Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 26
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Chemosphere ; 232: 9-17, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31152908

RESUMO

Amorphous molybdenum sulphide materials are attracting more attention in heterogeneous catalysis, gas adsorption and water remediation fields. Herein, a new type of amorphous molybdenum sulphide composite (poly(diallyldimethylammonium-MoS4), shorten as PDADMA-MoS4) was synthesized via a facile precipitation reaction. Metal adsorption tests of prepared PDADMA-MoS4 composite shows that Hg2+ and Pb2+ concentrations in solution can decrease from 10 ppm to <0.5 ppb level much lower than the drinking water requirement (<2 ppb) in 10 min. The metal adsorption isotherms suggest that maximum metal-uptake capacities are 1460.0 mg/g for Hg (pH = 5) and 433.7 mg/g for Hg (pH = 1), indicating that this sorbent works over a wide pH range (1.0-7.0) to effectively remove Hg from aqueous solution. More importantly, at very low pH = 1, this sorbent material exhibits extraordinarily high selectivity of Hg over Pb and Cu (separation factors ßHg/Cu=4.5×104 and ßHg/Pb=3.6×104). The excellent Hg capacity and selectivity at low pH region (pH < 2) has shed light on the new generation of adsorbent materials for acidic wastewater treatment.


Assuntos
Dissulfetos/química , Mercúrio/análise , Molibdênio/química , Eliminação de Resíduos Líquidos , Águas Residuárias/química , Adsorção , Concentração de Íons de Hidrogênio , Metais
2.
ISME J ; 13(9): 2196-2208, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31053831

RESUMO

Although it is widely recognized that cyanobacterial blooms have substantial influence on the plankton community in general, their correlations with the whole community of eukaryotic plankton at longer time scales remain largely unknown. Here, we investigated the temporal dynamics of eukaryotic plankton communities in two subtropical reservoirs over a 6-year period (2010-2015) following one cyanobacterial biomass cycle-the cyanobacterial bloom (middle 2010), cyanobacteria decrease (late 2010-early 2011), non-bloom (2011-2014), cyanobacteria increase, and second bloom (late 2014-2015). The eukaryotic community succession that strongly correlated with this cyanobacterial biomass cycle was divided into four periods, and each period had distinct characteristics in cyanobacterial biomass and environments in both reservoirs. Integrated co-occurrence networks of eukaryotic plankton based on the whole study period revealed that the cyanobacterial biomass had remarkably high network centralities, and the eukaryotic OTUs that had stronger correlations with the cyanobacterial biomass exhibited higher centralities. The integrated networks were also modularly responded to different eukaryotic succession periods, and therefore correlated with the cyanobacterial biomass cycle. Moreover, sub-networks based on the different eukaryotic succession periods indicated that the eukaryotic co-occurrence patterns were not constant but varied largely associating with the cyanobacterial biomass. Based on these long-term observations, our results reveal that the cyanobacterial biomass cycle created distinct niches between persistent bloom, non-bloom, decrease and increase of cyanobacteria, and therefore associated with distinct eukaryotic plankton patterns. Our results have important implications for understanding how complex aquatic plankton communities respond to cyanobacterial blooms under the changing environments.

3.
Environ Sci Pollut Res Int ; 26(16): 16449-16456, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30980377

RESUMO

The composition of SrCuxO mixed metal oxides (MMOs) was engineered via varying the amount of copper relative to strontium. As-synthesized SrCuxO were highly active for degrading methyl orange (MO) pollutant at dark ambient conditions without the aid of other reagents. The catalytic activity of SrCuxO demonstrated a reverse-volcano relationship with copper content. Copper-rich MMOs (SrCu2O) exhibited the highest degradation activity for MO by far and degraded ca. 96% MO within 25 min. MO degradation over SrCu2O was a surface-catalytic reaction and fitted pseudo-first-order reaction kinetics. The contact between MO molecules and catalyst surface initiated the reaction via the catalytic-active phase (Cu+/Cu2+ redox pair), which serves as an electron-transfer shuttle ([Formula: see text]) from MO to dissolved O2, inducing the consecutive generation of reactive oxygen species, which resulted in MO degradation as evidenced by radical trapping experiment. XPS and XRD analysis revealed that active phases in SrCu2O materials underwent irreversible transformation after reaction, contributing to the observed deactivation in the cycling experiment. The observations in this study demonstrate the significance of chemical composition tailoring in catalyst synthesis for environmental remediation under dark ambient conditions. Graphical abstract.


