Polycyclic Aromatic Hydrocarbons Degradation Efficiency Research Articles

Degradation of a mixture of 13 polycyclic aromatic hydrocarbons by commercial effective microorganisms.

The study focused on the contribution of effective microorganisms (EM) and their consortia, used in commercial biological preparations and formulations for soil revitalization, to the degradation of a mixture of 13 polycyclic aromatic hydrocarbons (PAHs) commonly found in the soil environment. PAHs, diverse forms of which are present in the environment, never occur individually but always as a part of a chemical mixture. Therefore, the research presented in this article, focusing on the EM impact on the mixture of PAHs, reflects the conditions most similar to natural ones. On Day 35 of the experiment, PAH levels decreased by 75.5-95.5%. The highest PAHs degradation efficiency was achieved for fluorene, with a preparation containing eight bacteria strains from the Bacillus genus: B. coagulans, B. amyloliquefaciens, B. laterosporus, B. licheniformis, B. mucilaginosus, B. megaterium, B. polymyxa, and B. pumilus. All tested preparations containing bacterial consortia and a preparation with the yeast S. cerevisiae intensified the PAHs degradation more effectively than formulations including only the yeast Yarrowia lipolytica or a mixture of Debaryomyces hansenii and Bacillus. The designed and proposed research will contribute to the development of biotechnological methods - bioremediation by microorganisms that are safe for the human and environment health.

Effects of electron acceptors and donors on anaerobic biodegradation of PAHs in marine sediments

Polycyclic aromatic hydrocarbons (PAHs) are typical organic pollutants accumulated in the environment. PAHs' bioremediation in sediments can be promoted by adding electron acceptor (EA) and electron donor (ED). Bicarbonate and sulfate were chosen as two EAs, and acetate and lactate were selected as two EDs. Six groups of amendments were added into the sediments to access their role in the anaerobic biodegradation of five PAHs, containing phenanthrene, anthracene, fluoranthene, pyrene, and benzo[a]pyrene. The concentrations of PAHs, EAs and EDs, electron transport system activity, and microbial diversity were analyzed during 126-day biodegradation in serum bottles. The HA group (bicarbonate and acetate) achieved the maximum PAH degradation efficiency of 89.67 %, followed by the SL group (sulfate and lactate) with 87.10 %. As the main PAHs degrading bacteria, the abundance of Marinobacter in H group was 8.62 %, and the addition of acetate significantly increased the abundance of Marinobacter in the HA group by 75.65 %.

Insight into the interactions between surfactants and microorganisms for the biodegradation of polycyclic aromatic hydrocarbons: Enhancing efficiency, cellular response, and elucidating mechanisms

The response mechanisms of polycyclic aromatic hydrocarbons (PAHs)-degrading strains to Tween 80 concentrations are key elements of microbial remediation efficacy. The degradation characteristics, cell morphology, and microbial metabolic activities of three strains (Arthrobacter (SZ-3), Pseudomonas putida (B6-2), and Klebsiella (CW-D3T)) at different Tween 80 concentrations (0∼2000 mg/L) were investigated. The results showed that the three PAHs degrading strains grow well with the maximum cell activity of 8.75–8.81 log CFU/ml and the electron transfer system activity (ETSA) of 0.341–0.655 μg O2 g−1min−1 at a Tween 80 concentrations range of 1000–2000 mg/L. The best degradation of PAHs by SZ-3 was achieved at a Tween 80 concentration of 500 mg/L. The degradation rates of phenanthrene (PHE), fluoranthene (FLU), and pyrene (PYR) were 91.42%, 54.62%, and 50.76%, respectively. For strains B6-2 and CW-D3T, the highest degradation rates for PHE were achieved at a Tween 80 concentration of 500 mg/L, and the highest degradation rates for FLU and PYR were reached in the absence of Tween 80. The changes of catechol 1,2-dioxygenase were consistent with the PAHs degradation efficiency. The cell surface hydrophobicity (CSH) of SZ-3 and CW-D3T increased with the increase of Tween 80, while that of B6-2 decreased. In addition, the detection of PAHs metabolites showed that SZ-3 had two metabolic pathways, salicylic acid, and phthalic acid. B6-2 metabolized PAHs mainly through the phthalic acid pathway, and CW-D3T mainly through the salicylic acid pathway. Tween 80 did not affect the metabolic pathway of PAHs by each strain.

