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1.
Chemosphere ; 246: 125717, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31918081

RESUMO

It is important to illuminate the effects of litter decomposition of invasive alien species on soil N-fixing bacterial communities (SoNiBa), especially under heavy metal pollution to better outline the mechanisms for invasion success of invasive alien species. This study attempts to identify the effects of litter decomposition of Solidago canadensis L. on SoNiBa under cadmium (Cd) pollution with different concentrations (i.e., low concentration, 7.5 mg/kg soil; high concentration, 15 mg/kg soil) via a polyethylene litterbags-experiment. Electrical conductivity and total N of soil were the most important environmental factors for determining the variations of SoNiBa composition. S. canadensis did not significantly affect the alpha diversity of SoNiBa but significantly affect the beta diversity of SoNiBa and SoNiBa composition. Thus, SoNiBa composition, rather than alpha diversity of SoNiBa, was the most important determinant of the invasion success of S. canadensis. Cd with 15 mg/kg soil did not address distinct effects on alpha diversity of SoNiBa, but Cd with 7.5 mg/kg soil noticeably raised the number of species and species richness of SoNiBa mainly due to the hormonal effects. The combined S. canadensis and Cd with 15 mg/kg soil obviously decreased cumulative mass losses and the rate of litter decomposition (k) of S. canadensis, but the combined S. canadensis and Cd with 7.5 mg/kg soil evidently accelerated cumulative mass losses and k of S. canadensis. Thus, Cd with 7.5 mg/kg soil can accelerate litter decomposition of S. canadensis, but Cd with 15 mg/kg soil can decline litter decomposition of S. canadensis.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Cádmio/toxicidade , Poluentes do Solo/toxicidade , Solidago/microbiologia , Ecossistema , Poluição Ambiental , Espécies Introduzidas , Metais Pesados , Fixação de Nitrogênio , Folhas de Planta , Solo
2.
PLoS One ; 15(1): e0227267, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31931513

RESUMO

The relevant information about the impacts caused by presence of emerging pollutants in mixtures on the ecological environment, especially on the more vulnerable compartments such as activated sludge (AS) is relatively limited. This study investigated the effect of ibuprofen (IBU) and triclosan (TCS), alone and in combination to the performance and enzymatic activity of AS bacterial community. The assays were carried out in a pilot AS reactor operating for two-weeks under continuous dosage of pollutants. The microbial activity was tracked by measuring oxygen uptake rate, esterase activity, oxidative stress and antioxidant enzyme activities. It was found that IBU and TCS had no acute toxic effects on reactor biomass concentration. TCS led to significant decrease of COD removal efficiency, which dropped from 90% to 35%. Continuous exposure to IBU, TCS and their mixtures increased the activities of glutathione s-transferase (GST) and esterase as a response to oxidative damage. A high increase in GST activity was associated with non-reversible toxic damage while peaks of esterase activity combined with moderate GST increase were attributed to an adaptive response.


Assuntos
Bactérias/enzimologia , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental/efeitos dos fármacos , Reatores Biológicos/microbiologia , Poluentes Químicos da Água/toxicidade , Bactérias/efeitos dos fármacos , Biomassa , Esterases/metabolismo , Glutationa Transferase/metabolismo , Ibuprofeno/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Oxigênio/metabolismo , Triclosan/toxicidade , Águas Residuárias/química , Águas Residuárias/toxicidade , Purificação da Água/métodos
3.
Bull Environ Contam Toxicol ; 104(2): 259-264, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31893300

RESUMO

Soil arsenic (As) pollution has become a global problem. It is urgent to improve the phytoextraction efficiency of soil As. This study found chemical activators (Span 80/SDS and GSH/Span 80/SDS) that can significantly improve the availability of As and the phytoextraction efficiency of As by Pteris vittata L. in As-contaminated soil. Compared with the control, in the soil screening experiment, Span 80/SDS and GSH/Span 80/SDS significantly increased available As in soil by 73.4% and 81.4%, respectively. And in the soil pot experiment, the Span 80/SDS and GSH/Span 80/SDS significantly increased the As concentration in the pinnae of Pteris vittata L. by 53.4% and 41.2%, respectively, and the total As amount extraction by Pteris vittata L. increased significantly by 31.7% and 94.2%, respectively. The results suggest that adding Span 80/SDS and GSH/Span 80/SDS to As-contaminated soil can be considered as an effectively method to improve the efficiency of phytoextraction.


