Degradation Of Polycyclic Aromatic Hydrocarbons Research Articles

In vitro analyses of cerium oxide nanoparticles in degrading anthracene/fluorene and revealing the antibiofilm activity against bacteria and fungi

A sol-gel method was used to synthesize the cerium dioxide nanoparticles. The nanoparticles formed were then characterized with UV–visible spectrophotometry, Fourier Transform Infrared Spectrophotometer (FTIR), SEM-EDAX, XRD, and Dynamic Light Scattering (DLS). The UV–visible absorbance at 282 nm and characteristic peak at 600-4000 cm−1 provided insight into the formation of cerium dioxide nanoparticles using a chemical method. SEM analysis and EDAX analysis confirmed nanoparticle formation and elements within the nanoparticles based on their irregular morphology. The hydrodynamic size obtained from the DLS analysis was 178.4 nm and the polydispersity was 0.275 nm. Furthermore, XRD results confirmed the crystalline nature of cerium dioxide nanoparticles. Using batch adsorption as a method, the effect of concentration of Polycyclic Aromatic Hydrocarbons (PAH), adsorbent concentration, pH, and irradiation source was investigated. Under UV light conditions, 10 μg/mL cerium dioxide nanoparticle at pH 5 degraded 2 μg/mL of PAH (anthracene and fluorene). Consequently, the synthesized cerium dioxide nanoparticles were effective photocatalysts. For anthracene and fluorene, kinetic studies showed the degradation process followed pseudo-second-order kinetics and Freundlich isotherms. Cerium oxide also exhibited significant antimicrobial and antibiofilm activity against bacteria and fungi. As a result, the cerium dioxide nanoparticle has proved to be a highly effective photocatalytic tool for the degradation of PAHs and exhibits strong antimicrobial activity.

Targeted degradation of naphthalene by peroxymonosulfate activation using molecularly imprinted biochar

Polycyclic aromatic hydrocarbons (PAHs) in aquatic environments are threatening ecosystems and human health. In this work, an effective and environmentally friendly catalyst based on biochar and molecular imprinting technology (MIT) was developed for the targeted degradation of PAHs by activating peroxymonosulfate. The results show that the adsorption amount of naphthalene (NAP) by molecularly imprinted biochar (MIP@BC) can reach 82% of the equilibrium adsorption capacity within 5 min, and it had well targeted adsorption for NAP in the solution mixture of NAP, QL and SMX. According to the comparison between the removal rates of NAP and QL by MIP@BC/PMS or BC/PMS system in respective pure solutions or mixed solutions, the MIP@BC/PMS system can better resist the interference of competing pollutants (i.e., QL) compared to the BC/PMS system; that is, MIP@BC had a good ability to selectively degrade NAP. Besides, the removal rate of NAP by MIP@BC/PMS gradually decreased as pH increased. The addition of Cl− greatly promoted the targeted removal of NAP in the MIP@BC/PMS system, while HCO3− and CO32− both had an inhibitory effect. Furthermore, SO4•-, O2•- and 1O2 produced by BC activating PMS dominated the NAP degradation, and it was inferred that the vacated imprinted cavities after NAP degradation can continue to selectively adsorb NAP and this could facilitate the reusability of the material. This study can promote the research on the targeted degradation of PAHs through the synergism of biochar/PMS advanced oxidation processes and MIT.

Sepiolite promotes photodegradation of pyrene under visible light

Mechanochemistry and photocatalysis are emergent technologies for the remediation of polycyclic aromatic hydrocarbons (PAHs) in soils. In this work, mechanochemistry and photocatalysis are combined for pyrene degradation. The photodegradation of pyrene, when in contact with sepiolite under pressure application, is studied. The mechanical treatment leads to a pyrene crystal phase transformation. In this new phase, pyrene undergoes a fast photodegradation in the 320–420 nm range. We show that sepiolite is superior as a photocatalyst in pyrene degradation to TiO2, the most exploited photocatalyst. A broad physicochemical characterization is carried out to propose a mechanism in which the photoexcitation of mechanically altered pyrene leads to an electron transfer to sepiolite matrix, which triggers the PAH degradation. Finally, we want to highlight that the pyrene/sepiolite combination is a simplified system to shed light on how PAH photodegradation may occur in soils.

