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1.
Sci Total Environ ; 688: 1348-1358, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31726564

RESUMO

Proliferating cyanobacterial blooms due eutrophication in reservoirs is a major global problem. The production of cyanotoxins often increases with grazing pressure and temperature while the sensitivity of zooplankton to cyanotoxins is directly related to temperature. Here we evaluate the effect of different concentrations of the crude extract of cyanobacteria from Valle de Bravo reservoir during dry (January) and rainy (September) seasons at 20 and 25 °C on the rotifer Brachionus calyciflorus based on acute and chronic toxicity tests. We filtered 20 or 150 l of lake water, depending on the intensity of the bloom, and estimated the density and diversity of the cyanobacteria. The crude extracts, after 5 cycles of freezing, thawing and sonication at 14 MHz, were filtered and the microcystin concentration quantified based on ELISA. The extracts were used to conduct the acute and chronic toxicity tests, all in quadruplicate. Acute toxicity tests were based on 24 h mortality. Chronic toxicity tests (population growth and life table experiments) were conducted at 5 and 10% of the median lethal concentration. The field samples were dominated by Microcystis sp. (January) or Woronichinia naegeliana (September). The microcystin concentration in lake water was 9.57 µg/l and 0.097 µg/l and the median lethal concentration was 5.34 µg microcystin/L and 0.35 µg microcystin/L in January and September, respectively. Survival and reproduction of B. calyciflorus were lower in the presence of the cyanobacteria crude extract, more so at 20° than at 25 °C. Our results highlight the urgency of regular monitoring based on zooplankton assays for reservoirs in tropical and temperate regions, subject to frequent and dominant cyanobacterial blooms, often as a result of climate change.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Monitoramento Ambiental , Proliferação Nociva de Algas , Microcistinas/toxicidade , Rotíferos/fisiologia , Animais , Eutrofização , México , Testes de Toxicidade Crônica
2.
Environ Monit Assess ; 191(11): 688, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31664528

RESUMO

Understanding the relative impact sizes of environmental factors and nutrients on the high annual variation of phytoplankton abundance in eutrophic rivers is important for aquatic ecosystem management efforts. In this study, we used phytoplankton dynamic datasets in the eutrophic Fenhe River to show the variations and drivers of phytoplankton abundance under complex, fluctuating environmental conditions during 2012-2017. The temporal and spatial variations of nutrients in the river depicted that the total phosphorus (TP) concentration was higher in the wet season and in downstream. There were increases in total nitrogen (TN) concentration in the normal season and in upstream. The structural equation model (SEM) showed that the phytoplankton abundance increased during the wet season despite the decrease in the TN:TP ratio and was reduced upstream due to the highest TN:TP ratio. Among the environmental variables, water temperature (WT) was an important predictor and positively correlated temporally and spatially to phytoplankton. The interaction of nutrients with the phytoplankton community at different temperature levels indicated that different phytoplankton groups have different nutrient requirements. We can conclude that enhances in temperature and TP concentration will significantly increase phytoplankton abundance and dominance of cyanobacteria and green algae in the future, whereas there was insignificant effect on diatoms. These data indicated that temperature and TP content were the important abiotic factors influencing the phytoplankton growth of the water body, which could provide a reference for the evaluation of environmental alterations in the future.


Assuntos
Monitoramento Ambiental , Fitoplâncton/crescimento & desenvolvimento , Temperatura Ambiente , Poluentes da Água/análise , China , Clorófitas , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Ecossistema , Eutrofização , Nitrogênio/análise , Nutrientes , Fósforo/análise , Rios/química , Estações do Ano
3.
Sci Total Environ ; 694: 133721, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31400686

RESUMO

The use of short-term, fast-acting curative treatments to rapidly suppress the proliferation of upcoming cyanobacterial blooms without negative side effects on overall water quality is important for environmental regulatory agencies. A 15-day in situ mesocosm experiment was conducted to evaluate the effects of algal harvest at different intensities and the effect of hydrogen peroxide on the mitigation of cyanobacterial blooms, subsequent algal growth and phytoplankton community structure. The results indicate that filtration through a 30-µm-pore-size net could remove most of the Microcystis colonies, leading to a decline in algal biomass. However, algal harvest at 30% and 60% intensities tended to promote cyanobacterial growth under nutrient-replete conditions, and the mitigation effect only lasted a few days, since cyanobacteria biomass exhibited no significant difference between the control and those two treatments on Day 6. When the algal harvest intensity was 90%, the cyanobacterial biomass remained at a relatively low level for 15 days. The average Microcystis colony size rapidly returned to the initial level after an initial decline across all the algal harvest intensities, indicating that algal harvest should be repeatedly performed within a short time period to mitigate Microcystis blooms. Furthermore, removing Microcystis colonies by filtration led to increased diversity in the phytoplankton community, as the proportion of non-Microcystis cyanobacteria increased with harvest intensity. This result might pose a challenge for cyanobacterial bloom control over the long term if filamentous cyanobacteria become dominant. The 10.0 mg L-1 H2O2 treatment selectively suppressed cyanobacteria throughout the experimental period, leading to succession from a cyanobacteria-dominated to a Chlorophyta-dominated community after Day 9. Overall, using hydrogen peroxide is more effective than algal harvesting as a one-time quick curative measure.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Recuperação e Remediação Ambiental/métodos , Proliferação Nociva de Algas , Peróxido de Hidrogênio , Monitoramento Ambiental , Microalgas , Microcistinas , Microcystis , Fitoplâncton/crescimento & desenvolvimento
4.
Sci Total Environ ; 696: 133909, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31454606