Assuntos
Arsênico/metabolismo , Pteris/metabolismo , Poluentes do Solo/metabolismo , Tensoativos/farmacologia , Biodegradação Ambiental/efeitos dos fármacos , Disponibilidade Biológica
4.
Chemosphere ; 238: 124512, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31430718

RESUMO

Lindane is an organochlorine pesticide that, due to its persistence in the environment, is still detected in different matrices. Bioremediation using actinobacteria consortia proved to be promising for the restoration of contaminated soils. Another alternative to remove xenobiotics is to use agricultural residues, which stimulates microbial activity, increasing its capacity to degrade organic pollutants. The present work studies the coupling of sugarcane bagasse biostimulation and bioaugmentation with the actinobacteria consortium composed of Streptomyces sp. A2, A5, A11 and M7 on lindane removal in different soil types. In this sense, factorial designs with three factors (proportion and size of sugarcane bagasse particles, and moisture content) were employed. A response optimizer identified the combination of factors levels that jointly allowed obtaining the maximum lindane removal in the evaluated conditions. In the optimal conditions, the effect of the bioremediation process on soil microbiota was studied by evaluating different parameters. The highest lindane removal percentages were detected in biostimulated microcosms bioaugmented with the microbial consortium, which were accompanied by a decrease in lindane half-life respect to the controls. Also, the bioaugmentation of biostimulated microcosms increased the microbial counts and enhanced soil enzymatic activities, corroborating the bioremediation process efficiency. The survival of the four actinobacteria at the end of the assay confirmed the ability of all Streptomyces strains to colonize amended soils. Bioremediation by simultaneous application of biostimulation with sugarcane bagasse and bioaugmentation with the actinobacteria consortium, in the optimized conditions, represents an efficient strategy to restore lindane contaminated soils.


Assuntos
Hexaclorocicloexano/isolamento & purificação , Hexaclorocicloexano/metabolismo , Poluentes do Solo/isolamento & purificação , Poluentes do Solo/metabolismo , Solo/química , Streptomyces/efeitos dos fármacos , Streptomyces/metabolismo , Biodegradação Ambiental/efeitos dos fármacos , Celulose/química , Celulose/farmacologia , Consórcios Microbianos/efeitos dos fármacos , Saccharum/química
5.
J Environ Sci (China) ; 87: 319-330, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791505

RESUMO

Silver nanoparticles (AgNPs) have been widely used in many fields, which raised concerns about potential threats to biological sewage treatment systems. In this study, the phosphorus removal performance, enzymatic activity and microbial population dynamics in constructed wetlands (CWs) were evaluated under a long-term exposure to AgNPs (0, 50, and 200 µg/L) for 450 days. Results have shown that AgNPs inhibited the phosphorus removal efficiency in a short-term exposure, whereas caused no obviously negative effects from a long-term perspective. Moreover, in the coexisting CW system of AgNPs and phosphorus, competition exhibited in the initial exposure phase, however, cooperation between them was observed in later phase. Enzymatic activity of acid-phosphatase at the moderate temperature (10-20°C) was visibly higher than that at the high temperature (20-30°C) and CWs with AgNPs addition had no appreciable differences compared with the control. High-throughput sequencing results indicated that the microbial richness, diversity and composition of CWs were distinctly affected with the extension of exposure time at different AgNPs levels. However, the phosphorus removal performance of CWs did not decline with the decrease of polyphosphate accumulating organisms (PAOs), which also confirmed that adsorption precipitation was the main way of phosphorus removal in CWs. The study suggested that AgNPs and phosphorus could be removed synergistically in the coexistence system. This work has some reference for evaluating the influences of AgNPs on the phosphorus removal and the interrelation between them in CWs.


Assuntos
Nanopartículas Metálicas/toxicidade , Prata/toxicidade , Eliminação de Resíduos Líquidos/métodos , Áreas Alagadas , Biodegradação Ambiental/efeitos dos fármacos , Fósforo/análise , Fósforo/metabolismo , Águas Residuárias , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade
6.
Chemosphere ; 240: 124915, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31563105

