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1.
Ecotoxicol Environ Saf ; 195: 110485, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32203776

RESUMO

Soil co-contaminated with cadmium (Cd) and decabromodiphenyl ether (BDE-209) is a widespread environmental problem, especially in electronic waste contaminated surroundings. Accumulation of Cd and BDE-209 in crops has possibly harmful effects on local human health. In order to assess the potential of arbuscular mycorrhizal (AM) fungi and amaranth (Amaranthus hypochondriacus L.) in remediation of soil co-contaminated with Cd and BDE-209, pot trials were performed to investigate interactive effects of AM fungi, Cd and BDE-209 on growth of amaranth, uptake of Cd and BDE-209, distribution of chemical forms of Cd and activities of antioxidant enzymes in shoots and dissipation of BDE-209 in soil. The present results showed that shoot biomass of non-mycorrhizal plants was significantly inhibited by increasing of Cd addition (5-15 mg kg-1), but were only slightly declined with BDE-209 addition (5 mg kg-1). The interaction of Cd and BDE-209 reduced the proportions of ethanol- and d-H2O-extractable Cd in shoots, consequently alleviated Cd toxicity to plants and enhanced root uptake of Cd and BDE-209. Inoculation of AM fungi resulted in significantly greater shoot biomass as well as higher concentrations of Cd and BDE-209 compared with non-mycorrhizal treatment. Moreover, AM fungi played a beneficial role in relieving oxidative stress on amaranth by increasing the activities of dismutase (SOD) and catalase (CAT) in shoots and significantly improved the dissipation of BDE-209 in soil. The present study suggested that combination of AM fungi and amaranth may be a potential option for remediation of Cd and BDE-209 co-contaminated soils.

2.
Environ Int ; 137: 105263, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32087481

RESUMO

Microplastics are emerging contaminants and their presence in water and soil ecosystems has recently drawn considerable attention because they pose a great threat to entire ecosystems. Recent researches have focused on the detection, occurrence, characterization, and toxicology of microplastics in marine and freshwater ecosystems; however, our understanding of the ecological effects of microplastics in soil ecosystems is still limited compared with that in aquatic ecosystems. Here, we have compiled literature, studying the sources, migration of microplastics in soil, negative impacts on soil health and function, trophic transfer in food chains, and the corresponding adverse effects on soil organisms in order to address the potential ecological and human health risks caused by microplastics in soil. This review aims to address gaps in knowledge, shed light on the ecological effects of microplastics in soil, and propose future studies on microplastic pollution and the resultant soil ecotoxicity. Furthermore, this review is focused on limiting microplastics in soil and establishing management and remediation measures to mitigate the risks posed by microplastic pollution.

3.
J Hazard Mater ; 391: 122211, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32036315

RESUMO

This study aims to clarify the interaction mechanism of substrate with catechol 2,3-dioxygenase (C23O) through multi-technique combination. A novel C23O (named C23O-2G) was cloned, heterogeneously expressed, and identified as a new member in subfamily I.2 of extradiol dioxygenases. Based on the simulations of molecular docking and dynamics, the exact binding sites of catechol on C23O-2G were identified, and the catalytic mechanism mediated by key residues was proposed. The roles of the predicted residues during catalysis were confirmed by site-directed mutagenesis, and the mutation of Thr254 could significantly increase catalytic efficiency and substrate specificity of C23O-2G. The binding and thermodynamic parameters obtained from fluorescence spectra suggested that catechol could effectively quench the intrinsic fluorescence of C23O-2G via static and dynamic quenching mechanisms and spontaneously formed C23O-2G/catechol complex by the binding forces of hydrogen bond and van der Waals force. The results of UV-vis spectra, synchronous fluorescence, and CD spectra revealed obvious changes in the microenvironment and conformation of C23O-2G, especially for the secondary structure. The atomic force microscope images further demonstrated the changes from an appearance point of view. This study could improve our mechanistic understanding of representative dioxygenases involved in aromatic compound degradation.

4.
Bioresour Technol ; 300: 122623, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31927344

RESUMO

Microbial fuel cell is a green and sustainable bio-electrochemical system that can harvest bioelectricity from organic matter conversion by bacteria in wastewater, but weak electrochemical activity and poor biocompatibility between electro-active bacteria and anode limit its scale-up application. In the present, the biomass carbon derived from mango wood was prepared via one-step carbonization method for anode materials in microbial fuel cell. A desirable anode C/1050 with large electrochemical active surface area (75.3 cm2), low electron transfer resistance (4.36 Ω), and benign biocompatibility were developed, achieving power density up to 589.8 mW·m-2. This study provides a low-cost and high-performance biomass carbon used as anode material in microbial fuel cell for practical application.