RESUMO

Cyanobacteria blooms are increasing globally, with further increases predicted in association with climate change. Recently, some cyanobacteria species have been identified as a source of estrogenic effects in aquatic animals. To explore possible estrogenic effects of Microcystis aeruginosa (an often-dominant cyanobacteria species) on zooplankton, we examined effects of cyanobacteria exudates (MaE, 2 × 104 and 4 × 105 cells/ml) on reproduction in Daphnia magna. We analyzed physiological, biochemical and molecular characteristics of exposed Daphnia via both chronic and acute exposures. MaE at both low and high cell density enhanced egg number (15.4% and 23.3%, respectively) and reproduction (37.7% and 52.4%, respectively) in D. magna similar to 10 µg/L estradiol exposure. In addition, both MaE of low and high cell densities increased population growth rate (15.8% and 19.6%, respectively) and reproductive potential (60% and 83%, respectively) of D. magna. These exudates promoted D. magna reproduction by stimulating 17ß-hydroxysteroid-dehydrogenase (17ß-HSD) activity and production of ecdysone and juvenile hormone, and by enhancing vitellogenin biosynthesis via up-regulating expression of Vtg1 and Vtg2. However, increased expression (6.6 times higher than controls) of a detoxification gene (CYP360A8) indicated that MaE might also induce toxicity in D. magna. Reproductive interference of zooplankton by blooming cyanobacteria might negatively affect foodwebs because MaE-induced zooplankton population increase would enhance grazing and reduce abundance of edible algae, thereby adding to the list of known disruptive properties of cyanobacterial blooms.


Assuntos
Cladóceros/fisiologia , Cianobactérias/crescimento & desenvolvimento , Congêneres do Estradiol , Eutrofização , Animais , Cianobactérias/metabolismo , Daphnia , Estradiol , Estrogênios , Microcystis , Reprodução , Poluentes Químicos da Água/toxicidade , Zooplâncton
5.
Artigo em Inglês | MEDLINE | ID: mdl-31159184

RESUMO

To study the microbial community structure in sediments and its relation to eutrophication environment factors, the sediments and the overlying water of Sancha Lake were collected in the four seasons. MiSeq high-throughput sequencing was conducted for the V3-V4 hypervariable regions of the 16S rRNA gene and was used to analyze the microbial community structure in sediments. Pearson correlation and redundancy analysis (RDA) were conducted to determine the relation between microbial populations and eutrophic factors. The results demonstrated four main patterns: (1) in the 36 samples that were collected, the classification annotation suggested 64 phyla, 259 classes, 476 orders, 759 families, and 9325 OTUs; (2) The diversity indices were ordered according to their values as with summer > winter > autumn > spring; (3) The microbial populations in the four seasons belonged to two distinct characteristic groups; (4) pH, dissolved oxygen (DO), total phosphorus (TP), and total nitrogen (TN) had significant effects on the community composition and structure, which further affected the dissolved total phosphorus (DTP) significantly. The present study demonstrates that the microbial communities in Sancha Lake sediments are highly diverse, their compositions and distributions are significantly different between spring and non-spring, and Actinobacteria and Cyanobacteria may be the key populations or indicator organisms for eutrophication.


