1
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Çelik G, Stolte S, Markiewicz M. NSO-heterocyclic PAHs - Controlled exposure study reveals high acute aquatic toxicity. JOURNAL OF HAZARDOUS MATERIALS 2023; 460:132428. [PMID: 37690200 DOI: 10.1016/j.jhazmat.2023.132428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/19/2023] [Accepted: 08/27/2023] [Indexed: 09/12/2023]
Abstract
Environmental occurrence and hazardous nature of heterocyclic polyaromatic hydrocarbons (heterocyclic PAHs) has the potential to threaten the health of aquatic ecosystems. Here, we investigate the acute toxicity of heterocyclic PAHs (log KOW 3.7-6.9) to aquatic organisms: marine bacteria (Aliivibrio fischeri), freshwater green algae (Raphidocelis subcapitata), and water fleas (Daphnia magna) using passive dosing to maintain stable exposure. The membrane-water partition coefficient (KMW) of the heterocycles was measured to elucidate its relationship with toxicity. Our findings show that the tested heterocycles had little inhibitory effect on A. fischeri, while most compounds were highly toxic to R. subcapitata and D. magna. Toxicity generally increased with increasing KMW values, and nonpolar narcosis was identified as the most likely mode of toxic action of the heterocycles. Comparison of standard protocols with passive dosing emphasizes the importance of maintaining a constant concentration during toxicity testing, as very high losses occurred in standard tests and passive dosing experiments revealed higher toxicities. These results indicate a potentially high risk to aquatic life and call for more in-depth investigation of the (eco)toxic effects of NSO-PAHs.
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Affiliation(s)
- Göksu Çelik
- Institute of Water Chemistry, Technische Universität Dresden, Bergstr. 66, D-01062 Dresden, Germany
| | - Stefan Stolte
- Institute of Water Chemistry, Technische Universität Dresden, Bergstr. 66, D-01062 Dresden, Germany
| | - Marta Markiewicz
- Institute of Water Chemistry, Technische Universität Dresden, Bergstr. 66, D-01062 Dresden, Germany.
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2
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Li Y, Li X, Cui Z, He F, Zong W, Liu R. Probing the toxic effect of quinoline to catalase and superoxide dismutase by multispectral method. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 293:122449. [PMID: 36753919 DOI: 10.1016/j.saa.2023.122449] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/29/2023] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Quinoline is a common nitrogen heterocyclic aromatic hydrocarbon with high water solubility. Studies have shown that quinoline can be teratogenic, carcinogenic and mutagenic. And Hepatocytes are the target cell of quinoline, which contain a large number of mitochondria and are related to cell function and the balance of reactive oxygen species (ROS). However, the research on the effect of quinoline on hepatocyte damage and anti-oxidation system is still unclear. Through the means of multispectral experiments, it is concluded that quinoline can affect the catalase (CAT) and superoxide dismutase (SOD), change their structure and affect their activity. The binding mode and binding site of quinoline to CAT/SOD were analyzed by isothermal calorimetric titration (ITC) and Molecular Operating Environment (MOE). In molecular docking simulation, the binding site of quinoline-CAT system is close to the active site, and affect the microenvironment of Tyr 357. This may be the reason why quinoline affects CAT activity and synchronous fluorescence (Δλ = 15 nm). This study demonstrated that quinoline has a great effect on CAT, which may affect the intracellular ROS balance and become a potential way to cause hepatocyte damage.
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Affiliation(s)
- Yuze Li
- School of Environmental Science and Engineering, China - America CRC for Environment & Health, Shandong University, 72# Jimo Binhai Road, Qingdao, Shandong 266237, PR China
| | - Xiangxiang Li
- School of Environmental Science and Engineering, China - America CRC for Environment & Health, Shandong University, 72# Jimo Binhai Road, Qingdao, Shandong 266237, PR China
| | - Zhihan Cui
- School of Environmental Science and Engineering, China - America CRC for Environment & Health, Shandong University, 72# Jimo Binhai Road, Qingdao, Shandong 266237, PR China
| | - Falin He
- School of Environmental Science and Engineering, China - America CRC for Environment & Health, Shandong University, 72# Jimo Binhai Road, Qingdao, Shandong 266237, PR China
| | - Wansong Zong
- College of Geography and Environment, Shandong Normal University, 88# East Wenhua Road, Jinan, Shandong 250014, PR China
| | - Rutao Liu
- School of Environmental Science and Engineering, China - America CRC for Environment & Health, Shandong University, 72# Jimo Binhai Road, Qingdao, Shandong 266237, PR China.
