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1.
Ecotoxicol Environ Saf ; 187: 109809, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31654861

RESUMO

A theoretical non-linear combined toxicity assessment method is proposed and evaluated using Microcystis aeruginosa as the test organism. The combined toxicity of binary heavy metals was evaluated by comparing the actual inhibitory rates shown from the experiments with the theoretically calculated inhibitory rates. It was identified that the binary mixtures of Cu2++ Cd2+, Cu2++ Cr3+ and Zn2++ Cr3+ had the synergistic effects when the combined concentrations were low, but exhibited the antagonistic effects with the higher combined concentrations. Furthermore, the toxic effect of Pb2+ was not influenced by the addition of Cu2+ when combined concentration was low, but it was enhanced by Cu2+ at the high combined concentration. The binary mixtures of Zn2++ Cd2+, Pb2++ Cr3+, Pb2++ Cd2+, Pb2++ Zn2+, and Cr3++ Cd2+ always presented antagonistic effects, while the synergistic toxicity effect on M. aeruginosa was observed for the binary mixtures of Cu2++ Zn2+ regardless of combined concentration. The proposed assessment method was also validated by the antioxidant enzyme activity, which showed synergistic or antagonistic effects under different binary mixtures of heavy metals.


Assuntos
Metais Pesados/toxicidade , Microcystis/efeitos dos fármacos , Modelos Teóricos , Antioxidantes/metabolismo , Sinergismo Farmacológico , Malondialdeído/metabolismo , Metais Pesados/química , Microcystis/enzimologia , Dinâmica não Linear , Espécies Reativas de Oxigênio/metabolismo
2.
J Agric Food Chem ; 67(45): 12538-12546, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31638796

RESUMO

Cyanobacteria harmful algal blooms are of global concern, but all currently available algicides in the market are nonselective and have potential side effects on nontarget species. In the present work, two series of compounds (4 and 6) comprising 16 novel 1,2,3-triazole aminopyrimidines were rationally designed and synthesized as control agent for cyanobacteria. Our design focus was the inhibiting cyanobacteria by inhibition against pyruvate dehydrogenase complex E1 (PDHc-E1). Compounds 4 and 6 showed potent inhibition against Escherichia coli PDHc-E1 (IC50 = 4.13-23.76 µM) and also strong algicidal activities against Synechocystis sp. PCC 6803 (EC50 = 1.7-8.1 µM) and Microcystis sp. FACHB905 (EC50 = 2.1-11.8 µM). In particular, the algicidal activities of 6d against four algal species were not only higher than that of prometryn; they were also comparable to or higher than that of copper sulfate. The analogues 4c, 4d, 6d, and 6e displayed potent algicidal activities and inhibition of E. coli PDHc-E1 but exhibited negligible inhibition of porcine PDHc-E1. As revealed by molecular docking, site-directed mutagenesis, enzymatic assays, and an inhibition kinetic analysis, 4c and 6d inhibited PDHc-E1 in a competitive manner. Our results suggest that highly selective, effective algicides can be developed by rationally designing competitive PDHc-E1 inhibitors.


Assuntos
Proteínas de Bactérias/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Herbicidas/farmacologia , Microcystis/efeitos dos fármacos , Pirimidinas/farmacologia , Piruvato Desidrogenase (Lipoamida)/antagonistas & inibidores , Synechocystis/efeitos dos fármacos , Triazóis/farmacologia , Proteínas de Bactérias/química , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Herbicidas/síntese química , Herbicidas/química , Cinética , Microcystis/química , Microcystis/enzimologia , Simulação de Acoplamento Molecular , Pirimidinas/química , Piruvato Desidrogenase (Lipoamida)/química , Relação Estrutura-Atividade , Synechocystis/química , Synechocystis/enzimologia , Triazóis/química
3.
Bull Environ Contam Toxicol ; 103(6): 802-807, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31587082

RESUMO

In this work, we assessed the toxic effects of ZnO nanoparticles (NPs; 1, 10, and 50 mg L-1) and the corresponding dissoluble Zn ions (0.71, 8.66, and 35.59 mg L-1) on Microcystis aeruginosa. After chronic exposure (28 days), significantly higher growth inhibition was observed under ZnO NPs at 1 mg L-1 (47%) than under Zn ions at 0.71 mg L-1 (-15%). The opposite effect pattern was observed for ZnO NPs at 10 (71% vs. 80%) and 50 mg L-1 (73% vs. 95%) compared to Zn ions at the corresponding concentrations. After 7 days of exposure, ZnO NPs at 10 and 50 mg L-1 led to an increase of 83 and 53% in malondialdehyde content, as well as an increase of 106 and 61% in superoxide dismutase activity, respectively. However, Zn ions at the corresponding concentrations showed negligible impacts on the two parameters. The different results indicate that the insoluble NPs during the initial exposure mostly account for lipid peroxidation, which further lead to microalgal antioxidant response. During the subsequent exposure, the contributors of ZnO NP toxicity shift with the concentration and exposure time of ZnO NPs. In conclusion, the study presents new insights into the different contributions of insoluble NPs and dissoluble metallic ions to metallic NP toxicity.