Enhanced photocatalytic degradation of polycyclic aromatic hydrocarbon by graphitic carbonitride-nickel (g–C3N4–Ni) nanocomposite

The objective of the present study is to synthesize g-C3N4–Ni nanocomposites composed of graphitic carbon nitride and magnetic nickel nanoparticles for benzopyrene degradation, which is one of the most potent polycyclic aromatic hydrocarbons (PAH) molecules. The concocted g-C3N4–Ni nanocomposites contained confined nanospheres with a mean particle dimension of 22 nm. Batch adsorption studies revealed that a rise in adsorbent dosage elevates benzopyrene degradation percentage in both water and soil samples with respect to time. The increase in the benzopyrene concentration did not have much influence on the degradation efficiency, and hence, the minimal concentration of PAH molecule is essential for the effective adsorption by g-C3N4–Ni nanocomposites. The rise in pH tends to increase the degradation of Benzopyrene till 3 h of the incubation period, and beyond 3 h, the degradation percentage declines. With regard to the effect of light source, UV light has been shown to accelerate the degradation of benzopyrene by g-C3N4–Ni nanocomposites than sunlight. The adsorption kinetic and isotherm investigations have proven that the Pseudo-second order kinetic model and Freundlich isotherm model were appropriate for our study. Thus, the g-C3N4–Ni nanocomposites were found to be efficient as a photocatalyst for the adsorption of benzopyrene from environmental samples.

The addition of Glomalin-related soil protein and functional microbial consortium increased bound PAH residue degradation in soil

Bound Polycyclic Aromatic Hydrocarbons (PAHs) residues are the “end point” of soil pollution remediation. However, bound PAH residues can be released and become bioavailable exerting ecological and human health impacts. Remediation of soils contaminated with bound PAHs is a critical pollution control issue that support safe and healthy agricultural production We conducted microcosmic experiments to study the degradation of bound PAH residues in the soil by exogenous functional microbial consortium with and without the addition of glomalin-related soil protein (GRSP). Our results showed limited degradation of bound PAHs by the functional microbial consortium, however, a high concentration of 1000 mg/kg could accelerate the process. The removal rates of low molecular weight PAHs, medium molecular weight PAHs, high molecular weight PAHs, and total PAHs increased by 6.6%–14.2%, 8.2%–14.6%, 5.2%–7.5% and 6.7%–12.0%, respectively. The application of high- concentration GRSP increased the content of PAHs degrading bacteria such as Sphingomonas and Arthrobacter in soil and the abundance of some vital functional genes during PAH biodegradation (phe, nahAc, and nidA) thus promoting the degradation of bound PAHs residues. This study fills the cognitive gap of GRSP in regulating the degradation of bound PAH residues in soil, and provides an important basis for the subsequent development of bound PAH residue removal technology. These findings contribute to our understanding of the role of GRSP in regulating the degradation of soil-bound PAHs.

Biochar alters the persistence of PAHs in soils by affecting soil physicochemical properties and microbial diversity: A meta-analysis

Polycyclic aromatic hydrocarbons (PAHs) pollution in soil is a pervasive environmental issue worldwide. Although biochar has the potential to immobilize PAHs in soils, there remains a study gap in the use of systematic analyses to assess the effectiveness of biochar for PAH removal and the factors that affect biochar. Hence, a meta-analysis utilizing 56 published studies was aimed to assess the impact of biochar on the PAH content, soil physicochemical properties, and microbial diversity in PAH-contaminated soils and to elucidate what factors impact the capability of biochar to alter PAH persistence. With biochar application, soil Ctot PAH concentrations were significantly reduced (15.4%), while the levels of Cfree PAHs and Cbioacc PAHs were reduced by 55.6% and 46.5%, respectively. Additionally, biochar improved the physicochemical properties of PAH-contaminated soil and increased the diversity of microorganisms. Particularly, the relative abundance of PAH degraders increased significantly (43.7%), which indicated that PAH biodegradation was significantly enhanced. Soil physicochemical properties and biochar production conditions are indispensable for the study of the PAH persistence. The overall findings revealed that the pyrolysis of woody biochar at 300–500 °C was beneficial for reducing the PAH persistence in acidic, coarse, or fine and high soil organic matter content (>20 g/kg) soils.

