Transformation Pathways of the Recalcitrant Pharmaceutical Compound Carbamazepine by the White-Rot Fungus Pleurotus ostreatus: Effects of Growth Conditions

Bio-electrochemical degradation of carbamazepine (CBZ): A comprehensive study on effectiveness, degradation pathway, and toxicological assessment

Recent attention on the detrimental effects of pharmaceutically active compounds (PhACs) in natural water has spurred researchers to develop advanced wastewater treatment methods. Carbamazepine (CBZ), a widely recognized anticonvulsant, has often been a primary focus in numerous studies due to its prevalence and resistance to breaking down. This study aims to explore the effectiveness of a bio-electrochemical system in breaking down CBZ in polluted water and to assess the potential harmful effects of the treated wastewater. The results revealed bio-electro degradation process demonstrated a collaborative effect, achieving the highest CBZ degradation compared to electrodegradation and biodegradation techniques. Notably, a maximum CBZ degradation efficiency of 92.01% was attained using the bio-electrochemical system under specific conditions: Initial CBZ concentration of 60 mg/L, pH level at 7, 0.5% (v/v) inoculum dose, and an applied potential of 10 mV. The degradation pathway established by identifying intermediate products via High-Performance Liquid Chromatography-Mass Spectrometry, revealed the complete breakdown of CBZ without any toxic intermediates or end products. This finding was further validated through in vitro and in vivo toxicity assays, confirming the absence of harmful remnants after the degradation process.

Low uptake of pharmaceuticals in edible mushrooms grown in polluted biogas digestate

The uptake dynamics of two sulfonamide antibiotics, two fluoroquinolone antibiotics, and the anticonvulsant carbamazepine during the cultivation of two species of edible mushrooms (Agaricus subrufescens and A. bisporus) was investigated. None of the antibiotics were accumulated by the mushrooms, while carbamazepine and its transformation product carbamazepine-10,11-epoxide were taken up by A. bisporus fruiting body but only in small amounts (up to 0.76 and 1.85 μg kg-1 dry weight, respectively). The sulfonamides were quickly removed from the mushroom growth substrate, while the recalcitrant fluoroquinolones and carbamazepine were only partially removed. Dissipation half-lives were generally lower for A. subrufescens than A. bisporus, but A. subrufescens was also grown at a slightly higher culture temperature. A. subrufescens also showed a lower uptake of contaminants. Comparison of maximum dietary intake with other common exposure sources showed that these mushrooms can safely be eaten although produced on a polluted substrate, with respect to the investigated compounds.

Various species of Basidiomycota fungi reveal different abilities to degrade pharmaceuticals and also different pathways of degradation

The presence of pharmaceuticals (PhACs) in the aquatic environment is an emerging problem worldwide. PhACs reach surface water via the effluents of wastewater treatment plants (WWTPs). WWTPs, although able to remove organic pollutants, do not always remove PhACs. Currently, in the treatment of sewage with the activated sludge method, numerous microorganisms are used, mostly bacteria. Nevertheless, these microorganisms are not resistant to many drug contaminants, and some may also pose a risk to human health. White-rot fungi (WRF), which degrade a wide spectrum of environmental pollutants, may be used as an alternative to microorganisms. However, little data exists comparing the removal of various PhACs by different WRF. In this study, we aimed to determine the ability of three WRF Basidiomycota species, Armillaria mellea, Phanerochaete chrysosporium, and Pleurotus ostreatus, to remove PhACs from various therapeutic groups over the course of 1 h-4 days. Additionally, we identified the fungal metabolites of PhACs, proposed the degradation pathways, and assessed the toxicity of the post-culture media. All selected WRF removed PhACs, but the degree of removal depended on WRF species and PhACs type. Antidepressants and immunosuppressants were removed most efficiently by P. ostreatus, cardiovascular drugs and sulfamethoxazole by A. mellea, and erythromycin by P. chrysosporium. The vast differences observed highlight the need for more intensive testing of different WRF species to select the best species for removing pharmaceuticals of interest. The structure of metabolites generated during degradation strongly depended on WRF species, but the most frequent xenobiotic transformations were oxidation and dealkylation. The obtained results gave insight into the substrate specificity of selected WRF while also providing a broad extension of the knowledge of pharmaceutical degradation by A. mellea.

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.

Ozone- and Hydroxyl Radical-Mediated Oxidation of Pharmaceutical Compounds Using Ni-Doped Sb-SnO2 Anodes: Degradation Kinetics and Transformation Products

Electrochemical oxidation provides a versatile technique for treating wastewater streams onsite. We previously reported that a two-layer heterojunction Ni-Sb-SnO₂ anode (NAT/AT) can produce both ozone (O₃) and hydroxyl radical (^•OH). In this study, we explore further the applicability of NAT/AT anodes for oxidizing pharmaceutical compounds using carbamazepine (CBZ) and fluconazole (FCZ) as model probe compounds. Details of the oxidation reaction kinetics and subsequent reaction products are investigated in the absence and presence of chloride (Cl^-) and sulfate (SO₄ ^2-). In all cases, faster or comparable degradation kinetics of CBZ and FCZ are achieved using the double-layered NAT/AT anode coupled with a stainless steel (SS) cathode in direct comparison to an identical setup using a boron-doped diamond anode. Production of O₃ on NAT/AT enhances the elimination of both parent compounds and their transformation products (TPs). Very fast CBZ degradation is observed during NAT/AT-SS electrolysis in both NaClO₄ and NaCl electrolytes. However, more reaction products are identified in the presence of Cl^- than ClO₄ ^- (23 TPs vs 6). Rapid removal of FCZ is observed in NaClO₄, while the degradation rate is retarded in NaCl depending on the [Cl^-]. In SO₄ ^2--containing electrolytes, altered reaction pathways and transformation product distributions are observed due to sulfate radical generation. SO₄ ^·- oxidation produces fewer hydroxylated products and promotes the oxidation of aldehydes to carboxylic acids. Similar trend in treatment performance is observed in mixtures of CBZ and FCZ with other pharmaceutical compounds in latrine wastewater and secondary WWTP effluent.

Understanding the biodegradation pathways of azo dyes by immobilized white-rot fungus, Trametes hirsuta D7, using UPLC-PDA-FTICR MS supported by in silico simulations and toxicity assessment

No biodegradation methods are absolute in the treatment of all textile dyes, which leads to structure-dependent degradation. In this study, biodegradation of three azo dyes, reactive black 5 (RB5), acid blue 113 (AB113), and acid orange 7 (AO7), was investigated using an immobilized fungus, Trametes hirsuta D7. The degraded metabolites were identified using UPLC-PDA-FTICR MS and the biodegradation pathway followed was proposed. RB5 (92%) and AB113 (97%) were effectively degraded, whereas only 30% of AO7 was degraded. Molecular docking simulations were performed to determine the reason behind the poor degradation of AO7. Weak binding affinity, deficiency in H-bonding interactions, and the absence of interactions between the azo (-NN-) group and active residues of the model laccase enzyme were responsible for the low degradation efficiency of AO7. Furthermore, cytotoxicity and genotoxicity assays confirmed that the fungus-treated dye produced non-toxic metabolites. The observations of this study will be useful for understanding and further improving enzymatic dye biodegradation.