Assuntos
Nanopartículas Metálicas/toxicidade , Microcystis/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Óxido de Zinco/toxicidade , Zinco/toxicidade , Antioxidantes/metabolismo , Relação Dose-Resposta a Droga , Íons , Peroxidação de Lipídeos/efeitos dos fármacos , Malondialdeído/metabolismo , Microcystis/metabolismo
4.
Bull Environ Contam Toxicol ; 103(5): 683-688, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31471659

RESUMO

Extensive use of the fungicides azoxystrobin (AZ) and pyraclostrobin (PYR) can have negative effects on aquatic environments, but comprehensive studies on their effect on aquatic microbial communities are still lacking. We found that AZ and PYR could both inhibit the growth of Chlorella vulgaris, but PYR also inhibited Microcystis aeruginosa more strongly than did AZ. High-throughput sequencing analysis showed that AZ promoted the growth of Cyanobacteria in microcosms, and both PYR and AZ disturbed the ecological balance in the aquatic bacterial community and created distinct ecological risks. Our study suggests that the ecological risk of fungicides is complex, and fungicide use should be better managed to reduce potential risks to the environment.


Assuntos
Água Doce/microbiologia , Fungicidas Industriais/toxicidade , Pirimidinas/toxicidade , Estrobilurinas/toxicidade , China , Chlorella vulgaris/efeitos dos fármacos , Cianobactérias/efeitos dos fármacos , Ecotoxicologia , Microcystis/efeitos dos fármacos , Microcystis/crescimento & desenvolvimento
5.
J Basic Microbiol ; 59(11): 1112-1124, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31502316

RESUMO

Microcystis aeruginosa blooms are a worldwide serious environmental problem and bloom control with bacteria is promising. In this study, a Bacillus licheniformis strain Sp34 with potent algicidal and inhibitory effects on the microcystins synthesis against fast-growing M. aeruginosa was isolated from Dianchi Lake. Sp34 killed the bloom-causing algal strain M. aeruginosa DCM4 of Dianchi Lake with an initial Chlorophyll-a concentration of 2.0 mg/L at a cell density of no less than 1.35 × 105 CFU/ml. It can also efficiently kill some other harmful algal species, such as M. wesenbergii and Phormidium sp. The algicidal activity of Sp34 relied on the release of algicidal substances, which had good heat (-20°C to 121°C) and acid-base (pH 3-11) resistance. In addition, the high algicidal activity depended on the good growth of algae indicated by the significantly positive correlations between algal growth and algicidal ratio (p < .001). The algicidal effect of Sp34 involved causing oxidative stress, lipid peroxidation, and morphological injury of algal cells, along with DNA damage and dysfunction of DNA-repair function, weakening the photosynthesis system, and inhibiting microcystin synthesis. In general, Sp34 can kill fast-growing M. aeruginosa and inhibit algal microcystin synthesis efficiently, so, it is a promising biocontrol agent to mitigate cyanobacterial blooms.


Assuntos
Bacillus licheniformis/metabolismo , Agentes de Controle Biológico/metabolismo , Agentes de Controle Biológico/farmacologia , Microcystis/efeitos dos fármacos , Antibiose , Bacillus licheniformis/classificação , Bacillus licheniformis/genética , Bacillus licheniformis/crescimento & desenvolvimento , Clorofila/análogos & derivados , Clorofila/biossíntese , Clorofila/genética , Eutrofização/efeitos dos fármacos , Lagos/microbiologia , Microcistinas/biossíntese , Microcistinas/genética , Microcystis/genética , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Transcrição Genética/efeitos dos fármacos
6.
Ultrason Sonochem ; 58: 104634, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31450346