Community pattern of potential phenanthrene (PHE) degrading bacteria in PHE contaminated soil revealed by 13C-DNA stable isotope probing

Quantification of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil and identification of potential PAH degraders are essential for comprehending their environmental fate and conducting bioremediation. However, the microbial population responsible for the breakdown of phenanthrene (PHE) in polluted soil environments is frequently disregarded. In this study, via DNA-stable-isotope probing (DNA-SIP), we found that soil microbiota likely plays a crucial part in the PHE degradation. The PHE removal rates were 98% and 99%, in 13C-PHE and 12C-PHE microcosmic incubations, respectively. 13CO2 was produced along with the degradation of 13C-PHE. According to the analysis of 16S rRNA gene, there was a relatively higher presence of unidentified bacteria in the ‘heavy’ DNA fractions treated with 13C-PHE. Genus of Enterobacteriales, Acidobacteria, Alphaproteobacteria, Paenibacillaceae, Flavobacteriia, Chloroflexi, Cyanobacteria, Caldilineae, Latescibacteria, Armatimonadetes and Blastocatellia were succseesfully labeled during the degradation of 13C-PHE, indicating their capacity of utilizing PHE. Co-occurrence network of 13C-heavy fractions exhibited greater complexity compared with that of 12C-heavy fractions, revealling an enhancement of bacterial interspecies interactions. Collectivley, this study eluidated the soil microbes involed in the PHE degradation and offered fresh perspectives on the community pattern of potential PHE degrading bacteria.

Comparative genomics reveals evidence of polycyclic aromatic hydrocarbon degradation in the moderately halophilic genus Pontibacillus

Polycyclic aromatic hydrocarbons (PAHs) are a common class of persistent organic pollutants (POPs) that are widely distributed in various environments and pose significant threats to both environmental and human health. The genus Pontibacillus, a type of moderately halophilic bacteria, has demonstrated potential for biodegrading aromatic compounds in high-salinity environments. However, no previous study has comprehensively investigated the PAH degradation mechanisms and environmental adaptability in the genus Pontibacillus. In this study, we sequenced the whole genome of the PAH-degrading strain Pontibacillus chungwhensis HN14 and conducted a comparative genomics analysis of genes associated with PAH degradation, as well as salt and arsenic tolerance using ten other Pontibacillus sp. strains. Here, we elucidated potential degradation pathways for benzo[a]pyrene and phenanthrene, which were initiated by cytochrome P450 monooxygenases, in most Pontibacillus strains. Moreover, four Pontibacillus strains were selected to investigate the biodegradation of benzo[a]pyrene and phenanthrene under high-salt (5% NaCl) stress, and all four strains exhibited exceptional degradation abilities. The results of comparative genomics and phenotypic analyses demonstrate that the genus Pontibacillus have the potential to degrade polycyclic aromatic hydrocarbons in high-salinity environments, thus providing valuable insights for biodegradation in extreme environments.

Degradation of multiple PAHs and co-contaminants by microbial consortia and their toxicity assessment.

The anthropogenic activities toward meeting the energy requirements have resulted in an alarming rise in environmental pollution levels. Among pollutants, polycyclic aromatic hydrocarbons (PAHs) are the most predominant due to their persistent and toxic nature. Amidst the several pollutants depuration methods, bioremediation utilizing biodegradation is the most viable alternative. This study investigated the biodegradation efficacy using developed microbial consortium PBR-21 for 2-4 ringed PAHs named naphthalene (NAP), anthracene (ANT), fluorene (FLU), and pyrene (PYR). The removal efficiency was observed up to 100 ± 0.0%, 70.26 ± 4.2%, 64.23 ± 2.3%, and 61.50 ± 2.6%, respectively, for initial concentrations of 400mg L-1 for NAP, ANT, FLU, and PYR respectively. Degradation followed first-order kinetics with rate constants of 0.39 d-1, 0.10 d-1, 0.08 d-1, and 0.07 d-1 and half-life of 1.8h, 7.2h, 8.5h, and 10h, respectively. The microbial consortia were found to be efficient towards the co-contaminants with 1 mM concentration. Toxicity examination indicated that microbial-treated PAHs resulted in lesser toxicity in aquatic crustaceans (Artemia salina) than untreated PAHs. Also, the study suggests that indigenous microbial consortia PBR-21 has the potential to be used in the bioremediation of PAH-contaminated environment.