Assuntos
Fontes de Energia Bioelétrica , Mangifera , Biomassa , Carbono , Eletricidade , Eletrodos , Madeira
5.
Sci Total Environ ; 707: 135609, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-31771853

RESUMO

Phthalate acid esters (PAEs) are of serious concern as a human health risk due to their ubiquitous presence in indoor air. In the present study, fifteen PAEs in the indoor air samples from physical, chemical, and biological laboratories in Guangzhou, southern China were analysed using gas chromatography mass spectrometry. Extremely high levels of PAEs of up to 6.39 × 104 ng/m3 were detected in some laboratories. Diisobutyl phthalate (DiBP), di(methoxyethyl) phthalate (DMEP), and di-n-butyl phthalate (DBP) were the dominant PAEs with median levels of 0.48 × 103, 0.44 × 103, and 0.39 × 103 ng/m3, respectively, followed by di-(2-propylheptyl) phthalate (DPHP) and di(2-ethylhexyl) phthlate (DEHP) (median levels: 0.16 × 103 and 0.13 × 103 ng/m3, respectively). DMEP and DPHP were found for the first time in indoor air. Principal component analysis indicated that profiles of PAEs varied greatly among laboratory types, suggesting notable variations in sources. The results of independent samples t-tests showed that levels of PAEs were significantly influenced by various environmental conditions. Both the non-carcinogenic and carcinogenic health risks from human exposure to PAEs based on the daily exposure dose in laboratory air were acceptable. Further research should be conducted to investigate the long-term health effects of exposure to PAEs in laboratories.

6.
J Agric Food Chem ; 68(1): 48-58, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31829629

RESUMO

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are perfluorinated alkyl substances widely used in industrial and domestic products. The European Food Safety Authority and United States Environmental Protection Agency have recently lowered the reference doses (RfDs) for PFOA and PFOS 4-1800-fold. The recently lowered RfDs call for re-evaluation of potential human health risks from PFOA and PFOS via food consumption. Serious concerns arise because some intakes of PFOA and PFOS exceeded the RfDs. Innovative cultivation of low-accumulating crop varieties becomes an option to decrease human exposure. We present an up-to-date review on low-accumulating crop varieties for PFOA and PFOS in reference to toxic metals and other organic pollutants, including the variety identification, physiological-biochemical mechanisms, molecular uptake mechanisms, and molecular docking, to call for attention and research efforts to decrease human intakes of PFOA and PFOS via crop consumption.


Assuntos
Ácidos Alcanossulfônicos/análise , Caprilatos/análise , Produtos Agrícolas/química , Fluorcarbonetos/análise , Contaminação de Alimentos/prevenção & controle , Ácidos Alcanossulfônicos/metabolismo , Caprilatos/metabolismo , Qualidade de Produtos para o Consumidor , Produtos Agrícolas/genética , Produtos Agrícolas/metabolismo , Fluorcarbonetos/metabolismo , Contaminação de Alimentos/análise , Inocuidade dos Alimentos , Humanos , Melhoramento Vegetal
7.
Sci Total Environ ; 702: 134878, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31726350

RESUMO

Sorption of organic contaminants by biochar greatly affects their bioavailability and fate in soils. Nevertheless, very little information is available regarding the effects of biochar on sorption and desorption of organic contaminants in different soil particle-size fractions. In this study, di-n-butyl phthalate (DBP), a prevalent organic contaminant in agricultural soils, was taken as a model contaminant. The effects of biochar on DBP sorption and desorption in six particle-size fractions (i.e., coarse sand, fine sand, coarse silt, fine silt, clay, and humic acid fractions) of paddy soil were investigated using batch sorption-desorption experiments. A straw-derived biochar with high specific surface area (116 m2/g) and high content of organic matter (OM) rich in aromatic carbon (67%) was prepared. Addition of this biochar (1% and 5%) significantly promoted the sorption and retention of DBP in all the paddy soil particle-size fractions at environmentally relevant DBP concentrations (2-12 mg/L) with 1.2-132-fold increase of the Kd values. With increasing addition rates of biochar, DBP retention by the biochar enhanced. The biochar's effectiveness was remarkably influenced by the physicochemical properties of the soil particle-size fractions, especially, the OM contents and pore size showed the most striking effects. A parameter (rkd) reflecting the biochar's effectiveness showed negative and positive correlations with OM contents and pore size of the soil particle-size fractions, respectively. Accordingly, strong effect of the biochar was found in the soil fractions with low OM contents and high pore size. The findings of this study gave insight into the effects and influencing factors of biochar on sorption and desorption of organic contaminants in soils at scale of various particle-size factions.


