Important Counteranion Effect on Adsorption Efficacity of Hydrogen Sulfide by Silver(I)-Dithione Coordination Polymers.

Four new coordination polymers (CPs) have been prepared and evaluated for their efficacy in adsorbing hydrogen sulfide. The reactions of the structurally flexible assembling dithione ligand, L, with different silver(I) salts lead to four new metal-organic coordination architectures (CPs I, III, V, and VIII) exhibiting either one- or two-dimensional networks. CP I, 2D-[(Ag2Cl2)L]n, exhibits a linear series of rhomboid (S)2Ag(µ2-Cl)2Ag(S)2 secondary building units (SBUs) where S is one of the thione functions of L, altogether forming a 2D-network. CP III, 2D-[(AgI)L]n, is built upon parallel staircase-shaped 1D-[Ag2(µ3-I)2]n SBUs bridged by S atoms of L that form a 2D-grid. CP V, 2D-[(AgL)(NO3)]n, presents parallel 1D-folded S-shaped [AgL]n+ chains linked by strong argentophilic Ag···Ag interactions, forming a 2D-scaffolding. CP VIII, 1D-[(Ag2L3)(Cr2O7)]n, shows 1D-zigzag [{Ag(η2-µ2,η-µ,µ-L)}2]n2n+ chains accompanied by Cr2O72- counteranions. The adsorption isotherms of H2S gas by these new CPs were examined and compared to those of related CPs [(Ag2Br2)L]n (II), [(AgCN)4L]n (IV), [(Ag2L)(CF3SO3)2]n (VI), and [(Ag2L)(NO3)(ClO4)]n (VII). Among the tested polymers, the 3D-CP IV featuring cyanide anions exhibits the highest adsorption capacity of the CPs studied in this work. In order to determine the reason for this marked difference, density functional theory (DFT) computations were used. All in all, it turns out that the electrostatic interactions (CN-···H-SH) are significantly stronger than the O-···H-SH ones. This investigation provides a valuable conceptual tool for other designs of CPs and MOFs having the purpose of capturing toxic gases.

Trace organic contaminants in lake waters: Occurrence and environmental risk assessment at the national scale in Canada.

Numerous contaminants are produced and used daily, a significant fraction ultimately finding their way into natural waters. However, data on their distribution in lakes is lacking. To address this gap, the presence of 54 trace organic contaminants (TrOCs), representative of various human activities, was investigated in the surface water of 290 lakes across Canada. These lakes ranged from remote to highly impacted by human activities. In 88% of the sampled lakes, contaminants were detected, with up to 28 detections in a single lake. The compounds most frequently encountered were atrazine, cotinine, and deethylatrazine, each of which was present in more than a third of the lakes. The range of detected concentrations was from 0.23 ng/L to about 2200 ng/L for individual compounds, while the maximum cumulative concentration exceeded 8100 ng/L in a single lake. A risk assessment based on effect concentrations for three aquatic species (Pimephales promelas, Daphnia magna, and Tetrahymena pyriformis) was conducted, revealing that 6% of lakes exhibited a high potential risk for at least one species. In 59% of lakes, some contaminants with potential sub-lethal effects were detected, with the detection of up to 17 TrOCs with potential impacts. The results of this work provide the first reference point for monitoring the evolution of contamination in Canadian lakes by TrOCs. They demonstrate that a high proportion of the sampled lakes bear an environmentally relevant anthropogenic chemical footprint.

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

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

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

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

Genipin and glutaraldehyde based laccase two-layers immobilization with improved properties: New biocatalysts with high potential for enzymatic removal of trace organic contaminants.

This research proposes the preparation of a two-layer laccase biocatalyst using genipin or/and glutaraldehyde as cross-linking agents. The multilayer biocatalysts were prepared using different combinations of genipin and glutaraldehyde in the individual preparation of the first and second laccase layers. First, chitosan was treated with genipin or glutaraldehyde, followed by the immobilization of the first laccase layer to form a single-layer biocatalyst. Then, the immobilized laccases were coated once again with genipin or glutaraldehyde, and a new laccase layer was immobilized onto the system, resulting in the final two-layer biocatalyst. Compared to the single-layer biocatalysts, catalytic activity increased 1.7- and 3.4-fold when glutaraldehyde coating was used to prepare the second laccase layer. However, adding a second layer did not always produce more active biocatalysts, since the two-layer biocatalysts prepared with genipin (GenLacGenLac and GluLacGenLac) presented a decrease in activity of 65% and 28%, respectively. However, these two-layer biocatalysts prepared with genipin maintained 100% of their initial activity after 5 cycles of ABTS oxidation. Nevertheless, the two-layer, genipin-coated biocatalyst resulted in a higher removal of trace organic contaminants, since it removed 100% of mefenamic acid and 66% of acetaminophen, compared with the glutaraldehyde-coated biocatalyst, which removed 20% of mefenamic acid, and 18% of acetaminophen.

