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1.
Sci Total Environ ; 702: 134993, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31726336

RESUMO

Since the establishment of the whole-contact sediment toxicity test using Heterocypris incongruens in 2012, this user-friendly method has been widely used for the assessment of many kinds of solid samples, such as sediment, soil, compost, and sewage sludge. There are two endpoints for this method: mortality and growth inhibition. Currently, there is no standard toxicity threshold established for the endpoint of growth inhibition. However, there is evidence showing that the calcite saturation state of the overlying water, which might be different among various samples, influences the growth and survival of H. incongruens. Thus, it is necessary to characterize the influence of the calcite saturation state to ensure that the test results are reliable and comparable among different samples. In the present study, we created artificial sediments comprised of quartz sand and 0-20% calcite particulates to manipulate the calcite saturation state in the overlying water and performed the test using H. incongruens for 6 d. The results show that a low calcite saturation state inhibited the growth of H. incongruens but had no effect on survival rate. The growth of ostracods was linearly related to the calcite saturation index of the overlying water. Additionally, a formula for artificial sediment consisting of 10% calcite and 90% quartz sand for the H. incongruens toxicity test was proposed. This study helps to distinguish H. incongruens growth inhibition caused by calcite saturation from that caused by toxicity.


Assuntos
Carbonato de Cálcio/química , Crustáceos/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Fenômenos Biológicos , Sedimentos Geológicos/química , Esgotos , Solo , Testes de Toxicidade , Poluentes Químicos da Água/normas
2.
Chemosphere ; 236: 124292, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31310968

RESUMO

This study aimed to explore candidates of microbial groups which is associated with quorum sensing in activated sludge. Activated sludge samples were collected from three wastewater treatment plants (WWTP) to analyze N-acyl homoserine lactone (AHL) by Fourier-transform mass spectrometry (FTMS) and 16S rRNA-based microbial community. Among activated sludge samples taken at 3 WWTPs in different seasons, 2 AHL species of N-3-hydroxyoctanoyl-l-homoserine lactone and N-3-hydroxydecanoyl-l-homoserine lactone were detected in the range of ranged of 0.1 ng/L to 1.6 ng/L. The detected AHL species were not dependent on treatment systems nor seasons. From microbial community analysis, population abundance of one strain in Verrucomicrobia and two strains in Holophagaceae had high correlation with AHL concentration in activated sludge. Comamonadaceae had also moderately correlated population with AHL concentrations among quorum sensing bacteria reported previously.


Assuntos
Acil-Butirolactonas/análise , Comamonadaceae/metabolismo , Percepção de Quorum/fisiologia , Esgotos/microbiologia , Verrucomicrobia/metabolismo , Comamonadaceae/classificação , Comamonadaceae/genética , RNA Ribossômico 16S/genética , Espectroscopia de Infravermelho com Transformada de Fourier , Verrucomicrobia/classificação , Verrucomicrobia/genética
3.
Sci Total Environ ; 675: 141-150, 2019 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-31026638

RESUMO

Urban road dust can potentially have adverse effects on aquatic and benthic ecosystems if discharged into receiving waters; however, little is known about the mode of action of road dust toxicity within aquatic organisms. With an aim to reveal the biological effects of road dust on benthic crustacean species, we performed a de novo transcriptome analysis of the estuarine amphipod Grandidierella japonica exposed to road dust collected from highways around Tokyo. A transcriptome analysis by Illumina HiSeq 2500 identified differentially expressed genes related to the gamma-aminobutyric acid (GABA) signaling pathway, oxidative damage, and cuticle metabolism. Among these, a GABAB receptor subunit showed down-regulation in the road dust treatment, but a constant expression in the treatment of road dust with a carbonaceous resin XAD-4, which can reduce the acute toxicity of road dust to G. japonica. These results and the time course expressions of the related genes were partially confirmed by quantitative PCR (qPCR) experiments. Although the linkage between acute lethal toxicity and the molecular initiating events induced by road dust was still unclear, our findings provide lines of evidence to identify the causative toxicants in urban road dust.