RESUMO

Iron oxide nanoparticles decorated on multi-wall nanotube (MWCNTs) were successfully fabricated through a facile and rapid sonochemical method without any pre-treatment on MWCNTs. Fe3O4/MWCNTs-20 showed a uniform and fine distribution of nanoparticles in the MWCNTs. The obtained Fe3O4/MWCNTs were analysed using TEM and XPS. Notably, Fe3O4/MWCNTs were used for persulfate activation on cyanobacterial cell removal. With 20 mg/L persulfate, Fe3O4/MWCNTs showed an efficient catalytic performance after 1 h treatment. In the Fe3O4/MWCNTs hybrid catalyst, Fe3O4 helps to produce sulfate radicals and hydroxyl radicals whereas the size of the Fe3O4 clusters could affect the electron transfer for radical generation. Moreover, using high frequency low intensity ultrasound, the combination of persulfate and Fe3O4/MWCNTs-20 reduced the remaining cell number to 9.4% within 30 min treatment. In conclusion, our work demonstrated that low frequency ultrasonic devices are capable of fabricating Fe3O4/MWCNTs via a simple and time-saving route, and the obtained catalysts showed superior catalytic performance on persulfate for harmful cyanobacteria control.


Assuntos
Nanopartículas de Magnetita/química , Viabilidade Microbiana/efeitos dos fármacos , Microcystis/efeitos dos fármacos , Microcystis/fisiologia , Nanotubos de Carbono/química , Sulfatos/química , Ondas Ultrassônicas , Catálise , Técnicas de Química Sintética
7.
Aquat Toxicol ; 215: 105271, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31470337

RESUMO

Microcystis blooms and their associated microcystins pose a significant health risk to humans. Microcystis normally occurs as colonies in eutrophic water bodies, and its physiological tolerance to algaecides is dissimilar to that of unicellular forms. However, the differences of physiological response to algaecides between unicellular and colonial Microcystis have been poorly explored. The current study investigated the effects of hexane extract of Acorus calamus rhizome (HEACR) on the physiological and photosynthetic mechanisms of unicellular and colonial M. aeruginosa in the laboratory. We analyzed the cell density, reactive oxygen species (ROS) level, malonaldehyde (MDA) content, photosynthetic pigments, capsular polysaccharide (CPS), and photosystem (PS II) parameters of the two morphological forms of Microcystis. Our results show that HEACR suppresses the growth of both unicellular and colonial M. aeruginosa, increases the intracellular ROS level and cause lipid peroxidation, as well as exerting a detrimental effect on chlorophyll a (chl a) content and photosynthetic efficiency. Almost 100% inhibition was observed for unicellular and colonial M. aeruginosa after 3 d exposure to 50 and 100 mg L-1 HEACR, respectively. The ROS level increase, MDA accumulation, the chl a decrease and carotenoid increase in unicellular M. aeruginosa were all more obvious than that in colonial cells. The fall in photosynthetic efficiency of unicellular M. aeruginosa were also more significant than that of colonial cells. After 3d exposure, the maximum quantum yield of PS II photochemistry (Fv/Fm), effective quantum yield of PS II photochemistry (Fv'/Fm') and effective quantum yield of photochemical energy conversion in PS II (YII) of unicellular M. aeruginosa was almost totally inhibited by 20 mg L-1 HEACR, while the Fv/Fm, Fv'/Fm' and YII of colonial M. aeruginosa decreased by 43%, 26% and 66% for 100 mg L-1 of HEACR, respectively. Comparing the two morphological forms of Microcystis, colonies show a greater increase in CPS level to more effectively resist the stress of HEACR and to mitigate ROS generation thereby better defending against oxidative damage. Furthermore, colonial M. aeruginosa shows better photoprotection ability than the unicellular form when exposed to HEACR. The colonies also sustain their maximum electron transport rate, increase their tolerance to strong light, and maintain a higher ability to disperse excess energy. These results demonstrated that HEACR can significantly interfere with the growth and physiological processes of both unicellular and colonial M. aeruginosa, but that colonial M. aeruginosa has a greater ability to adjust physiological tolerance to resist the stresses of HEACR.


Assuntos
Acorus/química , Microcystis/efeitos dos fármacos , Microcystis/fisiologia , Extratos Vegetais/farmacologia , Rizoma/química , Luz , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos da radiação , Microcystis/crescimento & desenvolvimento , Fotossíntese/efeitos dos fármacos , Fotossíntese/efeitos da radiação , Pigmentos Biológicos/metabolismo , Polissacarídeos/metabolismo , Espécies Reativas de Oxigênio/metabolismo
8.
Environ Pollut ; 253: 497-506, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31330342