Evaluation of the content and degradation rates of PAHs in biochars, in terms of assessing the environmental risks of their application for soil remediation

The growing worldwide practice of biochar application as soil ameliorants, as well as adsorbents for remediation of soil contaminated with oil products and heavy metals, can lead to an increase the risk of environmental pollution by pyrolysis by-products. One of the most dangerous components of biochars is polycyclic aromatic hydrocarbons (PAHs), which are inevitably formed during the production of pyrogenic material. In this work, biochars obtained from various plant materials (millet, corn, willow, linden) under different pyrolysis temperatures were tested for the content of polycyclic aromatic hydrocarbons. The total content of PAHs in the studied samples ranged from 8.49 to 221.21 µg/kg, which does not exceed the limit concentrations established by the International Biochar Initiative. At the same time, polynuclear hydrocarbons with high carcinogenic and immunotoxic properties are found in the composition of biochars. A natural question arises about the effect of the final pyrolysis temperature on the total content and composition of PAHs in pyrolysis by-products. To study the degradation of polycyclic aromatic hydrocarbons in soil, linden biochar obtained by pyrolysis at 250 °C was used, from which the contaminants were extracted and applied to the soil so that the concentration of the marker was 20 and 40 µg/kg. The determination of the residual amount of polycyclic aromatic hydrocarbons was carried out after 1, 2, 6, and 11 months of incubation. Complete degradation of some 3–5-membered polycyclic aromatic hydrocarbons was found after 1–2 months of incubation. The most persistent pollutants were benzo(a)pyrene, benzo(b)fluoranthene, and pyrene, the concentration of which decreased to 31–71% on after 11 months of incubation. The slower degradation was found in the variant of the experiment with the high concentration level of polycyclic aromatic hydrocarbons. It was concluded that in soils selective accumulation of polynuclear PAHs, that most resistant to biodegradation, can occur.

Evaluation of Azolla filiculoides potential in pyrene and phenanthrene accumulation and phytoremediation in contaminated waters

Polycyclic aromatic hydrocarbons (PAHs) are a serious threat to the health of the environment. This study investigated the potential of Azolla filiculoides for the uptake, accumulation, and biodegradation of phenanthrene and pyrene. A- filiculoides plants were treated with 10 and 30 mg L−1 concentrations of phenanthrene and pyrene for the experimental duration of ten days. Phenanthrene and pyrene concentrations were measured using the high-performance liquid chromatography (HPLC) technique. Identification of the intermediate by-products resulting from the biological degradation of PAHs was performed by gas chromatography-mass spectrometry (GC/MS). The quantities of phenanthrene and pyrene in the ten-day treatments with 10 and 30 mg L−1 were 0.007 and 0.011 mg g−1 FW, and 0.048 and 0.079 mg g−1 FW, respectively. The growth parameters in the plants such as fresh weight, dry weight and RFN as well as the content of photosynthetic pigment of the plant decreased significantly compared to the control sample (p < 0.05). Ten compounds were identified from the plant tissue during the decomposition of pyrene and phenanthrene, and none of the PAHs were identified in the aquatic environment. Therefore, the use of A-filiculoides for phytoremediation of water resources contaminated with PAHs is an effective and promising method.

Insights into ecotoxicity effects of PAHs and ecosystem responses of remediation strategies under cold stress: From PAHs degradation to ecological restoration regulated by signal molecular