Assuntos
Anfípodes/fisiologia , Poeira , Poluentes Ambientais/toxicidade , Anfípodes/efeitos dos fármacos , Animais , Monitoramento Ambiental , Perfilação da Expressão Gênica , Tóquio
4.
Environ Sci Technol ; 52(21): 12428-12435, 2018 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-30265799

RESUMO

Interpretation of environmental DNA (eDNA) is a major problem hindering the application of this emerging technology for environmental monitoring. The decay characteristics and bioabundance estimation of different DNA fragment lengths are largely unknown, especially for eDNA captured from surface sediments. An estuarine amphipod, Grandidierella japonica, was used as the target species in this study. We conducted a lab-scale experiment using DNA extraction to clarify the effect of bacteria on eDNA decay. We also conducted a microcosm experiment using amphipods to clarify interpretations of information regarding eDNA decay and bioabundance estimation by using two fragments with different lengths (126 and 358 bp). It was found that the bacteria concentration accelerated eDNA decay, and long fragments were more susceptible to bacteria, thus decaying faster, than short fragments in the exponential decay period. The fresh eDNA (collected within 24 h of removing the amphipods) was more indicative of bioabundance than old eDNA (collected 240-480 h after removing amphipods), and short fragments better reflected bioabundance than long fragments. Finally, we compared the half-life of eDNA in surface sediment with that in a water sample and found that the temporal scales of surface sediment and water are similar (days to weeks). Our results suggest that surface sediment also has the potential to monitor the environment at a temporal scale similar to water.


Assuntos
DNA , Monitoramento Ambiental , Água Doce , Água
5.
Environ Toxicol Chem ; 36(12): 3443-3449, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28755484

RESUMO

An acute sediment toxicity test using the ostracod Heterocypris incongruens is user friendly and has high sensitivity; however, a life-cycle test using this species has not been developed. The most challenging problem when developing a life-cycle test is that the egg development time varies greatly and is sometimes too long (> 150 d) to monitor. It is desirable to shorten the duration of life-cycle toxicity tests including the observation period of egg development while preserving the ecological relevance of the net reproductive rate (R0 ), an endpoint in the life-cycle test. Therefore, in the present study, we suggest a practical test duration for R0 using population growth rate (λ) as a measure of ecological relevance. We collected a range of life history characteristics of the ostracod by combining data from the literature and experimental results, constructed population matrix models, and calculated λ for 20 life history patterns. The results showed that a longer test period (> 150 d) did not increase the correlation coefficients between R0 and λ. Rather, a shorter test duration resulted in R0 being highly correlated with λ. Our results suggest that a life-cycle toxicity test using the ostracod can provide an ecologically relevant toxicity endpoint, even if the test is abandoned after approximately 50 d and unhatched eggs remain. Environ Toxicol Chem 2017;36:3443-3449. © 2017 SETAC.


Assuntos
Crustáceos/efeitos dos fármacos , Testes de Toxicidade/métodos , Poluentes Químicos da Água/toxicidade , Animais , Crustáceos/fisiologia , Estágios do Ciclo de Vida/efeitos dos fármacos , Reprodução/efeitos dos fármacos
6.
Ecotoxicol Environ Saf ; 143: 266-274, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28551584

RESUMO

This study reports on the development and application of a chronic sediment toxicity test using the benthic ostracod Heterocypris incongruens. H. incongruens reproduction parameters such as egg production, first day of brooding, egg-laying ratio, and hatching ratio were examined in this study. The test was first validated by determining the repeatability of the test method under seven control performances. The results showed good test repeatability of most endpoints, with coefficient of variation (CV) results below 15%. However, lifetime egg production, hatching ratio, and the reproductive rate were highly variable, with CVs ranging from 29.5% to 51.9%. Next, an application example of the proposed chronic method was performed using a series of urban road dust (URD) samples diluted with a reference sediment and compared to a 6 d H. incongruens toxicity test. The results of the proposed chronic test showed a statistically significant difference in the first day of brooding at 6.25% URD which did not exhibit significant mortality and growth inhibition in 6 d toxicity test.