The remediation of marine sediments containing polycyclic aromatic hydrocarbons by peroxymonosulfate activated with Sphagnum moss-derived biochar and its benthic microbial ecology

This research was to study the efficiency of Sphagnum moss-derived biochar (SMBC) in removing polycyclic aromatic hydrocarbons (PAHs) from marine sediment using a peroxymonosulfate (PMS)-based carbon-advanced oxidation process (PMS-CAOPs). Sphagnum moss-derived biochar (SMBC) was generated via a simple thermochemical process for PMS activation toward enhancing decontamination of sediments. At pH 6, the SMBC/PMS system achieved a PAH removal efficiency exceeding 78% in 12 h reaction time. Moreover, PAHs of 6-, 5-, 4-, 3-, and 2-ring structures exhibited 98%, 74%, 68%, 85%, and 91%, of removal, respectively. The SMBC activation of PMS generated both radicals (SO4•– and HO•) and nonradical (1O2), species responsible for PAHs degradation, attributed primarily to inherent iron and carbon moieties. The significant PAHs degradation efficiency showcased by the SMBC/PMS process holds promise for augmenting the performance of indigenous benthic microbial activity in sediment treatment contexts. The response of sediment microbial communities to PAH-induced stress was particularly associated with the Proteobacteria phylum, specifically the Sulfurovum genus. The findings of the present study highlight the efficacy of environmentally benign reactive radical/nonradical-based PMS-CAOP using pristine carbon materials, offering a sustainable strategy for sediment treatment.

New insights in the biodegradation of high-cyclic polycyclic aromatic hydrocarbons with crude enzymes of Trametes versicolor

ABSTRACT High-cyclic polycyclic aromatic hydrocarbons (PAHs), with complex fused aromatic structures, are widespread, refractory and harmful in soil, but the current remediation technologies for high-cyclic PAHs are often inefficient and costly. This study focused on the biodegradation process of high-cyclic benzo[a]pyrene by Trametes versicolor crude enzymes. The crude enzymes exhibited high laccase activity (22112 U/L) and benzo[a]pyrene degradation efficiency (42.21%) within a short reaction time. Through the actual degradation and degradation kinetics, the degradation efficiency of PAHs decreased with the increase of aromatic rings. And the degradation conditions (temperature, pH, Cu2+ concentration, mediator) were systematically optimised. The optimum degradation conditions (1.5 mM Cu2+, 28℃ and pH 6) showed significant degradation efficiency for the low and medium concentrations of benzo[a]pyrene. In addition, complete degradation of benzo[a]pyrene could be achieved using only 0.2 mM of HBT mediator compared with crude enzymes alone. Collectively, these results showed the high-cyclic PAHs degradation potential of Trametes versicolor crude enzymes, and provided references to evaluate applicable prospects of white rot fungus crude enzymes in PAHs-contaminated soils.

Enhanced Bioremediation of Aged Polycyclic Aromatic Hydrocarbons in Soil Using Immobilized Microbial Consortia Combined with Strengthening Remediation Strategies.

Microbial biodegradation is considered as one of the most effective strategies for the remediation of soil contaminated with polycyclic aromatic hydrocarbons (PAHs). To improve the degradation efficiency of PAHs, PAH-degrading consortia combined with strengthening remediation strategies was used in this study. The PAH biodegrading performance of seven bacterial consortia constructed by different ratios of Mycobacterium gilvum MI, Mycobacterium sp. ZL7 and Rhodococcus rhodochrous Q3 was evaluated in an aqueous system containing phenanthrene, pyrene, benzo[a]pyrene and benzo[b]fluoranthene. Bacterial consortium H6 (Q3:ZL7:MI = 1:2:2) performed a high degrading efficiency of 59% in 8 days. The H6 was subsequently screened to explore its potential ability and performance to degrade aged PAHs in soils from a coking plant and the effects of strengthening strategies on the aged PAH degradation, including the addition of glucose or sodium dodecyl benzene sulfonate (SDBS) individually or as a mixture along immobilization of the inoculant on biochar. The highest degradation efficiencies, which were 15% and 60% for low-molecular-weight (LMW) PAHs and high-molecular-weight (HMW) PAHs, respectively, were observed in the treatment using immobilized microbial consortium H6 combined with the addition of glucose and SDBS after 24 days incubation. This study provides new insights and guidance for future remediation of aged PAH contaminated soils.