Cost-effective, scalable production of glucose oxidase using Casuarina equisetifolia biomass and its application in the bio-Fenton oxidation process for the removal of trace organic contaminants from wastewater.

This study focuses on using Casuarina equisetifolia biomass for pilot-scale glucose oxidase production from Aspergillus niger and its application in the removal of trace organic contaminants (TrOCs) from municipal wastewater through the bio-Fenton oxidation. The cost of glucose oxidase was 0.005 $/U, including the optimum production parameters, 10% biomass, 7% sucrose, 1% peptone, and 3% CaCO3 at 96 h with an enzyme activity of 670 U/mL. Optimized conditions for H2O2 were 1 M glucose, 100 U/mL glucose oxidase, and 120 mins of incubation, resulting in 544.3 mg/L H2O2. Thus, H2O2 produced under these conditions lead to bio-Fenton oxidation resulting in the removal of 36-92% of nine TrOCs in municipal wastewater at pH 7.0 in 360 mins. Therefore, this work establishes the cost-effective glucose oxidase-producing H2O2 as an attractive bioremediating agent to enhance the removal of TrOCs in wastewater at neutral pH.

Coimmobilized enzymes as versatile biocatalytic tools for biomass valorization and remediation of environmental contaminants - A review.

Due to stringent regulatory norms, waste processing faces confrontations and challenges in adapting technology for effective management through a convenient and economical system. At the global level, attempts are underway to achieve a green and sustainable treatment for the valorization of lignocellulosic biomass as well as organic contaminants in wastewater. Enzymatic treatment in the environmental aspect thrived on being the promising rapid strategy that appeased the aforementioned predicament. On that account, coimmobilization of various enzymes on single support enhances the catalytic activity ensuing operational stability with industrial applications. This review pivoted towards the coimmobilization of enzymes on diverse supports and their applications in biomass conversion to industrial value-added products and removal of contaminants in wastewater. The limelight of this study chronicles the unique breakthroughs in biotechnology for the production of reusable biocatalysts, which inculcating various enzymes towards the scope of environment application.

Mycoremediation of lignocellulosic biorefinery sludge: A reinvigorating approach for organic contaminants remediation with simultaneous production of lignocellulolytic enzyme cocktail.

This research work aims to valorize lignocellulosic biorefinery sludge with genetically engineered Trichoderma atroviride for simultaneous removal of organic contaminants, fermentation inhibitors, and lignocellulolytic enzyme cocktail production. Upon analysis, three phenolic compounds (42.6 ± 3.6 µg/g), two polycyclic aromatic hydrocarbons (0.42 ± 0.06 µg/g) and five fermentation inhibitors (2.5 ± 0.3 mg/g) were detected in the sludge. Bioaugmentation of sludge with 72 h-old T. atroviride (5%) results in the production of cellulase (21 U/g), xylanase (84 U/g), laccase (20 U/g), lignin peroxidase (14 U/g) and aryl alcohol oxidase (116 U/g), along with the concomitant removal of organic contaminants (phenol, 2, 4-dinitrophenol, pentchlorophenol, phenanthrene, benzo(a)pyrene) and fermentation inhibitors (furfural, 5-hydroxymethylfurfural, levulinic acid, ferulic acid, and catechol). Subsequently, the enrichment of sludge with nutrients and rhamnolipids enhanced the enzyme production by 5-6-fold and resulted in the removal of 85-95% of organic contaminants and fermentation inhibitors, which constitutes an eco-friendly process.

Surfactant-aided mycoremediation of soil contaminated with polycyclic aromatic hydrocarbons.