Assuntos
Eutrofização/fisiologia , Sedimentos Geológicos/química , Lagos/microbiologia , Microbiota , Actinobacteria/crescimento & desenvolvimento , China , Cianobactérias/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Nitrogênio/análise , Oxigênio/análise , Fósforo/análise , RNA Ribossômico 16S , Estações do Ano
6.
Biochim Biophys Acta Bioenerg ; 1860(7): 549-561, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31173730

RESUMO

Phycoerythrin (PE) present in the distal ends of light-harvesting phycobilisome rods in Fremyella diplosiphon (Tolypothrix sp. PCC 7601) contains five phycoerythrobilin (PEB) chromophores attached to six cysteine residues for efficient green light capture for photosynthesis. Chromophore ligation on PE subunits occurs through bilin lyase catalyzed reactions, but the characterization of the roles of all bilin lyases for phycoerythrin is not yet complete. To gain a more complete understanding about the individual functions of CpeZ and CpeY in PE biogenesis in cyanobacteria, we examined PE and phycobilisomes purified from wild type F. diplosiphon, cpeZ and cpeY knockout mutants. We find that the cpeZ and cpeY mutants accumulate less PE than wild type cells. We show that in the cpeZ mutant, chromophorylation of both PE subunits is affected, especially the Cys-80 and Cys-48/Cys-59 sites of CpeB, the beta-subunit of PE. The cpeY mutant showed reduced chromophorylation at Cys-82 of CpeA. We also show that, in vitro, CpeZ stabilizes PE subunits and assists in refolding of CpeB after denaturation. Taken together, we conclude that CpeZ acts as a chaperone-like protein, assisting in the folding/stability of PE subunits, allowing bilin lyases such as CpeY and CpeS to attach PEB to their PE subunit.


Assuntos
Proteínas de Bactérias/metabolismo , Cianobactérias/metabolismo , Chaperonas Moleculares/metabolismo , Ficoeritrina/biossíntese , Proteínas Recombinantes/metabolismo , Proteínas de Bactérias/genética , Cianobactérias/genética , Cianobactérias/crescimento & desenvolvimento , Mutação , Proteínas Recombinantes/genética
7.
Chemosphere ; 229: 18-21, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31063876

RESUMO

Fungal parasites of the phylum Chytridiomycota (chytrids) are increasingly recognized as potent control agents of phytoplankton, including toxic bloom-forming cyanobacteria. We experimentally tested whether agricultural fungicides can interfere with natural epidemics caused by parasitic chytrid fungi and thereby favor cyanobacterial bloom formation. Specifically, we exposed the toxic bloom-forming cyanobacterium Planktothrix and its chytrid parasite Rhizophydium megarrhizum to different concentrations of the widely used agricultural fungicides tebuconazole and azoxystrobin, as well as the medical fungicide itraconazole (the latter was included to test its potential to suppress infection in vitro). Environmentally relevant concentrations of tebuconazole (20-200 µg/L) and azoxystrobin (1-30 µg/L) significantly decreased infection prevalence over a timespan of seven days, while not affecting the growth of uninfected cyanobacteria. Itraconazole suppressed infection completely. Our findings demonstrate that agricultural fungicide run-off has the potential to inhibit natural chytrid epidemics and, thereby, to promote the proliferation of toxic cyanobacteria.


Assuntos
Cianobactérias/patogenicidade , Fungicidas Industriais/efeitos adversos , Parasitos/crescimento & desenvolvimento , Animais , Proliferação de Células , Cianobactérias/crescimento & desenvolvimento , Epidemias , Fungicidas Industriais/farmacologia
8.
Mar Drugs ; 17(5)2019 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-31083362

RESUMO

Obesity is a complex disease resulting in several metabolic co-morbidities and is increasing at epidemic rates. The marine environment is an interesting resource of novel compounds and in particular cyanobacteria are well known for their capacity to produce novel secondary metabolites. In this work, we explored the potential of cyanobacteria for the production of compounds with relevant activities towards metabolic diseases using a blend of target-based, phenotypic and zebrafish assays as whole small animal models. A total of 46 cyanobacterial strains were grown and biomass fractionated, yielding in total 263 fractions. Bioactivities related to metabolic function were tested in different in vitro and in vivo models. Studying adipogenic and thermogenic gene expression in brown adipocytes, lipid metabolism and glucose uptake in hepatocytes, as well as lipid metabolism in zebrafish larvae, we identified 66 (25%) active fractions. This together with metabolite profiling and the evaluation of toxicity allowed the identification of 18 (7%) fractions with promising bioactivity towards different aspects of metabolic disease. Among those, we identified several known compounds, such as eryloside T, leptosin F, pheophorbide A, phaeophytin A, chlorophyll A, present as minor peaks. Those compounds were previously not described to have bioactivities in metabolic regulation, and both known or unknown compounds could be responsible for such effects. In summary, we find that cyanobacteria hold a huge repertoire of molecules with specific bioactivities towards metabolic diseases, which needs to be explored in the future.