Effect of terminal electron acceptors on the anaerobic biodegradation of PAHs in marine sediments

The existing polycyclic aromatic hydrocarbons (PAHs) in marine sediment has become a critical threat to biological security. Terminal electron acceptor (TEA) amendment has been applied as a potential strategy to accelerate bioremediation in sediment. HCO3-, NO3-, and SO42- were separately added to anaerobic sediment system containing five kinds of PAH, namely, phenanthrene, anthracene, fluoranthene, pyrene and benzo(a)pyrene. PAH concentration, PAH metabolites, TEA concentration, and electron transport system (ETS) activity were investigated. The HCO3- amendment group achieved the max PAH degradation efficiency of 84.98 %. SO42- group led to the highest benzo(a)pyrene removal rate of 69.26 %. NO3- had the lowest PAH degradation rate of 76.16 %. ETS activity test showed that NO3- significantly inhibited electron transport activity in the sediment. The identified PAH metabolites were the same in each group, including 4,5-dimethylphenanthrene, 3-acetylphenanthrene, 9,10-anthracenedione, pyrene-7-hydroxy-8-carboxylic acid, anthrone, and dibenzothiophene. After 126 d's anaerobic degradation at 25 °C, the utilization of HCO3- and SO42- as selected TEAs promoted the PAH biodegradation performance better than the utilization of NO3-.

Effect of activated persulfate on the properties of contaminated soil and degradation behavior of PAHs

Sulfate radical-based advanced oxidation processes have been applied in the remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soil, during which sulfate can be activated in different ways. In this work, effects of four different ways (FeSO4, NaOH, H2O2, and Heat) activated sodium persulfate (PS) on PAHs removal and soil physicochemical properties (pH, organic matter, functional groups, surface morphology, and partial heavy metal elements) were compared, and the influencing factors and mechanism of soil PAHs removal by thermally activated PS were also studied. The results showed that at the dosage of 3% of persulfate, the removal efficiency of PAHs followed the sequences of Heat (91.4%) > FeSO4 (86.6%) > H2O2 (86.2%) > NaOH (72.9%). However, thermal activation decreased the soil pH and organic matter content more significantly than other treatments. The reaction tended to reach equilibrium at 6 h when the dosage of persulfate was 3% and the activation temperature was 60 °C, and the reaction obeyed pseudo-first-order kinetics. Through quenching experiments, it was found that the free radicals playing a dominant role in the oxidation process were sulfate radicals. Compared with pH, liquid to soil (L/S ratio) and the temperature had more significant impacts on the degradation efficiency of PAHs.

A highly effective polycyclic aromatic hydrocarbon-degrading bacterium, Paracoccus sp. HPD-2, shows opposite remediation potential in two soil types

Bioaugmentation is an efficient and eco-friendly strategy for the bioremediation of polycyclic aromatic hydrocarbons (PAHs). Since the degrading abilities of soils can greatly alter the abilities of PAH-degrading bacteria, illustrating the potential and mechanism of highly efficient degrading bacteria in different soil environments is of great importance for bioremediation. A PAH-degrading bacterium, Paracoccus aminovorans HPD-2, and two soil types, red and paddy soils, with distinct PAH-degrading abilities, were selected for this study. A soil microcosm experiment was performed by adding pyrene (PYR) and benzo[a]pyrene (B[a]P). Illumina sequencing was used to examine bacterial community structure. The results showed that inoculation with HPD-2 significantly elevated PYR and B[a]P degradation rates by 44.7% and 30.7%, respectively, in the red soil, while it only improved the degradation rates by 1.9% and 11%, respectively, in the paddy soil. To investigate the underlying mechanism, the fate of strain HPD-2 and the response of the indigenous bacterial communities were determined. Strain HPD-2 occupied certain niches in both soils, and the addition of the bacterium changed the native community structure more noticeably in the red soil than in the paddy soil. The addition of PAHs and strain HPD-2 significantly changed the abundances of 7 phyla among the 15 detected phyla in the red soil. In the paddy soil, 5 of the 12 dominant phyla were significantly affected by PAHs and the inoculation of HPD-2, while 6 new phyla were detected in the low-abundance phyla (< 0.1%). The abundances of Massilia, Burkholderia , and Rhodococcus genera with PAH degradation efficiency were significantly increased by the inoculation of HPD-2 in the red soil during 42 d of incubation. Meanwhile, in the paddy soil, the most dominant effective genus, Massilia , was reduced by HPD-2 inoculation. This research revealed the remediation ability and inherent mechanism of the highly effective PAH-degrading strain HPD-2 in two different soil types, which would provide a theoretical basis for the application of degrading bacteria in different soils.