Assuntos
Carvão Vegetal/química , Dibutilftalato/química , Poluentes do Solo/química , Adsorção , Agricultura , Carbono/química , Substâncias Húmicas , Tamanho da Partícula , Solo/química
8.
Environ Int ; 133(Pt A): 105142, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31513927

RESUMO

Frequent cyanobacterial blooms in the eutrophic waters produce a variety of toxins such as the monocyclic heptapeptide microcystins, greatly harming aquatic ecosystems and human health. However, little information of microcystins in agricultural fields is known. This field study of three common microcystin variants (MC-LR, MC-RR, and MC-YR) in vegetables (n = 161), soils (n = 161) and irrigation water samples (n = 23) collected from southern China regions affected by cyanobacteria blooms, shows their prevalence with total concentrations up to 514 µg/L water, 187 µg/kg soil (dry weight) and 382 µg/kg vegetable (fresh weight). MC-RR was the primary variant in all types of samples, accounting for 51.3-100% of total microcystin concentrations. Significant concentration-dependent correlations (p < 0.05) demonstrated that microcystin-contained irrigation waters were the major source of microcystin accumulation in both vegetables and soils. Meanwhile, intracellular-microcystins in irrigation water was found to play an important role in microcystins bioaccumulation in vegetables for the first time. Most vegetable samples (≥60%), particularly celery posed moderate or high human health risk via diet based on toxicity equivalents of the microcystins and reference dose for MC-LR (0.04 µg/kg/d), showing high food safety hidden dangers. Soil microcystins, especially MC-RR in 46.4-88.3% of soils could pose high ecological risks. This study highlights the potential high ecological and human health risks of microcystins in the real soil-vegetable systems of areas affected by cyanobacteria blooms, implying the profound significance and urgent need of investigation on microcystins in terrestrial ecosystems.

9.
J Agric Food Chem ; 67(25): 6940-6949, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31021627

RESUMO

This work developed a bioaugmentation strategy that simultaneously reduced soil di(2-ethylhexyl) phthalate (DEHP) pollution and its bioaccumulation in Brassica parachinensis by inoculating the isolated strain Rhodococcus sp. 2G. This strain could efficiently degrade DEHP at a wide concentration range from 50 to 1600 mg/L and transformed DEHP through a unique biochemical degradation pathway that distinguished it from other Rhodococcus species. Besides, strain 2G colonized well in the rhizosphere soil of the inoculated vegetable without competition with indigenous microbes, resulting in increased removal of DEHP from soil (∼95%) and reduced DEHP bioaccumulation in vegetables (∼75% in the edible part) synchronously. Improved enzyme activities and DOC content in the rhizosphere of the planting vegetable and inoculating strain 2G were responsible for the high efficiency in mitigating DEHP contamination to vegetable cultivation. This work demonstrated a great potential application to grow vegetables in contaminated soil for safe food production.


Assuntos
Inoculantes Agrícolas/metabolismo , Brassica/crescimento & desenvolvimento , Produção Agrícola/métodos , Dietilexilftalato/metabolismo , Rhodococcus/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Verduras/crescimento & desenvolvimento , Biodegradação Ambiental , Brassica/metabolismo , Brassica/microbiologia , Rizosfera , Verduras/metabolismo , Verduras/microbiologia
10.
Sci Total Environ ; 668: 1117-1127, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31018452