Assuntos
Compostos Azo/química , Cobre/química , Óxidos/química , Estrôncio/química , Catálise , Poluentes Ambientais/química , Recuperação e Remediação Ambiental , Cinética , Oxirredução , Espectroscopia Fotoeletrônica , Difração de Raios X
4.
Sci Total Environ ; 673: 533-540, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-30995587

RESUMO

Although seasonality is a key driver of environmental fluctuation in aquatic ecosystems, there exists limited knowledge on the factors controlling the distribution of antibiotic resistance genes (ARGs) across seasons at a watershed scale. Here we used high-throughput quantitative PCR to quantify 285 ARGs conferring resistance to most major classes of antibiotics, reveal their spatial and seasonal distribution patterns, and depict the underlying mechanisms in a subtropical riverine ecosystem under low and high human pressures, in Xiamen city, southeast China. Our results showed that spatial differences in ARG richness and abundance overwhelmed their seasonal variations, with only ARGs that confer resistance to sulfonamide and vancomycin being significantly different across seasons. Only a few abundant ARGs (19 ARGs) could contribute to >70% of the total ARGs abundance and were found in all seasons. The significantly higher number of ARGs in the summer rainy period than other seasons coincided with high number of significant edges in ARG co-occurrence networks. Summer rainfall had strong dilution effect on ARGs in upstream waters and enrichment effect in downstream waters. The variance partitioning analysis indicated that the environment explained larger variance of ARG profiles than mobile genetic elements (MGEs), spatial predictors and the rainfall. Nevertheless, strong and significant correlations between transposase gene absolute abundance and aminoglycoside, chloramphenicol, MLS, multidrug and tetracycline classes of resistance genes inferred the role of MGEs on ARG distribution. Overall, our results imply that the modelling and management of ARGs in highly dynamic ecosystems could be better implemented by considering priority genes that dominate at spatial and seasonal gradients.


Assuntos
Resistência Microbiana a Medicamentos/genética , Monitoramento Ambiental , Genes Bacterianos , Microbiologia da Água , China , Ecossistema , Rios , Estações do Ano , Poluição da Água/análise , Poluição da Água/estatística & dados numéricos
5.
Sci Total Environ ; 660: 501-511, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30640117

RESUMO

The composition of microbial communities can vary at the microspatial scale between free-living (FL) and particle-attached (PA) niches. However, it remains unclear how FL and PA bacterial communities respond to cyanobacterial blooms across water depths. Here, we examined the community dynamics of the FL (0.2-3 µm) and PA (>3 µm) bacterioplankton based on 16S rRNA gene high-throughput sequencing in a subtropical stratified reservoir under Microcystis aeruginosa bloom and non-bloom conditions. Both FL and PA bacterioplankton communities showed different responses in alpha- and beta-diversities to the bloom, suggesting the idea that the responses of bacterial community could depend on lifestyle. Specifically, abundant PA subcommunities showed a greater variation between bloom and non-bloom groups than abundant FL ones. In contrast, rare FL subcommunities exhibited a stronger response to water depth than rare PA ones. Furthermore, the rare taxa exhibited a preference for PA status, shaped and stimulated by the M. aeruginosa bloom. Our analyses also showed that PA bacterial communities were generally more diverse and appeared to be more responsive to routinely measured environmental variables than FL bacteria. Microcystis blooms had a facilitative influence on specific bacteria by mediating the transitions from free-living to particle-attached lifestyles. Altogether, these findings highlight the importance of bacterial lifestyle and abundance in understanding the dynamics of microbial community in cyanobacterial bloom aquatic ecosystem.