Assuntos
Fármacos Antiobesidade/farmacologia , Cianobactérias/química , Obesidade/tratamento farmacológico , Adipócitos Marrons/efeitos dos fármacos , Adipócitos Marrons/fisiologia , Animais , Fármacos Antiobesidade/química , Fármacos Antiobesidade/toxicidade , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Expressão Gênica/efeitos dos fármacos , Glucose/metabolismo , Células Hep G2 , Humanos , Metabolismo dos Lipídeos/efeitos dos fármacos , Obesidade/metabolismo , PPAR gama/metabolismo , Testes de Toxicidade , Proteína Desacopladora 1/metabolismo , Peixe-Zebra
9.
Environ Sci Pollut Res Int ; 26(19): 19575-19587, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31079295

RESUMO

Long-term cyanobacterial blooms and hypereutrophic state have been typical for the shallow, urban Swarzedzkie Lake for many years. Diversion of sewage did not change its trophic status, so restoration began in autumn 2011 using the sustainable approach based on three methods. The aim of the study was to analyse how sustainable restoration affects zooplankton. We hypothesised that bottom-up and top-down methods reconstructed zooplankton composition. Thus, the abundance of large-size cladocerans increased and controlled phytoplankton effectively. The elimination of cyanobacteria bloom, the decrease of rotifer abundance and the twofold increase of filter-feeder effectiveness were observed in summer 2012. However, high phosphorus concentration, lack of regular cyprinid removal and insufficient fish stocking together with high temperature prevented zooplankton from controlling cyanobacteria bloom in summer 2013. Rotifer domination with high trophy species was noted, as before restoration. The number of rotifers decreased in 2014, while crustaceans increased due to the significant decrease of nutrient concentrations and an intensification of biomanipulation treatments. Therefore, summer phytoplankton growth was low, without cyanobacteria dominance. The rebuilding of zooplankton in Swarzedzkie Lake was observed during sustainable restoration. However, the treatments should be intensified when adverse changes were observed to obtain better results for the improvement of water quality.


Assuntos
Recuperação e Remediação Ambiental/métodos , Eutrofização , Lagos/química , Modelos Teóricos , Qualidade da Água , Zooplâncton/crescimento & desenvolvimento , Animais , Cianobactérias/crescimento & desenvolvimento , Peixes , Fósforo/análise , Fitoplâncton/crescimento & desenvolvimento , Polônia , Estações do Ano
10.
Environ Monit Assess ; 191(6): 382, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-31111231

RESUMO

At present, there are few studies on the quantitative analysis of connectivity from the perspective of biocenology. This study aimed to develop a new quantitative assessment method for river connectivity based on the analysis of the effect of river connectivity on the phytoplankton community in the Shaying River, which has multiple gates. The results showed that from the view of the phytoplankton density and biomass, cryptophytes were the dominant phytoplankton group, but the cyanobacteria density was highest in the summer. In the top 10 of degrees of dominance, there were 4 species of cyanobacteria, 3 species of cryptophytes, 2 species of diatoms, and 1 species of chlorophytes. Based on the seasonal compositions and variations of the phytoplankton community, the river barriers had a great effect on the community. The community composition of the Shaying River has been transformed from a river-type community dominated by diatoms to a lake-type community dominated by cyanophytes. PCA (principal component analysis) indicated that there were obvious differences in the community structure among the sections partitioned by various river gates. According to the relative positions of the entire phytoplankton community and the relative sequence of the river gates, a potential gradient representing the river connectivity can be found; thus, the river connectivity can be quantitatively described from the perspective of the phytoplankton community, and hereby, the corresponding quantitative methods can be established. Characterizing the connectivity of rivers based on biota will facilitate assessing the effects of multiple barriers and understanding river connectivity, and provide the support for the effective management of rivers.


Assuntos
Conservação dos Recursos Hídricos/métodos , Monitoramento Ambiental/métodos , Fitoplâncton/crescimento & desenvolvimento , Rios/química , Movimentos da Água , Biomassa , Biota , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Lagos/química , Análise de Componente Principal , Estações do Ano
11.
Environ Sci Pollut Res Int ; 26(21): 21151-21160, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31119540

RESUMO

Recent studies have expanded the interests about microbial community and function following the rapid development of high-throughput sequencing techniques in the freshwater ecosystem. In this study, we aimed to attain a deep understanding of microbial community structure and potential nitrogen metabolism in Hulun Lake, a shallow hypereutrophic steppe lake in the Mongolian Plateau in China. The result demonstrated that cyanobacteria were the most dominant phylum. Network analysis showed both intra- and inter-phylum co-occurrence were pervasive, and there were modular structures in the microbial assemblages. The cluster dominated by proteobacteria was mainly negatively connected to the cluster dominated by both proteobacteria and actinobacteria. Cyanobacteria were tightly clustered together and positively connected to these two clusters. The major nitrogen metabolism pathways were glutamine synthetase-glutamate synthase and assimilatory nitrate reduction, indicating the nitrogen was mainly retained in the lake by microbial uptake. Cyanobacteria contributed 43.25% gene reads involved in the overall nitrogen metabolism but mainly contributed to assimilatory nitrate reduction and nitrogen fixation, aggravating the lake eutrophication. This study adds to our knowledge of microbial assemblages and nitrogen metabolism in the shallow hypereutrophic lake and provided an insight understanding for the purposes of lake ecosystem's protection and efficient management in the Mongolian Plateau.