RESUMO

Sanguinarine has strong inhibitory effects against the cyanobacterium Microcystis aeruginosa. However, previous studies were mainly limited to laboratory tests. The efficacy of sanguinarine for mitigation of cyanobacterial blooms under field conditions, and its effects on aquatic microbial community structure remain unknown. To elucidate these issues, we carried out in situ cyanobacterial bloom mitigation tests. Our results showed that sanguinarine decreased population densities of the harmful cyanobacteria Microcystis and Anabaena. The inhibitory effects of sanguinarine on these cyanobacteria lasted 17 days, after which the harmful cyanobacteria recovered and again became the dominant species. Concentrations of microcystins in the sanguinarine treatments were lower than those of the untreated control except during the early stage of the field test. The results of community DNA pyrosequencing showed that sanguinarine decreased the relative abundance of the prokaryotic microorganisms Cyanobacteria, Actinobacteria, Planctomycetes and eukaryotic microorganisms of Cryptophyta, but increased the abundance of the prokaryotic phylum Proteobacteria and eukaryotic microorganisms within Ciliophora and Choanozoa. The shifting of prokaryotic microbial community in water column was directly related to the toxicity of sanguinarine, whereas eukaryotic microbial community structure was influenced by factors other than direct toxicity. Harmful cyanobacteria mitigation efficacy and microbial ecological effects of sanguinarine presented in this study will inform the broad application of sanguinarine in cyanobacteria mitigation.


Assuntos
Antibacterianos/farmacologia , Benzofenantridinas/farmacologia , Cianobactérias/efeitos dos fármacos , Eutrofização/efeitos dos fármacos , Isoquinolinas/farmacologia , Microbiota/efeitos dos fármacos , Anabaena/efeitos dos fármacos , Microcistinas , Microcystis/efeitos dos fármacos , Microbiologia da Água
9.
Chemosphere ; 235: 344-353, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31265980

RESUMO

The ecological risks of antibiotics in aquatic environments have raised great concerns worldwide, but the chronic effect of antibiotic contaminants on cyanotoxin production and release remains unclear. This study investigated the long-term combined effects of spiramycin (SP) and ampicillin (AMP) on microcystin (MC) production and release in both unicellular and colonial Microcystis aeruginosa (MA) through semi-continuous exposure test. At exposure concentration of 300 ng L-1, MA growth rates were stimulated till the end of exponential phase accompanied with the up-regulation of photosynthesis-related gene. The exponential growth phases of unicellular and colonial MA were prolonged for 2 and 4 days, respectively. The stimulation rate of growth rate and MC content in unicellular MA were significantly higher than that in colonial MA. The highest concentrations of intracellular MC (IMC) and extracellular MC (EMC) were observed in the binary mixture at equivalent SP/AMP ratio (1:1). The promotion of IMC concentration was in consistent with the stimulated expression of MC-synthesis-related gene and nitrogen-transport-related gene. The malondialdehyde content and activities of superoxide dismutase and catalase in unicellular MA were significantly higher than those in colonial MA. The EMC concentration and the antioxidant responses of both unicellular and colonial MA significantly increased with exposure time. Long-term exposure to mixture of SA and AMP at environmentally relevant concentrations would aggravate the disturbance to aquatic ecosystem balance through the stimulation of MA proliferation as well as the promotion of MC production and release.


Assuntos
Antibacterianos/toxicidade , Microcistinas/metabolismo , Microcystis/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Ampicilina , Antibacterianos/farmacologia , Ecossistema , Microcistinas/biossíntese , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Nitrogênio/metabolismo , Fotossíntese/efeitos dos fármacos , Espiramicina , Poluentes Químicos da Água/metabolismo
10.
Environ Sci Pollut Res Int ; 26(22): 22389-22399, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31154644

RESUMO

This paper studied the inhibitory effect of pomegranate peel (PP) extract on the growth of Microcystis aeruginosa, the model of harmful algal blooms in aquatic environment. The allelochemicals were identified by HPLC-MS/MS from PP and tested by batch experiment through measurement of algal density, chlorophyll a (Chl-a) concentration, maximum quantum yield of photosystem II (Fv/Fm), superoxide dismutase (SOD), and malondialdehyde (MDA) contents. Results showed that both PP powder and PP extract had obvious inhibitory effect on M. aeruginosa growth. Quercetin and luteolin were identified as the allelochemicals to M. aeruginosa growth. However, the inhibitory capacity of luteolin was stronger than that of quercetin. The growth inhibition ratio of luteolin can reach up to 98.7 and 99.1% of the control on day 7 at the dosages of 7 and 10 mg/L, respectively. Moreover, the changes of Chl-a, Fv/Fm, SOD, and MDA in M. aeruginosa confirmed jointly that the allelochemicals cause inhibition of photosystem and oxidative damage to M. aeruginosa cells with the antioxidant defense system being activated, which leads to the aggravation of membrane lipid peroxidation. Thus, luteolin could be used as a promising algaecide for emergency handling of M. aeruginosa blooms. This study might provide a new direction in the management of eutrophication in the future.