Assuntos
Eutrofização , Lagos/microbiologia , Microbiota/fisiologia , Microcystis/fisiologia , China , Sequenciamento de Nucleotídeos em Larga Escala , Microbiota/genética , Microcystis/genética , Dinâmica Populacional , RNA Bacteriano/análise , RNA Ribossômico 16S/análise
6.
Water Res ; 146: 177-186, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30243060

RESUMO

Free-living amoebae are widespread in freshwater ecosystems. Although many studies have investigated changes in their communities across space, the temporal variability and the drivers of community changes across different habitat types are poorly understood. A total of 108 surface water samples were collected on a seasonal basis from four reservoirs and two rivers in Xiamen city, subtropical China. We used high throughput sequencing and qPCR methods to explore the occurrence and abundance of free-living amoebae. In total, 335 amoeba OTUs were detected, and only 32 OTUs were shared by reservoir and river habitats. The reservoirs and rivers harbored unique amoebae communities and exhibited distinct seasonal patterns in community composition. High abundance of the 18S rRNA gene of Acanthamoeba was observed in spring and summer, whereas the abundance was low in autumn and winter. In addition, the abundance of Hartmannella was significantly higher when isolated from reservoirs in summer/autumn and from river in spring/summer. Moreover, the temporal patterns of amoebae communities were significantly associated with water temperature, indicating that temperature is an important variable controlling the ecological dynamics of amoebae populations. However, our comparative analysis indicated that both environmental selection, and neutral processes, significantly contributed to amoeba community assembly. The genera detected here include pathogenic species and species that can act as vectors for microbial pathogens, which can cause human infections.

7.
ISME J ; 12(9): 2263-2277, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29899512

RESUMO

Plankton communities normally consist of few abundant and many rare species, yet little is known about the ecological role of rare planktonic eukaryotes. Here we used a 18S ribosomal DNA sequencing approach to investigate the dynamics of rare planktonic eukaryotes, and to explore the co-occurrence patterns of abundant and rare eukaryotic plankton in a subtropical reservoir following a cyanobacterial bloom event. Our results showed that the bloom event significantly altered the eukaryotic plankton community composition and rare plankton diversity without affecting the diversity of abundant plankton. The similarities of both abundant and rare eukaryotic plankton subcommunities significantly declined with the increase in time-lag, but stronger temporal turnover was observed in rare taxa. Further, species turnover of both subcommunities explained a higher percentage of the community variation than species richness. Both deterministic and stochastic processes significantly influenced eukaryotic plankton community assembly, and the stochastic pattern (e.g., ecological drift) was particularly pronounced for rare taxa. Co-occurrence network analysis revealed that keystone taxa mainly belonged to rare species, which may play fundamental roles in network persistence. Importantly, covariations between rare and non-rare taxa were predominantly positive, implying multispecies cooperation might contribute to the stability and resilience of the microbial community. Overall, these findings expand current understanding of the ecological mechanisms and microbial interactions underlying plankton dynamics in changing aquatic ecosystems.