Assuntos
Lagos/microbiologia , Nitrogênio/metabolismo , Actinobacteria , China , Cianobactérias/crescimento & desenvolvimento , Ecossistema , Monitoramento Ambiental , Eutrofização , Lagos/química , Proteobactérias
12.
Biomolecules ; 9(5)2019 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-31117324

RESUMO

The production of poly-ß-hydroxybutyrate (PHB) under varying environmental conditions (pH, temperature and carbon sources) was examined in the cyanobacterium Scytonema geitleri Bharadwaja isolated from the roof-top of a building. The S. geitleri produced PHB and the production of PHB was linear with the growth of cyanobacterium. The maximum PHB production (7.12% of dry cell weight) was recorded when the cells of S. geitleri were at their stationary growth phase. The production of PHB was optimum at pH 8.5 and 30 °C, and acetate (30 mM) was the preferred carbon source.


Assuntos
Cianobactérias/metabolismo , Hidroxibutiratos/metabolismo , Poliésteres/metabolismo , Acetatos/metabolismo , Carbono/metabolismo , Cianobactérias/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Microbiologia Industrial/métodos
13.
Sci Total Environ ; 666: 994-1002, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-30970505

RESUMO

To study the mechanisms of chromium (Cr) mobilization in sediments of lakes with different ecotypes, seasonal sampling was performed in the macrophyte-dominated East Taihu (MDET) and cyanobacteria-dominated Meiliang Bay (CDMB) in Lake Taihu. Concentrations of labile Cr(VI) and dissolved Cr were assessed using diffusive gradients in thin films (DGT) and high-resolution dialysis passive sampling devices, respectively. Results indicated that in pore water the dissolved Cr concentrations and in sediments total Cr and Cr fractions concentrations (dissolved, exchangeable and carbonate fraction (F1), Fe-Mn oxide fraction (F2), organic/sulfide fraction (F3)) were lower in MDET than in CDMB. However, the highly toxic DGT-labile Cr(VI) concentrations were higher in MDET sediments than in CDMB sediments. In the two lake zones, the seasonal variations in concentrations of dissolved Cr and DGT-labile Cr(VI) were significant, while total Cr and Cr fractions showed negligible changes (except F1 fraction). In summer, the high mobility of dissolved Cr (MDET: 103.42±10.82µg/L; CDMB: 108.99±4.24µg/L) were mainly caused by dissolved organic matter complexing with Cr(III). In winter the high mobility of dissolved Cr (MDET: 100.27±22.04µg/L; CDMB: 102.01±8.81µg/L) and DGT-labile Cr(VI) (MDET: 28.26±3.73µg/L; CDLZ: 25.82±2.26µg/L) were primarily caused by the oxidization of Cr (III) by Mn(III/IV) oxides. This study establishes the mechanisms for seasonal variation of Cr mobilization in different lake ecological zones, highlighting the urgent need for remediation of Cr pollution, especially in macrophyte-dominated lake zones.


Assuntos
Cromo/análise , Monitoramento Ambiental , Sedimentos Geológicos/análise , Lagos/química , Poluentes Químicos da Água/análise , Organismos Aquáticos/crescimento & desenvolvimento , China , Cianobactérias/crescimento & desenvolvimento , Plantas , Estações do Ano
14.
Sci Total Environ ; 670: 613-622, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-30909039

RESUMO

Extreme natural events such as typhoons can amplify the effect of hydrodynamics on the lake ecosystems. Here we presented data on the effect of typhoons on algal cell size based on field observation. Then turbulence simulation systems were used to decipher the response of natural phytoplankton communities to a range of turbulence regimes (linked to typhoon-induced turbulence intensity) under laboratory conditions. Turbulence intensities of 6.17 × 10-3, 1.10 × 10-2 and 1.80 × 10-2 m2/s3 benefited algal growth and triggered abrupt switches from unicellular Chlorella dominated to colonial Microcystis dominance, and the abundance of colonial algae depended on the turbulence intensity. Under the influence of elevated turbulence, Microcystis dominated biomass increased by 2.60-6.58 times compared with that of Chlorella. At a given phytoplankton density and community composition, we observed a significant increase in extracellular microcystins (MCs) and a 47.5-fold increase in intracellular MCs with intensified turbulent mixing, suggesting that the damage of algal cells concomitantly the stimulation of toxin-producing Microcystis. Our results confirmed that the formation of large colonial algal cells, enhancement of the succession of algal species, and most importantly, the induction of toxin-producing Microcystis, were the active adaption strategy when phytoplankton were impacted by strong turbulence. The result implies that the ongoing climates changes and typhoon events are likely to contribute to undesirable outcomes concerning phytoplankton populations.