Assuntos
Crustáceos/efeitos dos fármacos , Poeira/análise , Poluentes Ambientais/toxicidade , Sedimentos Geológicos/química , Testes de Toxicidade Crônica/métodos , Urbanização , Animais , Poluentes Ambientais/análise , Reprodução/efeitos dos fármacos , Estações do Ano , Tailândia
7.
Ecotoxicol Environ Saf ; 140: 206-213, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28260686

RESUMO

Biomarkers of exposure can be used to identify specific contaminants that are adversely affecting aquatic organisms. However, it remains prohibitively costly to investigate multiple novel biomarkers of exposure in a non-model species, despite the development of next-generation sequencing technology. In this study, we focused on the use of cDNA-amplified fragment length polymorphism (AFLP) as a cost-effective biomarker discovery tool to test whether it could identify biomarkers of exposure in the non-model amphipod species Grandidierella japonica. Loci were identified that were differentially expressed in amphipods exposed to reference chemicals (Cu, Zn, and nicotine) and to an environmental sample (road dust) at sublethal concentrations. Eight loci were shown to respond consistently to nicotine at different concentrations, but not to Cu or Zn. Some of the loci also responded to an environmental road dust sample containing nicotine. These findings suggest that loci identified using cDNA-AFLP could be used as biomarkers of nicotine exposure in environmental samples with complex matrices. Further studies with other organisms and toxicants are needed, but we have demonstrated that the use of cDNA-AFLP to identify biomarkers for ecotoxicological studies of non-model species is at least feasible.


Assuntos
Anfípodes/genética , DNA Complementar/genética , Polimorfismo Genético/genética , Anfípodes/efeitos dos fármacos , Análise do Polimorfismo de Comprimento de Fragmentos Amplificados/métodos , Animais , Biomarcadores/metabolismo , Cobre/toxicidade , Poeira , Exposição Ambiental/efeitos adversos , Loci Gênicos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Nicotina/toxicidade , RNA Mensageiro/genética , Transportes , Zinco/toxicidade
8.
Chemosphere ; 168: 1365-1374, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27919536

RESUMO

Urban road dust can potentially have adverse effects on ecosystems if it is discharged into receiving waters. This study investigated the causes of highway road dust toxicity by performing sediment toxicity identification evaluation (TIE) tests with an estuarine amphipod, Grandidierella japonica. In addition to metals and polycyclic aromatic hydrocarbons, which are traditionally considered to be the major toxicants in road runoff, we focused on dissolved nicotine as a causative toxicant. The sediment TIE results suggested that organic contaminants contributed to the majority of toxicity, and that the contribution of unionized nicotine to the toxicity was the highest among the chemicals considered. However, additional mortality tests with 48-h pulsed nicotine exposure demonstrated that exposure to nicotine at the same concentration as the baseline level in TIE tests did not cause significant 10-day amphipod mortality. Thus, the road dust toxicity could not be explained only by unionized nicotine, thereby suggesting contributions from joint effects of the measured toxicants and the presence of other unmeasured factors.


Assuntos
Anfípodes/efeitos dos fármacos , Poeira , Poluentes Ambientais/toxicidade , Animais , Poeira/análise , Monitoramento Ambiental , Metais/toxicidade , Nicotina/toxicidade , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Testes de Toxicidade
9.
Water Res ; 96: 52-61, 2016 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-27019465

RESUMO

The control of membrane fouling is still the biggest challenge that membrane bioreactor (MBR) for wastewater treatment faces with. In this report, we evince that an in-situ electrochemical free chlorine generation is effective for membrane fouling mitigation. An electrochemical oxidation (EO) apparatus with perforated Ti/IrO2 anodes and Ti/Pt cathodes was integrated into a conventional MBR with microfiltration module (EO-MBR). The membrane fouling characteristics of EO-MBR fed with synthetic wastewater were monitored for about 2 months in comparison to control MBRs. In the EO-MBR at a direct current density of 0.4 mA/cm(2), the frequency of membrane fouling when the trans-membrane pressure (TMP) reached 30 kPa was effectively reduced by 40% under a physical membrane cleaning regime. The evolution patterns of TMP together with hydraulic resistance analysis based on resistance-in-series model indicated that the electrochemically generated active chlorine alleviated the physically irremovable membrane fouling. Further analysis on extracellular polymeric substances (EPS) of sludge cake layer (SCL) revealed significant reductions of protein contents in soluble EPS and fluorescence emission intensities from humic acids and other fluorophores in bound EPS, which in-turn would decrease the hydrophobic accumulation of organic foulants on membrane pores. The chlorine dosage from the EO apparatus was estimated to be 4.7 mg Cl2/g MLVSS/day and the overall physicochemical properties (bio-solids concentration, floc diameter, zeta-potential) as well as the microbial activity in terms of specific oxygen utilization rate and removal efficiency of dissolved organic carbon (>97%) were not affected significantly. A T-RFLP (terminal restriction fragment length polymorphism) analysis suggested noticeable shifts in microbial community both in mixed liquor and sludge cake layer. Consequently, our electrochemical chlorination would be an efficient fouling control strategy in membrane-based water treatment processes where additional electricity consumption and cathodic scale deposition are not of serious concerns.