8.
Environ Int ; 117: 107-115, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29734061

RESUMO

In freshwater systems, both antibiotic resistance genes (ARGs) and cyanobacterial blooms attract global public health concern. Cyanobacterial blooms can greatly impact bacterial taxonomic communities, but very little is known about the influence of the blooms on antibiotic resistance functional community. In this study, the ARGs in both free-living (FL) and particle-attached (PA) bacteria under bloom and non-bloom conditions were simultaneously investigated in a subtropical reservoir using high-throughput approaches. In total, 145 ARGs and 9 mobile genetic elements (MGEs) were detected. The most diverse and dominant of which (68.93%) were multidrug resistance genes and efflux pump mechanism. The richness of ARGs in both FL and PA bacteria was significantly lower during the bloom period compared with non-bloom period. The abundance of ARGs in FL bacteria was significantly lower under bloom condition than in the non-bloom period, but the abundance of ARGs in PA bacteria stayed constant. More importantly, the resistant functional community in PA bacteria was more strongly influenced by the cyanobacterial bloom than in the FL bacteria, although >96% ARGs were shared in both FL and PA bacteria or both bloom and non-bloom periods. We also compared the community compositions between taxonomy and function, and found antibiotic resistant communities were highly variable and exhibited lower similarity between bloom and non-bloom periods than seen in the taxonomic composition, with an exception of FL bacteria. Altogether, cyanobacterial blooms appear to have stronger inhibitory effect on ARG abundance in FL bacteria, and stronger influence on antibiotic resistant community composition in PA bacteria. Our results further suggested that both neutral and selective processes interactively affected the ARG composition dynamics of the FL and PA bacteria. However, the antibiotic resistant community of FL bacteria exhibited a higher level of temporal stochasticity following the bloom event than PA bacteria. Therefore, we emphasized the bacterial lifestyles as an important mechanism, giving rise to different responses of antibiotic resistant community to the cyanobacterial bloom.

9.
J Food Drug Anal ; 26(2): 649-656, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29567234

RESUMO

Rice husk extract, obtained using acid and alkali pretreatment extraction (AAPE), contains bioactive compounds and exhibits reducing abilities. Phenolic composition in rice husk extract was analyzed and the mechanism of silver nanoparticle (AgNP) biosynthesis by using AAPE rice husk extract was investigated in this study. Stable and spherically shaped AgNPs with a size of <15 nm were prepared under the following conditions: 0.001 M AgNO3, AAPE rice husk extract diluted 10 times, pH 10, and reacted at 25 °C for 60 min. Synergistic effects among phenolic acids contributed to the formation of AgNPs, with the acids acting as excellent reducing agents (owing to their abundant hydroxyl groups) and excellent dispersants (owing to their derived CO groups), which enhanced the NPs' stability. Caffeic acid (CA) was demonstrated to synthesize AgNPs independently and is suggested to be the most crucial compound for reducing Ag+ during the biosynthesis with rice husk extract. A possible mechanism and reaction process for the formation of AgNPs synthesized using CA in rice husk extracts is proposed.

10.
Sci Total Environ ; 630: 658-667, 2018 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-29494974

RESUMO

Although the influence of microbial community assembly processes on aquatic ecosystem function and biodiversity is well known, the processes that govern planktonic communities in human-impacted rivers remain largely unstudied. Here, we used multivariate statistics and a null model approach to test the hypothesis that environmental conditions and obstructed dispersal opportunities, dictate a deterministic community assembly for phytoplankton and bacterioplankton across contrasting hydrographic conditions in a subtropical mid-sized river (Jiulong River, southeast China). Variation partitioning analysis showed that the explanatory power of local environmental variables was larger than that of the spatial variables for both plankton communities during the dry season. During the wet season, phytoplankton community variation was mainly explained by local environmental variables, whereas the variance in bacterioplankton was explained by both environmental and spatial predictors. The null model based on Raup-Crick coefficients for both planktonic groups suggested little evidences of the stochastic processes involving dispersal and random distribution. Our results showed that hydrological change and landscape structure act together to cause divergence in communities along the river channel, thereby dictating a deterministic assembly and that selection exceeds dispersal limitation during the dry season. Therefore, to protect the ecological integrity of human-impacted rivers, watershed managers should not only consider local environmental conditions but also dispersal routes to account for the effect of regional species pool on local communities.


