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1.
Ecotoxicol Environ Saf ; 208: 111575, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396101

RESUMO

Microplastics (MPs) have aroused widespread concern due to their extensive distribution in aquatic environments and adverse effects on aquatic organisms. However, the underlying toxicity of different kinds of MPs on freshwater microalgae has not been examined in detail. In this study, we investigated the effects of polyvinyl chloride (PVC), polystyrene (PS) and polyethylene (PE) MPs on the growth of Microcystis aeruginosa, as well as on its toxin production and oxidative stress. We found that all three kinds of MPs had an obvious inhibition effect on the growth of M. aeruginosa. Considering the results of antioxidant-related indicators, the activity of superoxide dismutase (SOD) and catalase (CAT), and cell membrane integrity were greatly affected with exposure to PVC, PS and PE MPs. Moreover, the content of intracellular (intra-) and extracellular (extra-) microcystins (MCs) had a noticeable increase due to the presence of PVC, PS, and PE MPs. Finally, according to the comprehensive stress resistance indicators, the resistance of M. aeruginosa to three MPs followed the order: PE (3.701)> PS (3.607)> PVC (2.901). Our results provide insights into the effects of different kinds of MPs on freshwater algae and provide valuable data for risk assessment of different types of MPs.


Assuntos
Microcystis/fisiologia , Microplásticos/toxicidade , Poluentes Químicos da Água/toxicidade , Antioxidantes/metabolismo , Catalase/metabolismo , Água Doce , Microalgas/efeitos dos fármacos , Microcistinas , Microcystis/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Plásticos/toxicidade , Polietileno , Poliestirenos/toxicidade , Cloreto de Polivinila/toxicidade , Superóxido Dismutase/metabolismo
2.
Ecotoxicol Environ Saf ; 205: 111159, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32829212

RESUMO

Cyanobacteria blooms are crucial environmental issues by threatening both aquatic ecosystem and human health. A biomass by-product with antimicrobial activity, pyroligneous acid (PA) was tested for its suitability for removal of the cyanobacteria Microcystis aeruginosa (M. aeruginosa) in this work. Results show that the removal efficiency could reach up to 90% in the presence of 0.45% of PA and the inhibition to M. aeruginosa growth could extend to at least 40 days. The removal mechanism was studied. Both organic acids and phenols are functional content in M. aeruginosa removal and acetic acid is the most important one. Zeta potential analysis and morphology study show that the damage of cells dominates the flocculation and sedimentation of M. aeruginosa under low PA concentration (<0.7%), and increasing PA (≥0.7%) resulted in a trend of zeta potential to zero, thus removing any "shield" and triggering flocculation. Finally, study on the phenols residual after M. aeruginosa treatment shows that it could be close to 0 in 70 h. Therefore, this work proposes a possible method for world-wide treatment of cyanobacteria bloom and a new way for further utilization of PA.


Assuntos
Anti-Infecciosos/farmacologia , Eutrofização/efeitos dos fármacos , Microcystis/efeitos dos fármacos , Terpenos/farmacologia , Biomassa , Ecossistema , Floculação , Humanos , Microcystis/crescimento & desenvolvimento , Compostos Orgânicos
3.
Bull Environ Contam Toxicol ; 105(3): 358-365, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32740748

RESUMO

Sulfamethoxazole (SMZ) is a kind of sulfonamides antibiotic, which is widely used in human life. This study investigated the effects of SMZ on physiological and biochemical indexes of Chlorella vulgaris (C. vulgaris) and Microcystis aeruginosa (M. aeruginosa) for 35-day. The results showed that SMZ inhibited the growth and Chl-a content of C. vulgaris and M. aeruginosa, and growth inhibition rate was 8.06%-95.86%, Chl-a content decreased 2.44%-98.04%. SMZ resulting in increased SOD and CAT activity and destroyed the dynamic balance of antioxidant system. In addition, SMZ increased the content of malondialdehyde (MDA) in algae, destroyed the cell membrane to a certain extent, which was 1.8-7.3 folds higher than the control group. High concentration of SMZ can make algae cells exceed the limit of cell antioxidant capacity. Coupled with the serious damage of cell membrane, algae cells begin to appear a large number of death phenomenon.