Degradation of organic contaminants in marine sediments by peroxymonosulfate over LaFeO3 nanoparticles supported on water caltrop shell-derived biochar and the associated microbial community responses

Sediment is an important final repository of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). Herein, a novel catalyst of LaFeO3 nanoparticles supported on biochar was synthesized from water caltrop shell by chemical precipitation. The composite (LFBC) was used as peroxymonosulfate (PMS) activator to oxidize PAHs in real marine sediments. Systematic surface characterization confirmed the immobilization of well crystalline nano LaFeO3 particles onto the biochar surface. Under optimal conditions, i.e., [PMS] = 3 × 10-4 M, [LFBC] = 0.75 g/L, pH 6.0, and seawater, the total PAH degradation efficiency was 90%, while that of 2-, 3-, 4-, 5-, and 6-ring PAHs was 52%, 61%, 66%, 56%, and 29%, respectively, in 24 h. The Langmuir-Hinshelwood equation better predicted the PAHs degradation kinetics over LFBC by PMS. Interactions between surface oxygen species at LaFeO3 defective sites and the graphitized biochar network facilitated the PAHs degradation. Furthermore, changes in the bacterial community during the LFBC/PMS treatment were highlighted to assess the sustainable development of the sediment ecosystem. The LFBC/PMS process enhanced the biological richness and diversity of sediment eco-systems. The major phylum was Proteobacteria initially, while Hyphomonas was the genera after LFBC/PMS treatment of the sediment.

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by bacterial mixture

Polycyclic aromatic hydrocarbons (PAHs) are widespread pollutants and they can cause cancer, abnormality and mutation. Nine natural PAHs-degrading bacteria were obtained from polluted areas. These bacteria and the bacterial mixture can degrade phenanthrene, anthracene, pyrene and benzo[a]pyrene. The bacterial mixture can increase the degradation rates of several PAHs compounds, such as phenanthrene and benzo[a]pyrene, during the repaired process, and the degradation rates of these compounds were over 83%. The efficient degradation of PAHs should be the cooperation of key enzymes, such as dioxygenase and dehydrogenase, in the bacterial mixture. The main accumulated metabolite of above four PAHs was dibutyl phthalate detected by gas chromatography mass spectrometry, indicating that the degradation process of PAHs mainly represented the phthalic acid pathway in this work. And the toxicity of PAHs could be decreased by biodegradation. The effects of cultural factors, such as culture time, temperature, metal ions and pH on PAHs degradation efficiency were also studied.

Root exudates enhance the PAH degradation and degrading gene abundance in soils

Root exudates could influence the bioavailability of polycyclic aromatic hydrocarbons (PAHs), provide nutrients for soil microorganisms, and affect PAH biodegradation. However, it remains unclear how a bacterial community and its PAH-degrading genes play crucial roles in PAH biodegradation and respond to root exudates. In this study, a 32-day soil microcosm study was conducted to explore the impacts of artificial and actual root exudates on PAH degradation, degrading genes, and bacterial community structure. The results showed that 10–100 mg DOC/kg artificial and actual root exudates promoted the degradation of naphthalene, phenanthrene, and pyrene in soils, and their percent removal increased initially and then decreased with the increasing root exudates. Quantitative polymerase chain reaction analysis and 16S rRNA gene high-throughput sequencing suggested that the artificial root exudates significantly promoted the Nocardioides and Arthrobacter genera, which may harbor the nidA gene (the representative PAH-degrading gene from Gram-positive bacteria). In contrast, actual root exudates significantly stimulated the Pseudomonas genus that may harbor the nahAc gene (the representative PAH-degrading gene from Gram-negative bacteria). The correlation analysis further indicated that the absolute abundance of PAH degraders and degrading genes had strong correlations with PAH degradation efficiency. Therefore, these findings suggest that root exudates enhanced PAH biodegradation probably due to increases in abundance of both PAH-degraders and their degrading genes.