Investigating the biological degradation of the drug β-blocker atenolol from wastewater using the SBR

Drug compounds are one of the main contributors to the entry of micro-pollutants into the environment, known as a constant threat to environmental stability. Atenolol is a type of beta-blocker extensively used to cure cardiovascular disorders. The residues of this compound have been continuously detected in aquatic environments because it is a polar and poorly biodegradable compound. Thus, removing atenolol from wastewater is essential before discharging into the environment. Biological processes are considered the most important removal process for polar drugs in wastewater treatment plants. Accordingly, for the first time in this study, the SBR performance was investigated in the biodegradation and mineralization of atenolol under different concentrations (50-600 mg/L) and hydraulic retention times (48-32 h). Based on the results, the time required for the acclimation of biomass to atenolol (C: 50 mg/L and the HRT: 48 h) was 80 days. The SBR efficiencies under optimum conditions (C: 400 mg/L and HRT: 40 h) in removing the atenolol and COD were 91% and 87%, respectively. For the first time in this study, one of the main pathways of the atenolol biodegradation was identified. Based on the review and comparison of the results of this study with existing literature showing that the SBR used in this study was able to remove higher concentrations with better efficiencies than other processes. Therefore, it can be concluded that the SBR used in this study could be considered an efficient and promising technique for treating wastewaters containing atenolol and other beta-blocker group drugs.

Fate of contaminants of emerging concern in the reclaimed wastewater-soil-plant continuum

Reclaimed wastewater irrigation, a common agricultural practice in water-scarce regions, chronically exposes the agricultural environment to a wide range of contaminants of emerging concern (CECs) including pharmaceuticals and personal care products. Here we provide new data and insights into the processes governing the translocation of CECs in the irrigation water-soil-plant continuum based on a comprehensive dataset from 445 commercial fields irrigated with reclaimed wastewater. We report on CEC exposures in irrigation water, soils, and edible produce (leafy greens, carrots, potatoes, bananas, tomatoes, avocados, and citrus fruits). Our data show that CEC concentrations in irrigation water and their physiochemical properties (mainly charge and lipophilicity) are the main factors governing their translocation and accumulation in the soil-plant continuum. CECs exhibiting the highest detection frequency in plants (lamotrigine, venlafaxine, and carbamazepine) showed a reduction in their leaf accumulation factor with increasing soil organic matter content. The higher soil organic matter likely reduced the available CEC concentration in the soil solution due to soil-CEC interactions, leading to reduced uptake. Interestingly, the concentration of carbamazepine in the leaves showed a saturation-like trend when plotted against its concentration in the soils. This probably resulted from steady-state conditions when uptake equals in-planta decomposition. Our data indicate that due to continuous reclaimed wastewater irrigation, the soil acts as a sink for CECs. CECs in the soil reservoir can be desorbed into the soil solution during the rainy season and be taken up by rain-fed crops.

White Rot Fungi Produce Novel Tire Wear Compound Metabolites and Reveal Underappreciated Amino Acid Conjugation Pathways

There is increasing concern about tire wear compounds (TWCs) in surface water and stormwater as evidence grows on their toxicity and widespread detection in the environment. Because TWCs are prevalent in stormwater, there is a need to understand fate and treatment options including biotransformation in green infrastructure (e.g., bioretention). Particularly, fungal biotransformation is not well-studied in a stormwater context despite the known ability of certain fungi to remove recalcitrant contaminants. Here, we report the first study on fungal biotransformation of the TWCs acetanilide and hexamethoxymethylmelamine (HMMM). We found that the model white rot fungus, Trametes versicolor, removed 81.9% and 69.6% of acetanilide and HMMM, respectively, with no significant sorption to biomass. The bicyclic amine 1,3-diphenylguanidine was not removed. Additionally, we identified novel TWC metabolites using semi-untargeted metabolomics via high-resolution mass spectrometry. Key metabolites include multiple isomers of HMMM biotransformation products, melamine as a possible "dead-end" product of HMMM (verified with an authentic standard), and a glutamine-conjugated product of acetanilide. These metabolites have implications for environmental toxicity and treatment. Our discovery of the first fungal glutamine-conjugated product highlights the need to investigate amino acid conjugation as an important pathway in biotransformation of contaminants, with implications in other fields including natural products discovery.

Assessing a co-culture fungal granule ability to remove pharmaceuticals in a sequencing batch reactor

Biodegradation of carbamazepine (CBZ), diclofenac sodium (DCF) and ibuprofen (IBP) was evaluated through fungal granules development in a sequencing batch reactor (SBR). Fungal granules were developed in co-culture of T. polyzona, A. niger, T. longibrachiatum, M. circinelloides and R. microsporus at a retention time (RT) of 2 days and 1 day. Ligninolytic enzymes [laccase (Lac), lignin peroxidase (LiP) and manganese peroxidase (MnP)] were determined. Removal of pharmaceuticals was assessed and metabolites identified using the SPE-UPLC-QToF/MS methods. A pH range of 3-4.6 was found to improve the granulation development from day 6 and the production of ligninolytic enzymes [MnP (253.00 ± 14.19 U/L), Lac (111.58 ± 10.00 U/L) and LiP (95.25 ± 8.22 U/L)]. At steady-state, a removal of 97.41±0.25%, 99.83±0.14%, and 99.91±0.08 were achieved at an RT of 2 days for CBZ, DCF, and IBP, respectively, and of 91.94±0.05%, 99.31±0.12% and 97.72±0.23% at an RT of 1 days for the same PhCs. A variety of chemical reactions have been proposed for degradation pathways catalysed by enzyme-producing fungi, generating fragment ions of intermediate compounds. This study is highly relevant for cost-effective and environmentally friendly wastewater treatment processes in water scare countries.

