biogenic manganese (Mn) oxidation presents a promising approach for ciprofloxacin (CIP) removal from wastewater, yet the interaction between Mn bio-oxidation and CIP degradation remains unclear. The Mn-oxidizing fungus Cladosporium sp. XM01 was selected as a model strain in this study, to explore the impacts of CIP on microbial growth, function and biotransformation. Results showed that CIP exhibited a promotive effect on the growth and Mn(II) oxidation capacity of XM01. After 192 h of cultivation, 39.80 %-69.19 % of CIP was removed by XM01 in the absence of Mn(II), while over 84 % was removed with 300 μM Mn(II), demonstrating both direct and Mn(II)-enhanced indirect degradation of CIP. Transcriptomic analysis revealed that the upregulation of ribosome, peroxisome, and tyrosine metabolism pathways enhanced XM01's adaptation to CIP and supported microbial growth. Cytochrome P450 (CYP450) enzymes were implicated as key mediators in CIP degradation. Additionally, in the presence of Mn(II), the further upregulation of transmembrane transporters, NAD(P)H dehydrogenase, and CYP450 indicated that Mn bio-oxidation enhanced XM01's adaptation and response to CIP, thereby accelerating its degradation. Proposed CIP degradation pathways include piperazine epoxidation, decarboxylation, and hydroxylation. This study advances the understanding of fungal Mn oxidation in antibiotic removal, emphasizing its potential in wastewater treatment.

Interactions between the co-contamination system of oxcarbazepine-polypropylene microplastics and Chlorella sp. FACHB-9: Toxic effects and biodegradation

The co-contamination of microplastics and pharmaceutical pollutants has attracted increasing attention. However, studies on the joint toxicity of pollutants on organisms in aquatic ecosystems are still lacking. This study aimed to investigate the joint toxicity of oxcarbazepine (OXC, 30 mg/L) and polypropylene microplastics (PP-MPs, 500 mg/L and particle size of 180 μm) microplastics on microalgae (Chlorella sp. FACHB-9) and the biodegradation of OXC by strain FACHB-9. Compared to the single OXC exposure, the cell density of microalgae was decreased by 38.93% in OXC/PP-MPs co-contamination system, with enhanced oxidative stress and decreased photosynthetic efficiency. Transcriptomic analyses indicated that photosynthetic pathways and TCA cycle pathways were significantly inhibited, while DNA damage repair pathways were up regulated in microalgae co-exposed to OXC and PP-MPs. Moreover, strain FACHB-9 showed a remarkable degradation effect (91.61% and 86.27%) on OXC in single and mixture group, respectively. These findings significantly expanded the existing knowledge on the joint toxicity of pollutants on microalgae, indicating prospective promise of microalgae for the bioremediation of polluted aquatic environments.

Immobilization of Peniophora incarnata F1 in PVA-SA-biochar matrix and its degradation performance and mechanism for erythromycin degradation

Erythromycin is becoming one of the most common contaminants detected in surface water and wastewater, which poses a potential risk to ecological systems and human health. Until now, there is still no effective way to eliminate it. Herein, a novel and efficient erythromycin-degrading fungus Peniophora incarnata F1, capable of utilizing erythromycin as its sole source of carbon and energy, was isolated from contaminated sludge. Moreover, a fungal immobilization system was developed using polyvinyl alcohol (PVA), sodium alginate (SA) and rape straw biochar (RB) to enhance the removal ability of erythromycin. Under optimal conditions of 30 °C and pH 6.0, the removal rate of erythromycin with PVA-SA-RB@F1 within 5 d reached 89.90%, which is 31.43% higher than that of free strain F1 (58.47%). Furthermore, eight biodegradation products of erythromycin were identified, and five compounds were firstly reported. Based on these metabolites, we inferred erythromycin was transformed to simple products mainly by dehydration, desugar, dehydrogenation, ester bond hydrolysis and carbon chain cleavage reactions. Finally, PVA-SA-RB@F1 were applied to wastewater contained 10 mg/L and 50 mg/L erythromycin, with the removal rates of 100% and 64.97%, respectively. These results show that PVA-SA-RB@F1 can be used as an effective tool to remove erythromycin in water environment. Therefore, this study provides a feasible strategy for bioremediation of erythromycin polluted environment.