RESUMO

In animal livestock heavy metals are widely used as feed additives to control enteric bacterial infections as well as to enhance the integrity of the immune system. As these metals are only partially adsorbed by animals, the content of heavy metals in manure and wastewaters causes soil and ground water contamination, with Zn2+ and Cu2+ being the most critical output from pig livestock. Phytoremediation is considered a valid strategy to improve the purity of wastewaters. This work studied the effect of Zn2+ and Cu2+ on the morphology and protein expression in Thelypteris palustris and Typha latifolia plants, cultured in a wetland pilot system. Despite the absence of macroscopic alterations, remodeling of cell walls and changes in carbohydrate metabolism were observed in the rhizomes of both plants and in leaves of Thelypteris palustris. However, similar modifications seemed to be determined by the alterations of different mechanisms in these plants. These data also suggested that marsh ferns are more sensitive to metals than monocots. Whereas toleration mechanisms seemed to be activated in Typha latifolia, in Thelypteris palustris the observed modifications appeared as slight toxic effects due to metal exposure. This study clearly indicates that both plants could be successfully employed in in situ phytoremediation systems, to remove Cu2+ and Zn2+ at concentrations that are ten times higher than the legal limits, without affecting plant growth.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Cobre/toxicidade , Traqueófitas/metabolismo , Typhaceae/metabolismo , Eliminação de Resíduos Líquidos/métodos , Zinco/toxicidade , Animais , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Cobre/farmacocinética , Gado , Esterco , Projetos Piloto , Células Vegetais/efeitos dos fármacos , Células Vegetais/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Proteínas de Plantas , Especificidade da Espécie , Suínos , Traqueófitas/efeitos dos fármacos , Typhaceae/efeitos dos fármacos , Águas Residuárias/química , Águas Residuárias/toxicidade , Poluentes Químicos da Água/farmacocinética , Poluentes Químicos da Água/toxicidade , Áreas Alagadas , Zinco/farmacocinética
7.
Chemosphere ; 238: 124594, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31445334

RESUMO

Enhancing the biodegradation efficiency of atrazine, a kind of commonly applied herbicide, has been attracted much more concern. Here, Zn2+ which has long been considered essential in adjusting cell physiological status was selected to investigate its role on the biodegradation of atrazine by Arthrobacter sp. DNS10 as well as the transmembrane transport of atrazine during the biodegradation period. The results of gas chromatography showed that the atrazine removal percentages (initial concentration was 100 mg L-1) in 0.05 mM Zn2+ and 1.0 mM Zn2+ treatments were 94.42% and 86.02% respectively at 48 h, while there was also 66.43% of atrazine left in the treatment without exogenous Zn2+ existence. The expression of atrazine chlorohydrolase gene trzN in the strain DNS10 cultured with 0.05 mM and 1.0 mM Zn2+ was 7.30- and 4.67- times respectively compared with that of the non-zinc treatment. In addition, the flow cytometry test suggests that 0.05 mM of Zn2+ could better adjust the membrane permeability of strain DNS10, meanwhile, the amount of atrazine accumulation in the strain DNS10 co-cultured with this level Zn2+ was 2.21 times of that of the strain without Zn2+. This study may facilitate a better understanding of the mechanisms that exogenous Zn2+ enhances the biodegradation of atrazine by Arthrobacter sp. DNS10.


Assuntos
Arthrobacter/metabolismo , Atrazina/análise , Herbicidas/análise , Hidrolases/biossíntese , Zinco/farmacologia , Biodegradação Ambiental/efeitos dos fármacos , Transporte Biológico/fisiologia , Hidrolases/genética , Permeabilidade/efeitos dos fármacos , Microbiologia do Solo
8.
Biomed Res Int ; 2019: 2496905, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31886184

RESUMO

Disintegration of municipal waste activated sludge (WAS) using thermo-alkaline (TA) and electro-Fenton (EF) methods was investigated and compared in terms of the efficiency of sludge solubilisation and enhancement of anaerobic biodegradability. Performance of organic matter solubilisation (soluble COD, proteins, polysaccharides) of sludge pretreated with EF was proved to be better than that with TA pretreatment, which resulted in the enhancement of anaerobic biodegradability. Comparison of results indicated that percentages of PN and PS release obtained after EF pretreatment (68.95 and 65.22%) were higher than those obtained by TA method (45.25 and 35.22%) respectively. An improvement of biogas potential about 2 and 1.6 times was achieved respectively by EF and TA pretreatment in comparison to raw sludge. During semi-continuous fermentation study in continuous stirred tank reactor, EF pretreated sludge gave the best biogas yield (0.6 L biogas/g COD) at an OLR of 2.5 g COD/L. d in comparison to TA pretreated sludge (0.3 L biogas/g COD), where low biogas yield about 0.1 L biogas/g COD was registered by raw sludge in the same CSTR. Therefore, the integration of EF process to anaerobic digestion might be a promising process for sludge reduction and biogas recovery.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Álcalis/farmacologia , Anaerobiose , Biocombustíveis/microbiologia , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Humanos , Peróxido de Hidrogênio/farmacologia , Ferro/farmacologia , Metano/química , Polissacarídeos/química , Proteínas/química
9.
PLoS One ; 14(12): e0226229, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31856257