Assuntos
Cloro , Membranas Artificiais , Reatores Biológicos , Esgotos , Águas Residuárias/química
10.
Water Res ; 69: 120-130, 2015 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-25463933

RESUMO

Seawater-driven forward osmosis (FO) is considered to be a novel strategy to concentrate nutrients in treated municipal wastewater for further recovery as well as simultaneous discharge of highly purified wastewater into the sea with low cost. As a preliminary test, the performance of FO membranes in concentrating nutrients was investigated by both batch experiments and model simulation approaches. With synthetic seawater as the draw solution, the dissolved organic carbon, phosphate, and ammonia in the effluent from a membrane bioreactor (MBR) treating municipal wastewater were 2.3-fold, 2.3-fold, and 2.1-fold, respectively, concentrated by the FO process with approximately 57% of water reduction. Most of the dissolved components, including trace metals in the MBR effluent, were highly retained (>80%) in the feed side, indicating high water quality of permeate to be discharged. The effect of membrane properties on the nutrient enrichment performance was investigated by comparing three types of FO membranes. Interestingly, a polyamide membrane possessing a high negative charge demonstrated a poor capability of retaining ammonia, which was hypothesized because of an ion exchange-like mechanism across the membrane prompted by the high ionic concentration of the draw solution. A feed solution pH of 7 was demonstrated to be an optimum condition for improving the overall retention of nutrients, especially for ammonia because of the pH-dependent speciation of ammonia/ammonium forms. The modeling results showed that higher than 10-fold concentrations of ammonia and phosphate are achievable by seawater-driven FO with a draw solution to feed solution volume ratio of 2:1. The enriched municipal wastewater contains nitrogen and phosphorous concentrations comparable with typical animal wastewater and anaerobic digestion effluent, which are used for direct nutrient recovery.


Assuntos
Membranas Artificiais , Nitrogênio/isolamento & purificação , Osmose , Fósforo/isolamento & purificação , Água do Mar/química , Águas Residuárias/química , Purificação da Água/métodos , Técnicas de Cultura Celular por Lotes , Estudos de Viabilidade , Concentração de Íons de Hidrogênio , Modelos Teóricos , Permeabilidade , Soluções , Eletricidade Estática , Água/química
11.
Appl Microbiol Biotechnol ; 98(21): 9107-18, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25016344

RESUMO

Inclined plate membrane bioreactors (ip-MBRs) have been proposed as a highly effective method in wastewater treatment. With the help of settling enhancer inclined plates, dense excess sludge can be kept in the mainstream of the process, and consequently, suitable sludge mass can be maintained in the membrane tank. In this study, the relationship among sludge retention time (SRT), bacterial communities, and hydrolytic enzyme activities was investigated. Two identical bench-scale ip-MBRs were operated 1 year in real municipal wastewater treatment. Multidimensional scaling (MDS) plots of terminal restriction fragment length polymorphism (T-RFLP) fingerprints showed similar changes in the bacterial communities in terms of bacterial members and abundance over time in both the reactors, which was primarily caused by the changes of wastewater composition. However, the impact of SRT revealed significant differences in the dominant bacterial communities when both the reactors were operated with a largely different SRT (infinite SRT and SRT of 20 days). The sequences of bacterial 16S rRNA gene were classified into six libraries of A-F. The largest group of sequences belonged to the phylum Proteobacteria. The phylum Bacteroidetes was dominant in the seed sludge retrieved from the conventional activated sludge (CAS) as Flavobacterium-like bacterium was dominantly observed. Under the MBR operation (libraries B-F), bacterial communities belonging to the phyla Proteobacteria and Chloroflexi were dominant. Most of them may be responsible for protein degradation because aminopeptidase activity increased in proportion with the abundance of these bacteria.