Rhamnolipid-assisted mycoremediation of polycyclic aromatic hydrocarbons by Trametes hirsuta coupled with enhanced ligninolytic enzyme production

ABSTRACT The present study deals with the development of a wood assisted fungal system (WAFS) from wood chips using Trametes hirsuta to remove polycyclic aromatic hydrocarbons (PAHs) in BRW. The WAFS exhibited a 1.4-fold higher ligninolytic enzyme production than free fungi in the effluent. Further, to understand PAHs bioremediation by T. hirsuta, biodegradation along with biosorption were studied in model PAHs, phenanthrene (Phe) and benzo (a) pyrene (BaP), in the presence of synthesized rhamnolipids. The WAFS mineralized up to an average of 91.26% Phe and 87.72 % BaP along with biosorption of 12.35% Phe and 18.36 % BaP within 12 days. Thus, the addition of rhamnolipids showed 1.2-fold enhanced biodegradation. However, rhamnolipid concentrations beyond 50 ppm reduced the degradation efficiency of WAFS. Moreover, the degradation capability of total aromatic hydrocarbon (TAH) in biorefinery wastewater by WAFS is 1.8-fold higher than that of free fungi, which confirms the effectiveness of the system. Implications: Simultaneous application of white-rot fungus along with surfactant into a pollutant environment affects the microenvironment of the fungus and reduces the production of their degradative enzymes. In addition, the requirement of periodical supplement of external nutrient in the real-time matrix for the growth of white rot fungi may trigger competitive growth of indigenous microorganisms. Considering this glitch, the current work utilizes the carpenter waste for the strategical develop a wood assisted fungal system to protect the microenvironment of the fungi in the presence of rhamnolipids and contribute to their survival in real time matrix, with enhanced PAHs degradation efficiency.

Promoted oxidation of polycyclic aromatic hydrocarbons in soils by dual persulfate/calcium peroxide system

In situ chemical oxidations (ISCO) have been demonstrated as effective ways for remediating soils contaminated with organic pollutants by complete mineralization. This work aims to develop a technology for the oxidation remediation of soils contaminated with Polycyclic Aromatic Hydrocarbons (PAHs) using a dual calcium peroxide (CP)/persulfate (PS) oxidant system activated by oxalic acid (OA)-chelating Fe2+. The dual peroxide system was set up, and the effects of 5 single factors (i.e., CP dosage, PS dosage, Fe2+ dosage, OA concentration, and soil/water ratio) on PAHs degradation were studied using the single-factor experiment. The response surface method was then introduced to obtain the optimized experimental conditions (CP dosage, PS dosage, OA concentration) of the dual peroxide system. The result shows that the dual peroxide system significantly increased the PAHs degradation and the maximum PAHs degradation efficiency (70.8%) was achieved by the dual peroxide system under optimal conditions (PS dosage, CP concentration, Fe2+/PS ratio, and Fe2+/OA ratio was 8.89 g/kg, 0.18 mol/L, 1/4 and 0.62) at neutral soil condition. This study is an illustration of the promising efficiency of the dual peroxide system for PAH oxidation in the neutral soil and has great potential for remediation of PAHs contaminated farmland soils.

Photocatalytic ozonation of offshore produced water by TiO2 nanotube arrays coupled with UV-LED irradiation