Polycyclic aromatic hydrocarbons (PAHs) known as persistent contaminants have been detected in soils worldwide, especially in cryogenic environment. Although researchers have conducted lots of researches on PAHs, the ecological toxicity of PAHs and the remediation mechanism of PAHs polluted soils under low temperature are still unclear. Herein, we attempted to characterize remediation of PAHs polluted environment by coupling the PAH degradation with ecological restoration. PAHs could not degrade completely in natural and multiple metabolites accumulate in soil under low temperature. Long-term accumulation of pollutants could cause severe oxidative stress, inhibit the growth of plants and normal process and transformation of substances of microorganisms, while increased the relative abundance of PAHs degrading bacteria (Sphingobacterium, Pseudomonas, Rhodococcus and Massilia etc) and degradation genes (nidA nidB, nahAa, nahAb, nahAc, nidD, phdJ and phdG). As soil amendents, biochar, microbial agent, biochar together with microbial agent could remove 75%, 83%, and 93% of PAHs from soil, and 47%, 50%, and 58% of PAHs from plants, respectively. Under the bioaugmentation of soil amendments, soil microorganisms played an important role in PAHs degradation and ecological restoration. Meanwhile, we identified three signal molecules related to ecological restoration which play a crucial role in regulating pollution removal and ecological restoration by indigenous microorganisms. OOHL and C10-HSL are involved in environmental resistance, degradation of PAHs and transformation of nutrients. 3-oxo-C14-HSL promoted the degradation of PAHs and cold adaption of microorganism. Our study provided an innovative strategy for controlling PAHs degradation and ecological restoration from the perspective of microbial transboundary informatics.

Characterization of three rapidly growing novel Mycobacterium species with significant polycyclic aromatic hydrocarbon bioremediation potential.

Mycobacterium species exhibit high bioremediation potential for the degradation of polycyclic aromatic hydrocarbons (PAHs) that are significant environmental pollutants. In this study, three Gram-positive, rapidly growing strains (YC-RL4T, MB418T, and HX176T) were isolated from petroleum-contaminated soils and were classified as Mycobacterium within the family Mycobacteriaceae. Genomic average nucleotide identity (ANI; < 95%) and digital DNA-DNA hybridization (dDDH; < 70%) values relative to other Mycobacterium spp. indicated that the strains represented novel species. The morphological, physiological, and chemotaxonomic characteristics of the isolates also supported their affiliation with Mycobacterium and their delineation as novel species. The strains were identified as Mycobacterium adipatum sp. nov. (type strain YC-RL4T = CPCC 205684T = CGMCC 1.62027T), Mycobacterium deserti sp. nov. (type strain MB418T = CPCC 205710T = KCTC 49782T), and Mycobacterium hippophais sp. nov. (type strain HX176T = CPCC 205372T = KCTC 49413T). Genes encoding enzymes involved in PAH degradation and metal resistance were present in the genomes of all three strains. Specifically, genes encoding alpha subunits of aromatic ring-hydroxylating dioxygenases were encoded by the genomes. The genes were also identified as core genes in a pangenomic analysis of the three strains along with 70 phylogenetically related mycobacterial strains that were previously classified as Mycolicibacterium. Notably, strain YC-RL4T could not only utilize phthalates as their sole carbon source for growth, but also convert di-(2-ethylhexyl) phthalate into phthalic acid. These results indicated that strains YC-RL4T, MB418T, and HX176T were important resources with significant bioremediation potential in soils contaminated by PAHs and heavy metals.

Degradation of crude oil-associated polycyclic aromatic hydrocarbons by marine-derived fungi.

The online version contains supplementary material available at 10.1007/s13205-023-03753-2.

Nano-composite rGO-Ag-Cu-Ni mediated photocatalytic degradation of anthracene and benzene