Novel pathway and acetate-facilitated complete atenolol degradation by Hydrogenophaga sp. YM1 isolated from activated sludge

Atenolol is a widely prescribed beta-blocker that has been detected in wastewater at concentrations up to 300 μg/L. The parent compound and its transformation products pose risks to aquatic organisms. Efficient atenolol degrading microorganism has yet to be identified, and its biodegradation pathway is unknown. In this study, Hydrogenophaga sp. YM1 isolated from activated sludge can degrade atenolol efficiently (286.1 ± 4.0 μg/g dry wt/h in actual wastewater), where atenolol acid, and four newly detected products (4-hydroxyphenylacetic acid, 3-(isopropylamino)-1,2-propanediol, 3-amino-1,2-propanediol and 4-(1-amino-2-hydroxy-3-propoxy) benzeneacetic acid) were the main intermediates. Key genes involved in atenolol degradation were proposed based on RNA-seq and validated by RT-qPCR. The ether bond cleavage of atenolol acid was the rate-limiting step likely catalyzed by the α-ketoglutarate dependent 2,4-dichlorophenoxyacetate dioxygenase. The further degradation of 4-hydroxyphenylacetic acid followed the homoprotocatechuate degradation pathway, enabling complete conversion to CO₂. Acetate addition (39-156 mg COD/L) under aerobic condition enhanced atenolol degradation by 29-37% and decreased the accumulation of atenolol acid, likely because acetate oxidation provided α-ketoglutarate and additional reducing power. Activated sludge core microorganisms have limited atenolol mineralization potentials. Enriching Hydrogenophaga-like populations and/or providing such as acetate can drive more complete conversion of atenolol in natural and engineered biosystems.

Ecotoxicological risk assessment of wastewater irrigation on soil microorganisms: Fate and impact of wastewater-borne micropollutants in lettuce-soil system

The implementation of the new Water Reuse regulation in the European Union brings to the forefront the need to evaluate the risks of using wastewater for crop irrigation. Here, a two-tier ecotoxicological risk assessment was performed to evaluate the fate of wastewater-borne micropollutants in soil and their ecotoxicological impact on plants and soil microorganisms. To this end, two successive cultivation campaigns of lettuces were irrigated with wastewater (at agronomical dose (not spiked) and spiked with a mixture of 14 pharmaceuticals at 10 and 100 µg/L each) in a controlled greenhouse experiment. Over the two cultivation campaigns, an accumulation of PPCPs was observed in soil microcosms irrigated with wastewater spiked with 100 μg/L of PPCPs with the highest concentrations detected for clarithromycin, hydrochlorothiazide, citalopram, climbazole and carbamazepine. The abundance of bacterial and fungal communities remained stable over the two cultivation campaigns and was not affected by any of the irrigation regimes applied. Similarly, no changes were observed in the abundance of ammonium oxidizing archaea (AOA) and bacteria (AOB), nor in clade A of commamox no matter the cultivation campaign or the irrigation regime considered. Only a slight increase was detected in clade B of commamox bacteria after the second cultivation campaign. Sulfamethoxazole-resistant and -degrading bacteria were not impacted either. The irrigation regimes had only a limited effect on the bacterial evenness. However, in response to wastewater irrigation the structure of soil bacterial community significantly changed the relative abundance of Acidobacteria, Chloroflexi, Verrucomicrobia, Beta-, Gamma- and Deltaprotebacteria. Twenty-eight operational taxonomic units (OTUs) were identified as responsible for the changes observed within the bacterial communities of soils irrigated with wastewater or with water. Interestingly, the relative abundance of these OTUs was similar in soils irrigated with either spiked or non-spiked irrigation solutions. This indicates that under both agronomical and worst-case scenario the mixture of fourteen PPCPs had no effect on soil bacterial community.

Prospects on coupling UV/H2O2 with activated sludge or a fungal treatment for the removal of pharmaceutically active compounds in real hospital wastewater

Conventional active sludge (AS) process at municipal centralized wastewater treatment facilities may exhibit little pharmaceuticals (PhACs) removal efficiencies when treating hospital wastewater (HWW). Therefore, a dedicated efficient wastewater treatment at the source point is recommended. In this sense, advanced oxidation processes (AOPs) and fungal treatment (FG) have evidenced promising results in degrading PhACs. The coupling of the AOP based on UV/H₂O₂ treatment with biological treatment (AS or FG) treating a real non-sterile HWW, was evaluated in this work. In addition, a coagulation-flocculation pretreatment was applied to improve the efficiency of all approaches. Twenty-two PhACs were detected in raw HWW, which were effectively removed (93-95%) with the combination of any of the biological treatment followed by UV/H₂O₂ treatment. Similar removal results (94%) were obtained when placing UV/H₂O₂ treatment before FG, while a lower removal (83%) was obtained in the combination of UV/H₂O₂ followed by AS. However, the latest was the only treatment combination that achieved a decrease in the toxicity of water. Moreover, deconjugation of conjugated PhACs has been suggested for ofloxacin and lorazepam after AS treatment, and for ketoprofen after fungal treatment. Monitoring of carbamazepine and its transformation products along the treatment allowed to identify the same carbamazepine degradation pathway in UV/H₂O₂ and AS treatments, unlike fungal treatment, which followed another degradation route.

Colour Changes during the Carbamazepine Oxidation by Photo-Fenton

The oxidation of aqueous solutions of carbamazepine is conducted using the Fenton reagent, combined with the photolytic action of a 150 W medium pressure UV lamp, operating at T = 40 °C. The effect of acidity is analysed at an interval pH = 2.0–5.0, verifying that operating at pH = 5.0 promotes colour formation (Colour = 0.15 AU). The effect of iron is studied, finding that the colour of the water increases in a linear way, Colour = 0.05 + 0.0075 [Fe]0. The oxidising action of hydrogen peroxide is tested, confirming that when operating with [H2O2]0 = 2.0 mM, the maximum colour is generated (Colourmax = 0.381 AU). The tint would be generated by the degradation of by-products of carbamazepine, which have chromophoric groups in their internal structure, such as oxo and dioxocarbazepines, which would produce tint along the first minutes of oxidation, while the formation of acridones would slowly induce colour in the water.

Simultaneous removal of chlorite and contaminants of emerging concern under UV photolysis: Hydroxyl radicals vs. chlorate formation

It is well known that using chlorine dioxide (ClO₂) as a disinfectant inevitably produces a common disinfection byproducts chlorite (ClO₂^‒). In this study, we found that UV photolysis after ClO₂ disinfection can effectively eliminate both ClO₂^‒ and contaminants of emerging concern (CECs). However, the kinetic mechanisms of UV/ClO₂^‒ process destructing CECs, as well as transformation of ClO₂^‒ in UV/ClO₂^‒ system are not clear yet. Therefore, we systematically investigated the UV/ClO₂^‒ system to assist us appropriately design this process under optimal operational conditions. In this work, we first investigated the impact of water matrix conditions (i.e., pH, bicarbonate and natural organic matter (NOM)) and ClO₂^‒ dosage on the UV/ClO₂^‒ process. We found that bicarbonate and NOM have inhibition effects, while lower pH and higher ClO₂^‒ dosage have enhancement effects. Besides, hydroxyl radical (HO^•) and reactive chlorine species (RCS) are generated from UV/ClO₂^‒ system, and RCS are main contributors to CBZ degradation. Then we proposed a possible degradation pathway of CBZ based on the determined products from experiments. Additionally, we found that photolysis of ClO₂^‒ resulted in the generation of chloride (Cl^‒) and chlorate (ClO₃^‒). As the ClO₂^‒ dosage increases, the yield of ClO₃^‒ increased while that of Cl^‒ decreased. Finally, we elucidated the second order rate constant of the target organic compound with HO• has a strong correlation with the formation of ClO₃^‒.