Remediation of persistent polycyclic aromatic hydrocarbons (PAHs) contaminated soil has become a major challenge in recent years. Further, conventional application of bioaugmentation strategies for PAHs remediation require continuous supply of microbial specific nutrients, which makes these processes less feasible. Hence, the present study focused on PAHs remediation using surfactants along with wood assisted fungal system in a microcosm set up. In this study, in absence of surfactants, a saturation in PAHs degradation was noted in bioaugmentation with wood assisted fungal system (BAW) with 61 ± 1.25% degradation, followed by bioaugmentation with free fungi system (BAF) (54 ± 0.46%). However, with addition of 1500 mg/L of surface-active compounds (SAC), a maximum PAHs degradation in BAW (100%) and BAF (86 ± 1.30%) strategies were noted on 21st day. Irrespective of the strategies, presence of SAC and rhamnolipids enhanced PAHs degradation by increasing the enzymes production in Trametes hirsuta when compared to Triton x-100 and sodium dodecyl sulphate (SDS). Among the detected PAHs, 100% degradation within 17 days was noted for naphthalene and acenaphthene in SAC-supplemented BAW system. Further, ecotoxicity analysis established showed the LC50 of sediment soil at 26.5 ± 0.24%, which was reduced by an average of 71% after soil remediation. Hence, the current microcosm system proved that the application of SAC with BAW enhanced the PAHs remediation rate, which supports its application in real time soil remediation.

Insolubilization of Tramates versicolor laccase as cross-linked enzyme aggregates for the remediation of trace organic contaminants from municipal wastewater.

The novelty of this study deals with the biocatalytic treatment of trace organic contaminants (TrOCs) from municipal wastewater by insolubilized laccase. Laccase from Trametes versicolor was aggregated by three-phase partitioning technique followed by cross-linking with glutaraldehyde to produce insolubilized laccase as cross-linked enzyme aggregates (CLEAs). The optimal conditions for CLEAs preparation include ammonium sulphate concentration of 83% (w/v), crude to t-butanol ratio of 1.00: 1.05 (v/v), pH 5.3, and glutaraldehyde concentration of 20 mM obtained via statistical design. The efficiency of insolubilization of the CLEAs laccase based on the kcat/km ratio was approximately 4.8-fold greater than that of free laccase. The developed CLEAs showed greater resistance to product inhibition mediated by ABTS than the free enzyme and exhibited excellent catalytic activity even after the tenth successive cycle. Further, free laccase and the synthesized CLEAs laccase were utilized to treat five analgesics, two NSAIDS, three antibiotics, two antilipemics, and three pesticides in the municipal wastewater. Under the batch process with operating conditions of pH 7.0 and 20 °C, 1000 U/L of CLEAs, laccase removed 11 TrOCs in the range of about 20-99%. However, the inactivated CLEAs only adsorbed 2-25% of TrOCs. It was observed that acetaminophen, mefenamic acid, trimethoprim, and metolachlor depicted almost complete removal with CLEAs laccase. The performance of CLEAs laccase in a perfusion basket reactor was tested for the removal of TrOCs from municipal wastewater.

Biological elimination of a high concentration of hydrogen sulfide from landfill biogas.

Hydrogen sulfide (H2S) is one of the main contaminants found in biogas, which is one of the end products of the anaerobic biodegradation of proteins and other sulfur-containing compounds in solid waste. The presence of H2S is one of the factors limiting the valorization of biogas. To valorize biogas, H2S must be removed. This study evaluated the performance of a pilot-scale biotrickling filter system on H2S removal from landfill biogas. The biotrickling filter system, which was packed with stainless-steel pall rings and inoculated with an H2S-oxidizing consortium, was designed to process 1 SCFM of biogas, which corresponds to an empty bed residence time (EBRT) of 3.9 min and was used to determine the removal efficiency of a high concentration of hydrogen sulfide from landfill biogas. The biofiltration system consisted of two biotrickling filters connected in series. Results indicate that the biofiltration system reduced H2S concentration by 94 to 98% without reducing the methane concentration in the outlet biogas. The inlet concentration of hydrogen sulfide, supplied to the two-phase bioreactor, was in the range of 900 to 1500 ppmv, and the air flow rate was 0.1 CFM. The EBRTs of the two biotrickling filters were 3.9 and 0.9 min, respectively. Approximately 50 ± 15.7 ppmv of H2S gas was detected in the outlet gas. The maximum elimination capacity of the biotrickling filter system was found to be 24 g H2S·m-3·h-1, and the removal efficiency was 94 ± 4.4%. During the biological process, the performance of the biotrickling filter was not affected when the pH of the recirculated liquid decreased to 2-3. The overall performance of the biotrickling filter system was described using a modified Michaelis-Menten equation, and the Ks and Vm values for the biosystem were 34.7 ppmv and 20 g H2S·m-3·h-1, respectively.

Effect of alkaline treatment on the removal of contaminants of emerging concern from municipal biosolids: Modelling and optimization of process parameters using RSM and ANN coupled GA.

The current study aimed in enhancing the efficiency of alkaline treatment for CECs remediation in biosolids through the application of RSM and ANN. Due to the seasonal variation of CECs in biosolids, a complete CECs profile over a period of three years were performed. Out of 64 targeted CECs, 13 PhACs (70.1 µg/kg) and 10 pesticides (57.2 µg/kg) were detected in biosolids. In order to enhance the remediation efficiency of CECs by alkaline treatment, process parameters - pH (9.0-13.0), time (3.0-12.0 h) and biosolids age (1-28 days) were optimized by statistical modelling. Using Box-Behnken design, experiments were designed and the resultant data was employed as input for model building using RSM and ANN. The developed mathematical model for alkaline treatment of biosolids using ANN predicted CECs removal with 3.2-fold lower MSE and exhibited high regression coefficient (R2 > 0.99) than the conventional RSM model. Further, the multiparameter model was optimized for achieving maximum of 95.7 % CECs removal using ANN-GA. On analyzing the acute toxicity of alkaline treated residual biosolids under the optimized conditions, a reduction in LC50 by an average of 2.1-fold than initial biosolids was observed. This study not only established the application of statistical modelling in the development of an efficient remediation strategy for biosolids, which can be further applied for large-scale remediation process, but also proved the reliability and efficiency of ANN-GA.

Impact of Pharmaceutical Compounds in the Bioremediation of Municipal Biosolids by the White-Rot-Fungi Trametes hirsuta.

The potential of microorganisms for the treatment of municipal biosolids is continuously growing. The present studies evaluated the potency of Trametes hirsuta for the reduction in biosolid mass, production of extracellular enzymes, and removal of pharmaceutical compounds (PhACs) in biosolid slurry in the presence and absence of spiked PhACs [5 non-steroidal anti-inflammatories (NSAIs) and 2 psychoactive compounds (PACs)]. Toxicity after 35 days of fungal treatment was also assessed. Results showed that the growth of T. hirsuta is limited above 25% and wholly inhibited above 50% of biosolids in the slurry. At 12% of biosolid concentration, biosolid mass was reduced by 90%, NSAIs were entirely removed, but PACs' removal was only ~20%. Increasing biosolid content to 25% did not markedly affect biosolid reduction but significantly enhanced the removal of PACs (>50%). Results also showed that both PhACs and biosolids induced the production of oxidative enzymes. In 12% biosolids in the slurry, the oxidative potential measured by the ABTS assay (OABTS) reached 5,000 mM of OABTS in the presence of PhACs, and 2,500 mM of OABTS without PhACs, as compared to 1,200 mM of OABTS in control culture. Finally, we report that white rot fungi (WRF) treatment significantly decreased the toxicity of the biosolids.

Recent Developments in the Immobilization of Laccase on Carbonaceous Supports for Environmental Applications - A Critical Review.

Τhe ligninolytic enzyme laccase has proved its potential for environmental applications. However, there is no documented industrial application of free laccase due to low stability, poor reusability, and high costs. Immobilization has been considered as a powerful technique to enhance laccase's industrial potential. In this technology, appropriate support selection for laccase immobilization is a crucial step since the support could broadly affect the properties of the resulting catalyst system. Through the last decades, a large variety of inorganic, organic, and composite materials have been used in laccase immobilization. Among them, carbon-based materials have been explored as a support candidate for immobilization, due to their properties such as high porosity, high surface area, the existence of functional groups, and their highly aromatic structure. Carbon-based materials have also been used in culture media as supports, sources of nutrients, and inducers, for laccase production. This study aims to review the recent trends in laccase production, immobilization techniques, and essential support properties for enzyme immobilization. More specifically, this review analyzes and presents the significant benefits of carbon-based materials for their key role in laccase production and immobilization.

Efficiencies of selected biotreatments for the remediation of PAH in diluted bitumen contaminated soil microcosms.