Offshore produced water (OPW) containing hazardous substances such as polycyclic aromatic hydrocarbons (PAHs) needs to be treated prior to discharge. This study integrated a photocatalytic ozonation system with TiO2 nanotube arrays (TNA) and UV-light-emitted diode (UV-LED) irradiation and applied to treat OPW. Experimental and modeling efforts were made to evaluate the degradation efficiencies of PAHs, examine the behaviors of the OPW composition (e.g., phenols, iodide, and bromide), and investigate the oxidation intermediates and the associated toxicity and biodegradability. The results indicated that ozone significantly enhanced the oxidation rates and removed the PAHs within 30 min, while the TNA showed strong photocatalytic capability. In the early stage, iodide was a strong ozone competitor, accelerating phenol degradation but inhibiting PAH oxidation, whereas UV-LED fortified the effect. The degradation of aromatics was altered by iodide and bromide at different stages. The contributions of four toxicants to the acute toxicity of OPW were quantified and ranked (PAHs > bromoform > phenols > dibromopentane). The EC50 value increased from 3 % to 57 %, and the biodegradability was doubled with less footprint in 28-day biodegradation tests. Overall, it is recommended to sequentially oxidize the matrix of OPW by ozonation and PAHs by the UV-LED/TNA/ozone system.

Effect of compost amendment and bioaugmentation on PAH degradation and microbial community shifting in petroleum-contaminated soil

Efficient degradation of polycyclic aromatic hydrocarbons (PAHs) in a petroleum-contaminated soil was challenging which requires ample PAH-degrading flora and nutrients. In this study, we investigated the effects of ‘natural attenuation’, ‘bioaugmentation’, ‘compost only (raw materials of compost included pig manure and rice husk mixed at a 1:2 proportion, supplemented with 2.5% charcoal)’, and ‘compost with bioaugmentation’ treatments on degradation of polycyclic aromatic hydrocarbons (PAHs) and microbial community shifts during the remediation of petroleum-contaminated soil. After sixteen weeks of incubation, the removal efficiencies of PAHs were 0.52 ± 0.04%, 6.92 ± 0. 32%, 9.53 ± 0.29%, and 18.2 ± 0.64% in the four treatments, respectively. ‘Compost with bioaugmentation’ was the most effective for PAH removal among all the treatments. Illumina sequencing analysis suggested that both the ‘compost only’ and ‘compost with bioaugmentation’ treatments changed soil microbial community structures and enhanced microbial biodiversity. Some of the microorganisms affiliated with the compost including Azomonas, Luteimonas, Pseudosphingobacterium, and Parapedobacter were able to survive and become dominant in the contaminated soil. The ‘bioaugmentation and ‘natural attenuation’ treatments had no significant effects on soil microbial community structure. Inoculation of the PAH degraders including Bacillus, Pseudomonas, and Acinetobacter directly into the contaminated soil led to lower biodiversity under natural conditions. This result suggested that compost addition increased the α-diversity of both the bacterial and fungal communities in petroleum-contaminated soil, leading to higher PAH degradation efficiency in petroleum-contaminated soil.

Sludge treatment by integrated ultrasound-Fenton process: Characterization of sludge organic matter and its impact on PAHs removal

In this work, the impact of organic matter on the degradation of polycyclic aromatic hydrocarbons (PAHs) in textile dyeing sludge by ultrasound-Fenton process has been studied. Sludge organic matter (SOM) was characterized and the degradation efficiencies of PAHs at various oxidation intensities (Fenton’s reagent of 20, 70, and 140mmol/L, ultrasonic densities of 0.36, 0.90, and 1.80W/cm3, and reaction time of 15, 25, and 40min) were determined. The results showed that 75.52–84.40% of PAHs and 16.32–31.13% of SOM had degraded after ultrasound-Fenton treatment, confirming the competitive relation between both of them for degradation. The aliphatic SOM fractions were preferentially oxidized owing to their easily degradable properties, while equimolar amounts of the aromatic moieties would require more oxidant compared to the aliphatic fractions. Correlation analysis demonstrated that SOM with its lower content, stronger polarity, and a higher proportion of labile organic fraction was more favourable for PAHs degradation. In addition, the SOM fractions were decomposed to biodegradable matter after treatment, which further enhance the biodegradability of sludge. This study provides insights into the role of SOM in PAHs removal by AOPs, and confirms that the ultrasound-Fenton treatment could not only effectively degrade PAHs, but also modify SOM.

Removal Capacities of Polycyclic Aromatic Hydrocarbons (PAHs) by a Newly Isolated Strain from Oilfield Produced Water.