RESUMO

Vermicomposting has been recommended as an eco-friendly method to transform organic waste into nutrient resources with minimum energy input. However, odor and pest issues associated with this method limit the use of vermicomposting, especially in indoor conditions. This study evaluated the effectiveness of applying hypochlorous acid (HOCl) to deodorize the vermicomposting process and improve the breeding environment for earthworms (Eisenia fetida). The deodorization performance of HOCl was compared by measuring the amount of ammonia (NH3) and amine (R-NH2) released from the decaying process of two types of food waste: HOCl-treated (HTW) waste and non-treated waste (NTW). The total and individual weights of earthworms in the waste treated with HOCl was measured to evaluate the impact on earthworm reproduction after applying HOCl. The results showed that HOCl application could reduce NH3 by 40% and R-NH2 by 80%, and increase the earthworm population size and total weight by up to 29% and 92%, respectively, compared to the control group. These results suggest that HOCl application is potentially an efficient method to control the odor and to boost earthworm reproduction and thus facilitate vermicomposting for improved food waste treatment and environmental quality.


Assuntos
Compostagem/métodos , Alimentos , Ácido Hipocloroso/farmacologia , Odorantes/prevenção & controle , Oligoquetos/crescimento & desenvolvimento , Oligoquetos/metabolismo , Resíduos , Animais , Biodegradação Ambiental/efeitos dos fármacos , Oligoquetos/efeitos dos fármacos
10.
Sci Total Environ ; 697: 134151, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31491633

RESUMO

Alkaline phosphatase (AP) is commonly found in aquatic ecosystems as an extracellular enzyme closely related to the biogeochemical cycling of phosphorus. Although the AP activity (APA) is conventionally thought to be a main response to PO43- starvation, significant effects of macro metal elements (Al, Fe, and Ca) and S on the APA were found in this study. The APA was reduced by Al primarily through the adsorption of the enzyme onto AlOOH colloids. Fe2+ inhibited the APA via a mechanism involving free radical oxidation. The main mechanism by which Ca2+ inhibited the APA was by competing with Mg2+ and Zn2+ for the active sites of the enzyme. Excessive S2- could reduce the APA by removing Zn2+ from the active sites of the enzyme. The inhibition of APA could be reversed if some metal ions (e.g., Fe2+) were precipitated by S2- under reducing conditions. Therefore, in anaerobic ecosystems, the effects of macro metals on APA under conditions of sulfide accumulation may have innovative implications for phosphorus management.


Assuntos
Fosfatase Alcalina/metabolismo , Biodegradação Ambiental/efeitos dos fármacos , Fenômenos Ecológicos e Ambientais , Poluentes Ambientais/toxicidade , Metais/toxicidade , Ecossistema , Fósforo
11.
Environ Sci Pollut Res Int ; 26(31): 31822-31833, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31487012