RESUMO

Crops can take up and accumulate di-n-butyl phthalate (DBP), an extensively used plasticizer with endocrine disrupting effect, which poses potential risk to human health. Our previous study found the genotype variation in accumulation of DBP by different cultivars of rice (Oryza sativa L.). Nevertheless, the effect of DBP metabolism in vivo on the accumulation variation among different plant cultivars remains unknown. In this study, metabolism variation of DBP by low (Fengyousimiao) and high (Peizataifeng) DBP-accumulating cultivars of rice and the key enzymes involving in DBP metabolism in rice plants were investigated using in vivo exposure of rice plants and in vitro exposure of root crude enzyme extracts. Both mono-n-butyl phthalate (MBP) and phthalic acid (PA) were detected as DBP metabolites in all rice tissues (i.e., roots, stems, leaves) and crude enzyme extracts with MBP predominance. DBP metabolism occurred simultaneously when DBP uptake with the highest metabolism in roots in vivo. Degradation of DBP in root crude enzyme extracts fitted well with the first order kinetics (R2 = 0.49-0.76, P < 0.05). The activity of carboxylesterase (CXE) in root crude enzyme extracts was significantly positively correlated with DBP degradation rates. CXE played an important role in DBP metabolism of rice plants, confirming by the fact that triphenyl phosphate of CXE inhibitor could inhibit DBP metabolism of in vivo and in vitro exposure. This result was further confirmed by in vitro degradation of DBP with the commercial pure CXE. The crude enzyme solution from roots of Fengyousimiao with higher CXE activity had significantly higher DBP degradation rates than that of Peizataifeng. However, Fengyousimiao with lower tolerance to DBP stress and higher inhibition by triphenyl phosphate displayed lower DBP metabolism ability in vivo than Peizataifeng.


Assuntos
Dibutilftalato/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Misturas Complexas/metabolismo , Oryza/enzimologia , Oryza/genética , Proteínas de Plantas/isolamento & purificação , Proteínas de Plantas/metabolismo
11.
J Agric Food Chem ; 67(17): 4734-4745, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30957994

RESUMO

Di- n-butyl phthalate (DBP) is a prevalent pollutant in agricultural soils due to use of plastic film. This study focused on sorption mechanism, kinetics, and isotherms of DBP to six paddy soil particle-size fractions (i.e., coarse sand, fine sand, coarse silt, fine silt, clay, and humic acid fractions). DBP sorption involved in both boundary layer diffusion and intraparticle diffusion, following pseudo-second-order kinetics. DBP sorption was a spontaneous physical process, which fit the Freundlich model. Hydrophobic and ionic interaction relevant to the organic matter content, cation exchange capacity, surface area, and pore volume of soil fractions played key roles in DBP sorption. DBP was strongly adsorbed to humic acid and the sorption was reversely associated with soil particle sizes. DBP may exhibit higher mobility and bioavailability in a soil-crop system at lower temperature (15 °C), due to the lower log Koc values.


Assuntos
Dibutilftalato/química , Poluentes do Solo/química , Solo/química , Adsorção , Substâncias Húmicas/análise , Interações Hidrofóbicas e Hidrofílicas , Cinética , Tamanho da Partícula , Temperatura Ambiente
12.
Sci Total Environ ; 670: 170-180, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-30903891

RESUMO

Urban rivers in some countries have been heavily polluted and the water became black and odor. Nevertheless, only few studies reported the occurrence of antibiotics and their corresponding antibiotic resistant genes (ARGs) in urban rivers with black-odor water with and without remediation. In this study, nine antibiotics (belonging to sulfonamides, tetracyclines, quinolones, and macrolides) and their corresponding ARGs in water and sediments of six urban rivers in Guangzhou, South China were analyzed to investigate their spatial distribution and the influence of water remediation. The concentrations of individual antibiotics varied from ND (not detectable) to 2702 ng/L and ND to 449 µg/kg in surface water and sediments, respectively. Norfloxacin displayed the highest average concentrations, followed by ciprofloxacin. The relative abundance of quinolone-resistance gene qnrA (~103 ARGs/16S rRNA) was the highest, followed by tetracyclines-resistance genes tetC (~10-2 ARGs/16S rRNA). The antibiotics and ARGs in sediments from various rivers exhibited distinct spatial distribution with large variation from upstream to downstream. Generally, levels of antibiotics and tetracyclines-resistance genes (tetA, tetC and tetM) in urban rivers with black-odor water (affected by industrial and domestic sewage) were higher than those in remediated urban rivers. Significant positive correlations were observed only between the relative abundances of tetA (or tetC) with the concentrations of some antibiotics (e.g., ciprofloxacin and norfloxacin). TetA was also significantly positively correlated with the concentrations of Ni, Cr, and As in sediments. This study found that urban rivers remediated with dredging might lower antibiotic levels in sediment, but high relative abundance of certain ARGs (e.g., tetB, qnrA) may still exist.


Assuntos
Antibacterianos/análise , Resistência Microbiana a Medicamentos/genética , Monitoramento Ambiental , Microbiologia da Água , Poluentes Químicos da Água/análise , China , Genes Bacterianos
13.
Sci Total Environ ; 665: 41-51, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30772572

RESUMO

Ciprofloxacin is a broad spectral and highly refractory antibiotic. It is an emerging pollutant. This study aimed to utilise co-metabolism as a means to degrade ciprofloxacin by a bacterial consortium. The stable bacterial consortium XG capable of efficiently degrading ciprofloxacin was successfully established through successive acclimation of indigenous microorganisms. The consortium XG was primarily consisted of Achromobacter, Bacillus, Lactococcus, Ochrobactrum, and Enterococcus as well as at least other five minor genera. A novel strain YJ17 with CIP-degrading ability was isolated from the consortium and identified as Ochrobactrum sp. The consortium XG utilised amino acids, carbohydrates, and carboxylic acids at a rate approximately 16.6-243-fold greater than the other carbon substrates, but only slow utilisation of ciprofloxacin as a sole carbon source. Ciprofloxacin can be co-metabolized along with many carbon sources, attaining degradation rates up to 63%. Glycyl-l-glutamic acid, d-cellobiose, and itaconic acid are among the substrates most favourable for co-metabolism. The metabolites of ciprofloxacin were identified by LC-QTOF-MS. Co-metabolic degradation of ciprofloxacin by consortium XG led to the removal of essential functional groups from parent compound, thus resulting in formation of metabolites with less bioactive potency. Finally, a possible biochemical pathway for the degradation of ciprofloxacin was proposed. Consortium XG possesses high potential for bioremediation of ciprofloxacin-contaminated environments in the presence of a co-substrate.


Assuntos
Biodegradação Ambiental , Ciprofloxacino/metabolismo , Poluentes Ambientais/metabolismo , Consórcios Microbianos , Antibacterianos/metabolismo , Ochrobactrum/metabolismo
14.
Sci Total Environ ; 658: 474-484, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30579204

RESUMO

A great amount of insoluble phosphate in agricultural soils is not available for crops. Three strains of bacteria (Bacillus megaterium YLYP1, Pseudomonas prosekii YLYP6 and Pseudomonas sp. YLYP29) isolated from activated sludge and soil could efficiently solubilise tricalcium phosphate. In particular, the novel strain P. prosekii YLYP6 produced 716 mg L-1 of available phosphate within 6 days under the optimal culture conditions [20 °C, pH 7.9, inoculum size of 0.5% (v:v)] determined by response surface methodology. P. prosekii YLYP6 demonstrated efficient phosphate solubilisation in response to broad variations in pH (5-9) and temperature (15-35 °C). The phosphate solubilisation curves of the strains fit well with a first-order kinetic model (R2 > 0.939), with a half-life of 1.51-5.94 d for 5.0 g L-1 calcium phosphate. Continuous culture experiments combined with scanning electron microscopic observations and gas chromatography-mass spectrometry analysis revealed that 2,3-dimethylfumaric acid, gluconic and N-butyl-tert-butylamine that were produced by P. prosekii YLYP6 were responsible for phosphate solubilisation by supplying H+ ions and organic anions. Efficient phosphate solubilisation in actual soil by P. prosekii YLYP6 demonstrated the strong application potential to reduce the use of chemical P fertilisers and the resulting agricultural nonpoint pollution.


Assuntos
Bacillus megaterium/metabolismo , Fosfatos de Cálcio/metabolismo , Pseudomonas/metabolismo , Esgotos/microbiologia , Microbiologia do Solo , Bacillus megaterium/isolamento & purificação , Cromatografia Gasosa-Espectrometria de Massas , Microscopia Eletrônica de Varredura , Pseudomonas/isolamento & purificação , Solo/química
15.
J Agric Food Chem ; 66(51): 13541-13551, 2018 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-30525579

RESUMO

Di- n-butyl phthalate (DBP), as an endocrine-disrupting chemical that tends to be accumulated in crops, poses great risks to human health through the food chain. To identify the molecular mechanism underlying differences in their DBP accumulation, the root physiological and proteomic responses to DBP stress of two Brassica parachinensis cultivars, a high-DBP accumulator (Huaguan) and a low-DBP accumulator (Lvbao), were investigated. Root damage of greater severity and significantly greater ( p < 0.05) decreases in root protein content and root activity were detected in Lvbao than in Huaguan, suggesting that Lvbao had lower tolerance to DBP. In total, 52 DBP-responsive proteins were identified by two-dimensional electrophoresis and MALDI-TOF mass spectrometry. More proteins involved in basic metabolic processes, such as protein synthesis and energy metabolism, were downregulated in Lvbao, possibly explaining its lower tolerance and root damage. Several proteins involved in starch metabolism, cell-wall biosynthesis and modification, and stress response were activated in Huaguan, suggesting greater tolerance to DBP. Overall, differences in root proteome between the two cultivars might be responsible for the genotype-dependent DBP tolerance and accumulation in B. parachinensis.


Assuntos
Brassica/metabolismo , Dibutilftalato/metabolismo , Raízes de Plantas/metabolismo , Brassica/química , Brassica/genética , China , Dibutilftalato/análise , Disruptores Endócrinos/análise , Disruptores Endócrinos/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/química , Raízes de Plantas/genética , Proteômica , Poluentes do Solo/análise , Poluentes do Solo/metabolismo
16.
J Agric Food Chem ; 66(50): 13096-13106, 2018 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-30461281

RESUMO

Perfluorooctanesulfonate (PFOS) is a toxic and persistent organic pollutant that can be widely detected in agricultural soils. In this study, two lettuce cultivars with low PFOS accumulation were screened out to reduce the exposure of PFOS to the human body via vegetable consumption. The screened low-PFOS cultivars may help to ensure food safety, despite planting in highly PFOS-polluted soils (1.0 mg/kg), due to their high tolerance to PFOS and 4.4-5.7 times lower shoot PFOS concentration than the high-PFOS cultivars. Protein content and protein-mediated transpiration played key roles in regulating PFOS accumulation in the lettuce cultivars tested. Lower protein content, lower stomatal conductance, and lower transpiration rate resulted in low PFOS accumulation. This study reveals the mechanism of forming low-PFOS accumulation of lettuce cultivars at physiological and biochemical levels and lays a foundation for developing a cost-effective and safe approach to grow vegetables in PFOS-polluted soils.


Assuntos
Ácidos Alcanossulfônicos/metabolismo , Fluorcarbonetos/metabolismo , Alface/metabolismo , Poluentes do Solo/metabolismo , Ácidos Alcanossulfônicos/análise , Transporte Biológico , Fluorcarbonetos/análise , Inocuidade dos Alimentos , Humanos , Alface/química , Alface/crescimento & desenvolvimento , Raízes de Plantas/química , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Poluentes do Solo/análise , Verduras/química , Verduras/crescimento & desenvolvimento , Verduras/metabolismo
17.
J Agric Food Chem ; 66(44): 11569-11579, 2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30240199

RESUMO

Sorption of perfluorooctanoic acid (PFOA), a toxic and persistent organic pollutant, by various size fractions of an agricultural soil at environmentally relevant concentrations was evaluated. PFOA sorption to all fractions involved both film diffusion and intraparticle diffusion with the rate-limiting step by the latter. PFOA isotherm data fitted a linear model. Organic matter (OM), cation exchange capacity, pore volume, and the Brunauer-Emmett-Teller area played key roles in PFOA sorption. The sorption capacity followed the order of humic acid > clay (0.15-4.4 mm) > fine silt (1.9-39.8 mm) > coarse silt (17.3-79.4 mm) > fine sand (45.7-316.2 mm) > coarse sand (120-724.4 mm), opposite to their contributions to overall PFOA sorption due to the influence of their percentage weight in the original soil. Percentage OM content was the dominant factor controlling the fraction contributions to overall PFOA sorption, demonstrating influence of the hydrophobic force on sorption. PFOA should be highly mobile and bioavailable in soil-crop systems due to the low log Koc values.