Unconventional oils such as diluted bitumen from oil sands differs from most of conventional oils in terms of physiochemical properties and PAHs composition. This raises concerns regarding the effectiveness of current remediation strategies and protocols originally developed for conventional oil. Here we evaluated the efficiency of different biotreatment approaches, such as fungi inoculation (bioaugmentation), sludge addition (bioaugmentation/biostimulation), perennial grasses plantation (phytoremediation) and their combinations as well as natural attenuation (as control condition), for the remediation of soil contaminated by synthetic crude oil (a product of diluted bitumen) in laboratory microcosms. We specifically monitored the PAHs loss percentage (alkylated PAHs and unsubstituted 16 EPA Priority PAHs), the residue of PAHs and evaluated the ecotoxicity of soil after treatment. All treatments were highly efficient with more than ~ 80% of ∑PAHs loss after 60 days. Distinctive loss efficiencies between light PAHs (≤ 3 rings, ~ 96% average loss) and heavy PAHs (4-6 rings, ~ 29% average loss) were observed. The lowest average PAHs residue (0.10 ± 0.02 mg·kg-1, for an initial concentration of 0.29 ± 0.12 mg·kg-1) was achieved with the "sludge-plants (grasses)" combination. Sludge addition was the only treatment that achieved significantly lower ecotoxicity (3% ± 4% of growth inhibition of L. sativa) than the control (natural attenuation, 13% ± 4% of inhibition). Sludge addition, grasses plantation and "sludge-fungi combination" treatments could result in lower PAH exposure (than other treatments) in post-treated soil when using the Canadian Soil Quality Guidelines for the protection of environmental and human health for potentially carcinogenic and other PAHs.

Enzyme polymer engineered structure strategy to enhance cross-linked enzyme aggregate stability: a step forward in laccase exploitation for cannabidiol removal from wastewater.

Despite all its advantages and potential, cross-linking enzyme aggregate (CLEA) technology is still not applied at an industrial scale for enzyme insolubilization for bioremediation purposes. In this study, the enzyme polymer engineered structure (EPES) method was used to enhance CLEA stability and reuse. A crude laccase from Trametes hirsuta was successfully insolubilized to form EPES-CLEAs. The polymeric network provided excellent stability (> 90%) to CLEAs after a 24-h incubation in a non-buffered municipal wastewater effluent (WW), and the biocatalysts were recycled using a centrifugation process. While CLEAs activity dropped to 17%, EPES-CLEAs showed a laccase activity retention of 67% after five cycles of 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) oxidation. After 8 h of treatment in WW, the EPES-CLEAs were equally as effective in removing cannabidiol (CBD) as the free-LAC (~ 37%). This research demonstrates that the EPES method is a promising alternative for CLEA stabilization and reuse in environmental conditions.

Preparation of highly diffusible porous cross-linked lipase B from Candida antarctica conjugates: Advances in mass transfer and application in transesterification of 5-Hydroxymethylfurfural.

The present work pronounces the three phase partitioning (TPP)-facilitated preparation of porous cross-linked Candida antarctica lipase B (CaLB) aggregates (pCLEAs) for 5-Hydroxymethylfurfural (HMF) esters synthesis. CLEAs and pCLEAs of CaLB were prepared with eupergit as the support under the optimized conditions of pH 8.0, eupergit/protein ratio of 3.0:1.0, 50 mM cross-linker concentration and 3.3 mg/mL BSA concentration in 4 h. The optimum starch concentration for pCLEAs was 0.20%, m/v. The maximum biocatalytic load was 650 U/g (CLEAs) and 721 U/g (pCLEAs), and the immobilized biocatalysts were stable over a pH range of 6.0-9.0 and temperature range of (40-60)°C. The BET surface area of CLEAs and pCLEAs were 21.3 and 29.1 m2/g, respectively, and the catalytic efficiency of pCLEAs was 2.2-fold higher than that of CLEAs. Subsequently, the pCLEAs of CaLB were utilized for the manufacturing of industrially significant HMF esters. Under the optimized transesterification conditions, HMF conversion with pCLEAs CaLB was 1.41- and 1.25-fold higher than with free and CLEAs CaLB, respectively. The pCLEAs were reused upto 8 consecutive transesterification cycles and the produced HMF esters reduced the surface tension of water from 72 mN/m to 32.6 mN/m, proving its potential application as surface-active compounds.

Tracking gene expression, metabolic profiles, and biochemical analysis in the halotolerant basidiomycetous yeast Rhodotorula mucilaginosa EXF-1630 during benzo[a]pyrene and phenanthrene biodegradation under hypersaline conditions.