RESUMO

Remediation of heavy metal-contaminated soils is essential for safe agricultural or urban land use, and phytoremediation is among the most effective methods. The success of phytoremediation relies on the size of the plant biomass and bioavailability of the metal for plant uptake. This research was carried out to determine the effect of Ethylenediaminetetraacetic acid (EDTA) ligand and Cu-resistant plant growth-promoting rhizobacteria (PGPR) on phytoremediation efficiency of selected plants as well as fractionation and bioavailability of copper (Cu) in a contaminated soil. The test conditions included three plant species (maize: Zea mays L., sunflower: Helianthus annuus L., and pumpkin: Cucurbita pepo L.) and six treatments, comprising two PGPR strains (Pseudomonas cedrina K4 and Stenotrophomonas sp. A22), two PGPR strains with EDTA, EDTA, and control (without PGPR and EDTA). The combination of EDTA and PGPR enhanced the Cu concentration in both shoot and root tissues and increased the plant biomass. The Cu specific uptake was at a maximum level in the shoots of pumpkin plants when treated with the PGPR strain K4 + EDTA (202 µg pot-1), and the minimum amount of Cu was recorded for sunflower with no PGPR or EDTA addition (29.6 µg pot-1). The result of the PGPR-EDTA treatments showed that the combined application of EDTA and PGPR increased the shoot Cu-specific uptake approximately fourfold in pumpkin. Pumpkin with the highest shoot Cu specific uptake and maize with the highest root Cu specific uptake were the most effective plants in phytoextraction and phytostabilization, respectively. The effectiveness of different PGPR-EDTA treatments in increasing Cu specific uptake by crop plants was assessed by measuring the amount of Cu extracted from the rhizosphere soil adhering to the roots of crop species, by the use of the single extractants Diethylenetriamine pentaacetic acid (DTPA), H2O, NH4NO3, and NH4OAc. PGPR-EDTA treatments increased the amount of water-extractable Cu from rhizosphere soils more than ten times that of the control. The combined application of the EDTA and PGPR reduced the carbonated Fe and Mn oxide-bound Cu in the contaminated soil, and increased the soluble and exchangeable concentration of Cu. Pumpkin, with high shoot biomass and the highest shoot Cu specific uptake was found to be the most effective field crop in phytoextraction of Cu from the contaminated soil. The results of this pot study demonstrated that the EDTA+PGPR treatment could play an important role in increasing the Cu bioavailability and specific uptake by plants, and thus increasing the phytoremediation efficiency of plants in Cu-contaminated areas.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Cobre/toxicidade , Ácido Edético/farmacologia , Pseudomonas/efeitos dos fármacos , Poluentes do Solo/toxicidade , Inoculantes Agrícolas , Disponibilidade Biológica , Biomassa , Cobre/análise , Cobre/farmacocinética , Cucurbita/efeitos dos fármacos , Cucurbita/microbiologia , Helianthus/efeitos dos fármacos , Helianthus/microbiologia , Brotos de Planta/efeitos dos fármacos , Pseudomonas/fisiologia , Rizosfera , Poluentes do Solo/farmacocinética , Zea mays/efeitos dos fármacos , Zea mays/microbiologia
12.
Chemosphere ; 236: 124360, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31545186

RESUMO

Cadmium (Cd) uptake and accumulation in plant tissues is affected by physiological stage of a plant and presence of mineral nutrients in soil. We investigate the effect of micronutrient Mo (0.5, 1.0 and 2.0 ppm) on biomass, Cd accumulation, photosynthetic pigments and endogenous phenolics and soluble proline in Cannabis sativa plant grown in 25 and 50 ppm Cd polluted soil. Molybdenum was applied as seed soaking and soil addition treatments. The plants were harvested in two stages i.e. vegetative (6 weeks) and reproductive stages (12 weeks). It was found that seed soaking treatment of 1.0 ppm Mo most significantly increased biomass, Cd accumulation (1.76 ±â€¯0.19 mg Cd/DBM) and phenolics (104.5 ±â€¯4.46 ppm) concentration in the plant tissues. Molybdenum treatments highly increased Cd bio-concentration at reproductive stage as compared to vegetative stage in plants grown in 50 ppm Cd polluted soil. Translocation of Cd from roots into leaves was significantly increased by Mo treatments at reproductive stage as compared to vegetative stage. Strong inter-correlations existed between total phenolics, Cd accumulation, dry biomass and chlorophyll contents of the plant.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Cádmio/análise , Cannabis/metabolismo , Molibdênio/farmacologia , Poluentes do Solo/análise , Oligoelementos/farmacologia , Antioxidantes/farmacologia , Biomassa , Cannabis/crescimento & desenvolvimento , Clorofila/análise , Fenóis/análise , Fotossíntese/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Prolina/metabolismo , Sementes/efeitos dos fármacos , Solo
13.
Environ Pollut ; 255(Pt 1): 113169, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31539847

RESUMO

Concentrations of atmospheric carbon dioxide have been continuously increasing, and more investigations are needed in regard to the responses of various plants to the corresponding climatic conditions. In particular, potential variations in phytoremediation efficiency induced by global warming have rarely been investigated. Objective of this research was to evaluate the changes in phytoremediation efficiency of Noccaea caerulescens exposed to different concentrations of CO2. The concentrations of CO2 in the elevated CO2 treatments were adjusted to 550 ±â€¯50 ppm to match the level of atmospheric CO2 predicted in 2050-2070. Compared to ambient controls (400 ppm), biomass yields and metal concentrations of N. caerulescens increased under elevated CO2 conditions, thus indicating that the phytoremediation efficiency of the species could increase in higher CO2 environment. In addition, water soluble and exchangeable Pb and Cu concentrations in soils decreased under elevated CO2 conditions, which reduced the leaching risks of the metals. The concentrations of malondialdehyde (MDA) of N. caerulescens decreased to different degrees with the increased CO2 concentrations. The overall findings suggested that elevations in CO2 can reduce the oxidative damage caused by metals in this species. The phytoremediation efficiency of N. caerulescens grown in multiple metal-enriched soils could be enhanced with global warming.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Brassicaceae/metabolismo , Dióxido de Carbono/farmacologia , Biomassa , Cobre/análise , Aquecimento Global , Chumbo/análise , Malondialdeído/análise , Metais/análise , Solo/química , Poluentes do Solo/análise
14.
Mater Sci Eng C Mater Biol Appl ; 104: 109943, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500025