Assuntos
Biodiversidade , Ecossistema , Monitoramento Ambiental , Fitoplâncton/crescimento & desenvolvimento , Organismos Aquáticos , Bactérias/classificação , Bactérias/crescimento & desenvolvimento , China , Hidrologia , Fitoplâncton/classificação , Plâncton/classificação , Plâncton/crescimento & desenvolvimento , Rios , Estações do Ano , Microbiologia da Água
11.
Environ Microbiol ; 20(2): 462-476, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28881067

RESUMO

Benthic microeukaryotes are key ecosystem drivers in marine sandy beaches, an important and dynamic environment; however, little is known about their diversity and biogeography on a large spatial scale. Here, we investigated the community composition and geographical distributions of benthic microeukaryotes using high-throughput sequencing of the 18S rRNA gene and quantified the contributions of environmental factors and spatial separation on the distribution patterns of both rare and abundant taxa. We collected 36 intertidal samples at 12 sandy beaches from four regions that spanned distances from 0.001 to 12,000 km. We found 12,890 operational taxonomic units (OTUs; 97% sequence identity level) including members of all eukaryotic super-groups and several phyla of uncertain position. Arthropoda and Diatomeae dominated the sequence reads in abundance, but Ciliophora and Discoba were the most diverse groups across all samples. About one-third of the OTUs could not be definitively classified at a similarity level of 80%, supporting the view that a large number of rare and minute marine species may have escaped previous characterization. We found generally similar geographical patterns for abundant and rare microeukaryotic sub-communities, and both showed a significant distance-decay similarity trend. Variation partitioning showed that both rare and abundant sub-communities exhibited a slightly stronger response to environmental factors than spatial (distance) factors. However, the abundant sub-community was strongly correlated with variations in spatial, environmental and sediment grain size factors (66% of variance explained), but the rare assemblage was not (16%). This suggests that different or more complex mechanisms generate and maintain diversity in the rare biosphere in this habitat.

12.
FEMS Microbiol Ecol ; 93(10)2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28961823

RESUMO

The degradation of freshwater quality induced by cyanobacterial blooms is a major global environmental concern. Microbially driven nitrogen removal could alleviate eutrophication to some degree in freshwater ecosystems. However, the response of anaerobic ammonium oxidizing (anammox) bacterial communities to cyanobacterial blooms remains poorly understood, especially in reservoir ecosystems. Here we compared the dynamics of anammox bacterial communities during and after a cyanobacterial bloom in a subtropical reservoir. Our data showed that a cyanobacterial bloom triggered a significant increase in bottom anammox bacterial abundance. During the bloom period, anammox bacterial abundance in bottom waters was 9-fold and 52-fold higher compared with non-bloom stratification and mixing periods, respectively. The community composition of anammox bacteria in surface waters changed substantially accompanied by the disappearance of the cyanobacterial bloom, and a shift of dominance from unidentified anammox genera to Ca. Brocadia was observed. Although Ca. Brocadia was always predominant in both middle and bottom waters, the non-bloom period had more unique taxa than the bloom period. Cyanobacterial bloom-related changes in environmental conditions (e.g. NH4-N and total organic carbon) and water stratification together influenced the distribution and dynamics of anammox bacteria. Altogether, our study lays the basis for a better understanding of the breakdown of cyanobacterial blooms in a stratified reservoir.


Assuntos
Cianobactérias/metabolismo , Eutrofização/fisiologia , Água Doce/análise , Qualidade da Água , Compostos de Amônio/análise , Anaerobiose/fisiologia , Cianobactérias/classificação , Cianobactérias/crescimento & desenvolvimento , Ecossistema , Água Doce/microbiologia , Nitratos/análise , Nitritos/análise , Oxirredução
13.
Water Res ; 120: 52-63, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28478295