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3
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Yao NH, Du YN, Xiong JX, Xiao Y, He HH, Xie ZF, Huang D, Song Q, Chen J, Yan D, Chao HJ. Microbial detoxification of 3,5-xylenol via a novel process with sequential methyl oxidation by Rhodococcus sp. CHJ602. ENVIRONMENTAL RESEARCH 2023; 220:115258. [PMID: 36634895 DOI: 10.1016/j.envres.2023.115258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/29/2022] [Accepted: 01/09/2023] [Indexed: 06/17/2023]
Abstract
The compound 3,5-xylenol is an essential precursor used in pesticides and industrial intermediate in the disinfectants and preservatives industry. Its widespread application makes it an important source of pollution. Microbial bioremediation is more environmentally friendly than the physicochemical treatment process for removing alkylphenols from a polluted environment. However, the 3,5-xylenol-degrading bacteria is unavailable, and its degradation mechanism remains unclear. Here, a 3,5-xylenol-metabolizing bacterial strain, designated Rhodococcus sp. CHJ602, was isolated using 3,5-xylenol as the sole source of carbon and energy from a wastewater treatment factory. Results showed that strain CHJ602 maintained a high 3,5-xylenol-degrading performance under the conditions of 30.15 °C and pH 7.37. The pathway involved in 3,5-xylenol degradation by strain CHJ602 must be induced by 3,5-xylenol. Based on the identification of intermediate metabolites and enzyme activities, this bacterium could oxidize 3,5-xylenol by a novel metabolic pathway. One methyl oxidation converted 3,5-xylenol to 3-hydroxymethyl-5-methylphenol, 3-hydroxy-5-methyl benzaldehyde, and 3-hydroxy-5-methylbenzoate. After that, another methyl oxidation is converted to 5-hydroxyisophthalicate, which is metabolized by the protocatechuate pathway. It is catalyzed by a series of enzymes in strain CHJ602. In addition, toxicity bioassay result indicates that 3,5-xylenol is toxic to zebrafish and Rhodococcus sp. CHJ602 could eliminate 3,5-xylenol in water to protect zebrafish from its toxicity. The results provide insights into the bioremediation of wastewater contaminated 3,5-xylenol.
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Affiliation(s)
- Ni-Hong Yao
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, PR China
| | - Ya-Nan Du
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, PR China
| | - Jia-Xi Xiong
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, PR China
| | - Ying Xiao
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, PR China
| | - Hang-Hang He
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, PR China
| | - Ze-Feng Xie
- Hubei Accurate Inspection & Testing Co., Ltd., Wuhan, 430223, PR China
| | - Duo Huang
- Hubei Accurate Inspection & Testing Co., Ltd., Wuhan, 430223, PR China
| | - Qi Song
- Hubei Accurate Inspection & Testing Co., Ltd., Wuhan, 430223, PR China
| | - Jing Chen
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, PR China
| | - Dazhong Yan
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, PR China
| | - Hong-Jun Chao
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, PR China.
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4
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Zhang M, Hu Y, Li W, Sun C, Guan C, Peng Y, Zheng J. In Vitro and In Vivo Metabolic Activation and Hepatotoxicity of Environmental Pollutant 2,6-Dimethylphenol. Chem Res Toxicol 2022; 35:1036-1044. [PMID: 35583464 DOI: 10.1021/acs.chemrestox.2c00048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
2,6-Dimethylphenol (2,6-DMP) is an environmental pollutant found in industrial wastewater. Exposure to 2,6-DMP is of increasing concern as it endangered reportedly some aquatic animals. In this study, we investigated the metabolic activation and hepatotoxicity of 2,6-DMP. 2,6-DMP was metabolized to an o-quinone methide intermediate in vitro and in vivo. The electrophilic metabolite was reactive to the sulfhydryl groups of glutathione, N-acetyl cysteine, and cysteine. NADPH was required for the formation of the reactive metabolite. The quinone methide intermediate reacted with cysteine residues to form hepatic protein adduction. A single dose of 2,6-DMP induced marked elevation of serum ALT and AST in mice. Both the protein adduction and hepatotoxicity of 2,6-DMP showed dose dependency.