RESUMO

The main objective of this work was to reduce the inhibitory effects of high contents of organics, ammonia, and heavy metals in an anaerobic buffled reactor (ABR), and to prevent the sludge wash-out using zeolites as media. In this work, a pilot scale of ABR with 8 compartments and a working volume of 14.4 L was used, and the last four ABR compartments were filled with a zeolite. The bioreactor was operated at HRTs of 3, 4, and 5 days, zeolite filling ratios of 10, 20, and 30%, and influent chemical oxygen demand (COD) concentrations of 10,000, 20,000, and 30,000 mg/L. The results obtained showed that the maximum removal efficiencies of COD and BOD5 reached 78 and 68%, respectively. The maximum removal was observed at a HRT of 5 days, a 30% medium filling ratio, and a COD of 10,000 mg/L. Increasing the filling ratio in the reactor increased the removal efficiencies of COD and BOD5 but increasing the concentration of the influent COD and decreasing HRT reduced the removal efficiency of the reactor. The initial BOD5/COD ratio was equal to 0.36, which increased by 46% when the medium filling ratio was elevated to 30%. The maximum biogas yield was 0.23 L/g of CODRemoved, and the specific methanogenic activity test verified the toxicity effect of the leachate on the gas-producer organisms. The results of scanning electronic microscopy and EDS showed that the zeolite medium immobilized the microorganisms and a biofilm was formed. Also the zeolite, as a well-known ion exchanger, decreased the concentrations of the major inhibitors (ammonia and heavy metals) and improved the reactor efficiency.


Assuntos
Anaerobiose/efeitos dos fármacos , Biodegradação Ambiental/efeitos dos fármacos , Zeolitas/química , Amônia/química , Biofilmes/efeitos dos fármacos , Biocombustíveis , Análise da Demanda Biológica de Oxigênio/métodos , Reatores Biológicos , Metais Pesados/química , Oxigênio/química , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química
15.
Chemosphere ; 237: 124545, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549657

RESUMO

N and P are the key limiting nutrients considered most important for the stimulation of crude oil degradation but other trace nutrients may also be important. Experimental soil microcosms were setup to investigate crude oil degradation in the context of Ni amendments. Amended Nickel as NiO, NiCl2, or, a porphyrin complex either inhibited, had no effect, or, enhanced aerobic hydrocarbon degradation in an oil-contaminated soil. Biodegradation was significantly (95% confidence) enhanced (70%) with low levels of Ni-Porph (12 mg/kg) relative to an oil-only control; whereas, NiO (200 and 350 mg/kg) significantly inhibited (36 and 87%) biodegradation consistent with oxide particle induced reactive oxygen stress. Microbial community compositions were also significantly affected by Ni. In 16S rRNA sequence libraries, the enriched hydrocarbon degrading genus, Rhodococcus, was partially replaced by a Nocardia sp. in the presence of low levels of NiO (12 and 50 mg/kg). In contrast, the highest relative and absolute Rhodococcus abundances were coincident with the maximal rates of oil degradation observed in the Ni-Porph-amended soils. Growth dependent constitutive requirements for Ni-dependent urease or perhaps Ni-dependent superoxide dismutase enzymes (found in Rhodococcus genomes) provided a mechanistic explanation for stimulation. These results suggest biostimulation technologies, in addition to N and P, should also consider trace nutrients such as Ni tacitly considered adequately supplied and available in a typical soil.