RESUMO

Many countries in the world still suffer from high toxic cyanobacterial blooms in inland waters used for human consumption. Regional climate change and human activities within watersheds exert a complex and diverse influence on aquatic ecosystem structure and function across space and time. However, the degree to which these factors may contribute to the long-term dynamics of plankton communities is still not well understood. Here, we explore the impacts of multiple disturbance events (e.g. human-resettlement, temperature change, rainfall, water level fluctuations), including six combined disturbances, on phytoplankton and cyanobacteria in two subtropical reservoirs over six years. Our data showed that combined environmental disturbances triggered two apparent and abrupt switches between cyanobacteria-dominated state and non-cyanobacterial taxa-dominated state. In late 2010, the combined effect of human-resettlement (emigration) and natural disturbances (e.g. cooling, rainfall, water level fluctuations) lead to a 60-90% decrease in cyanobacteria biomass accompanied by the disappearance of cyanobacterial blooms, in tandem with an abrupt and persistent shift in phytoplankton community. After summer 2014, however, combined weather and hydrological disturbances (e.g. warming, rainfall, water level fluctuations) occurred leading to an abrupt and marked increase of cyanobacteria biomass, associated with a return to cyanobacteria dominance. These changes in phytoplankton community were strongly related to the nutrient concentrations and water level fluctuations, as well as water temperature and rainfall. As both extreme weather events and human disturbances are predicted to become more frequent and severe during the twenty-first century, prudent sustainable management will require consideration of the background limnologic conditions and the frequency of disturbance events when assessing the potential impacts on reservoir biodiversity and ecosystem functioning and services.


Assuntos
Mudança Climática , Eutrofização , Fitoplâncton , Biomassa , Cianobactérias , Água Doce , Humanos
14.
Front Plant Sci ; 8: 771, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28553304

RESUMO

Kenaf (Hibiscus cannabinus L.), an environmental friendly and economic fiber crop, has a certain tolerance to abiotic stresses. Identification of reliable reference genes for transcript normalization of stress responsive genes expression by quantitative real-time PCR (qRT-PCR) is important for exploring the molecular mechanisms of plants response to abiotic stresses. In this study, nine candidate reference genes were cloned, and their expression stabilities were assessed in 132 abiotic stress and hormonal stimuli samples of kenaf using geNorm, NormFinder, and BestKeeper algorithms. Results revealed that HcPP2A (Protein phosphatase 2A) and HcACT7 (Actin 7) were the optimum reference genes across all samples; HcUBC (Ubiquitin-conjugating enzyme like protein) was the worst reference gene for transcript normalization. The reliability of the selected reference genes was further confirmed by evaluating the expression profile of HcWRKY28 gene at different stress durations. This work will benefit future studies on discovery of stress-tolerance genes and stress-signaling pathways in this important fiber crop.

15.
Mol Ecol Resour ; 17(5): 991-1002, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28063202

RESUMO

Microeukaryotic plankton (0.2-200 µm) are critical components of aquatic ecosystems and key players in global ecological processes. High-throughput sequencing is currently revolutionizing their study on an unprecedented scale. However, it is currently unclear whether we can accurately, effectively and quantitatively depict the microeukaryotic plankton communities using traditional size-fractionated filtering combined with molecular methods. To address this, we analysed the eukaryotic plankton communities both with, and without, prefiltering with a 200 µm pore-size sieve -by using SSU rDNA-based high-throughput sequencing on 16 samples with three replicates in each sample from two subtropical reservoirs sampled from January to October in 2013. We found that ~25% reads were classified as metazoan in both size groups. The species richness, alpha and beta diversity of plankton community and relative abundance of reads in 99.2% eukaryotic OTUs showed no significant changes after prefiltering with a 200 µm pore-size sieve. We further found that both >0.2 µm and 0.2-200 µm eukaryotic plankton communities, especially the abundant plankton subcommunities, exhibited very similar, and synchronous, spatiotemporal patterns and processes associated with almost identical environmental drivers. The lack of an effect on community structure from prefiltering suggests that environmental DNA from larger metazoa is introduced into the smaller size class. Therefore, size-fractionated filtering with 200 µm is insufficient to discriminate between the eukaryotic plankton size groups in metabarcoding approaches. Our results also highlight the importance of sequencing depth, and strict quality filtering of reads, when designing studies to characterize microeukaryotic plankton communities.