A Chromosome-Scale Genome of Trametes versicolor and Transcriptome-Based Screening for Light-Induced Genes That Promote Triterpene Biosynthesis

Trametes versicolor is an important fungus with medicinal properties and a significant role in lignocellulose degradation. In this study, we constructed a high-quality chromosome-level genome of T. versicolor using Illumina, PacBio HiFi, and Hi-C sequencing technologies. The assembled genome is 47.42 Mb in size and contains 13,307 protein-coding genes. BUSCO analysis revealed genome and gene completeness results of 95.80% and 95.90%, respectively. Phylogenetic analysis showed that T. versicolor is most closely related to T. pubescens, followed by T. cinnabarina and T. coccinea. Comparative genomic analysis identified 266 syntenic blocks between T. versicolor and Wolfiporia cocos, indicating a conserved evolutionary pattern between the two species. Gene family analysis highlighted the expansion and contraction of genes in functional categories related to the biosynthesis of secondary metabolites, including several T. versicolor-specific genes. Key genes involved in lignocellulose degradation and triterpene production were identified within the CAZyme and CYP450 gene families. Transcriptomic analysis under dark and light conditions revealed significant changes in the expression of genes related to secondary metabolism, suggesting that light signals regulate metabolic pathways. A total of 2577 transporter proteins and 2582 membrane proteins were identified and mapped in the T. versicolor genome, and 33 secondary metabolite gene clusters were identified, including two light-sensitive triterpene biosynthesis clusters. This study offers a comprehensive genomic resource for further investigation into the functional genomics, metabolic regulation, and triterpene biosynthesis of T. versicolor, providing valuable insights into fungal evolution and biotechnological applications.

Isolation and screening of wood-decaying fungi for lignocellulolytic enzyme production and bioremediation processes

The growing demand for novel enzyme producers to meet industrial and environmental needs has driven interest in lignocellulose-degrading fungi. In this study, lignocellulolytic enzyme production capabilities of environmental fungal isolates collected from boreal coniferous and nemoral summer green deciduous forests were investigated, using Congo Red, ABTS, and Azure B as indicators of cellulolytic and ligninolytic enzyme productions. Through qualitative and quantitative assays, the study aimed to identify promising species for lignocellulose-degrading enzyme secretion and assess their potential for biotechnological applications. Primary screening tests showed intensive enzyme secretion by certain isolates, particularly white rot fungi identified as Trametes pubescens and Cerrena unicolor. These fungi exhibited high efficiency in degrading Congo Red and Azure B. The isolates achieved up to a 93.30% decrease in Congo Red induced color intensity and over 78% decolorization of Azure B within 168 hours. Within 336 hours, these fungi reached nearly 99% removal of Congo Red and up to 99.79% decolorization of Azure B. Enzyme activity analysis confirmed the lignin-degrading capabilities of T. pubescens, which exhibited laccase activity exceeding 208 U/mL. Furthermore, Fomitopsis pinicola showed the highest cellulose-degrading potential among the studied fungi, achieving cellulase activity over 107 U/L during Congo Red decolorization. Previously undescribed enzyme-producing species, such as Peniophora cinerea, Phacidium subcorticalis, and Cladosporium pseudocladosporioides, also demonstrated promising lignocellulolytic enzyme production potential, achieving up to 98.65% and 99.80% decolorization of Congo Red and Azure B, respectively. The study demonstrates novel candidates for efficient lignocellulolytic enzyme production with broad biotechnological applications such as biomass conversion, wastewater treatment, textile dye and other complex chemical removal, and environmental remediation.

Insights into the removal of antibiotics from livestock and aquaculture wastewater by algae-bacteria symbiosis systems

With the burgeoning growth of the livestock and aquaculture industries, antibiotic residues in treated wastewater have become a serious ecological threat. Traditional biological wastewater treatment technologies-while effective for removing conventional pollutants, such as organic carbon, ammonia and phosphate-struggle to eliminate emerging contaminants, notably antibiotics. Recently, the use of microalgae has emerged as a sustainable and promising approach for the removal of antibiotics due to their non-target status, rapid growth and carbon recovery capabilities. This review aims to analyse the current state of antibiotic removal from wastewater using algae-bacteria symbiosis systems and provide valuable recommendations for the development of livestock/aquaculture wastewater treatment technologies. It (1) summarises the biological removal mechanisms of typical antibiotics, including bioadsorption, bioaccumulation, biodegradation and co-metabolism; (2) discusses the roles of intracellular regulation, involving extracellular polymeric substances, pigments, antioxidant enzyme systems, signalling molecules and metabolic pathways; (3) analyses the role of treatment facilities in facilitating algae-bacteria symbiosis, such as sequencing batch reactors, stabilisation ponds, membrane bioreactors and bioelectrochemical systems; and (4) provides insights into bottlenecks and potential solutions. This review offers valuable information on the mechanisms and strategies involved in the removal of antibiotics from livestock/aquaculture wastewater through the symbiosis of microalgae and bacteria.

Transformation of antibiotics to non-toxic and non-bactericidal products by laccases ensure the safety of Stropharia rugosoannulata

The substantial use of antibiotics contributes to the spread and evolution of antibiotic resistance, posing potential risks to food production systems, including mushroom production. In this study, the potential risk of antibiotics to Stropharia rugosoannulata, the third most productive straw-rotting mushroom in China, was assessed, and the underlying mechanisms were investigated. Tetracycline exposure at environmentally relevant concentrations (<500 μg/L) did not influence the growth of S. rugosoannulata mycelia, while high concentrations of tetracycline (>500 mg/L) slightly inhibited its growth. Biodegradation was identified as the main antibiotic removal mechanism in S. rugosoannulata, with a degradation rate reaching 98.31 % at 200 mg/L tetracycline. High antibiotic removal efficiency was observed with secreted proteins of S. rugosoannulata, showing removal efficiency in the order of tetracyclines > sulfadiazines > quinolones. Antibiotic degradation products lost the ability to inhibit the growth of Escherichia coli, and tetracycline degradation products could not confer a growth advantage to antibiotic-resistant strains. Two laccases, SrLAC1 and SrLAC9, responsible for antibiotic degradation were identified based on proteomic analysis. Eleven antibiotics from tetracyclines, sulfonamides, and quinolones families could be transformed by these two laccases with degradation rates of 95.54-99.95 %, 54.43-100 %, and 5.68-57.12 %, respectively. The biosafety of the antibiotic degradation products was evaluated using the Toxicity Estimation Software Tool (TEST), revealing a decreased toxicity or no toxic effect. None of the S. rugosoannulata fruiting bodies from seven provinces in China contained detectable antibiotic-resistance genes (ARGs). This study demonstrated that S. rugosoannulata can degrade antibiotics into non-toxic and non-bactericidal products that do not accelerate the spread of antibiotic resistance, ensuring the safety of S. rugosoannulata production.

Quantitative assessment, molecular docking and novel metabolic pathways reveal the interaction mechanisms between norfloxacin biodegradation and environmental implications

Norfloxacin (NOR) is widely used in medicine and animal husbandry, but its accumulation in the environment poses a substantial threat to ecological and human health. Traditional physical, chemical, and rudimentary biological methods often fall short in mitigating NOR contamination, necessitating innovative biological approaches. This study proposes an engineered bacterial consortium found in marine sediment as a strategy to enhance NOR degradation through inter-strain co-metabolism of diverse substrates. Strategically supplementing the engineered bacterial consortium with exogenous carbon sources and metal ions boosted the activity of key degradation enzymes like laccase, manganese peroxidase, and dehydrogenase. Iron and amino acids demonstrated synergistic effects, resulting in a remarkable 70.8% reduction in NOR levels. The innovative application of molecular docking elucidated enzyme interactions with NOR, uncovering potential biodegradation mechanisms. Quantitative assessment reinforced the efficiency of NOR degradation within the engineered bacterial consortium. Four metabolic routes are herein proposed: acetylation, defluorination, ring scission, and hydroxylation. Notably, this study discloses distinctive, co-operative metabolic pathways for NOR degradation within the specific microbial community. These findings provide new ways of understanding and investigating the bioremediation potential of NOR contaminants, which may lead to the development of more sustainable and effective environmental management strategies.

Detoxification of tetracycline and synthetic dyes by a newly characterized Lentinula edodes laccase, and safety assessment using proteomic analysis

Fungal laccase has strong ability in detoxification of many environmental contaminants. A putative laccase gene, LeLac12, from Lentinula edodes was screened by secretome approach. LeLac12 was heterogeneously expressed and purified to characterize its enzymatic properties to evaluate its potential use in bioremediation. This study showed that the extracellular fungal laccase from L. edodes could effectively degrade tetracycline (TET) and the synthetic dye Acid Green 25 (AG). The growth inhibition of Escherichia coli and Bacillus subtilis by TET revealed that the antimicrobial activity was significantly reduced after treatment with the laccase-HBT system. 16 transformation products of TET were identified by UPLC-MS-TOF during the laccase-HBT oxidation process. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that LeLac12 could completely mineralize ring-cleavage products. LeLac12 completely catalyzed 50 mg/L TET within 4 h by adding AG (200 mg/L), while the degradation of AG was above 96% even in the co-contamination system. Proteomic analysis revealed that central carbon metabolism, energy metabolism, and DNA replication/repair were affected by TET treatment and the latter system could contribute to the formation of multidrug-resistant strains. The results demonstrate that LeLac12 is an efficient and environmentally method for the removal of antibiotics and dyes in the complex polluted wastewater.