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Affiliation(s)
- Mingyu Zhang
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Yaodong Hu
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Wei Li
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Chen Sun
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Chunjing Guan
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Ying Peng
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Jiang Zheng
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China.,State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, Guizhou Medical University, Guiyang, Guizhou 550025, P. R. China.,Key Laboratory of Environmental Pollution, Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, Guizhou 550025, P. R. China
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Characterization of the 2,6-Dimethylphenol Monooxygenase MpdAB and Evaluation of Its Potential in Vitamin E Precursor Synthesis. Appl Environ Microbiol 2022; 88:e0011022. [PMID: 35380460 DOI: 10.1128/aem.00110-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
2,6-Dimethylphenol (2,6-DMP) is a widely used chemical intermediate whose residue has been frequently detected in the environment, posing a threat to some aquatic organisms. Microbial degradation is an effective method to eliminate 2,6-DMP in nature. However, the genetic and biochemical mechanisms of 2,6-DMP metabolism remain unknown. Mycobacterium neoaurum B5-4 is a 2,6-DMP-degrading bacterium isolated in our previous study. Here, a 2,6-DMP degradation-deficient mutant of strain B5-4 was screened. Comparative genomic, transcriptomic, gene disruption, and genetic complementation data indicated that mpdA and mpdB are responsible for the initial step of 2,6-DMP degradation in M. neoaurum B5-4. MpdAB was predicted to be a two-component flavin-dependent monooxygenase system, which shows 32% and 36% identities with HsaAB from Mycobacterium tuberculosis CDC1551. The transcription of mpdA and mpdB was substantially increased upon exposure to 2,6-DMP. Nuclear magnetic resonance analysis showed that purified 6×His-MpdA and 6×His-MpdB hydroxylated 2,6-DMP and 2,3,6-trimethylphenol (2,3,6-TMP) at the para-position using NADH and flavin adenine dinucleotide (FAD) as cofactors. The apparent Km values of MpdAB for 2,6-DMP and 2,3,6-TMP were 0.12 ± 0.01 and 0.17 ± 0.01 mM, respectively, and the corresponding kcat/Km values were 4.02 and 2.84 s-1 mM-1, respectively. Since para-hydroxylated 2,3,6-TMP is a major precursor for vitamin E synthesis, the potential of MpdAB in vitamin E synthesis was preliminarily evaluated using whole-cell catalysis. Low expression levels of MpdA and 2,3,6-TMP cytotoxicity limited the efficiency of whole-cell catalysis. Together, this study reveals the genetic and biochemical basis for the initial step of 2,6-DMP biodegradation and provides candidate enzymes for vitamin E synthesis. IMPORTANCE Although the microbial degradation of the six isomers of dimethylphenol has been extensively studied, the genetic and biochemical mechanisms of 2,6-DMP degradation remain unclear. This study identified the genes responsible for the initial step in the 2,6-DMP catabolic pathway in M. neoaurum B5-4. Moreover, MpdAB also catalyzed the transformation of 2,3,6-TMP to 2,3,5-trimethylhydroquinone (2,3,5-TMHQ), a crucial step in vitamin E synthesis. Overall, this study provides candidate enzymes for both the bioremediation of 2,6-DMP contamination and the development of a green method to synthesize vitamin E.