Assuntos
Mudança Climática , Cianobactérias/crescimento & desenvolvimento , Proliferação Nociva de Algas , Microbiologia da Água , Ecossistema , Monitoramento Ambiental , Lagos , Microcystis , Fitoplâncton , Movimentos da Água
15.
Environ Sci Pollut Res Int ; 26(15): 14977-14987, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30919182

RESUMO

In freshwater aquaculture ponds, application of algicidal Bacillus is a promising way in the control of cyanobacterial blooms. To best understand Bacillus algicidal characters and mechanisms in the field, different-sized colonial cyanobacteria were isolated from an aquaculture pond, and the effects of B. subtilis on their growth, colony maintenance, and colony-attached bacterial community composition were investigated. The results showed that B. subtilis could inhibit the growth of colonial cyanobacteria. Bigger-sized colonies isolated from the field could spontaneously disintegrate into smaller-sized colonies in the laboratory. Algicidal B. subtilis could accelerate the disintegration of colonies and decrease colony size. B. subtilis not only decreased the colony-attached bacterial community diversity but also changed its composition. B. subtilis increased the relative abundances of some attached bacterial genera, including Pseudomonas, Shewanella, Bacillus, Shinella, Rhizobium, and Ensifer. These bacteria with algicidal, microcystin-degrading, and flocculating activities might be an important contributor to algicidal effects of B. subtilis on colonial cyanobacteria.


Assuntos
Bacillus subtilis/crescimento & desenvolvimento , Cianobactérias/crescimento & desenvolvimento , Tanques/microbiologia , Aquicultura , Bacillus subtilis/fisiologia , Água Doce/microbiologia , Microcistinas/metabolismo , Pseudomonas/crescimento & desenvolvimento , Shewanella/crescimento & desenvolvimento
16.
Sci Total Environ ; 670: 837-848, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-30921717

RESUMO

With increased global warming, cyanobacteria are blooming more frequently in lakes and reservoirs, severely damaging the health and stability of aquatic ecosystems and threatening drinking water safety and human health. There is an urgent demand for the effective prediction and prevention of cyanobacterial blooms. However, it is difficult to effectively reduce the risks and loss caused by cyanobacterial blooms because most methods are unable to successfully predict cyanobacteria blooms. Therefore, in this study, we proposed a new cyanobacterial bloom occurrence prediction method to analyze the probability and driving factors of the blooms for effective prevention and control. Dominant cyanobacterial species with bloom capabilities were initially determined using a dominant species identification model, and the principal driving factors of the dominant species were then analyzed using canonical correspondence analysis (CCA). Cyanobacterial bloom probability was calculated using a newly-developed model, after which, the probable mutation points were identified and thresholds for the principal driving factors of cyanobacterial blooms were predicted. A total of 141 phytoplankton data sets from 90 stations were collected from six large-scale hydrology, water-quality ecology, integrated field surveys in Jinan City, China in 2014-2015 and used for model application and verification. The results showed that there were six dominant cyanobacterial species in the study area, and that the principal driving factors were water temperature, pH, total phosphorus, ammonia nitrogen, chemical oxygen demand, and dissolved oxygen. The cyanobacterial blooms corresponded to a threshold water temperature range, pH, total phosphorus (TP), ammonium nitrogen level, chemical oxygen demand, and dissolved oxygen levels of 19.5-32.5 °C, 7.0-9.38, 0.13-0.22 mg L-1, 0.38-0.63 mg L-1, 10.5-17.5 mg L-1, and 4.97-8.28 mg L-1, respectively. Comparison with research results from other global regions further supported the use of these thresholds, indicating that this method could be used in habitats beyond China. We found that the probability of cyanobacterial bloom was 0.75, a critical point for prevention and control. When this critical point was exceeded, cyanobacteria could proliferate rapidly, increasing the risk of cyanobacterial blooms. Changes in driving factors need to be rapidly controlled, based on these thresholds, to prevent cyanobacterial blooms. Temporal and spatial scales were critical factors potentially affecting the selection of driving factors. This method is versatile and can help determine the risk of cyanobacterial blooms and the thresholds of the principal driving factors. It can effectively predict and help prevent cyanobacterial blooms to reduce the global probability of occurrence, protect the health and stability of water ecosystems, ensure drinking water safety, and protect human health.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Monitoramento Ambiental , Eutrofização , Microbiologia da Água , Lagos/microbiologia
17.
Ecotoxicol Environ Saf ; 175: 236-242, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30903879