Assuntos
Níquel/farmacologia , Petróleo/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Biodegradação Ambiental/efeitos dos fármacos , Hidrocarbonetos/metabolismo , Microbiota/efeitos dos fármacos , Microbiota/genética , Microbiota/fisiologia , RNA Ribossômico 16S/genética , Rhodococcus/genética , Rhodococcus/metabolismo , Solo/química , Poluentes do Solo/química
16.
Environ Int ; 132: 105087, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31430607

RESUMO

The persistence of extracellular DNA (eDNA) is crucial for ensuring species diversity and ecological function in aquatic systems. However, scarce information exists about the impact of pesticides on eDNA, although they often co-exist in the aquatic environment. Using a variety of spectroscopic analyses, eDNA degradation and the associated alterations in DNA secondary structure was investigated by exposing DNase I to tested DNA in the presence of chlorpyrifos, a commonly used organophosphate pesticide. Molecular dynamics simulation was used to explore the weak interactions between the tested DNA and chlorpyrifos. The results indicated that chlorpyrifos significantly enhanced DNA degradation without affecting the enzyme activity of DNase I in an aqueous system. Spectroscopic experiments confirmed that chlorpyrifos and the analog chlorpyrifos-methyl could bind with DNA to cause the bases noncovalent stacking interaction. Molecular simulations further demonstrated that pesticide binding with DNA molecules caused widening of the DNA grooves and destruction of the hydrated layer, which enhanced DNA degradation. The findings presented herein provide novel insight into the genotoxicity and ecotoxicity of chlorpyrifos and chlorpyrifos-methyl, as well as their impacts on DNA persistence in aquatic environments.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Clorpirifos/análogos & derivados , Clorpirifos/farmacologia , DNA/metabolismo , Praguicidas/farmacologia , Poluentes Químicos da Água/química , Clorpirifos/toxicidade , Desoxirribonuclease I/metabolismo , Praguicidas/análise , Praguicidas/toxicidade
17.
Environ Pollut ; 254(Pt A): 112983, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31394342

RESUMO

Concerns regarding microplastic contamination have spread from aquatic environments to terrestrial systems with a growing number of studies have been reported. Notwithstanding, the potential effects on soil ecosystems remain largely unexplored. In this study, the effects of polyethylene microplastics on soil enzymatic activities and the bacterial community were evaluated, and the microbiota colonizing on microplastics were also investigated. Microplastic amendment (2000 fragments per kg soil) significantly increased the urease and catalase activities in soil after 15 days, and no discernible alteration of invertase activities was detected. Results from high-throughput sequencing of 16S rRNA revealed that the alpha diversities (richness, evenness, and diversity) of the microbiota in soil were not obviously changed by the PE amendment, whereas the diversity indexes of microbiota on plastic fragments were significantly lower than those in the control and amended soils. Different taxonomic composition was observed in between the control and amended soils after 90 days of incubation. Bacterial assemblages with distinct community structure colonized the PE microplastics. Additionally, several taxa including plastic-degrading bacteria and pathogens were more abundant on microplastics. Simultaneously, the predicted functional profiles showed that the pathways of amino acid metabolism and xenobiotics biodegradation and metabolism were higher on the microplastics. These results indicated that microplastics in soil, compared with those in aquatic environments, can also act as a distinct microbial habitat, potentially altering the ecological functions of soil ecosystems.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Plásticos/toxicidade , Microbiologia do Solo , Poluentes do Solo/toxicidade , Bactérias/efeitos dos fármacos , Microbiota/efeitos dos fármacos , Polietileno/farmacologia , RNA Ribossômico 16S , Solo/química
18.
J Appl Microbiol ; 127(4): 1057-1068, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31260173

RESUMO

AIMS: To evaluate hexavalent chromium (Cr (VI)) reduction potential of indigenous isolate M5, under growing and nongrowing conditions. METHODS AND RESULTS: Microbacterium sp. M5 was isolated from soil samples collected from a common effluent treatment plant, after enrichment of indigenous microbial diversity in the presence of 200 mg l-1 of Cr (VI). The isolate achieved complete reduction of 400 mg l-1 Cr (VI) supplement to Luria Bertani medium having initial pH of 9·0 after 48 h incubation. Furthermore, the reduction potential of resting and surfactant treated cell membrane compromised cells of M5 was evaluated. The control and biosurfactant treated cells achieved 22·71 ± 0·5% and 40·56 ± 0·5% reduction of 50 mg l-1 Cr (VI) in Tris-HCl buffer, under resting cells conditions. To the best of our knowledge, this is the first report where cells with compromised cell membrane obtained after exposure to biosurfactant have been evaluated for Cr (VI) reduction. CONCLUSION: The Cr (VI) reduction potential of Microbacterium sp. M5 could be effectively exploited for treatment of chromium-rich effluents, under nongrowing conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The isolate M5 could be a potential inoculum for effluent treatment plants as it is able to support Cr (VI) reduction under wide range of pH, salinity and in the presence of different metal ions.