Polycyclic aromatic hydrocarbons (PAHs) are omnipresent, persistent, and carcinogenic pollutants continuously released in the atmosphere due to the rapid increase in population and industrialization worldwide. Hence, there is an ultimate rise in concern about eliminating the toxic PAHs and their related aromatic hydrocarbons from the air, water, and soil environment by employing efficient removal technologies using nanoparticles as a catalyst. Here, the degradation of selective PAHs viz., anthracene and benzene using laboratory synthesized rGO-Ag-Cu-Ni nanocomposite (catalyst) was studied. Characterization studies revealed the nanocomposites exhibited surface plasma resonance at 350 - 450 nm, confirming the presence of Ag, Cu, and Ni metal ions embedded on the reduced graphene substrate. It was found that the nanocomposites synthesized were spherical, amorphous in nature, and aggregated together with measurements ranging from 423 to 477 nm. An SEM-EDX analysis of the nanocomposite demonstrated that it contained 25.13% O, 14.24% Ni, 27.79% Cu, and 32.84% Ag, which confirms the synthesis of the nanocomposite. Crystalline, sharp nanocomposites of average size 17–41 nm with an average diameter of 118.5 nm (X-ray diffraction and DLS) were observed. FTIR spectra showed that the nanocomposites had the functional groups alkanes, alkenes, alkynes, carboxylic acids, and halogen derivatives. Batch adsorption studies revealed that the maximum degradation achieved at optimum nano-composite concentration of 10 μg/mL, pH value of 5, PAHs concentration of 2 μg/mL and effective irradiation source being UV radiations in the case of both benzene and anthracene pollutants. The degradation of benzene and anthracene followed Freundlich & Langmuir isotherm with the highest R2 value of 0.9894 & 0.9885, respectively. Adsorption kinetic studies under optimum conditions revealed that the adsorption of both benzene and anthracene followed Pseudo-second order kinetics. Antimicrobial studies revealed that the synthesized nano-composite exhibited potential antimicrobial activity against Gram positive bacterium (Bacillus subtilis, Staphylococcus aureus), Gram negative bacterium (Klebsiella pneumonia, Escherichia coli) and fungal strain (Aspergillus niger) respectively. Thus, the synthesized rGO-Ag-Cu-Ni nano-composite acts as an effective antimicrobial agent as well as a PAHs degrading agent, helping to overcome antibiotics resistance and to mitigate the overgrowing PAHs pollution in the environment.

Integrating metal-organic framework ZIF-8 with green modifier empowered bacteria with improved bioremediation

Suspended microorganisms often experience diminished efficacy in the bioremediation of polycyclic aromatic hydrocarbons (PAHs). In this study, the potential of zeolite imidazolate framework-8 (ZIF-8) and the eco-friendly modifier citric acid (CA) was harnessed to generate a biomimetic mineralized protective shell on the surface of Bacillus subtilis ZL09–26, resulting in an enhanced capability for PAH degradation. This investigation encompassed the integrated responses of B. subtilis ZL09–26 to ZIF-8 and ZIF-8-CA at both cellular and proteomic levels. The amalgamation of ZIF-8 and CA not only stimulated the growth and bolstered the cell viability of B. subtilis ZL09–26, but also counteracted the toxic effects of phenanthrene (PHE) stress. Remarkably, the bioremediation prowess of B. subtilis ZL09–26@ZIF-8-CA surpassed that of ZL09–26@ZIF-8 and ZL09–26, achieving a PHE removal rate of 94.14 % within 6 days. After undergoing five cycles, ZL09–26@ZIF-8-CA demonstrated an enduring PHE removal rate exceeding 83.31 %. A complex interplay of various metabolic pathways orchestrated cellular responses, enhancing PHE transport and degradation. These pathways encompassed direct PHE biodegradation, central carbon metabolism, oxidative phosphorylation, purine metabolism, and aminoacyl-tRNA biosynthesis. This study not only extends the potential applications of biomineralized organisms but also offers alternative strategies for effective contaminant management.

Microbiome based approaches for the degradation of polycyclic aromatic hydrocarbons (PAHs): A current perception

Globally, polycyclic aromatic hydrocarbons (PAHs) pollution is primarily driven by their release into the air through various combustion processes, including burning fossil fuels such as coal, oil, and gas in motor vehicles, power plants, and industries, as well as burning organic matter like wood, tobacco, and food in fireplaces, cigarettes, and grills. Apart from anthropogenic pollution sources, PAHs also occur naturally in crude oil, and their potential release during oil extraction, refining processes, and combustion further contributes to contamination and pollution concerns. PAHs are resistant and persistent in the environment because of their inherent features, viz., heterocyclic aromatic ring configurations, hydrophobicity, and thermostability. A wide range of microorganisms have been found to be effective degraders of these recalcitrant contaminants. The presence of hydrocarbons as a result of numerous anthropogenic activities is one of the primary environmental concerns. PAHs are found in soil, water, and the air, making them ubiquitous in nature. The presence of PAHs in the environment creates a problem, as their presence has a detrimental effect on humans and animals. For a variety of life forms, PAH pollutants are reported to be toxic, carcinogenic, mutation-inducing, teratogenic, and immune toxicogenics. Degradation of PAHs via biological activity is an extensively used approach in which diverse microorganisms (fungal, algal, clitellate, and protozoan) and plant species and their derived composites are utilized as biocatalysts and biosurfactants. Some microbes have the ability to transform and degrade these PAHs, allowing them to be removed from the environment. The goal of this review is to provide a critical overview of the existing understanding of PAH biodegradation. It also examines current advances in diverse methodologies for PAH degradation in order to shed light on fundamental challenges and future potential.

Shrimp laccase degrades polycyclic aromatic hydrocarbons from an oil spill disaster in Brazil: A tool for marine environmental bioremediation

Our work aims to purify, characterize and evaluate a laccase from by-products of the shrimp farming industry (Litopenaeus vannamei) for the degradation of Polycyclic Aromatic Hydrocarbons (PAHs) from 2019 oil spill in Brazilian coast. The enzyme was purified by affinity chromatography and characterized as thermostable, with activity above 90 °C and at alkaline pH. In addition, the laccase was also tolerant to copper, lead, cadmium, zinc, arsenic, hexane and methanol, with significant enzymatic activation in acetone and 10 mM mercury. Concerning PAHs' degradation, the enzyme degraded 42.40 % of the total compounds, degrading >50 % of fluorene, C4-naphthalenes, C3-naphthalenes, C2-naphthalenes, anthracene, acenaphthene, 1-methylnaphthalene and 2-methylnaphthalene. Thus, this laccase demonstrated important characteristics for bioremediation of marine environments contaminated by crude oil spills, representing a viable and ecological alternative for these purposes.

Enhancement of electrokinetic-phytoremediation by Ophiopogon japonicus: stimulation of electrokinetic on root system and improvement of polycyclic aromatic hydrocarbon degradation.

Root systems are sensitive to voltage and tend to improve the degradation of organic pollutants by promoting the root exudates and increasing microbial enzyme activity in the rhizosphere under the effect of electrokinetic. In this study, electrokinetic-assisted phytoremediation (EKPR) was applied for the remediation of soil containing phenanthrene (PHE) and pyrene (PYR). Direct current (DC) voltage (1Vcm-1) was applied across the soils for 30days following 3 treatment schedules (0h, 4h, and 12h per day), referred to as treatments EK0, EK4, and EK12. Electrokinetic assistance improved phytoremediation. Compared to EK0, the removal of PHE and PYR increased by 51.79% and 45.07% for EK4 and by 43.18% and 38.75% for EK12. The applied voltage promoted root growth, stimulated the root exudate release, and increased accumulation of PHE and PYR by plants, and the effect was most pronounced in treatment EK4. Catalase and urease activities in rhizosphere soil also increased, by respective increments of 44.51% and 40.86% for EK4 and by 28.53% and 21.24% for EK12. In this study, we demonstrated that a low voltage applied for an appropriate duration (4h per day) improves removal of PAHs by stimulating root growth, promoting the root exudate release and enhancing enzyme activity in the microbiome of rhizosphere soil.

The mycoremediation potential of the armillarioids: a comparative genomics analysis.

Genes involved in mycoremediation were identified by comparative genomics analysis in 10 armillarioid species and selected groups of white-rot Basidiomycota (14) and soft-rot Ascomycota (12) species to confine the distinctive bioremediation capabilities of the armillarioids. The genomes were explored using phylogenetic principal component analysis (pPCA), searching for genes already documented in a biocatalysis/biodegradation database. The results underlined a distinct, increased potential of aromatics-degrading genes/enzymes in armillarioids, with particular emphasis on a high copy number and diverse spectrum of benzoate 4-monooxygenase [EC:1.14.14.92] homologs. In addition, other enzymes involved in the degradation of various monocyclic aromatics were more abundant in the armillarioids than in the other white-rot basidiomycetes, and enzymes involved in the degradation of polycyclic aromatic hydrocarbons (PAHs) were more prevailing in armillarioids and other white-rot species than in soft-rot Ascomycetes. Transcriptome profiling of A. ostoyae and A. borealis isolates confirmed that several genes involved in the degradation of benzoates and other monocyclic aromatics were distinctively expressed in the wood-invading fungal mycelia. Data were consistent with armillarioid species offering a more powerful potential in degrading aromatics. Our results provide a reliable, practical solution for screening the likely fungal candidates for their full biodegradation potential, applicability, and possible specialization based on their genomics data.