Assuntos
Bactérias/classificação , Reatores Biológicos/microbiologia , Biota , Esgotos/microbiologia , Bactérias/enzimologia , Bactérias/genética , Análise por Conglomerados , Impressões Digitais de DNA , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dados de Sequência Molecular , Filogenia , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Águas Residuárias , Purificação da Água
12.
FEMS Microbiol Lett ; 342(1): 70-5, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23441921

RESUMO

The goal of this study was to develop and validate a novel fosmid-clone-based metagenome isotope array approach - termed the community isotope array (CIArray) - for sensitive detection and identification of microorganisms assimilating a radiolabeled substrate within complex microbial communities. More specifically, a sample-specific CIArray was used to identify anoxic phenol-degrading microorganisms in activated sludge treating synthetic coke-oven wastewater in a single-sludge predenitrification-nitrification process. Hybridization of the CIArray with DNA from the (14) C-phenol-amended sample indicated that bacteria assimilating (14) C-atoms, presumably directly from phenol, under nitrate-reducing conditions were abundant in the reactor, and taxonomic assignment of the fosmid clone end sequences suggested that they belonged to the Gammaproteobacteria. The specificity of the CIArray was validated by quantification of fosmid-clone-specific DNA in density-resolved DNA fractions from samples incubated with (13) C-phenol, which verified that all CIArray-positive probes stemmed from microorganisms that assimilated isotopically labeled carbon. This also demonstrated that the CIArray was more sensitive than DNA-SIP, as the former enabled positive detection at a phenol concentration that failed to yield a 'heavy' DNA fraction. Finally, two operational taxonomic units distantly related to marine Gammaproteobacteria were identified to account for more than half of 16S rRNA gene clones in the 'heavy' DNA library, corroborating the CIArray-based identification.


Assuntos
Gammaproteobacteria/classificação , Gammaproteobacteria/genética , Isótopos/metabolismo , Metagenômica/métodos , Consórcios Microbianos , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Fenol/metabolismo , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Esgotos/microbiologia , Coloração e Rotulagem/métodos , Águas Residuárias/microbiologia
13.
FEMS Microbiol Lett ; 328(1): 86-9, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22188467

RESUMO

The use of randomly generated DNA fragment sequences as probes on DNA arrays offers a unique potential for exploring unsequenced microorganisms. In this study, the detection specificity was evaluated with respect to probe-target sequence similarity using genomic DNAs of four Pseudomonas strains. Genome fragments averaging 2000 bp were found to be specific enough to discriminate 85-90% similarity under highly stringent hybridization conditions. Such stringent conditions compromised signal intensities; however, specific signals remained detectable at the highest stringency (at 75 °C hybridization) with negligible false negatives. These results suggest that, without any probe design or selection, genomic fragments can provide a reasonable specificity for microbial diagnostics or species delineation by DNA-DNA similarities.


Assuntos
Análise em Microsséries/métodos , Hibridização de Ácido Nucleico/métodos , Pseudomonas/genética , DNA Bacteriano/genética , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Sondas de Oligonucleotídeos/genética , Sensibilidade e Especificidade
14.
Appl Environ Microbiol ; 77(20): 7430-2, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21873478

RESUMO

The shotgun isotope array method has been proposed to be an effective new tool for use in substrate-specific microbe exploration without any prior knowledge of the community composition. Proof of concept was demonstrated by detection of acetate-degrading microorganisms in activated sludge and further verified by independent stable isotope probing (SIP).


Assuntos
Bactérias/classificação , Bactérias/isolamento & purificação , Técnicas Bacteriológicas/métodos , Isótopos/metabolismo , Coloração e Rotulagem/métodos , Bactérias/genética , Bactérias/metabolismo , DNA Bacteriano/química , DNA Bacteriano/genética , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dados de Sequência Molecular , Plasmodium/genética , Plasmodium/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Esgotos/microbiologia
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