Ozonation of carbamazepine and its main transformation products: product determination and reaction mechanisms

Carbamazepine (CBZ) is a recalcitrant pharmaceutical often detected in wastewater and in the environment. CBZ can be removed from wastewater through advanced oxidation treatment methods such as ozonation. In this study, CBZ and its transformation product 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD) were ozonated, and the formation and transformation of their ozonation products were investigated using liquid chromatography coupled to ion trap mass spectrometry and high-resolution mass spectrometry as well as nuclear magnetic resonance (NMR). The main products, 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM) and BQD were quantified using isolated standards and LC-UV. Of the original CBZ concentration, 74% was transformed into BQM and 83% of BQM was further transformed into BQD. Both products are more stable than CBZ and could still be detected after 240 min of ozonation. Another major product, 2,2'-azanediyldibenzaldehyde (TP225) was for the first time identified using NMR. Twelve further CBZ products were identified.

Mechanism and kinetics of methylisothiazolinone removal by cultivation of Scenedesmus sp. LX1

Methylisothiazolinone (MIT) is a widely used non-oxidizing biocide for membrane biofouling control in reverse osmosis (RO) systems usually with high dosages. However, few investigations have focused on MIT removal through bio-processes, since it is highly bio-toxic. This study proposed a novel biotreatment approach for efficient MIT degradation by Scenedesmus sp. LX1, a microalga with strong resistance capability against extreme MIT toxicity. Results showed that MIT (3 mg/L) could be completely removed within 4 days' cultivation with a half-life of only 0.79 d. Biodegradation was the primary removal mechanism and this metabolic process did not rely on bacterial consortia, soluble algal products secretion or algal growth. The main pathway was proposed as ring cleavage followed by methylation and carboxylation through the identification of MIT transformation products. MIT biodegradation followed the pseudo-first-order kinetics under growth control. A new kinetic model was presented to depict the MIT removal considering algal growth, and this model could be used for generally describing non-nutritive contaminants biodegradation. The algal biodegradation capability was independent of the initial biocide concentration, and MIT removal could be enhanced by increasing the initial algal density. Our results highlight the potential application of algal cultivation for MIT-containing wastewater biotreatment, such as RO concentrate.

A critical evaluation of comparative regulatory strategies for monitoring pharmaceuticals in recycled wastewater

Pharmaceuticals are a subset of micropollutants, present in the environment in trace concentrations. Because of their persistent nature, these chemicals are of particular concern. Little is known about how mixtures of pharmaceutical residues, found in WWTP effluents, affect the environment or public health. Yet, numerous studies show negative outcomes for both aquatic and terrestrial organisms, suggesting that they are given both to bioaccumulation and uptake in plants. Israel leads the world in effluent reuse (86%), almost exclusively utilized for purposes of agricultural irrigation. Pharmaceuticals, however, are not included in Israel's water regulatory oversight or management, essentially creating an epidemiological experiment among its citizens and environment. Globally, these compounds also are not commonly subject to monitoring or regulation. This study reviews and analyzes water policies and regulation worldwide that address the presence of pharmaceuticals in water resources, with a particular focus on Australia, Singapore, Switzerland, and the USA. Furthermore, the study investigates the reasons why these chemicals are not yet regulated in Israel. Based on a comprehensive evaluation of the data and analysis of the regulatory rationale in other countries, a list of recommended pharmaceutical standards that should be measured and monitored in Israel's wastewater treatment system is proposed. The suggested prioritization criteria should be at the heart of a new regulatory agenda for controlling pharmaceutical contamination in wastewater.

Carbamazepine is degraded by the bacterial strain Labrys portucalensis F11

The occurrence of pharmaceuticals in the environment is a topic of concern. Carbamazepine (CBZ) is a widespread antiepileptic drug and due to its physical-chemical characteristics minimal removal is achieved in conventional water treatments, and thus has been suggested as a molecular marker of wastewater contamination in surface water and groundwater. The present study reports the biotransformation of CBZ by the bacterial strain Labrys portucalensis F11. When supplied as a sole carbon source, a 95.4% biotransformation of 42.69 μM CBZ was achieved in 30 days. In co-metabolism with acetate, complete biotransformation was attained at a faster rate. Following a target approach, the detection and identification of 14 intermediary metabolites was achieved through UPLC-QTOF/MS/MS. Biotransformation of CBZ by the bacterial strain is mostly based on oxidation, loss of -CHNO group and ketone formation reactions; a biotransformation pathway with two routes is proposed. The toxicity of untreated and treated CBZ solutions was assessed using Vibrio Fischeri and Lepidium sativum acute toxicity tests and Toxi-Chromo Test. The presence of CBZ and/or its degradations products in solution resulted in moderate toxic effect on Vibrio Fischeri, whereas the other organisms were not affected. To the best of our knowledge this is the first report that proposes the metabolic degradation pathway of CBZ by a single bacterial strain.

Transformation of lamotrigine by white-rot fungus Pleurotus ostreatus

One of the most persistent pharmaceutical compounds commonly found in treated wastewater is lamotrigine (LTG). It has also been detected in soils and crops irrigated with treated wastewater. Here we focused on the ability of the white-rot edible mushroom Pleurotus ostreatus to remove and transform LTG in liquid cultures. At concentrations of environmental relevance (1 and 10 μg L^-1) LTG was almost completely removed from the culture medium within 20 days. To elucidate the mechanism of LTG removal and transformation, we applied a physiological-based approach using inhibitors and a competing agent. These experiments were conducted at a higher concentration for metabolites detection. Based on identification of sulfur-containing metabolites and LTG N2-oxide and the effect of specific inhibitors, cytochrome P450 oxidation is suggested as one of the reaction mechanisms leading to LTG transformation. The variety and number of transformation products (i.e., conjugates) found in the current study were larger than reported in mammals. Moreover, known conjugates with glucuronide, glutathione, or cysteine/glycine, were not found in our system. Since the majority of the identified transformation products were conjugates of LTG, this study highlights the persistence of LTG as an organic pollutant in ecosystems exposed to wastewater.