Assuntos
Código de Barras de DNA Taxonômico/métodos , Eucariotos/classificação , Eucariotos/genética , Filtração/métodos , Metagenômica/métodos , Plâncton/classificação , Plâncton/genética , Análise por Conglomerados , DNA Ribossômico/química , DNA Ribossômico/genética , Filogenia , RNA Ribossômico 18S/genética , Análise de Sequência de DNA
16.
Arch Virol ; 162(5): 1335-1339, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28050737

RESUMO

Bamboo mosaic virus (BaMV) is a well-characterized virus and a model of virus-host interaction in plants. Here, we identified naturally occurring BaMV isolates from Fujian Province, China and furthermore describe a naturally occurring BaMV coinfection in bamboo (Bambusa xiashanensis) plants. Two different types of BaMV were identified, represented by isolates BaMV-XSNZHA7 (X7) and BaMV-XSNZHA10 (X10). The phylogenetic relationships between X7- and X10-like isolates and published BaMV isolates were determined based on genomic RNA and amino acid sequences. Three clusters were identified, indicating that BaMV is highly diverse. The in planta viral replication kinetics were determined for X7 and X10 in single infections and in an X7/X10 coinfection. The peak viral load during coinfection was significantly greater than that during single infection with either virus and contained a slightly higher proportion of X10 virus than X7, suggesting that X10-like viruses may have a fitness advantage when compared to X7-like viruses.


Assuntos
Bambusa/virologia , Doenças das Plantas/virologia , Potexvirus/classificação , Potexvirus/genética , RNA Viral/genética , Sequência de Aminoácidos/genética , Sequência de Bases , China , Coinfecção/virologia , Interações Hospedeiro-Patógeno , Filogenia , Potexvirus/isolamento & purificação , Análise de Sequência de RNA , Carga Viral
17.
Arch Virol ; 162(2): 505-510, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27743256

RESUMO

We characterised the virus-derived small interfering RNAs (vsiRNA) of bamboo mosaic virus (Ba-vsiRNAs) and its associated satellite RNA (satRNA)-derived siRNAs (satsiRNAs) in a bamboo plant (Dendrocalamus latiflorus) by deep sequencing. Ba-vsiRNAs and satsiRNAs of 21-22 nt in length, with both (+) and (-) polarity, predominated. The 5'-terminal base of Ba-vsiRNA was biased towards A, whereas a bias towards C/U was observed in sense satsiRNAs, and towards A in antisense satsiRNAs. A large set of bamboo genes were identified as potential targets of Ba-vsiRNAs and satsiRNAs, revealing RNA silencing-based virus-host interactions in plants. Moreover, we isolated and characterised new isolates of bamboo mosaic virus (BaMV; 6,350 nt) and BaMV-associated satRNA (satBaMV; 834 nt), designated BaMV-MAZSL1 and satBaMV-MAZSL1, respectively.


Assuntos
Bambusa/virologia , Genes de Plantas , Potexvirus/genética , RNA Satélite/genética , RNA Interferente Pequeno/genética , RNA Viral/genética , Sequenciamento de Nucleotídeos em Larga Escala , Interações Hospedeiro-Patógeno , Fases de Leitura Aberta , Doenças das Plantas/virologia , Potexvirus/classificação , Potexvirus/isolamento & purificação , Interferência de RNA
18.
J Food Sci ; 81(5): M1184-91, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27074534

RESUMO

We investigated the combined antimicrobial effect of nisin and chitosan hydrolysates (CHs) by regulating the antimicrobial reaction order of substances due to differential releasing rate from hydroxypropylmethylcellulose-modified bacterial cellulose (HBC). The minimum inhibitory concentration of nisin against Staphylococcus aureus and that of CHs against Escherichia coli were 6 IU and 200 µg/mL, respectively. Hurdle and additive effects in antimicrobial tests were observed when nisin was used 6 h before CH treatment against S. aureus; similar effects were observed when CH was used before nisin treatment against E. coli. Simultaneously combined treatment of nisin and CHs exhibited the low antimicrobial effect. HBC was then selected as the carrier for the controlled release of nisin and CHs. A 90% inhibition in the growth of S. aureus and E. coli was achieved when 30 IU-nisin-containing HBC and 62.5 µg/mL-CH-containing HBC were used simultaneously. The controlled release of nisin and CHs by using HBC minimized the interaction between nisin and CHs as well as increased the number of microbial targets.