Assuntos
Antioxidantes/farmacologia , Clorofila A/química , Proliferação Nociva de Algas/efeitos dos fármacos , Malondialdeído/farmacologia , Microcystis/efeitos dos fármacos , Feromônios/farmacologia , Complexo de Proteína do Fotossistema II/química , Lythraceae , Malondialdeído/química , Oxirredução , Complexo de Proteína do Fotossistema II/metabolismo , Superóxido Dismutase/metabolismo , Espectrometria de Massas em Tandem
11.
Anal Bioanal Chem ; 411(21): 5531-5543, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31201458

RESUMO

Single cell-inductively coupled plasma-mass spectrometry (SC-ICP-MS) is an emerging technology. In this work, we have developed a novel SC-ICP-MS method to quantify metal ions in individual cells of a toxic cyanobacterial species, Microcystis aeruginosa (M. aeruginosa), without complicated post-dosing sample preparation, and applied this method to study the treatment effectiveness of copper-based algaecides (cupric sulfate and EarthTec®) on the toxic algae M. aeruginosa. The developed SC-ICP-MS method uses new intrinsic metal element magnesium to determine real transport efficiency and cell concentration. The cell viability and microcystin-LR release by algaecide treatment were studied by flow cytometry and ultra-fast liquid chromatography-tandem mass spectrometry, respectively. The results showed that this novel method was very rapid, highly sensitive (detection limits of intracellular copper and magnesium were 65 ag/cell and 98 ag/cell, respectively), and reproducible (relative standard deviation within 12%). The algaecide effectiveness study further demonstrated that copper in the forms of cupric sulfate and copper-based algaecide EarthTec® successfully diminished M. aeruginosa populations. The higher the copper concentration used to treat the cells, the faster the speeds of copper uptake and cell lysis in the copper concentrations ranged from 0 to 200 µg/L of copper-based algaecide. The cells exhibit obvious heterogeneity in copper uptake. The result suggests that M. aeruginosa cells uptake and cumulate copper followed by cellular lysis and microcystin-LR release. These novel results indicated that though the copper-based algaecides could control this type of harmful algal bloom, further treatment to remove the released algal toxin from the treated water would be needed. Graphical abstract.


Assuntos
Cobre/química , Herbicidas/farmacologia , Microcystis/efeitos dos fármacos , Espectrometria de Massas em Tandem/métodos , Cromatografia Líquida/métodos , Cobre/análise , Cobre/metabolismo , Citometria de Fluxo , Herbicidas/análise , Herbicidas/química , Limite de Detecção , Reprodutibilidade dos Testes
12.
Appl Microbiol Biotechnol ; 103(14): 5907-5916, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31115631

RESUMO

Allelopathy by hydrophytes can be utilized to control algal blooms. This study was conducted to investigate the allelopathic effect (inhibition) of Scenedesmus quadricauda on Microcystis flos-aquae. When M. flos-aquae was co-cultured with S. quadricauda, the secretion of high-MW biopolymer by M. flos-aquae was inhibited by S. quadricauda. We further identified the allelochemicals and found that 4-tert-butylpyrocatechol (TBC) was the main active ingredient that could inhibit the growth of M. flos-aquae. When the dose of TBC was larger than 0.2 mg/L, almost all of the M. flos-aquae died. Additionally, TBC was found to suppress the growth of M. flos-aquae by disturbing the synthesis and secretion of proteins and polysaccharides and harming the chlorophyll to affect the light harvesting of algal cells. Therefore, TBC has the potential for use as a potential and promising algaecide to restrain the biomass of M. flos-aquae.


Assuntos
Microcystis/efeitos dos fármacos , Microcystis/crescimento & desenvolvimento , Feromônios/farmacologia , Scenedesmus/fisiologia , Catecóis/farmacologia , Clorofila/metabolismo , Técnicas de Cocultura , Eutrofização/efeitos dos fármacos , Herbicidas/farmacologia , Superóxido Dismutase
13.
Ecotoxicol Environ Saf ; 177: 18-24, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30954008

RESUMO

Flavonoids are natural polyphenolic compounds from plants. As a new biotechnological algaecide, the molecular mechanism of plant flavonoids on the inhibition of Microcystis aeruginosa is still unknown. Therefore, in this study, we analyzed the variation of expressions of photosynthesis-related genes, microcystin synthesis-related genes and the genes involved in N and P acquisition in M. aeruginosa under the flavonoids stress. The results showed that the expression of psbD1, psaB and rbcL related to photosynthesis were influenced by three flavonoids but with different changing tendencies. The transcription of mcyA, mcyD and mcyH related to microcystin synthesis were decreased after 5-d of exposure, which could block microcystin synthesis. Meanwhile, flavonoids treatments resulted in the inhibition of N and P acquisition related genes transcription to affect the absorption of N and P in algal cells, and further influenced the physiological metabolic process of M. aeruginosa.


Assuntos
Flavonoides/farmacologia , Microcistinas/metabolismo , Microcystis/efeitos dos fármacos , Feromônios/farmacologia , Fotossíntese , Metabolismo Secundário , Flavonoides/metabolismo , Variação Genética , Microcistinas/genética , Microcystis/genética , Microcystis/metabolismo , Nutrientes , Feromônios/metabolismo
14.
Aquat Toxicol ; 211: 81-91, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30954847

RESUMO

The excessive proliferation of toxin producing cyanobacteria constitutes a significant health risk to the environment and humans. This is due to the contamination of potable water and accumulation of cyanotoxins in plant and animal tissues. As a means of controlling bloom forming cyanobacteria, secondary metabolites with pro-oxidative activities from plants are used to treat water bodies contaminated with cyanobacterial blooms and their associated toxins. The objective of the present study was to evaluate the mechanism of action of extract, fractions and isolated flavonoids of Tridax procumbens L. on Microcystis aeruginosa (Kützing) Kützing. by monitoring changes in growth, oxidative stress, antioxidant response, and cyanatoxin microcystins (MCs) production. The extract, fraction 3 and the isolated flavonoids significantly reduced the cell density of the cyanobacterium. Furthermore, the extract and fraction 3 increased the production of reactive oxygen species, induced lipid peroxidation, and altered antioxidant enzyme activities of M. aeruginosa. The total MCs content of the cyanobacterium was negatively affected by the presence of the extract, fractions and isolated flavonoids. The present study show that T. procumbens has secondary metabolites that are capable of interfering with the physiology and microcystins production of M. aeruginosa. These characteristics are promising for the control of this noxious cyanobacterium in aquatic ecosystems.


Assuntos
Asteraceae/química , Flavonoides/farmacologia , Microcistinas/análise , Microcystis/efeitos dos fármacos , Extratos Vegetais/química , Poluentes Químicos da Água/análise , Animais , Antioxidantes/metabolismo , Relação Dose-Resposta a Droga , Flavonoides/isolamento & purificação , Peroxidação de Lipídeos/efeitos dos fármacos , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo
15.
Chemosphere ; 225: 424-433, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30889406

RESUMO

Microcystis aeruginosa (M. aeruginosa), as the dominant algae in eutrophic water bodies, has caused a serious harm to the local eco-environment. A biological tool, employing allelopathic inhibitory of eucalyptus to control M. aeruginosa, has been receiving tremendous attention. This work presents the results of the allelopathic inhibitory effects of eucalyptus (Eucalyptus grandis × E.urophylla 'GLGU9') extracts of roots (ERE), stems (ESE), and leaves (ELE) on culture solutions of M. aeruginosa and its eco-physiological mechanism. The inhibitory effects of the extracts on the growth of M. aeruginosa varied greatly with ELE exhibiting the highest level of potency. Modes of action by which ELE inhibited M. aeruginosa growth were established. They involved reduction in photosynthesis, disruption of the cell membrane integrity, and inhibition of esterase activities of the cyanobacterial cells. However, ELE did not exhibit any gradients of toxicity towards zebrafish nor Washington grass plant. Species abundance and diversity in the systems remained likewise unaffected by ELE. The synergistic interaction between ELE and single-component allelochemicals (e.g., gallic acid and berberine) was ascribed to the increase in efficacy of allelochemicals in the various systems. The results of this study provide an underlying, novel, and attractive approach for controlling the growth of M. aeruginosa in aquatic environments.


Assuntos
Antibacterianos/farmacologia , Berberina/farmacologia , Eucalyptus/química , Ácido Gálico/farmacologia , Microcystis/crescimento & desenvolvimento , Feromônios/farmacologia , Extratos Vegetais/farmacologia , Alelopatia , Animais , Sinergismo Farmacológico , Esterases/antagonistas & inibidores , Microcystis/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Folhas de Planta/química , Raízes de Plantas/química , Caules de Planta/química , Poaceae/efeitos dos fármacos , Washington , Peixe-Zebra/metabolismo
16.
Environ Sci Pollut Res Int ; 26(15): 15218-15228, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30927222

RESUMO

Marine macroalgae are a promising source of diverse bioactive compounds with applications in the biocontrol of harmful cyanobacteria blooms (cyanoHABs). In this work, we evaluated the potential algicidal activities of 14 species of seaweed collected from the coast of Souiria Laqdima, Morocco. Methanol extracts were screened in solid and liquid medium against the growth of the toxic cyanobacteria Microcystis aeruginosa and the microalgae Chlorella sp. used as food supplement. The results in solid medium revealed that the algicidal activity was limited to M. aeruginosa with the extract of Bornetia secundiflora showing the highest growth inhibition activity against Microcystis (27.33 ± 0.33 mm), whereas the extracts of Laminaria digitata, Halopytis incurvus, Ulva lactuca, and Sargasum muticum showed no inhibition. In liquid medium, the results indicated that all methanolic extracts of different macroalgae tested have a significant inhibitory effect on M. aeruginosa compared with that of the negative control. The maximum inhibition rates of M. aeruginosa were produced by the extracts of Bifurcaria tuberculata, Codium elongatum, and B. secundiflora. Moreover, the extracts of B. secundiflora recorded the maximum inhibition rate of Chlorella sp. Overall, the results highlight the potential of the extracts from macroalgae to control toxic cyanobacteria species.


Assuntos
Antibacterianos/farmacologia , Cianobactérias/efeitos dos fármacos , Microalgas/química , Microcystis/efeitos dos fármacos , Alga Marinha/metabolismo , Ulva/metabolismo , Antibacterianos/química , Chlorella , Marrocos , Alga Marinha/química
17.
Toxins (Basel) ; 11(1)2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30650515

RESUMO

Globally, eutrophication and warming of aquatic ecosystems has increased the frequency and intensity of cyanobacterial blooms and their associated toxins, with the simultaneous detection of multiple cyanotoxins often occurring. Despite the co-occurrence of cyanotoxins such as microcystins and anatoxin-a (ATX) in water bodies, their effects on phytoplankton communities are poorly understood. The individual and combined effects of microcystin-LR (MC-LR) and ATX on the cyanobacteria Microcystis spp., and Anabaena variabilis (a.k.a. Trichormus variabilis), and the chlorophyte, Selenastrum capricornutum were investigated in the present study. Cell density, chlorophyll-a content, and the maximum quantum efficiency of photosystem II (Fv/Fm) of Microcystis cells were generally lowered after exposure to ATX or MC-LR, while the combined treatment with MC-LR and ATX synergistically reduced the chlorophyll-a concentration of Microcystis strain LE-3. Intracellular levels of microcystin in Microcystis LE-3 significantly increased following exposure to MC-LR + ATX. The maximum quantum efficiency of photosystem II of Anabaena strain UTEX B377 declined during exposure to the cyanotoxins. Nitrogen fixation by Anabaena UTEX B377 was significantly inhibited by exposure to ATX, but was unaffected by MC-LR. In contrast, the combination of both cyanotoxins (MC-LR + ATX) caused a synergistic increase in the growth of S. capricornutum. While the toxins caused an increase in the activity of enzymes that scavenge reactive oxygen species in cyanobacteria, enzyme activity was unchanged or decreased in S. capricornutum. Collectively this study demonstrates that MC-LR and ATX can selectively promote and inhibit the growth and performance of green algae and cyanobacteria, respectively, and that the combined effect of these cyanotoxins was often more intense than their individual effects on some strains. This suggests that the release of multiple cyanotoxins in aquatic ecosystems, following the collapse of blooms, may influence the succession of plankton communities.


Assuntos
Anabaena/efeitos dos fármacos , Clorofíceas/efeitos dos fármacos , Microcistinas/toxicidade , Microcystis/efeitos dos fármacos , Tropanos/toxicidade , Anabaena/crescimento & desenvolvimento , Anabaena/metabolismo , Clorofíceas/crescimento & desenvolvimento , Clorofíceas/metabolismo , Sinergismo Farmacológico , Glutationa Transferase/metabolismo , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Fixação de Nitrogênio/efeitos dos fármacos , Peroxidase/metabolismo , Superóxido Dismutase/metabolismo
18.
Water Environ Res ; 91(1): 21-31, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30682229

RESUMO

The effects and control of typical metal nutrients, copper, iron, and zinc, on the growth and bloom of Microcystis aeruginosa were investigated with a series of flask-shaking tests. The optimal concentrations of copper, iron, and zinc for algal growth were 0.001, 3-12, and 0.05 mg/L, respectively. The order of toxicity to the alga was Cu > Zn > Fe. The effects of the species, for a trace metal at the same concentrations, on the growth of M. aeruginosa were relatively remarkable. Ionic and complexation species induced more algal growth than the carbonate and sulfide-bound species. Changes in copper concentration and iron species were adopted to adjust and control the bloom of M. aeruginosa. Increases in copper concentrations significantly suppressed the M. aeruginosa bloom. The growth rate of M. aeruginosa slowed significantly when ionic iron was replaced with sulfide-bound iron, and the control of bloom was remarkable. PRACTITIONER POINTS: Using trace metal nutrient species and concentration to regulate and control algal growth and bloom may pave another way for the management of cyanobacterial bloom.