RESUMO

Cyanobacteria can produce potent natural toxins known as cyanotoxins. Blooms of cyanobacteria, produced mainly as result of the pollution of water bodies with excessive amounts of phosphorus, represent a severe environmental problem; not only do they affect the normal equilibrium of the aquatic ecosystem but may also affect animal and human health. The occurrence of algal blooms have been increasing globally (it has been recently reported in at least 100 countries) and it has been considered by WHO as an emerging public health issue. The toxic effects of cyanotoxins have been thoroughly demonstrated in laboratory experiments, however, the effects on humans and the extent of these effects have been more difficult to assess. Epidemiological research is difficult as there are no specific symptoms or routine biomarkers to diagnose intoxication with cyanotoxins, in particular those cases associated with chronic exposure. The objectives of this study were to assess the exposure of a population settled near a lake with recurrent cyanobacteria blooms and to investigate the presence of biological markers of chronic exposure to cyanotoxins, in particular the microcystins (MCs). We first investigated the exposure of the population to cyanobacteria by using a questionnaire on how the population used the water and by analyzing water samples for the presence of cyanobacteria and total microcystins (TMCs). Secondly, we investigated the presence of biological indicators by analyzing the biochemical and immunological parameters in sera of the exposed population. The questionnaires and the water analyses revealed that the population under study (n = 47) is exposed to several exposure routes. The biochemical analyses of the sera showed the alteration of at least one hepatic enzyme in 25% of the exposed people, but this cannot be associated solely to MCs exposure. On the contrary, the immunological analyses, which included microcystin-LR specific antibodies IgE and IgG, showed significant differences between the exposed and non-exposed groups. The presence of MCs specific antibodies confirms the exposure to MCs. We propose the study of specific antibodies as a non-complex biomarker to detect chronic exposure to the toxin and to assist epidemiological studies.


Assuntos
Cianobactérias , Biomarcadores Ambientais/efeitos dos fármacos , Exposição Ambiental/análise , Imunoglobulina E/sangue , Imunoglobulina G/sangue , Microcistinas/toxicidade , Poluentes Químicos da Água/toxicidade , Argentina , Cianobactérias/crescimento & desenvolvimento , Ecossistema , Eutrofização , Humanos , Lagos/química , Inquéritos e Questionários
18.
BMC Genomics ; 20(1): 207, 2019 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-30866821

RESUMO

BACKGROUND: Halomicronema hongdechloris was the first cyanobacterium to be identified that produces chlorophyll (Chl) f. It contains Chl a and uses phycobiliproteins as its major light-harvesting components under white light conditions. However, under far-red light conditions H. hongdechloris produces Chl f and red-shifted phycobiliprotein complexes to absorb and use far-red light. In this study, we report the genomic sequence of H. hongdechloris and use quantitative proteomic approaches to confirm the deduced metabolic pathways as well as metabolic and photosynthetic changes in response to different photo-autotrophic conditions. RESULTS: The whole genome of H. hongdechloris was sequenced using three different technologies and assembled into a single circular scaffold with a genome size of 5,577,845 bp. The assembled genome has 54.6% GC content and encodes 5273 proteins covering 83.5% of the DNA sequence. Using Tandem Mass Tag labelling, the total proteome of H. hongdechloris grown under different light conditions was analyzed. A total of 1816 proteins were identified, with photosynthetic proteins accounting for 24% of the total mass spectral readings, of which 35% are phycobiliproteins. The proteomic data showed that essential cellular metabolic reactions remain unchanged under shifted light conditions. The largest differences in protein content between white and far-red light conditions reflect the changes to photosynthetic complexes, shifting from a standard phycobilisome and Chl a-based light harvesting system under white light, to modified, red-shifted phycobilisomes and Chl f-containing photosystems under far-red light conditions. CONCLUSION: We demonstrate that essential cellular metabolic reactions under different light conditions remain constant, including most of the enzymes in chlorophyll biosynthesis and photosynthetic carbon fixation. The changed light conditions cause significant changes in the make-up of photosynthetic protein complexes to improve photosynthetic light capture and reaction efficiencies. The integration of the global proteome with the genome sequence highlights that cyanobacterial adaptation strategies are focused on optimizing light capture and utilization, with minimal changes in other metabolic pathways. Our quantitative proteomic approach has enabled a deeper understanding of both the stability and the flexibility of cellular metabolic networks of H. hongdechloris in response to changes in its environment.