Assuntos
Anti-Infecciosos/farmacologia , Celulose/química , Quitosana/farmacologia , Escherichia coli/efeitos dos fármacos , Embalagem de Alimentos/métodos , Nisina/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Microbiologia de Alimentos , Conservação de Alimentos/métodos , Humanos , Derivados da Hipromelose , Testes de Sensibilidade Microbiana , Staphylococcus aureus/crescimento & desenvolvimento
19.
Sci Total Environ ; 557-558: 445-52, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27016690

RESUMO

Globally aquatic ecosystems are likely to become more vulnerable to extreme water fluctuation rates due to the combined effects of climate change and human activity. However, relatively little is known about the importance of water level fluctuations (WLF) as a predictor of phytoplankton community shifts in subtropical reservoirs. In this study, we used one year of data (2010-2011) from four subtropical reservoirs of southeast China to quantify the effects of WLF and other environmental variables on phytoplankton and cyanobacteria dynamics. The reservoirs showed an apparent switch between a turbid state dominated by cyanobacteria and a clear state dominated by other non-cyanobacterial taxa (e.g., diatoms, green algae). Cyanobacterial dominance decreased, or increased, following marked changes in water level. Multiple regression analysis demonstrated that pH, euphotic depth, WLF, and total phosphorus provided the best model and explained 30.8% of the variance in cyanobacteria biomass. Path analysis showed that positive WLF (i.e. an increase in water level) can reduce the cyanobacteria biomass either directly by a dilution effect or indirectly by modifying the limnological conditions of the reservoirs in complex pathways. To control the risk of cyanobacterial dominance or blooms, WLF should be targeted to be above +2m/month; that is an increase in water level of 2m or more. Given that WLF is likely to be of more frequent occurrence under future predicted conditions of climate variability and human activity, water level management can be widely used in small and medium-sized reservoirs to prevent the toxic cyanobacterial blooms and to protect the ecosystem integrity or functions.

20.
Appl Microbiol Biotechnol ; 99(21): 9255-66, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26156239

RESUMO

The spatiotemporal distribution of microbial diversity, community composition, and their major drivers are fundamental issues in microbial ecology. In this study, the planktonic bacterial and microeukaryotic communities of the Jiulong River were investigated across both wet and dry seasons by using denaturing gradient gel electrophoresis (DGGE). We found evidence of temporal change between wet and dry seasons and distinct spatial patterns of bacterial and microeukaryotic communities. Both bacterial and microeukaryotic communities were strongly correlated with temperature, NH4-N, PO4-P, and chlorophyll a, and these environmental factors were significant but incomplete predictors of microbial community composition. Local environmental factors combined with spatial and temporal factors strongly controlled both bacterial and microeukaryotic communities in complex ways, whereas the direct influence of spatial and temporal factors appeared to be relatively small. Path analysis revealed that the microeukaryotic community played key roles in shaping bacterial community composition, perhaps through grazing effects and multiple interactions. Both Betaproteobacteria and Actinobacteria were the most dominant and diverse taxa in bacterial communities, while the microeukaryotic communities were dominated by Ciliophora (zooplankton) and Chlorophyta (phytoplankton). Our results demonstrated that both bacterial and microeukaryotic communities along the Jiulong River displayed a distinct spatiotemporal pattern; however, microeukaryotic communities exhibited a stronger distance-decay relationship than bacterial communities and their spatial patterns were mostly driven by local environmental variables rather than season or spatial processes of the river. Therefore, we have provided baseline data to support further research on river microbial food webs and integrating different microbial groups into river models.


Assuntos
Bactérias/classificação , Biota , Células Eucarióticas/classificação , Plâncton/crescimento & desenvolvimento , Rios/microbiologia , Amônia/análise , China , Clorofila/análise , Clorofila A , Eletroforese em Gel de Gradiente Desnaturante , Fosfatos/análise , Estações do Ano , Análise Espaço-Temporal , Temperatura Ambiente
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA