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1.
J Environ Manage ; 320: 115870, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-36056489

RESUMO

Biopurification systems (BPS) or biobeds are bioprophylaxis systems to prevent pesticide point-source contamination, whose efficiency relies mostly on the pesticide removal capacity of the biomixture, the majority component of a BPS. The adaptation of the components of the biomixtures to local availabilities is a key aspect to ensure the sustainability of the system. In this work, the removal of atrazine (ATZ) was evaluated in biomixtures formulated with three sugarcane by-products as alternative lignocellulosic substrates. Based on the capacity of actinobacteria to tolerate and degrade diverse pesticides, the effect of biomixtures bioaugmentation with actinobacteria was evaluated as a strategy to enhance the depuration capacity of biobeds. Also, the effect of ATZ and/or the bioaugmentation on microbial developments and enzymatic activities were studied. The biomixtures formulated with bagasse, filter cake, or harvest residue, reached pesticide removal values of 37-41% at 28 d of incubation, with t1/2 between 37.9 ± 0.4 d and 52.3 ± 0.4 d. The bioaugmentation with Streptomyces sp. M7 accelerated the dissipation of the pesticide in the biomixtures, reducing ATZ t1/2 3-fold regarding the controls, and achieving up to 72% of ATZ removal. Atrazine did not exert a clear effect on microbial developments, although most of the microbial counts were less in the contaminated biomixtures at the end of the assay. The bioaugmentation improved the development of the microbiota in general, specially actinobacteria and fungi, regarding the non-bioaugmented systems. The inoculation with Streptomyces sp. M7 enhanced acid phosphatase activity and/or reversed a possible effect of the pesticide over this enzymatic activity.


Assuntos
Actinobacteria , Atrazina , Praguicidas , Poluentes do Solo , Streptomyces , Actinobacteria/metabolismo , Atrazina/metabolismo , Biodegradação Ambiental , Solo/química , Poluentes do Solo/metabolismo , Streptomyces/metabolismo
2.
J Hazard Mater ; 439: 129626, 2022 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-36104896

RESUMO

Arsenic (As) pollution in paddy fields is a major threat to rice safety. Existing As remediation techniques are costly, require external chemical addition and degrade soil properties. Here, we report the use of plastic tubes as a recyclable tool to precisely extract As from contaminated soils. Following insertion into flooded paddy soils, polyethylene tube walls were covered by thin but massive Fe coatings of 76.9-367 mg Fe m-2 in 2 weeks, which adsorbed significant amounts of As. The formation of tube-wall Fe oxides was driven by local Fe-oxidizing bacteria with oxygen produced by oxygenic phototrophs (e.g., Cyanobacteria) or diffused from air through the tube wall. The tubes with As-bound Fe oxides can be easily separated from soil and then washed and reused. We tested the As removal efficiency in a pot experiment to remove As from ~ 20 cm depth/40 kg soils in a 2-year experiment and achieved an overall removal efficiency of 152 mg As m-2 soil year-1, comparable to phytoremediation with the As hyperaccumulator Pteris vittata. The cost of Fe hooks was estimated at 8325 RMB ha-1 year-1, and the profit of growing rice (around 16080 RMB ha-1 year-1 can be still maintained. The As accumulated in rice tissues was markedly decreased in the treatment (>11.1 %). This work provides a low-cost and sustainable soil remediation method for the targeted removal of As from soils and a useful tool for the study and management of the biogeochemical Fe cycle in paddy soils.


Assuntos
Arsênio , Oryza , Poluentes do Solo , Arsênio/metabolismo , Biodegradação Ambiental , Compostos Férricos , Ferro/química , Oryza/metabolismo , Óxidos/metabolismo , Plásticos/metabolismo , Solo/química , Poluentes do Solo/metabolismo
3.
Int J Mol Sci ; 23(17)2022 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-36077288