Assuntos
Proteínas de Bactérias/metabolismo , Cianobactérias/crescimento & desenvolvimento , Proteômica/métodos , Sequenciamento Completo do Genoma/métodos , Adaptação Fisiológica , Proteínas de Bactérias/genética , Ciclo do Carbono , Clorofila/análogos & derivados , Clorofila/metabolismo , Cianobactérias/genética , Cianobactérias/metabolismo , Evolução Molecular , Tamanho do Genoma , Luz , Anotação de Sequência Molecular , Fotossíntese , Ficobiliproteínas/genética , Ficobiliproteínas/metabolismo , Filogenia , Espectrometria de Massas em Tandem
19.
Ecotoxicol Environ Saf ; 174: 584-591, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30870659

RESUMO

Single and multispecies algal bioassays were assessed using copper toxicity with three green algae (Scenedesmus subspicatus, Scenedesmus quadricauda and Ankistrodesmus angustus) and one blue-green algae species (Oscillatoria prolifera). Single and multispecies toxicity tests were conducted based on cell density as per standard toxicity testing, and on equivalent surface area. A higher copper sulfate toxicity was registered for O. prolifera, followed by S. subspicatus, S. quadricauda, and A. angustus in single-species toxicity tests based on cell density. Single species toxicity tests based on surface area showed increased copper toxicity with increasing algal surface area except for A. angustus. In multispecies control bioassays, the growth of A. angustus was inhibited in the presence of other species in surface area-based tests. As compared to single species bioassays, O. prolifera, and S. quadricauda showed a decreased sensitivity to copper sulfate in both cell density and surface area based multispecies tests. However, for the algae species with the smallest surface area, S. subspicatus, 96h-EC50 value decreased in multispecies bioassays based on surface area as compared to the single species test, while it increased in multispecies bioassays based on cell density. The difference in S. subspicatus sensitivity to copper between tests based on cell density and surface area supports the need to adopt multispecies toxicity testing based on surface area to avoid the confounding effect on copper toxicity of increased biomass for metal binding. 96h-EC50 values for all species combined in the multispecies test based on cell density and on surface area were significantly different from 96h-EC50 values obtained in single species bioassays. These results demonstrate that single-species bioassays may over- or underestimate metal toxicity in natural waters.


Assuntos
Clorófitas/efeitos dos fármacos , Sulfato de Cobre/toxicidade , Herbicidas/toxicidade , Bioensaio , Contagem de Células , Clorófitas/citologia , Clorófitas/crescimento & desenvolvimento , Cianobactérias/citologia , Cianobactérias/efeitos dos fármacos , Cianobactérias/crescimento & desenvolvimento , Scenedesmus/citologia , Scenedesmus/efeitos dos fármacos , Scenedesmus/crescimento & desenvolvimento , Testes de Toxicidade
20.
Sci Total Environ ; 660: 1355-1366, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30743930

RESUMO

Many lakes worldwide, especially shallow, experience great changes due to eutrophication, manifested in severe, usually toxic water blooms, disqualifying them from recreation. In order to improve water quality, restoration programs are implemented, including numerous methods. Intense nutrient cycling resulting from detrimental role of sediments impede obtaining of clear water state. One of the restoration methods proposed in recent years was Effective Microorganisms (EM), i.e. the set of microorganisms aiming at the inhibition of harmful bacteria through competitive exclusion. This approach was introduced in shallow Konin Lake (Western Poland), suffering from severe cyanobacterial water blooms. Prior to the treatment, protective action was conducted i.e. the elimination of external nutrient loads with backwater from the river. Changes in water chemistry, phytoplankton structure and macrophytes distribution were noted during the 5-year studies (2011-2015), covering the treatment (2013-2015) as well as two previous years. Oscillatoriacean cyanobacteria were most abundant in (2011-2012), while Nostocales in summer 2014-2015, as a result of decreased phosphorus but increased nitrogen concentrations. Slight increase in Cladoceran zooplankton was observed, but none in submerged macrophytes due to low water transparency. EM application initiated positive changes in the ecosystem by means of excessive organic matter decomposition and increased diversity of phytoplankton, nevertheless cyanobacteria blooms were still present due to high nutrient content.


Assuntos
Recuperação e Remediação Ambiental , Fitoplâncton/fisiologia , Microbiologia da Água , Qualidade da Água , Cianobactérias/crescimento & desenvolvimento , Ecossistema , Monitoramento Ambiental , Eutrofização , Hordeum , Lagos/química , Fósforo/análise , Polônia , Dinâmica Populacional
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