Assuntos
Actinomycetales/crescimento & desenvolvimento , Actinomycetales/metabolismo , Cromo/metabolismo , Poluentes do Solo/metabolismo , Purificação da Água/métodos , Actinomycetales/efeitos dos fármacos , Biodegradação Ambiental/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Oxirredução , Salinidade , Esgotos/microbiologia , Tensoativos/farmacologia
19.
Environ Pollut ; 253: 939-948, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31351302

RESUMO

The continued increase in the global demand for oil, which reached 4,488 Mtoe in 2018, leads to large quantities of petroleum products entering the environment posing serious risks to natural ecosystems if left untreated. In this study, we evaluated the impact of co-contamination with lead on the efficacy of two bioremediation processes, natural attenuation and biostimulation of Total Petroleum Hydrocarbons (TPH) as well as the associated toxicity and the changes in the microbial community in contaminated soils. The biostimulated treatment resulted in 96% and 84% reduction in TPH concentration in a single and a co-contamination scenario, respectively, over 28 weeks of a mesocosm study. This reduction was significantly more in comparison to natural attenuation in a single and a co-contamination scenario, which was 56% and 59% respectively. In contrast, a significantly greater reduction in the associated toxicity of in soils undergoing natural attenuation was evident compared with soils undergoing biostimulation despite the lower TPH degradation when bioassays were applied. The earthworm toxicity test showed a decrease of 72% in the naturally attenuated toxicity versus only 62% in the biostimulated treatment of a single contamination scenario. In a co-contamination scenario, toxicity decreased only 30% and 8% after natural attenuation and biostimulation treatments, respectively. 16s rDNA sequence analysis was used to assess the impact of both the co-contamination and the bioremediation treatment. NGS data revealed major bacterial domination by Nocardioides spp., which reached 40% in week 20 of the natural attenuation treatment. In the biostimulated soil samples, more than 50% of the bacterial community was dominated by Alcanivorax spp. in week 12. The presence of Pb in the natural attenuation treatment resulted in an increased abundance of a few Pb-resistant genera such as Sphingopyxis spp. and Thermomonas spp in addition to Nocardioides spp. In contrast, Pb co-contamination completely shifted the bacterial pattern in the stimulated treatment with Pseudomonas spp. comprising approximately 45% of the bacterial profile in week 12. This study confirms the effectiveness of biostimulation over natural attenuation in remediating TPH and TPH-Pb contaminated soils. In addition, the presence of co-contaminants (e.g. Pb) results in serious impacts on the efficacy of bioremediation of TPH in contaminated soils, which must be considered prior to designing any bioremediation strategy.


Assuntos
Biodegradação Ambiental/efeitos dos fármacos , Chumbo/toxicidade , Microbiologia do Solo , Poluentes do Solo/toxicidade , Bactérias/metabolismo , Ecossistema , Hidrocarbonetos/análise , Petróleo/análise , Petróleo/metabolismo , Pseudomonas/metabolismo , Solo , Poluentes do Solo/análise , Poluentes do Solo/metabolismo
20.
J Basic Microbiol ; 59(9): 867-878, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31347180

RESUMO

Removal of heavy metals from food material by growing micro-organisms is limited by the toxicity to cells. In this study, different preincubation treatments were investigated to analyze their effects on cadmium resistance and removal ability of Pichia kudriavzevii A16 and Saccharomyces cerevisiae CICC1211. Sucrose preincubation improved the cadmium resistance of both yeast cells and increased the cadmium-removal rate of P. kudriavzevii A16. An evident decrease of intracellular and cell-surface cadmium accumulation was observed after sucrose preincubation, which may be the primary reason responsible for the improved cadmium resistance. Flow cytometry assay showed that sucrose significantly reduced the production of reactive oxygen species (ROS) and cell death rate of both yeasts under cadmium compared with those normally cultured cells. Under cadmium stress, the content of both protein carbonyls and malonyldialdehyde were also reduced by the addition of sucrose, the results were in accordance with the tendency of ROS, exhibiting a defending function of sucrose. Osmotic regulators as proline and trehalose were increased by sucrose preincubation in P. kudriavzevii A16 in the presence of cadmium. The results suggested that sucrose preincubation could be applied to improve cadmium resistance and removal rate of yeasts.


Assuntos
Cádmio/metabolismo , Pichia/efeitos dos fármacos , Pichia/metabolismo , Sacarose/farmacologia , Biodegradação Ambiental/efeitos dos fármacos , Cádmio/toxicidade , Viabilidade Microbiana/efeitos dos fármacos , Pichia/fisiologia , Prolina/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Estresse Fisiológico/efeitos dos fármacos , Trealose/metabolismo
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