RESUMO

Chlorimuron-ethyl is a widely used herbicide in agriculture. However, uncontrolled chlorimuron-ethyl application causes serious environmental problems. Chlorimuron-ethyl can be effectively degraded by microbes, but the underlying molecular mechanisms are not fully understood. In this study, we identified the possible pathways and key genes involved in chlorimuron-ethyl degradation by the Chenggangzhangella methanolivorans strain CHL1, a Methylocystaceae strain with the ability to degrade sulfonylurea herbicides. Using a metabolomics method, eight intermediate degradation products were identified, and three pathways, including a novel pyrimidine-ring-opening pathway, were found to be involved in chlorimuron-ethyl degradation by strain CHL1. Transcriptome sequencing indicated that three genes (atzF, atzD, and cysJ) are involved in chlorimuron-ethyl degradation by strain CHL1. The gene knock-out and complementation techniques allowed for the functions of the three genes to be identified, and the enzymes involved in the different steps of chlorimuron-ethyl degradation pathways were preliminary predicted. The results reveal a previously unreported pathway and the key genes of chlorimuron-ethyl degradation by strain CHL1, which have implications for attempts to enrich the biodegradation mechanism of sulfonylurea herbicides and to construct engineered bacteria in order to remove sulfonylurea herbicide residues from environmental media.


Assuntos
Herbicidas , Methylocystaceae , Poluentes do Solo , Biodegradação Ambiental , Herbicidas/metabolismo , Methylocystaceae/metabolismo , Pirimidinas/metabolismo , Poluentes do Solo/metabolismo , Compostos de Sulfonilureia/metabolismo
4.
J Hazard Mater ; 438: 129526, 2022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-35999739

RESUMO

The mechanism of silicon (Si) influencing cadmium (Cd) speciation and bioavailability in alkaline paddy soil solution remains unclear. Therefore, this study sought to elucidate the effect of Si on Cd by combining chemical analysis and rice pot experiments. In this work, the effects of Na2SiO3 alkalinity and the differences in Na+ were eliminated in all treatments, and the Cd speciation in soil solutions was determined in-situ using a Field-Donnan membrane technology (DMT) cell. Additionally, rice yields and the Cd content in various parts of the rice plant were studied. The results showed that Si application significantly increased rice biomass by 32% (P < 0.05) while significantly reduced the Cd content in brown rice by 52% (P < 0.01) and the free Cd2+ concentration in the soil solution. Further analysis of the interaction of Si and Cd using Fourier transform-infrared spectroscopy (FT-IR), Raman, and X-ray photoelectron spectroscopy (XPS) indicated that a Si-Cd complex was formed by Cd and Si-O groups. In summary, Si changed the chemical speciation of Cd in the alkaline soil solution and formed a water-soluble Si-Cd complex that the rice could not absorb, consequently reducing Cd bioavailability.


Assuntos
Oryza , Poluentes do Solo , Disponibilidade Biológica , Cádmio/metabolismo , Oryza/metabolismo , Silício , Solo/química , Poluentes do Solo/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier
5.
Int J Mol Sci ; 23(16)2022 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-36012598

RESUMO

The main mechanism of plant tolerance is the avoidance of metal uptake, whereas the main mechanism of hyperaccumulation is the uptake and neutralization of metals through specific plant processes. These include the formation of symbioses with rhizosphere microorganisms, the secretion of substances into the soil and metal immobilization, cell wall modification, changes in the expression of genes encoding heavy metal transporters, heavy metal ion chelation, and sequestration, and regenerative heat-shock protein production. The aim of this work was to review the natural plant mechanisms that contribute towards increased heavy metal accumulation and tolerance, as well as a review of the hyperaccumulator phytoremediation capacity. Phytoremediation is a strategy for purifying heavy-metal-contaminated soils using higher plants species as hyperaccumulators.


Assuntos
Metais Pesados , Poluentes do Solo , Biodegradação Ambiental , Quelantes/metabolismo , Metais Pesados/metabolismo , Plantas/genética , Plantas/metabolismo , Solo , Poluentes do Solo/metabolismo
6.
Sci Rep ; 12(1): 14082, 2022 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-35982100

RESUMO

Long-term industrial pollution, wastewater irrigation, and fertilizer application are known factors that can contribute to the contamination of heavy metals (HMs) in agricultural soil. In addition, dissolved organic matter (DOM) plays key roles in the migration and fate of HMs in soil. This study investigated the effects of amending exogenous DOM extracted from chicken manure (DOMc), humus soil (DOMs), rice husk (DOMr), and its sub-fractions on the mobilization and bio-uptake of Cd, Zn, and Pb. The results suggested that the exogenous DOM facilitate the dissolution of HMs in rhizosphere soil, and the maximum solubility of Zn, Cd, and Pb were 1264.5, 121.3, and 215.7 µg L-1, respectively. Moreover, the proportion of Zn-DOM and Cd-DOM increased as the DOM concentration increased, and the highest proportions were 97.5% and 86.9%. However, the proportion of Pb-DOM was stable at > 99% in all treatments. In addition, the proportion of hydrophilic acid (Hy) and Pb/Cd in the rhizosphere soil solution were 17.5% and 8.3%, respectively. This finding suggested that the Hy-metals complex has a vital influence on the mobilization of metals, besides its complexation with fulvic acid and humic acid. Furthermore, the elevated DOM addition contributed to an increment of HMs uptake by Sedum alfredii, in the following order, DOMc > DOMs > DOMr. This study can provide valuable insights to enhance the development of phytoremediation technologies and farmland manipulation. Since the risk that exogenous DOM would increase the uptake of HMs by crops, it is also needed to evaluate this case from an agricultural management perspective.


Assuntos
Metais Pesados , Poluentes do Solo , Cádmio/metabolismo , Matéria Orgânica Dissolvida , Chumbo , Metais Pesados/análise , Rizosfera , Solo , Poluentes do Solo/metabolismo
7.
Environ Sci Technol ; 56(17): 12734-12744, 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-35977088

RESUMO

Dynamic behaviors of the newly deposited atmospheric heavy metals in the soil-pak choi (Brassica chinensis L.) system are investigated by a fully factorial atmospheric exposure experiment using soils exposed to 0.5-year and 1.5-year atmospheric depositions. The results showed approximately 17-87%, 19-64%, and 43-84% of the Cu, Cd, and Pb in pak choi edible parts were contributed from the new depositions, respectively. For the newly deposited metals, foliar uptake was the key pathway of shoot bioaccumulation rather than from root uptake of the deposited metals in soils, resulting in no significant soil contribution differences between pak chois growing in 0.5-year and 1.5-year exposed soils. Indeed, highly bioavailable metals in atmospheric deposition significantly increased the soil plant-bioavailable Cu, Cd, and Pb fractions; however, soil aging resulted in similar percentages of the plant-bioavailable fractions in 0.5-year and 1.5-year exposed soils, which indicated the bioavailability of metals deposited into soils rapidly decreased with aging. The soil aging process of the deposited metals was well fitted with the first-order exponential decay model, and soil organic matter and clay were the major driving factors. Our findings highlight high plant bioaccumulation rates and the rapid soil aging process of newly deposited metals during the plant growth period.


Assuntos
Metais Pesados , Poluentes do Solo , Cádmio/metabolismo , Chumbo , Solo , Poluentes do Solo/metabolismo
8.
Environ Pollut ; 311: 120018, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-36002099

RESUMO

2,4,6-trinitrotoluene (TNT) is a highly toxic explosive that contaminates soil and water and may interfere with the degradation of co-occurring compounds, such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). We proposed that TNT may influence RDX-degrading bacteria via either general toxicity or a specific effect on the |RDX degradation mechanisms. Thus, we examined the impact of TNT on RDX degradation by Rhodococcus strains YH1, T7, and YY1, which were isolated from an explosives-polluted environment. Although partly degraded, TNT did not support the growth of any of the strains when used as either sole carbon or sole nitrogen sources, or as carbon and nitrogen sources. The incubation of a mixture of TNT (25 mg/l) and RDX (20 mg/l) completely inhibited RDX degradation. The effect of TNT on the cytochrome P450, catalyzing RDX degradation, was tested in a resting cell experiment, proving that TNT inhibits XplA protein activity. A dose-response experiment showed that the IC50/trans values for YH1, T7, and YY1 were 7.272, 5.098, and 9.140 (mg/l of TNT), respectively, illustrating variable sensitivity to TNT among the strains. The expression of xplA was also strongly suppressed by TNT. Cells that were pre-grown with RDX (allowing xplA expression) and incubated with ammonium chloride, glucose, and TNT, completely transformed into their amino dinitrotoluene isomers and formed azoxy toluene isomers. The presence of oxygen-insensitive nitroreductase that enable reduction of the nitro group in the presence of O2 in the genomes of these strains suggests that they are responsible for TNT transformation in the cultures. The experimental results concluded that TNT has an adverse effect on RDX degradation by the examined strains. It inhibits RDX degradation due to the direct impact on cytochrome P450, xplA, or its expression. The tested strains can transform TNT independently of RDX. Thus, degradation of both compounds is possible if TNT concentrations are below their IC50 values.


Assuntos
Substâncias Explosivas , Rhodococcus , Poluentes do Solo , Trinitrotolueno , Biodegradação Ambiental , Carbono/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Substâncias Explosivas/toxicidade , Nitrogênio/metabolismo , Rhodococcus/metabolismo , Solo , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade , Triazinas/metabolismo , Triazinas/toxicidade , Trinitrotolueno/toxicidade , Água/metabolismo
9.
Environ Res ; 214(Pt 3): 113940, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35952736

RESUMO

As a common pyrethroid insecticide, allethrin is widely used for various purposes in agriculture and home applications. At present, allethrin residues have been frequently detected worldwide, yet little is known about the kinetics and degradation mechanisms of this insecticide. In this study, a highly efficient allethrin-degrading bacterium, Bacillus megaterium strain HLJ7, was obtained through enrichment culture technology. Strain HLJ7 can remove 96.5% of 50 mg L-1 allethrin in minimal medium within 11 days. The first-order kinetic analysis of degradation demonstrated that the half-life of allethrin degradation by strain HLJ7 was 3.56 days, which was significantly shorter than the 55.89 days of the control. The Box-Behnken design of the response surface method optimized the degradation conditions for strain HLJ7: temperature 32.18 °C, pH value 7.52, and inoculation amount 1.31 × 107 CFU mL-1. Using Andrews equation, the optimal concentration of strain HLJ7 to metabolize allethrin was determined to be 21.15 mg L-1, and the maximum specific degradation rate (qmax), half-rate constant (Ks) and inhibition coefficient (Ki) were calculated to be 1.80 d-1, 1.85 mg L-1 and 68.13 mg L-1, respectively. Gas chromatography-mass spectrometry identified five intermediate metabolites, suggesting that allethrin could be degraded firstly by cleavage of its carboxylester bond, followed by degradation of the five-carbon ring and subsequent metabolism. The results of soil remediation experiments showed that strain HLJ7 has excellent bioremediation potential in the soils. After 15 days of treatment, about 70.8% of the initial allethrin (50 mg kg-1) was removed and converted into nontoxic intermediate metabolites, and its half-life was significantly reduced in the soils. Taken together, these findings shed light on the degradation mechanisms of allethrin and also highlight the promising potentials of B. megaterium HLJ7 in bioremediation of allethrin-comtaminated environment.


Assuntos
Bacillus megaterium , Inseticidas , Poluentes do Solo , Aletrinas , Bacillus megaterium/metabolismo , Biodegradação Ambiental , Inseticidas/metabolismo , Cinética , Solo/química , Microbiologia do Solo , Poluentes do Solo/metabolismo , Água
10.
World J Microbiol Biotechnol ; 38(11): 189, 2022 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-35972701

RESUMO

The carcinogenic metalloid arsenic (As), owing to its persistent behavior in elevated levels in soils, aggravates environmental and human health concerns. The current strategies used in the As decontamination involve several physical and chemical approaches. However, it involves high cost and even leads to secondary pollution. Therefore, it is quite imperative to explore methods that can eradicate As menace from the environment in an eco-friendly, efficient, and cost-competitive way. Searching for such viable alternatives leads to the option of bioremediation technology by utilizing various microorganisms, green plants, enzymes or even their integrated methods. This review is intended to give scientific and technical details about recent advances in the bioremediation strategies of As in soil. It takes into purview the extent, toxicological manifestations, pathways of As exposure and exemplifies the substantive need of bioremediation technologies such as phytoremediation and biosorption in a descriptive manner. Additionally, the paper looks into the wide potential of some plant growth promoting microorganisms (PGPMs) that improve plant growth on one hand and alleviate As toxicity on the other. Furthermore, it also makes a modest attempt to assimilate the use of nanoparticles, non-living biomass and transgenic crops which are the emerging alternative bioremediation technologies.


Assuntos
Arsênio , Poluentes do Solo , Arsênio/metabolismo , Biodegradação Ambiental , Humanos , Solo , Poluentes do Solo/metabolismo
11.
Environ Sci Technol ; 56(15): 10691-10698, 2022 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-35833964

RESUMO

This study is the first to investigate the emission and environmental fate of one type of modified methylsiloxane with double-bond (vinyl) groups. During 2018-2020, 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane (V3), 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4), and 2,4,6,8,10-pentavinyl-2,4,6,8,10-pentamethylcyclopentasiloxane (V5) were found in aqueous (

Assuntos
Poluentes do Solo , Purificação da Água , Biossólidos , Cloreto de Polivinila , Esgotos , Solo/química , Poluentes do Solo/metabolismo , Águas Residuárias
12.
Bull Environ Contam Toxicol ; 109(3): 571-576, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35841406

RESUMO

In this work, biphenyl was used as carbon source to enrich microorganisms from polychlorinated biphenyls (PCBs)-contaminated paddy soil samples, and the taxonomic structures in both of the soil samples and the fourth-generation enrichments were examined with high-throughput sequencing. Single cells were isolated from the enrichments via single cell sorting technology named Laser Induced Visualized Ejection Separation Technology (LIVEST) and also traditional single colony sorting, and the genera of the isolates were identified using 16S rRNA sequencing. The results from high-throughput sequencing present that enrichment from generation to generation can considerably change the microbial community. Comparing the two sorting methods, the LIVEST is more time-saving and cell-targeted for microbial resource exploration. Based on the further verification of biphenyl degradation, it was found that some strains belonging to genera Macrococcus, Aerococcus and Metabacillus are capable in degrading biphenyl, which have not been reported yet.


Assuntos
Bifenilos Policlorados , Poluentes do Solo , Bactérias/metabolismo , Biodegradação Ambiental , Compostos de Bifenilo , Lasers , Filogenia , Bifenilos Policlorados/metabolismo , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Solo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Tecnologia
13.
J Hazard Mater ; 438: 129482, 2022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-35785734

RESUMO

Nanoscale zero-valent iron (nZVI) is a prominent nanomaterial for the remediation of organochlorine-contaminated soil and groundwater. However, a knowledge gap regarding the effects of the coexistence of nZVI and pollutants on soil microorganisms remains. Here, we studied the effects of nZVI on the microbial community structure, co-occurrence network, and keystone taxa in pentachlorophenol (PCP, a typical organochlorine pesticide) contaminated soils. The addition of nZVI (1000 mg/kg) had no obvious recovery effect on the microbial community structure of PCP-contaminated soil, but enhanced the connection and lowered the modularity of the microbial network. These changes were mainly present in the bacterial network rather than in the fungal or archaeal network. Moreover, the addition of nZVI increased the number of keystone taxa in the PCP-contaminated soil from 29 to 76. These keystone taxa are related to the degradation of organochlorine pollutants, carbon metabolism, and nitrogen metabolism and may thus be helpful in recovering soil ecological functions. These findings provide new insights into the interaction among nanomaterials, microorganisms, and pollutants.


Assuntos
Recuperação e Remediação Ambiental , Pentaclorofenol , Poluentes do Solo , Ferro/química , Solo/química , Poluentes do Solo/metabolismo
14.
J Hazard Mater ; 438: 129492, 2022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-35803192

RESUMO

Co-contamination of heavy metals and organic pollutants is widespread in the environment. Metal-tolerant/hyperaccumulating plants have the advantage of enhancing co-operation between plants and rhizospheric microbes under heavy metal stress, but the underlying mechanism remains unclear. In the present study, the effects of Elsholtzia splendens and Lolium perenne on the rhizospheric microbial community and degraders of phenanthrene (PHE) and polychlorinated biphenyls (PCBs) were investigated. The results showed E. splendens could tolerate high Cu concentrations, while L. perenne was sensitive to Cu toxicity. Although Cu played the most important role in microbial community construction, both E. splendens and L. perenne caused shifts in the rhizospheric microbial community. For PHE and PCB degradation, L. perenne was more efficient under low Cu concentrations, whereas E. splendens performed better under high Cu concentrations. This difference can be attributed to shifts in the degrader community and key degradation genes identified by stable isotope probing. Moreover, higher abundances of various genes for organic pollutant degradation were observed in the rhizosphere of E. splendens than L. perenne based on gene prediction under high Cu stress. Our study reveals underlying mechanism of the advantages of heavy metal-tolerant plants for organic pollutant removal in soils co-contaminated with heavy metals.


Assuntos
Lamiaceae , Metais Pesados , Fenantrenos , Bifenilos Policlorados , Poluentes do Solo , Biodegradação Ambiental , Cobre/análise , Lamiaceae/metabolismo , Metais Pesados/metabolismo , Metais Pesados/toxicidade , Fenantrenos/metabolismo , Raízes de Plantas/metabolismo , Bifenilos Policlorados/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo
15.
J Hazard Mater ; 438: 129466, 2022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-35803194

RESUMO

Biochar has been widely used for the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil, but its mechanism of influencing PAH biodegradation remains unclear. Here, DNA-stable isotope probing coupled with high-throughput sequencing was employed to assess its influence on phenanthrene (PHE) degradation, the active PHE-degrading microbial community and PAH-degradation genes (PAH-RHDα). Our results show that both Low-BC and High-BC (soils amended with 1 % and 4 % w/w biochar, respectively) treatments significantly decreased PHE biodegradation and bioavailable concentrations with a dose-dependent effect compared to Non-BC treatment (soils without biochar). This result could be attributed to the immobilisation of PHE and alteration of the composition and abundance of the PHE-degrading microbial consortium by biochar. Active PHE degraders were identified, and those in the Non-BC, Low-BC and High-BC microcosms differed taxonomically. Sphaerobacter, unclassified Diplorickettsiaceae, Pseudonocardia, and Planctomyces were firstly linked with PHE biodegradation. Most importantly, the abundances of PHE degraders and PAH-RHDα genes in the 13C-enriched DNA fractions of biochar-amended soils were greatly attenuated, and were significantly positively correlated with PHE biodegradation. Our findings provide a novel perspective on PAH biodegradation mechanisms in biochar-treated soils, and expand the understanding of the biodiversity of microbes involved in PAH biodegradation in the natural environment.


Assuntos
Fenantrenos , Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Biodegradação Ambiental , Carvão Vegetal , DNA , Fenantrenos/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Solo , Microbiologia do Solo , Poluentes do Solo/metabolismo
16.
J Hazard Mater ; 438: 129527, 2022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-35816798

RESUMO

The magnetic field can alter the hydrogen-bond structure and polarity characteristics of water; therefore, we hypothesize that magnetized water can affect plant physiological functions, including metal detoxification and excretion. In this study, the amount of Cd excreted on the leaves of Festuca arundinacea was estimated using magnetized water and normal water irrigation patterns. Irrigation with magnetized water improved the shoot dry weight and Cd content in F. arundinacea by 13.6% and 52.8%, respectively, compared to the control. Magnetized water irrigation also increased antioxidant enzyme activities in plant leaves, thereby alleviating the oxidative damage. The concentration of ferritin was 0.91 folds higher than that of the control, increasing the Fe sequestration and detoxification capacity of F. arundinacea. The amount of Cd excreted was significantly higher under magnetized water irrigation, thereby increasing the annual Cd removal by 109.7% from soil by leaf washing compared with that of the control. In contrast, F. arundinacea irrigated with magnetized water excreted 38.1% less Fe owing to the increase in ferritin levels, compared with that of the control. This study suggests a novel pathway of Cd phytoremediation by rinsing excreted Cd from the leaf surface without harvesting and replanting F. arundinacea.


Assuntos
Festuca , Lolium , Poluentes do Solo , Antioxidantes/metabolismo , Biodegradação Ambiental , Cádmio/metabolismo , Ferritinas/metabolismo , Festuca/metabolismo , Lolium/metabolismo , Poluentes do Solo/metabolismo , Água
17.
J Hazard Mater ; 438: 129469, 2022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-35820335

RESUMO

Heavy metals (HMs) contamination around smelters poses serious stress to soil microbiome. However, the co-effect of multiple HMs and native vegetation rhizosphere on the soil ecosystem remains unclear. Herein, effects of high HMs level and the rhizosphere (Tamarix ramosissima) on soil bacterial community structure and metabolic profiles in sierozem were analyzed by coupling high-throughput sequencing and soil metabolomics. Plant roots alleviated the threat of HMs by absorbing and stabilizing them in soil. High HMs level decreased the richness and diversity of soil bacterial community and increased numbers of special bacteria. Plant roots changed the contribution of HMs species shaping the bacterial community. Cd and Zn were the main contributors to bacterial distribution in non-rhizosphere soil, however, Pb and Cu became the most important HMs in rhizosphere soil. HMs induced more dominant metal-tolerant bacteria in non-rhizosphere than rhizosphere soil. Meanwhile, critical metabolites varied by rhizosphere in co-occurrence networks. Moreover, the same HMs-tolerant bacteria were regulated by different metabolites, e.g. unclassified family AKYG1722 was promoted by Dodecanoic acid in non-rhizosphere soil, while promoted by Octadecane, 2-methyl- in rhizosphere soil. The study illustrated that high HMs level and rhizosphere affected soil properties and metabolites, by which soil microbial community structure was reshaped.


Assuntos
Metais Pesados , Microbiota , Poluentes do Solo , Tamaricaceae , Bactérias/genética , Bactérias/metabolismo , Metaboloma , Metais Pesados/metabolismo , Metais Pesados/toxicidade , Solo/química , Microbiologia do Solo , Poluentes do Solo/metabolismo , Tamaricaceae/metabolismo
18.
J Hazard Mater ; 438: 129430, 2022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-35780738

RESUMO

Plants often up-regulate gene expression of P transporters under P deficiency, but down-regulate them under arsenic stress. Different from other P transporters, PvPht1;3 and PvPht1;4 expressions in As-hyperaccumulator Pteris vittata are up-regulated under P deficiency and As stress, showing strong transport capacity for both As and P. This study examined the mechanisms behind As-induced up-regulation of P transporters in P. vittata after exposing to 10-50 µM arsenate (AsV) for 14 d under hydroponics, with non-hyperaccumulator P. ensiformis as a control. Under As stress, P. vittata was more efficient in taking up both As and P than P. ensiformis, showing 48-84% more P content in the fronds and roots, leading to 18-79% greater biomass. Though As enhanced the P uptake by P. vittata, the inorganic P was reduced by 25-64% from 140-347 to 65-126 mg kg-1. It is likely that, under As stress, more P was utilized by P. vittata to counter As toxicity, causing reduction in inorganic P. This was supported by As-induced conversion of inorganic P to phytate in P. vittata, with phytate-P being increased by 26-75% from 239-713 to 418-1221 mg kg-1, maintaining internal low P levels. Under As-induced low inorganic-P conditions, the expressions of P transporters PvPht1;3 and PvPht1;4 were up-regulated by 1.4- and 2.7-fold in the roots, helping greater As and P uptake by P. vittata. Clearly, As-induced overexpression of P transporters in P. vittata roots plays a critical role in taking up both As and P, thereby increasing its efficiency in As-hyperaccumulation from contaminated media.


Assuntos
Arsênio , Pteris , Poluentes do Solo , Arsênio/metabolismo , Biodegradação Ambiental , Proteínas de Membrana Transportadoras/metabolismo , Ácido Fítico , Raízes de Plantas/metabolismo , Pteris/metabolismo , Poluentes do Solo/metabolismo , Regulação para Cima
19.
BMC Plant Biol ; 22(1): 383, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35909101

RESUMO

BACKGROUND: Alhagi maurorum Medik. (camelthorn) is a dominant desert plant indigenous in various habitats, including the Western Desert of Egypt. The plant is especially prevalent in and around economic iron ore deposits. Nutrient and heavy metal levels in A. maurorum tissues and soil samples were assessed to identify associations between heavy metal levels in plants and soil. The objective was to evaluate this species as an indicator of heavy metal pollution. Photosynthetic pigments, protein, proline, alkaloids, flavonoids, 2,2-diphenyl-1-picrylhydrazylscavenging, reduced glutathione, malondialdehyde, antioxidant enzymes, and stress-related gene expression were assessed to determine their functional roles in metal stress adaptation in ultra- and molecular structure. Additionally, the molecular genetic variation in A. maurorum samples was assessed using co-dominant sequence-related amplified polymorphism (SRAP) and inter simple sequence repeats (ISSR). RESULTS: A substantial difference in enzymatic and non-enzymatic antioxidants of A. maurorum was observed in samples collected from three sites. A. maurorum is suited to the climate in mineralized regions. Morphologically, the stem shows spines, narrow leaves, and a reduced shoot system. Anatomically, modifications included a cuticle coating on leaves and stems, sunken stomata, a compact epidermis, and a thick cortex. Significant anatomical-physiological differences were observed with varying heavy metal soil content, antioxidative enzyme activities increased as a tolerance strategy, and glutathione levels decreased in response to heavy metal toxicity. Heavy metal accumulation also affected the expression of stress-related genes. The highest levels of expression of GST, G6PDH, 6PGD, nitrate reductase 1, and sulfate transporter genes were found in plants collected from site A1. However, auxin-induced protein exhibited its highest expression in plants collected from A2. Six SRAP combinations yielded 25 scoreable markers with a polymorphism rate of 64%, and 5 ISSR markers produced 11 bands with a polymorphism rate of 36.36% for three A. maurorum genotypes. The ME1xEM7 primer combinations provided the most polymorphic information content and resolving power, making it the most useful primer for differentiating A. maurorum genotypes. SRAP markers exhibited a higher diversity index (0.24) than ISSR markers (0.16). CONCLUSIONS: A. maurorum displayed adaptive characteristics for heavy metal sequestration from mining site soils and is proposed as a strong candidate for phytoremediation.


Assuntos
Fabaceae , Metais Pesados , Poluentes do Solo , Antioxidantes/metabolismo , Biodegradação Ambiental , Fabaceae/metabolismo , Metais Pesados/metabolismo , Biologia Molecular , Plantas/genética , Solo , Poluentes do Solo/metabolismo
20.
Int J Mol Sci ; 23(14)2022 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-35886940

RESUMO

Poplars are proposed for the phytoremediation of heavy metal (HM) polluted soil. Characterization of genes involved in HM uptake and accumulation in poplars is crucial for improving the phytoremediation efficiency. Here, Natural Resistance-Associated Macrophage Protein 1 (NRAMP1) encoding a transporter involved in cadmium (Cd) uptake and transport was functionally characterized in Populus × canescens. Eight putative PcNRAMPs were identified in the poplar genome and most of them were primarily expressed in the roots. The expression of PcNRAMP1 was induced in Cd-exposed roots and it encoded a plasma membrane-localized protein. PcNRAMP1 showed transport activity for Cd2+ when expressed in yeast. The PcNRAMP1-overexpressed poplars enhanced net Cd2+ influxes by 39-52% in the roots and Cd accumulation by 25-29% in aerial parts compared to the wildtype (WT). However, Cd-induced biomass decreases were similar between the transgenics and WT. Further analysis displayed that the two amino acid residues of PcNRAMP1, i.e., M236 and P405, play pivotal roles in regulating its transport activity for Cd2+. These results suggest that PcNRAMP1 is a plasma membrane-localized transporter involved in Cd uptake and transporting Cd from the roots to aerial tissues, and that the conserved residues in PcNRAMP1 are essential for its Cd transport activity in poplars.


Assuntos
Populus , Poluentes do Solo , Biodegradação Ambiental , Transporte Biológico/genética , Cádmio/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Populus/metabolismo , Poluentes do Solo/metabolismo
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