Polyaromatic phenanthrene (Phe) and benzo[a]pyrene (BaP) are highly toxic, mutagenic, and carcinogenic contaminants widely dispersed in nature, including saline environments. Polyextremotolerant Rhodotorula mucilaginosa EXF-1630, isolated from Arctic sea ice, was grown on a huge concentration range -10 to 500 ppm- of Phe and BaP as sole carbon sources at hypersaline conditions (1 M NaCl). Selected polycyclic aromatic hydrocarbons (PAHs) supported growth as well as glucose, even at high PAH concentrations. Initially, up to 40% of Phe and BaP were adsorbed, followed by biodegradation, resulting in 80% removal in 10 days. While extracellular laccase, peroxidase, and un-specific peroxygenase activities were not detected, NADPH-cytochrome c reductase activity peaked at 4 days. The successful removal of PAHs and the absence of toxic metabolites were confirmed by toxicological tests on moss Physcomitrium patens, bacterium Aliivibrio fischeri, human erythrocytes, and pulmonary epithelial cells (A549). Metabolic profiles were determined at the midpoint of the biodegradation exponential phase, with added Phe and BaP (100 ppm) and 1 M NaCl. Different hydroxylated products were found in the culture medium, while the conjugative metabolite 1-phenanthryl-ß-D-glucopyranose was detected in the medium and in the cells. Transcriptome analysis resulted in 870 upregulated and 2,288 downregulated transcripts on PAHs, in comparison to glucose. Genomic mining of 61 available yeast genomes showed a widespread distribution of 31 xenobiotic degradation pathways in different yeast lineages. Two distributions with similar metabolic capacities included black yeasts and mainly members of the Sporidiobolaceae family (including EXF-1630), respectively. This is the first work describing a metabolic profile and transcriptomic analysis of PAH degradation by yeast.

Performance evaluation of biocatalytic and biostimulation approaches for the remediation of trace organic contaminants in municipal biosolids.

Trace organic contaminants (TrOCs) in biosolids is creating potential threats for reuse of biosolids. Out of the tested 64 trace organic contaminants, seven pharmaceutically active compounds (PhACs), and three pesticides were detected in biosolids from a municipal wastewater treatment plant. This study encompasses the removal of TrOCs and improvement in the aerobic digestion of biosolids by various pretreatments including utilization of indigenous microbes present in biosolids (T1), the effect of an enzymatic pretreatment (T2), biostimulation by the addition of an external carbon source (T3) and the synergic effect of biostimulation and enzymatic pretreatment (T4). After 28 days of aerobic digestion, total PhACs removal was 44% with T1, which improved to 51%, 54% and 62% in T2, T3 and T4, respectively. Also, total pesticides removal was 10% in T1, which enhanced to 44%, 14% and 54% in T2, T3 and T4, respectively. The extracellular enzyme activities were also monitored in all the treatments and the maximum activities (114 ± 11 U/L lipase, 382 ± 29 U/L phosphatase, 155 ± 8 U/L protease, 304 ± 26 U/L amylase, 108 ± 7 U/L laccase, and 63 ± 2 U/L lignin peroxidase) were observed in T4 after 28 days of digestion. Thus, this study aids in providing changing aspects of enzyme profiles during these processes and the enhanced bioremediation of biosolids through the hydrolytic and oxidoreductase enzymes produced by the indigenous microorganisms.

Transcriptomic analysis of polyaromatic hydrocarbon degradation by the halophilic fungus Aspergillus sydowii at hypersaline conditions.

Polycyclic aromatic hydrocarbons (PAHs) are among the most persistent xenobiotic compounds, with high toxicity effects. Mycoremediation with halophilic Aspergillus sydowii was used for their removal from a hypersaline medium (1 M NaCl). A. sydowii metabolized PAHs as sole carbon sources, resulting in the removal of up to 90% for both PAHs [benzo [a] pyrene (BaP) and phenanthrene (Phe)] after 10 days. Elimination of Phe and BaP was almost exclusively due to biotransformation and not adsorption by dead mycelium and did not correlate with the activity of lignin modifying enzymes (LME). Transcriptomes of A. sydowii grown on PAHs, or on glucose as control, both at hypersaline conditions, revealed 170 upregulated and 76 downregulated genes. Upregulated genes were related to starvation, cell wall remodelling, degradation and metabolism of xenobiotics, DNA/RNA metabolism, energy generation, signalling and general stress responses. Changes of LME expression levels were not detected, while the chloroperoxidase gene, possibly related to detoxification processes in fungi, was strongly upregulated. We propose that two parallel metabolic pathways (mitochondrial and cytosolic) are involved in degradation and detoxification of PAHs in A. sydowii resulting in intracellular oxidation of PAHs. To the best of our knowledge, this is the most comprehensive transcriptomic analysis on fungal degradation of PAHs.