The polycyclic aromatic hydrocarbon (PAH)-degrading strain Q8 was isolated from oilfield produced water. According to the analysis of a biochemical test, 16S rRNA gene, house-keeping genes and DNA–DNA hybridization, strain Q8 was assigned to a novel species of the genus Gordonia. The strain could not only grow in mineral salt medium (MM) and utilize naphthalene and pyrene as its sole carbon source, but also degraded mixed naphthalene, phenanthrene, anthracene and pyrene. The degradation ratio of these four PAHs reached 100%, 95.4%, 73.8% and 53.4% respectively after being degraded by Q8 for seven days. A comparative experiment found that the PAHs degradation efficiency of Q8 is higher than that of Gordonia alkaliphila and Gordonia paraffinivorans, which have the capacities to remove PAHs. Fourier transform infrared spectra, saturate, aromatic, resin and asphaltene (SARA) and gas chromatography–mass spectrometry (GC–MS) analysis of crude oil degraded by Q8 were also studied. The results showed that Q8 could utilize n-alkanes and PAHs in crude oil. The relative proportions of the naphthalene series, phenanthrene series, thiophene series, fluorene series, chrysene series, C21-triaromatic steroid, pyrene, and benz(a)pyrene were reduced after being degraded by Q8. Gordonia sp. nov. Q8 had the capacity to remediate water and soil environments contaminated by PAHs or crude oil, and provided a feasible way for the bioremediation of PAHs and oil pollution.

Amycolatopsis sp. Poz14 isolated from oil-contaminated soil degrades polycyclic aromatic hydrocarbons

The main actinobacterial genera able to degrade polycyclic aromatic hydrocarbons (PAHs) include Mycobacterium, Nocardia, Rhodococcus, and Gordonia. However, it is unknown if other actinobacterial genera can degrade PAHs. In this work, three actinobacteria strains that utilize PAHs as the sole source of carbon and energy, were isolate and termed Amycolatopsis sp. Poz14, Gordonia sp. Poz20, and Rhodococcus sp. Poz54. The strains use low-molecular-weight (LMW; naphthalene and anthracene) and high-molecular-weight (HMW; pyrene and fluoranthene) PAHs at 50 mg L−1 as the sole carbon and energy sources; except Amycolatopsis sp. Poz14 which tolerate up to 200 mg L−1. Amycolatopsis sp. Poz14 exhibited higher degradation percentages for LMW-PAH than HMW-PAH, from 100% for naphthalene, 37.87% for anthracene, 25.10% for pyrene, and 18.18% for fluoranthene within 45-day. Degradation efficiency of PAHs by Amycolatopsis sp. Poz14 improved by adding tween 20 to 1000 mg L−1. Moreover, degradation kinetics of binary mixtures of PAHs were conducted, Amycolatopsis sp. Poz14 used both PAHs from the beginning of the kinetics, and degradation efficiencies in binary mixtures were better than those achieved in single PAH. To the best of our knowledge, this is the first report involving to genus Amycolatopsis in the degradation of LMW- and HMW-PAHs.

Combination of biochar amendment and mycoremediation for polycyclic aromatic hydrocarbons immobilization and biodegradation in creosote-contaminated soil

Soils impregnated with creosote contain high concentrations of polycyclic aromatic hydrocarbons (PAH). To bioremediate these soils and avoid PAH spread, different bioremediation strategies were tested, based on natural attenuation, biochar application, wheat straw biostimulation, Pleurotus ostreatus mycoremediation, and the novel sequential application of biochar for 21 days and P. ostreatus 21 days more. Soil was sampled after 21 and 42 days after the remediation application. The efficiency and effectiveness of each remediation treatment were assessed according to PAH degradation and immobilization, fungal and bacterial development, soil eco-toxicity and legal considerations. Natural attenuation and biochar treatments did not achieve adequate PAH removal and soil eco-toxicity reduction. Biostimulation showed the highest bacterial development but low PAH degradation rate. Mycoremediation achieved the best PAH degradation rate and the lowest bioavailable fraction and soil eco-toxicity. This bioremediation strategy achieved PAH concentrations below Spanish legislation for contaminated soils (RD 9/2005). Sequential application of biochar and P. ostreatus was the second treatment most effective for PAH biodegradation and immobilization. However, the activity of P. ostreatus was increased by previous biochar application and PAH degradation efficiency was increased. Therefore, the combined strategy for PAH degradation have high potential to increase remediation efficiency.