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Machado ME, Nascimento MM, Bomfim Bahia PV, Martinez ST, Bittencourt de Andrade J. Analytical advances and challenges for the determination of heterocyclic aromatic compounds (NSO-HET) in sediment: A review. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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7
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Salowsky H, Schäfer W, Schneider AL, Müller A, Dreher C, Tiehm A. Beneficial effects of dynamic groundwater flow and redox conditions on Natural Attenuation of mono-, poly-, and NSO-heterocyclic hydrocarbons. JOURNAL OF CONTAMINANT HYDROLOGY 2021; 243:103883. [PMID: 34479119 DOI: 10.1016/j.jconhyd.2021.103883] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 08/19/2021] [Accepted: 08/21/2021] [Indexed: 06/13/2023]
Abstract
Natural Attenuation (NA) processes have been demonstrated to reduce pollutant loads at different contaminated groundwater sites world-wide and are increasingly considered in contaminated site management concepts. However, data are mainly available for steady state groundwater flow and stable redox conditions as well as pollutants listed in standard regulatory schemes. In this study, the influence of transient groundwater flow and redox conditions on NA was examined at a former gas works site near the river Rhine in Germany. The investigated 78 pollutants included 40 mono- and polyaromatic hydrocarbons (MAHs, PAHs) and 38 NSO-heterocyclic aromatic hydrocarbons (NSO-HET). In the highly polluted areas, the MAHs benzene, indene and indane, the PAHs naphthalene, acenaphthene, 1- and 2-methylnaphthalene and the NSO-HET 2-methylquinoline, carbazole, benzothiophene, dibenzofuran and benzofuran were predominant. Pollutant concentrations decreased with increasing distance from the sources of contamination. At the plume fringes, the MAHs benzene and indane, the PAH acenaphthene, the NSO-HET carbazole, 5-methylbenzothiophene, 2- and 3-methylbenzofuran and 2-methyldibenzofuran were predominant, indicating low retention and slow intrinsic biodegradation of these compounds. The influence of surface water on groundwater level, pollutant concentrations, and redox conditions in the monitoring wells was observed with a permanently installed groundwater sensor. The temporary availability of oxygen was observed at the plume fringes, resulting in aerobic and ferric iron reducing biodegradation processes. Field and laboratory data were used to set-up a groundwater flow and reactive transport model used for quantification of the field mass transfer rates. In conclusion, the study demonstrates that NA is effective under transient flow and redox conditions. A conceptual model and reactive transport simulation can facilitate the interpretation of pronounced fluctuations of pollutant concentration in monitoring wells. Based on the analysis of 78 pollutants, indane, indene and several NSO-HET like carbazole, benzothiophene and 2-methyldibenzofuran are recommended for monitoring at tar oil polluted sites, besides EPA-PAHs and BTEX.
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Affiliation(s)
- Helena Salowsky
- Department Water Microbiology, TZW: DVGW-Technologiezentrum Wasser (German Water Centre), Karlsruher Straße 84, 76139 Karlsruhe, Germany
| | - Wolfgang Schäfer
- Steinbeis Transfercenter for Groundwater Modelling, Schustergasse 2, 69168 Wiesloch, Germany
| | - Anna-Lena Schneider
- Department Water Microbiology, TZW: DVGW-Technologiezentrum Wasser (German Water Centre), Karlsruher Straße 84, 76139 Karlsruhe, Germany
| | - Axel Müller
- Department Water Microbiology, TZW: DVGW-Technologiezentrum Wasser (German Water Centre), Karlsruher Straße 84, 76139 Karlsruhe, Germany
| | - Carolin Dreher
- Department Water Microbiology, TZW: DVGW-Technologiezentrum Wasser (German Water Centre), Karlsruher Straße 84, 76139 Karlsruhe, Germany
| | - Andreas Tiehm
- Department Water Microbiology, TZW: DVGW-Technologiezentrum Wasser (German Water Centre), Karlsruher Straße 84, 76139 Karlsruhe, Germany.
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8
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Rózsa ZB, Szőri-Dorogházi E, Viskolcz B, Szőri M. Transmembrane penetration mechanism of cyclic pollutants inspected by molecular dynamics and metadynamics: the case of morpholine, phenol, 1,4-dioxane and oxane. Phys Chem Chem Phys 2021; 23:15338-15351. [PMID: 34254082 DOI: 10.1039/d1cp01521d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The presence of industrially produced chemicals in water is often not monitored, while their passive transport and accumulation can cause serious damage in living cells. Molecular dynamics simulations are an effective way to understand the mechanism of the action of these pollutants. In this paper, the passive membrane transport of 1,4-dioxane, phenol, oxane and morpholine was investigated and analyzed thoroughly from structural and energetic points of view. Free energy profiles for pollutant and water penetration into the bilayer were obtained from well-tempered metadynamics (WT-MD) simulations and a mass density-based approach. It was found that all four investigated compounds can penetrate biological membranes and affect the free energy profile of water penetration. Out of the investigated species, oxane has the thermodynamically most preferred position in the bilayer center, leading to a lower free energy barrier of water molecules by 3 kJ mol-1, resulting in 5 times more water molecules in the bilayer center. The concentration dependence of free energy was tested at two different phenol concentrations using WT-MD, and it was found that the higher phenol concentration lowers the main barrier by 3 kJ mol-1. Density-based free energy calculations were found to reproduce the results of WT-MD within the limits of chemical accuracy.
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Affiliation(s)
- Zsófia Borbála Rózsa
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary.
| | - Emma Szőri-Dorogházi
- Centre for Higher Education and Industrial Cooperation, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary
| | - Béla Viskolcz
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary.
| | - Milán Szőri
- Institute of Chemistry, University of Miskolc, Egyetemváros A/2, H-3515 Miskolc, Hungary.
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Cao J, Wang W, Zhao Z, Liu X, Li QX. Genome, metabolic pathways and characteristics of cometabolism of dibenzothiophene and the biodiesel byproduct glycerol in Paraburkholderia sp. C3. BIORESOURCE TECHNOLOGY 2021; 326:124699. [PMID: 33535150 DOI: 10.1016/j.biortech.2021.124699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
Utilization of glycerol, a biodiesel byproduct, has not been well explored. In the present study, glycerol and the other carbon sources were studied for cometabolism of dibenzothiophene (DBT), a model chemical commonly used in bioremediation studies, by Paraburkholderia sp. C3. This study showed a direct association between rhamnolipids (RLs) biosynthesis and DBT biodegradation induced by different carbon sources in a Paraburkholderia specie. Glycerol can induce the strain C3 produce at least four RLs. The RL precursor is mainly derived from the fatty acid synthesis (FAS II) and β-oxidation pathway. The genome contained two (fabF and fabG) and four (fadA, fadE, fadB and echA) genes involved in FAS II and β-oxidation, respectively. The genome also carried the rhlA and rhlB genes involved in rhamnosyltransferase for RL biosynthesis and two DBT dioxygenase genes (nahAc and catA). The findings suggest a viable approach of using the biodiesel byproduct glycerol to remediate contaminated environments.
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Affiliation(s)
- Jia Cao
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China; Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Weijun Wang
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Zixi Zhao
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Xiaolu Liu
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China.
| | - Qing X Li
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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10
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Chibwe L, Roberts S, Shang D, Yang F, Manzano CA, Wang X, Kirk JL, Muir DCG. A one-century sedimentary record of N- and S-polycyclic aromatic compounds in the Athabasca oil sands region in Canada. CHEMOSPHERE 2020; 260:127641. [PMID: 32688322 DOI: 10.1016/j.chemosphere.2020.127641] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/29/2020] [Accepted: 07/05/2020] [Indexed: 05/05/2023]
Abstract
The atmospheric deposition of polycyclic aromatic compounds (PACs) is considered a major pathway to isolated lakes and bogs in the Athabasca oil sands region (AOSR), Canada. However, the suite of PACs measured has been limited. We report the detailed depositional history of nitrogen and sulphur heterocyclic PACs using a 210Pb dated sediment core (1914-2015) near major developments in the AOSR. We observed (1) an exponential growth in the deposition of heterocyclic PACs to recent times with an average doubling time of 12 years, (2) significant breakpoints in PAC fluxes in the mid to late 1980s, and (3) a synchronous increase of PACs with crude oil production (r2 = 0.82, p = 0.001). NPACs were not detected prior to the 1960s in the sediment core studied, suggesting they may hold promise in serving as indicators for atmospheric PAC deposition of industrial origin. Furthermore, a change in heterocyclic PAC distribution profiles beginning in the 1970-1980s, after the onset of mining, resembling a petcoke signature, was also observed. Significant positive correlations (p < 0.05) were observed between heterocyclic PACs, and several metal(loid)s, including priority pollutant elements, chromium and beryllium, and rare earth elements, cerium, lanthanum and yttrium (r2 > 0.75), suggesting the potential of a common source or similar transport and fate mechanisms. Significant negative or no correlations were observed between heterocyclic PACs and other metal(loid)s, including vanadium, total mercury and lead, possibly reflecting the impact of broader regulatory controls introduced in the mid-1970s on some metal(loids) but not on PACs, including the installation of electrostatic precipitators in major upgrader stacks.
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Affiliation(s)
- Leah Chibwe
- Aquatic Contaminants Research Division, Environment & Climate Change Canada, Burlington, ON, Canada; The University of Guelph. School of Environmental Sciences, Guelph ON, Canada
| | - Sarah Roberts
- Aquatic Contaminants Research Division, Environment & Climate Change Canada, Burlington, ON, Canada
| | - Dayue Shang
- Pacific and Yukon Laboratory for Environmental Testing, Environment & Climate Change Canada, North Vancouver, BC, Canada
| | - Fan Yang
- Aquatic Contaminants Research Division, Environment & Climate Change Canada, Burlington, ON, Canada
| | - Carlos A Manzano
- Center for Environmental Science, Faculty of Science, University of Chile, Santiago, Chile; School of Public Health, San Diego State University, San Diego, CA, USA
| | - Xiaowa Wang
- Aquatic Contaminants Research Division, Environment & Climate Change Canada, Burlington, ON, Canada
| | - Jane L Kirk
- Aquatic Contaminants Research Division, Environment & Climate Change Canada, Burlington, ON, Canada
| | - Derek C G Muir
- Aquatic Contaminants Research Division, Environment & Climate Change Canada, Burlington, ON, Canada.
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11
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Ji J, Zhang Y, Liu Y, Zhu P, Yan X. Biodegradation of plastic monomer 2,6-dimethylphenol by Mycobacterium neoaurum B5-4. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 258:113793. [PMID: 31864921 DOI: 10.1016/j.envpol.2019.113793] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 11/06/2019] [Accepted: 12/10/2019] [Indexed: 06/10/2023]
Abstract
2,6-Dimethylphenol (2,6-DMP), an important chemical intermediate and the monomer of plastic polyphenylene oxide, is widely used in chemical and plastics industry. However, the pollution problem of 2,6-DMP residues is becoming increasingly serious, which is harmful to some aquatic animals. Microbial degradation provided an effective approach to eliminate DMPs in nature, which is considered as a prospective way to remediate DMPs-contaminated environments. But the 2,6-DMP-degrading bacteria is not available and the molecular mechanism of 2,6-DMP degradation is unclear as well. Here, a 2,6-DMP-degrading bacterium named B5-4 was isolated and identified as Mycobacterium neoaurum. M. neoaurum B5-4 could utilize 2,6-DMP as the sole carbon source for growth. Furthermore, M. neoaurum B5-4 could degrade 2,6-DMP with concentrations ranging from 1 to 500 mg L-1. Six intermediate metabolites of 2,6-DMP were identified and a metabolic pathway of 2,6-DMP in M. neoaurum B5-4 was proposed, in which 2,6-DMP was initially converted to 2,6-dimethyl-hydroquinone and 2,6-dimethyl-3-hydroxy-hydroquinone by two consecutive hydroxylations at C-4 and γ position; 2,6-dimethyl-3-hydroxy-hydroquinone was then subjected to aromatic ring ortho-cleavage to produce 2,4-dimethyl-3-hydroxymuconic acid, which was further transformed to citraconate, and subsequently into TCA cycle. In addition, toxicity bioassay of 2,6-DMP in water using zebrafish indicates that 2,6-DMP is toxic to zebrafish and M. neoaurum B5-4 could effectively eliminate 2,6-DMP in water to protect zebrafish from 2,6-DMP-induced death. This work provides a potential strain for bioremediation of 2,6-DMP-contaminated environments and lays a foundation for elucidating the molecular mechanism and genetic determinants of 2,6-DMP degradation.
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Affiliation(s)
- Junbin Ji
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, PR China
| | - Yanting Zhang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, PR China
| | - Yongchuang Liu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, PR China
| | - Pingping Zhu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, PR China
| | - Xin Yan
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, PR China; Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, PR China.
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