Assuntos
Eutrofização/efeitos dos fármacos , Metais/farmacologia , Microcystis/efeitos dos fármacos , Microcystis/crescimento & desenvolvimento , Nutrientes/farmacologia , Relação Dose-Resposta a Droga
19.
J Agric Food Chem ; 67(6): 1631-1637, 2019 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-30673265

RESUMO

The enantioselective effects of chiral herbicides on aquatic organisms have received increasing attention. As one kind of freshwater algae responsible for most algal blooms, Microcystis aeruginosa can produce hepatotoxic microcystin and cause serious health concerns for drinking water. Thus, the effects of chiral herbicides on M. aeruginosa are of vital significance but poorly understood, especially as the structures of chiral herbicides become more complex. In this study, the enantioselective effects of four metolachlor enantiomers based on carbon center and axis chirality on M. aeruginosa were investigated for the first time at an enantiomeric level. The results of the investigation into algal growth inhibition, chlorophyll a content, and cell integrity indicated that ( S)-metolachlor [( S)-Met] was significantly more toxic than any other isomer. The toxicity ranking of different enantiomers at the highest concentration (15 mg/L) against M. aeruginosa was ( S)-Met > (α R,1' S)-Met > (α S,1' S)-Met > (α S,1' R)-Met > (α R,1' R)-Met, with (α S,1' S)-Met and (α R,1' S)-Met displaying a synergistic effect. Additionally, the Fe distribution in M. aeruginosa presented distinct enantioselectivity, which may contribute to the enantioselective toxicity of metolachlor. Furthermore, metolachlor upregulated the expression of genes mcyD and mcyH in an enantioselective manner, indicating that this herbicide can potentially promote the synthesis and efflux of microcystin, thus aggravating agricultural water contamination to different extents. Overall, this study will help to understand the ecotoxicity of metolachlor at a deeper level and provide theoretical insights into the enantioselective behaviors of metolachlor.


Assuntos
Acetamidas/toxicidade , Herbicidas/química , Herbicidas/toxicidade , Microcystis/efeitos dos fármacos , Acetamidas/química , Clorofila A/metabolismo , Microcistinas/metabolismo , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Estereoisomerismo
20.
Environ Pollut ; 247: 165-171, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30669084

RESUMO

The frequent outbreaks of cyanobacteria bloom are often accompanied by the generation and release of reduced phosphorus species (e.g., phosphine), which raises interesting questions regarding their potential algae-related effects. To clarify the physiological and biochemical responses of cyanobacteria to phosphine, Microcystis aeruginosa was treated with different concentrations of phosphine. Net photosynthetic rate, total antioxidant capacity (T-AOC), catalase (CAT) activity, and the concentrations of chlorophyll a, carotenoid and total protein were investigated and scanning electron microscopy (SEM) was conducted to elucidate the physiological and biochemical responses of M. aeruginosa to phosphine. The results showed that phosphine was beneficial to the growth of algal cells after M. aeruginosa acclimatized to the treatment of phosphine, and treatment with 2.48 × 10-2 mg/L phosphine had a greater positive effect on the growth and reproduction of M. aeruginosa than 7.51 × 10-3 mg/L phosphine, in which most algal cells were smooth and flat on day 16. Treatment with the high concentration of phosphine (7.51 × 10-2 mg/L) for 16 d reduced T-AOC, CAT activity, net photosynthetic rate, and the concentrations of chlorophyll a, carotenoid and total protein of M. aeruginosa to the minimums, resulting in the lysis and death of M. aeruginosa cells, which indicates phosphine has a toxic effect on the growth of algal cells. However, the high concentration of phosphine (7.51 × 10-2 mg/L) had a greater positive effect on the growth of M. aeruginosa cells than the lower two (7.51 × 10-3 mg/L and 2.48 × 10-2 mg/L) from 3 d to 12 d. Our findings provide insight into how phosphine potentially affects the growth of M. aeruginosa cells and the important roles of elevated phosphine on the outbreak of cyanobacteria bloom.


Assuntos
Microcystis/efeitos dos fármacos , Microcystis/crescimento & desenvolvimento , Fosfinas/toxicidade , Carotenoides , Clorofila/metabolismo , Clorofila A , Cianobactérias/metabolismo , Oxirredução , Fósforo/metabolismo , Fotossíntese/efeitos dos fármacos
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