Removal of pharmaceutical' estrogenic activity of sequencing batch reactor effluents assessed in the T47D-KBluc reporter gene assay

Various water treatment processes may be ineffective to remove pharmaceutical compounds (PhCs) and their by-products, leading to endocrine-disruptive activity that might be detrimental to wildlife and human health. This study investigated the degradation of carbamazepine (CBZ), diclofenac (DCF), ibuprofen (IBP), and their intermediates, as well as estrogenic activity that is not effectively removed by conventional methods. A consortium of isolated South African indigenous fungi A. niger, M. circinelloides, T. polyzona, T. longibrachiatum and R. microsporus, was used in a sequencing batch reactor (SBR) to remove PhCs, their intermediates and strongly reduce their estrogenic activity. The fungal ligninolytic enzymatic activity was determined for laccase (Lac), manganese peroxidase (MnP) and lignin peroxidase (LiP) using a spectrophotometric method. The biodegradation of PhCs and their intermediates was monitored by SPE-UPLC/MS. The in vitro estrogenic activity was assessed in the T47D-KBluc reporter gene assay. Lac, MnP and LiP production appeared to be biomass growth dependent. During a lag phase of growth, a constant biomass of about 122.04 mg/100 mL was recorded with average enzymatic activity around 63.62 U/L for Lac, 151.91 U/L for MnP and 42.12 U/L for LiP. The exponential growth phase from day 7 to day 17, was characterised by a biomass increase of 124.46 units, and an increase in enzymatic activity of 9.91 units for Lac, 99.03 units for MnP and 44.24 units for LiP. These enzymes played an important synergistic role in PhCs degradation in the cytochrome P450 system. A decrease of 13.89%, 29.7% and 16.15% in PhC concentrations was observed for CBZ, DCF and IBP, respectively, and their intermediates were identified within 4 h of incubation. The removal efficiency achieved after 24 h in the SBR was about 89.77%, 95.8% and 91.41% for CBZ, DCF and IBP, respectively. The estradiol equivalent (EEq) values of 1.71 ± 0.30 ng/L and 2.69 ± 0.17 ng/L were recorded at the start-up time and after 4 h, respectively. The presence of intermediates was found to induce estrogenic activity. The EEq values after 24 h incubation was found to be below the LoQ and below the LoD of the assay. None of the samples exhibited any anti-estrogenic activity. The fungal consortium inoculum was found to induce toxicity at a 0.4× concentration, as observed under a microscope. This study revealed that the use of the fungal consortium can remove the estrogenic activity of pharmaceutical metabolites, which appeared to be the most significant contributors to the endocrine-disrupting activity of the wastewater treatment plant effluents.

Biodegrading Two Pesticide Residues in Paddy Plants and the Environment by a Genetically Engineered Approach

Accumulating pesticide (and herbicide) residues in soils have become a serious environmental problem. This study focused on identifying the removal of two widely used pesticides, isoproturon (IPU) and acetochlor (ACT), by a genetically developed paddy (or rice) plant overexpressing an uncharacterized glycosyltransferase (IRGT1). IRGT1 conferred plant resistance to isoproturon-acetochlor, which was manifested by attenuated cellular injury and alleviated toxicity of rice under isoproturon-acetochlor stress. A short-term study showed that IRGT1-transformed lines removed 33.3-48.3% of isoproturon and 39.8-53.5% of acetochlor from the growth medium, with only 59.5-72.1 and 58.9-70.4% of the isoproturon and acetochlor remaining in the plants compared with the levels in untransformed rice. This phenotype was confirmed by IRGT1-expression in yeast ( Pichia pastoris) which grew better and contained less isoproturon-acetochlor than the control cells. A long-term study showed that isoproturon-acetochlor concentrations at all developmental stages were significantly lower in the transformed rice, which contain only 59.3-69.2% (isoproturon) and 51.7-57.4% (acetochlor) of the levels in wild type. In contrast, UPLC-Q-TOF-MS/MS analysis revealed that more isoproturon-acetochlor metabolites were detected in the transformed rice. Sixteen metabolites of isoproturon and 19 metabolites of acetochlor were characterized in rice for Phase I reactions, and 9 isoproturon and 13 acetochlor conjugates were characterized for Phase II reactions in rice; of these, 7 isoproturon and 6 acetochlor metabolites and conjugates were reported in plants for the first time.

Carbaryl biodegradation by Xylaria sp. BNL1 and its metabolic pathway

Although ascomycetes occupy a vaster niche in soil than the well-studied basidiomycetes, they have received limited attention in studies related to bioremediation. In this study, the degradation of carbaryl by Xylaria sp. was studied in different culture conditions and its possible metabolic pathway was elucidated. In liquid culture, 99% of the added carbaryl was eliminated when cytochrome P450 (CYP450) was active, which was similar to the degradation rate of Pleurotus ostreatus, a fungus with strong bioremediation ability. Mn²⁺ is beneficial to the degradation of carbaryl. Compared to the 72.17% degradation rate in sterile soil, 59.0% carbaryl was eliminated in non-sterile soil, which suggested that Xylaria sp. BNL1 can resist microorganismal infection. Furthermore, the intracellular fractions containing laccase, CYP450, and carbaryl esterase efficiently degraded carbaryl. The presence of carbaryl metabolites suggested that Xylaria sp. BNL1 initiated its attack on carbaryl via carbaryl esterase to release α-naphthol, which was further degraded to 1,4-naphthoquinone and benzoic acid by CYP450 and laccase. Thus, our study highlights the potential of using Xylaria sp. for bioremediation.

Degradation mechanisms of carbamazepine by δ-MnO2: Role of protonation of degradation intermediates

Carbamazepine (CBZ), a widely used antiepileptic drug, is refractory to biological wastewater treatment. Rapid removal of CBZ is possible using synthetic manganese oxide (δ-MnO₂) but the removal mechanisms require further investigation. In this study, CBZ degradation by δ-MnO₂ was carried out at different pH to further explore the degradation mechanisms. Results show that CBZ degradation by δ-MnO₂ was highly pH dependent, and rapid degradation occurred when pH <2.8. Based on the density functional theory calculations, increasing [H⁺] not only increased the reactivity of δ-MnO₂, but also enhanced the secondary reactions of the intermediates. During the degradation process, protonation of CBZ degradation intermediates, instead of CBZ, played an important role. The overall kinetics of CBZ degradation was then described by the retarded first-order model. The initial rate (r_init) in the model between pH 2.0 and 6.2 was determined to be r_init = (2.41 ± 0.51) × 10^-3[CBZ]^1.21[MnO₂]^1.07[H⁺]^1.41. This is the first report revealing that protonation of intermediates from CBZ degradation can improve the CBZ oxidation by δ-MnO2. The pathways of CBZ degradation by δ-MnO₂ were also proposed. The results of this study provide a new insight into the processing mechanism.

Sorption of pharmaceuticals to soil organic matter in a constructed wetland by electrostatic interaction

There is a growing interest in the removal of pharmaceuticals from wastewater because pharmaceuticals have potential ecotoxicological effects. Among several removal mechanisms, the sorption of pharmaceuticals to sediment organic matter is an important mechanism related to the mobility of pharmaceuticals. This study investigated the sorption of pharmaceuticals to soil organic matter (SOM) by electrostatic interactions. SOM located on the surface of soil/sediment generally has a negative charge because of the functional groups present (i.e., carboxylic and phenolic groups). Thus, the electrical characteristics of SOM can induce electrical attraction with positively charged chemical compounds. In this study, SOM was extracted from soils under different aquatic plants (Acorus and Typha) in a constructed wetland in Korea. Experiments were carried out with the following three pharmaceuticals with different electrical characteristics at pH 7: atenolol (positive charge; pKa 9.5), carbamazepine (neutral; no pKa), and ibuprofen (negative charge; pKa 4.9). The SOM in the Acorus pond had a higher hydrophobicity and electrical charge density than that in the Typha pond. Regarding the sorption efficiency between SOM and charged pharmaceuticals, atenolol showed highest sorption efficiency (~60%), followed by carbamazepine (~40%) and ibuprofen (<~30%). In addition, the removal efficiency of the targeted pharmaceuticals in the constructed wetland was estimated by comparing the concentrations of the pharmaceuticals at sampling points with flowing water. The results showed that the removal efficiency of atenolol and carbamazepine was almost 50%, whereas that of ibuprofen was only ~10%. A comparison of the results of lab-scale and field experiments showed that electrostatic interaction is one of the major pharmaceutical removal mechanisms in a constructed wetland.

Photochemistry of 9-acridinecarboxaldehyde in aqueous media

Dark and photolysis reactions in solution were investigated for 9-acridinecarboxaldehyde (ACL). ACL reacts in the dark at T = 20 °C and pH = 7.0 in an air saturated solution to the main product 9-acridinecarboxylic acid (ACA) and to the minor product 9-acridinemethanol (ACM) with a lifetime of τ = 4.3 days. The dissociation constant of the base ACLH+ was determined to be pKa ± σ = 4.38 ± 0.04. The photolysis of ACL was investigated using a polychromatic Xe-light source. The quantum yield in aqueous solution at T = 20 °C in a concentration range of c0(ACL) = 0.18-16.6 μM for pH > pKa and for nitrogen, air and oxygen aerated solutions was found to be Φ ± σ = (0.015 ± 0.003) mol/mol, independent from concentration. The quantum yield of ACLH+, i.e. for pH ≪ pKa, is by a factor of 2 higher (Φ = 0.029 mol/mol). Quantum yields in methanol and isopropanol are slightly lower compared to water and in acetone lower by about a factor of 20. In acetonitrile ACL was found to be practically photostable. Minimum lifetimes in sunlight for a measurement on September 5, 2017 were in the range of τ = 5-10 minutes. The diurnal photolysis of ACL in sunlight was satisfactory explained using the mean quantum yield, the absorption spectrum and photon fluxes with suitable corrections for cloudiness and the dimensions of the setup. For low concentrations ACR is formed with a yield of practically 100% in the photolysis reaction. However, with increasing concentration of ACL yields of ACR decrease and yields of ACA increase. 9(10H)-Acridinone and ACM were always detected as minor products with yields below 2%. 9-Methylacridine was never detected in any reaction of ACL. Strong indications are presented of a photolysis reaction of ACL in a river located in Lower Saxony (Germany) with a corresponding equimolar formation of ACR. ACL is therefore a direct precursor of ACR in natural surface water.

Pharmacokinetics in Plants: Carbamazepine and Its Interactions with Lamotrigine

Carbamazepine and lamotrigine prescribed antiepileptic drugs are highly persistent in the environment and were detected in crops irrigated with reclaimed wastewater. This study reports pharmacokinetics of the two drugs and their metabolites in cucumber plants under hydroponic culture, testing their uptake, translocation, and transformation over 96 h in single and bisolute systems at varying pH. Ruling out root adsorption and transformations in the nutrient solution, we demonstrate that carbamazepine root uptake is largely affected by the concentration gradient across the membrane. Unlike carbamazepine, lamotrigine is adsorbed to the root and undergoes ion trapping in root cells thus its translocation to the shoots is limited. On the basis of that, carbamazepine uptake was not affected by the presence of lamotrigine, while lamotrigine uptake was enhanced in the presence of carbamazepine. Transformation of carbamazepine in the roots was slightly reduced in the presence of lamotrigine. Carbamazepine metabolism was far more pronounced in the shoots than in the roots, indicating that most of the metabolism occurs in the leaves, probably due to higher concentration and longer residence time. This study indicates that the uptake of small nonionic pharmaceuticals is passive and governed by diffusion across the root membrane.

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.

Metabolism of carbamazepine in plant roots and endophytic rhizobacteria isolated from Phragmites australis

Carbamazepine (CBZ) is a pharmaceutical frequently categorized as a recalcitrant pollutant in the aquatic environment. Endophytic bacteria previously isolated from reed plants have shown the ability to promote growth of their host and to contribute to CBZ metabolism. In this work, a horseradish (Armoracia rusticana) hairy root (HR) culture has been used as a plant model to study the interactions between roots and endophytic bacteria in response to CBZ exposure. HRs could remove up to 5% of the initial CBZ concentration when they were grown in spiked Murashige and Skoog (MS) medium. Higher removal rates were observed when HRs were inoculated with the endophytic bacteria Rhizobium radiobacter (21%) and Diaphorobacter nitroreducens (10%). Transformation products resulting from CBZ degradation were identified using liquid chromatography-ultra high-resolution quadrupole time of flight mass spectrometry (LC-UHR-QTOF-MS). CBZ metabolism could be divided in four pathways. Metabolites involving GSH conjugation and 2,3-dihydroxylation, as well as acridine related compounds are described in plants for the first time. This study presents strong evidence that xenobiotic metabolism and degradation pathways in plants can be modulated by the interaction with their endophytic community. Hence it points to plausible applications for the elimination of recalcitrant compounds such as CBZ from wastewater in CWs.

Composted biosolids and treated wastewater as sources of pharmaceuticals and personal care products for plant uptake: A case study with carbamazepine

Irrigation with treated wastewater (TWW) and application of biosolids to arable land expose the agro-environment to pharmaceuticals and personal care products (PPCPs) which can be taken up by crops. In this project, we studied the effect of a carrier medium (e.g., biosolids and TWW) on plant (tomato, wheat and lettuce) uptake, translocation and metabolism of carbamazepine as a model for non-ionic PPCPs. Plant uptake and bioconcentration factors were significantly lower in soils amended with biosolids compared to soils irrigated with TWW. In soils amended with biosolids and irrigated with TWW, the bioavailability of carbamazepine for plant uptake was moderately decreased as compared to plants grown in soils irrigated with TWW alone. While TWW acts as a continuous source of PPCPs, biosolids act both as a source and a sink for these compounds. Moreover, it appears that decomposition of the biosolids in the soil after amendment enhances their adsorptive properties, which in turn reduces the bioavailability of PPCPs in the soil environment. In-plant metabolism of carbamazepine was found to be independent of environmental factors, such as soil type, carrier medium, and absolute amount implemented to the soil, but was controlled by the total amount taken up by the plant.

Overview on the Biochemical Potential of Filamentous Fungi to Degrade Pharmaceutical Compounds

Pharmaceuticals represent an immense business with increased demand due to intensive livestock raising and an aging human population, which guarantee the quality of human life and well-being. However, the development of removal technologies for these compounds is not keeping pace with the swift increase in their use. Pharmaceuticals constitute a potential risk group of multiclass chemicals of increasing concern since they are extremely frequent in all environments and have started to exhibit negative effects on micro- and macro-fauna as well as on human health. In this context, fungi are known to be extremely diverse and poorly studied microorganisms despite being well suited for bioremediation processes, taking into account their metabolic and physiological characteristics for the transformation of even highly toxic xenobiotic compounds. Increasing studies indicate that fungi can transform many structures of pharmaceutical compounds, including anti-inflammatories, β-blockers, and antibiotics. This is possible due to different mechanisms in combination with the extracellular and intracellular enzymes, which have broad of biotechnological applications. Thus, fungi and their enzymes could represent a promising tool to deal with this environmental problem. Here, we review the studies performed on pharmaceutical compounds biodegradation by the great diversity of these eukaryotes. We examine the state of the art of the current application of the Basidiomycota division, best known in this field, as well as the assembly of novel biodegradation pathways within the Ascomycota division and the Mucoromycotina subdivision from the standpoint of shared enzymatic systems, particularly for the cytochrome P450 superfamily of enzymes, which appear to be the key enzymes in these catabolic processes. Finally, we discuss the latest advances in the field of genetic engineering for their further application.

Extensive Transformation of the Pharmaceutical Carbamazepine Following Uptake into Intact Tomato Plants

Carbamazepine (CBZ) is an antiepileptic drug which is persistent in wastewater treatment plants and the environment. It has been frequently detected in plant material after irrigation with treated wastewater. To date, little information is, however, available on the transformation of CBZ in plants. In the present study, the uptake, translocation, and transformation of CBZ was studied in hydroponically grown tomato plants. After 35 days of exposure >80% of the total spiked amount of CBZ was taken by the tomato plants and mainly stored in the leaves. A total of 11 transformation products (TP) (mainly phase-I) were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and their total amount corresponded to 33% of the CBZ taken up. The ratio of CBZ metabolites to CBZ was highest in fruits (up to 2.5) and leaves (0.5), suggesting an intensive transformation of CBZ in these compartments. Further 10 TPs (phase-I and II) were identified by LC-high resolution mass spectrometry screening, likely comprising another 12% of CBZ. On the basis of these experiments and on an experiment with CBZ-10,11-epoxide a transformation pathway of CBZ in intact tomato plants is proposed that involves epoxidation, hydrolysis, hydroxylation, ring contraction, or loss of the carbamoyl group, followed by conjugation to glucose or cysteine, but also reduction of CBZ. This transformation pathway and analytical data of CBZ transformation products allow for their determination also in field grown vegetable and for the generation of more accurate exposure data of consumers of vegetable irrigated with treated municipal wastewater.

Pharmaceuticals removal and microbial community assessment in a continuous fungal treatment of non-sterile real hospital wastewater after a coagulation-flocculation pretreatment

Hospital wastewaters are a main source of pharmaceutical active compounds, which are usually highly recalcitrant and can accumulate in surface and groundwater bodies. Fungal treatments can remove these contaminants prior to discharge, but real wastewater poses a problem to fungal survival due to bacterial competition. This study successfully treated real non-spiked, non-sterile wastewater in a continuous fungal fluidized bed bioreactor coupled to a coagulation-flocculation pretreatment for 56 days. A control bioreactor without the fungus was also operated and the results were compared. A denaturing gradient gel electrophoresis (DGGE) and sequencing approach was used to study the microbial community arisen in both reactors and as a result some bacterial degraders are proposed. The fungal operation successfully removed analgesics and anti-inflammatories, and even the most recalcitrant pharmaceutical families such as antibiotics and psychiatric drugs.

Intracellular Enzymes Contribution to the Biocatalytic Removal of Pharmaceuticals by Trametes hirsuta

The use of white rot fungi (WRF) for bioremediation of recalcitrant trace organic contaminants (TrOCs) is becoming greatly popular. Biosorption and lignin modifying enzymes (LMEs) are the most often reported mechanisms of action. Intracellular enzymes, such as cytochrome P450 (CYP450), have also been suggested to contribute. However, direct evidence of TrOCs uptake and intracellular transformation is lacking. The aim of this study was to evaluate the relative contribution of biosorption, extracellular LMEs activity, TrOCs uptake, and intracellular CYP450 on the removal of six nonsteroidal anti-inflammatories (NSAIs) by Trametes hirsuta. Results show that for most tested NSAIs, LMEs activity and biosorption failed to explain the observed removal. Most tested TrOCs are quickly taken up and intracellularly transformed. Fine characterization of intracellular transformation using ketoprofen showed that CYP450 is not the sole intracellular enzyme responsible for intracellular transformation. The contribution of CYP450 in further transformation of ketoprofen byproducts is also reported. These results illustrate that TrOCs transformation by WRF is a more complex process than previously reported. Rapid uptake of TrOCs and intracellular transformation through diverse enzymatic systems appears to be important components of WRF efficiency toward TrOCs.

In Silico Identification of Bioremediation Potential: Carbamazepine and Other Recalcitrant Personal Care Products

Emerging contaminants are principally personal care products not readily removed by conventional wastewater treatment and, with an increasing reliance on water recycling, become disseminated in drinking water supplies. Carbamazepine, a widely used neuroactive pharmaceutical, increasingly escapes wastewater treatment and is found in potable water. In this study, a mechanism is proposed by which carbamazepine resists biodegradation, and a previously unknown microbial biodegradation was predicted computationally. The prediction identified biphenyl dioxygenase from Paraburkholderia xenovorans LB400 as the best candidate enzyme for metabolizing carbamazepine. The rate of degradation described here is 40 times greater than the best reported rates. The metabolites cis-10,11-dihydroxy-10,11-dihydrocarbamazepine and cis-2,3-dihydroxy-2,3-dihydrocarbamazepine were demonstrated with the native organism and a recombinant host. The metabolites are considered nonharmful and mitigate the generation of carcinogenic acridine products known to form when advanced oxidation methods are used in water treatment. Other recalcitrant personal care products were subjected to prediction by the Pathway Prediction System and tested experimentally with P. xenovorans LB400. It was shown to biodegrade structurally diverse compounds. Predictions indicated hydrolase or oxygenase enzymes catalyzed the initial reactions. This study highlights the potential for using the growing body of enzyme-structural and genomic information with computational methods to rapidly identify enzymes and microorganisms that biodegrade emerging contaminants.

Physiology and bioprocess of single cell of Stenotrophomonas maltophilia in bioremediation of co-existed benzo[a]pyrene and copper

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals are generally present in mixtures in the e-waste dismantling areas, posing serious health risk to the local people. Bioremediation has been considered as a promising approach for PAHs and heavy metals removal. In this study, we applied flow cytometry to obtain a better understanding of membrane potential (MP), apoptosis and cell cycle of Stenotrophomonas maltophilia affected by combined pollutants of benzo[a]pyrene(BaP) and Cu(II). The results showed that BaP was the main factor damaging the cell membrane and influencing the MP. S. maltophilia could even protect against upsetting situation by encouraging early apoptosis, whereby compromised cells committed suicide, as a result, which, in turn, facilitated the metabolism of the bacteria with high-vitality. Furthermore, even if the bacterial cell division was blocked and stopped reproduction, a large number of key enzymes inside cells could still be used for degradation of BaP. The expression of protein related to the transport and metabolism of BaP, regulation of redox reactions and phosphorylation in bacterial cell during bioprocess were evident different.

Biotransformation of 2,4-dinitroanisole by a fungal Penicillium sp

Insensitive munitions explosives are new formulations that are less prone to unintended detonation compared to traditional explosives. While these formulations have safety benefits, the individual constituents, such as 2,4-dinitroanisole (DNAN), have an unknown ecosystem fate with potentially toxic impacts to flora and fauna exposed to DNAN and/or its metabolites. Fungi may be useful in remediation and have been shown to degrade traditional nitroaromatic explosives, such as 2,4,6-trinitrotoluene and 2,4-dinitrotoluene, that are structurally similar to DNAN. In this study, a fungal Penicillium sp., isolated from willow trees and designated strain KH1, was shown to degrade DNAN in solution within 14 days. Stable-isotope labeled DNAN and an untargeted metabolomics approach were used to discover 13 novel transformation products. Penicillium sp. KH1 produced DNAN metabolites resulting from ortho- and para-nitroreduction, demethylation, acetylation, hydroxylation, malonylation, and sulfation. Incubations with intermediate metabolites such as 2-amino-4-nitroanisole and 4-amino-2-nitroanisole as the primary substrates confirmed putative metabolite isomerism and pathways. No ring-cleavage products were observed, consistent with other reports that mineralization of DNAN is an uncommon metabolic outcome. The production of metabolites with unknown persistence and toxicity suggests further study will be needed to implement remediation with Penicillium sp. KH1. To our knowledge, this is the first report on the biotransformation of DNAN by a fungus.

Synergistic effect between UV and chlorine (UV/chlorine) on the degradation of carbamazepine: Influence factors and radical species

For successful wastewater reclamation, advanced oxidation processes have attracted attention for elimination of emerging contaminants. In this study, the synergistic treatment with UV irradiation and chlorine (UV/chlorine) was used to degrade carbamazepine (CBZ). Neither UV irradiation alone nor chlorination alone could efficiently degraded CBZ. UV/chlorine oxidation showed a significant synergistic effect on CBZ degradation through generation of radical species (OH and Cl), and this process could be well depicted by pseudo first order kinetic. The degradation rate constants (kobs,CBZ) of CBZ increased linearly with increasing UV irradiance and chlorine dosage. The degradation of CBZ by UV/chlorine in acidic solutions was more efficient than that in basic solutions mainly due to the effect of pH on the dissociation of HOCl and OCl(-) and then on the quantum yields and radical species quenching of UV/chlorine. When pH was increased from 5.5 to 9.5, the rate constants of degradation of CBZ by OH decreased from 0.65 to 0.14 min(-1) and that by Cl decreased from 0.40 to 0.11 min(-1). The rate constant for the reaction between Cl and CBZ was 5.6 ± 1.6 × 10(10) M(-1) s(-1). Anions of HCO3(-) (1-50 mM) showed moderate inhibition of CBZ degradation by UV/chlorine, while Cl(-) did not. UV/chlorine could efficiently degrade CBZ in wastewater treatment plant effluent, although the degradation was inhibited by about 30% compared with that in ultrapure water with chlorine dosage of 0.14-0.56 mM. Nine main oxidation products of the CBZ degradation by UV/chlorine were identified using the HPLC-QToF MS/MS. Initial oxidation products arose from hydroxylation, carboxylation and hydrogen atom abstraction of CBZ by OH and Cl, and were then further oxidized to generate acylamino cleavage and decarboxylation products of acridine and acridione.

Electrochemistry Combined with LC-HRMS: Elucidating Transformation Products of the Recalcitrant Pharmaceutical Compound Carbamazepine Generated by the White-Rot Fungus Pleurotus ostreatus

Transformation products (TPs) of environmental pollutants must be identified to understand biodegradation processes and reaction mechanisms and to assess the efficiency of treatment processes. The combination of oxidation by an electrochemical cell (EC) with analysis by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) is a rapid approach for the determination and identification of TPs generated by natural microbial processes. Electrochemically generated TPs of the recalcitrant pharmaceutical carbamazepine (CBZ) were used for a target screening for TPs formed by the white-rot fungus Pleurotus ostreatus. EC with LC-HRMS facilitates detection and identification of TPs because the product spectrum is not superimposed with biogenic metabolites and elevated substrate concentrations can be used. A group of 10 TPs formed in the microbial process were detected by target screening for molecular ions, and another 4 were detected by screening on the basis of characteristic fragment ions. Three of these TPs have never been reported before. For CBZ, EC with LC-HRMS was found to be more effective than software tools in defining targets for the screening and faster than nontarget screening alone in TP identification. EC with LC-HRMS may be used to feed MS databases with spectra of possible TPs of larger numbers of environmental contaminants for an efficient target screening.