Assuntos
Caprilatos/química , Fluorcarbonetos/química , Praguicidas/química , Poluentes do Solo/química , Solo/química , Adsorção , Substâncias Húmicas/análise , Cinética , Tamanho da Partícula
18.
Sci Total Environ ; 640-641: 1121-1131, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30021277

RESUMO

A novel bacterial strain designated as Rhodococcus pyridinivorans XB, capable of utilizing various endocrine disruptor phthalates or phthalic acid (PA) as sole source of carbon and energy, was isolated from activated sludge. Under the optimal culture conditions (pH 7.08, 30.4 °C, inoculum size (OD600 nm) of 0.6) obtained by response surface methodology, di-(2-ethylhexyl) phthalate (DEHP, 200 mg/L) could be degraded by strain XB with a removal rate of 98% within 48 h. Under the observation of an atomic force microscope, it was confirmed that DEHP did not inhibit the growth of strain XB which might produce some extracellular polymeric substances as a response to DEHP stress, resulting in rapid degradation of DEHP. At initial concentrations of 50-800 mg/L DEHP, its degradation curves were well fitted with the first-order kinetic model, and the half-life of DEHP degradation varied from 5.44 to 23.5 h. The degradation intermediates of DEHP were identified by both GC-MS and high performance liquid chromatography-time of flight-mass spectrometry (HPLC-TOF-MS). Significant up-regulation was observed for the relative expression levels of genes (i.e., phthalate hydrolase, PA 3,4-dioxygenase, protocatechuate 3,4-α and 3,4-ß dioxygenase) involved in DEHP degradation determined by real-time quantitative PCR (RT-qPCR). A DEHP biodegradation pathway by strain XB was proposed based on the identified intermediates and the degrading genes. Bioaugmentation of DEHP-contaminated soils with strain XB could efficiently promote DEHP removal, offering great potential in bioremediation of DEHP-contaminated environment.


Assuntos
Biodegradação Ambiental , Dietilexilftalato/metabolismo , Rhodococcus/fisiologia , Poluentes do Solo/metabolismo , Ácidos Ftálicos , Solo
19.
Sci Total Environ ; 640-641: 646-652, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29870940

RESUMO

Microbial degradation is considered the most promising method for removing phthalate acid esters (PAEs) from polluted environments; however, a comprehensive genomic understanding of the entire PAE catabolic process is still lacking. In this study, the repertoire of PAE catabolism genes in the metabolically versatile bacterium Rhodococcus sp. 2G was examined using genomic, metabolic, and bioinformatic analyses. A total of 4930 coding genes were identified from the 5.6 Mb genome of the 2G strain, including 337 esterase/hydrolase genes and 48 transferase and decarboxylase genes that were involved in hydrolysing PAEs into phthalate acid (PA) and decarboxylating PA into benzoic acid (BA). One gene cluster (xyl) responsible for transforming BA into catechol and two catechol-catabolism gene clusters controlling the ortho (cat) and meta (xyl &mhp) cleavage pathways were also identified. The proposed PAE catabolism pathway and some key degradation genes were validated by intermediate-utilising tests and real-time quantitative polymerase chain reaction. Our results provide novel insight into the mechanisms of PAE biodegradation at the molecular level and useful information on gene resources for future studies.


Assuntos
Biodegradação Ambiental , Ácidos Ftálicos/metabolismo , Rhodococcus/genética , Ésteres , Genômica
20.
Sci Total Environ ; 636: 999-1008, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29729517

RESUMO

The cultivation of crop cultivars with low pollutant accumulation is an important strategy to reduce the potential health risks of food produced from polluted soils. In this study, we identified three loose-leaf lettuce cultivars with low accumulation of perfluorooctanoic acid (PFOA), a highly toxic and persistent organic pollutant. PFOA concentrations in the shoots of low-PFOA cultivars were 3.7-5.5-fold lower than those of high-PFOA cultivars. The identification of low-PFOA cultivars could contribute to ensuring food safety despite cultivation in highly polluted soils (1 mg/kg) based on the tolerable daily PFOA intake (1.5 µg/kg/d). We detected lower desorbing fractions of PFOA in rhizosphere soil, lower bioconcentration factors, and higher distribution in the cell walls and organelles of roots in low-PFOA cultivars, all of which are key factors in limiting PFOA uptake and translocation from soil to shoots, than in high-PFOA cultivars. This study reveals the mechanism of PFOA uptake from soil to crop and lays a foundation for establishing a cost-effective strategy to plant crops in polluted soil and reduce exposure risk due to persistent organic pollutants in crops.


Assuntos
Caprilatos/metabolismo , Fluorcarbonetos/metabolismo , Alface/fisiologia , Poluentes do Solo/metabolismo , Caprilatos/análise , Fluorcarbonetos/análise , Alface/genética , Raízes de Plantas , Solo , Poluentes do Solo/análise
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