Assuntos
Antibacterianos/toxicidade , Chlorella vulgaris/fisiologia , Microcystis/fisiologia , Sulfametoxazol/toxicidade , Antioxidantes/metabolismo , Chlorella vulgaris/efeitos dos fármacos , Malondialdeído/metabolismo , Microcystis/efeitos dos fármacos , Sulfametoxazol/metabolismo
4.
Chemosphere ; 259: 127430, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32593822

RESUMO

The frequent outbreaks of cyanobacterial blooms which caused serious societal and economic loss have become a worldwide problem. Interactions between toxic cyanobacteria and heterotrophic bacteria competitors play a pivotal role in the formation of toxic cyanobacterial bloom, but the underlying mechanisms of interactions between them await further research. The antagonist activity of Pseudomonas grimontii (P.grimontii) was confirmed by reduction in chlorophyll a concentration of Microcystis aeruginosa (M. aeruginosa) in an infected culture for a 7d period. The initial concentration of P.grimontii affected the M. aeruginosa activity significantly. When the 10% (V/V) concentration of P.grimontii A01 and P.grimontii A14 cultures were infected, the reduction of M. aeruginosa reached to 91.81% and 78.25% after 7 days, respectively. While a 0.1% (v/v) concentration of P.grimontii A01 and P.grimontii A14 cultures were infected, the M. aeruginosa increased 31.13% and 16.67% occurred, respectively. The content of reactive oxygen species (ROS) and malondialdehyde (MDA) increased with increasing of P.grimontii fermentation liquid, indicating the M. aeruginosa underwent oxidative stress. Using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) imaging mass spectrometry (IMS) profiling of co-cultures of M. aeruginosa and its antagonist P.grimontii, we revealed novel interspecies allelopathic interactions and compete molecule. We showed the spatial secondary metabolites may mediate the interactions in which P.grimontii inhibits growth of M. aeruginosa. Additionally, we revealed how M. aeruginosa feedback to the P.grimontii, which stimulates secondary metabolites such as [D-Asp3]-microcystin-LR released by M. aeruginosa. IMS method highlights the significance of allelopathic interactions between a widely distributed toxic cyanobacteria and its bacteria competitors.


Assuntos
Microcystis/fisiologia , Alelopatia , Clorofila A , Cianobactérias , Malondialdeído , Espectrometria de Massas , Microcistinas , Microcystis/efeitos dos fármacos , Microcystis/crescimento & desenvolvimento , Estresse Oxidativo , Pseudomonas , Espécies Reativas de Oxigênio
5.
Chemosphere ; 255: 126935, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32387731

RESUMO

Essential oils (EOs) are naturally occurring substances that have shown great prospect in the field of antimicrobial, antioxidant and pest control by nontoxic mechanisms. In this regard, EOs are considered the promising and eco-friendly approach for controlling harmful algae. In this study, the anti-cyanobacterial activity of EOs eugenol against Microcystis aeruginosa are evaluated from the perspective of photosynthetic efficiency, the behavior of extracellular organic matter (EOM), endogenous plant hormone synthesis, and nitric oxide signaling pathway. Results showed that the photosynthetic activity of M. aeruginosa decreased significantly after eugenol treatments. Eugenol treatment resulted in cells rupture and the release of EOM. Levels of endogenous plant hormones salicylic acid (SA) and jasmonic acid (JA) were enhanced separately by 2.32 and 2.01 times after 4 d of exposure to eugenol. And the inhibition of SA and JA biosynthesis further promotes the inhibitory effects of eugenol on algae. Additionally, the signaling molecule nitric oxide (NO) increased significantly by 3.78-fold. Furthermore, the influence of NO on microalgae exposed to eugenol was also determined, suggesting that the inhibitory effect of eugenol stress might be associated with NO generation in M. aeruginosa. These findings will be helpful for the understanding of the fate and potential of eugenol in harmful algae control.


Assuntos
Anti-Infecciosos/toxicidade , Eugenol/toxicidade , Microcystis/efeitos dos fármacos , Cianobactérias , Microalgas , Fotossíntese/efeitos dos fármacos , Plantas , Transdução de Sinais
6.
Bull Environ Contam Toxicol ; 104(6): 834-839, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32306073

RESUMO

The interaction between metal oxide nanoparticles and toxin-producing cyanobacteria is relatively unknown. The present work exposed Microcystis sp.7806 to different concentrations of cerium oxide nanoparticles (CeO2 NPs) (1 mg/L, 10 mg/L and 50 mg/L), and evaluated the growth, photosynthetic activity, reactive oxygen species level, and the extra-(intra-) cellular microcystin-LR (MC-LR) contents. The particle size, zeta potential and cerium ions released into the medium were analyzed. Results showed 10 mg/L NP treatment promoted algae growth but slightly inhibited the photosynthetic yield of algae, and the 50 mg/L treatment reduced algae biomass. The algal cells remarkably responded to oxidative stress at higher concentrations (10 mg/L and 50 mg/L). CeO2 NPs largely increased the intracellular MC-LR content at 50 mg/L, and significantly reduced the extracellular MC-LR content at any concentration. This demonstrates CeO2 NPs may pose an ecological risk potential during harmful algal blooms by stimulating toxin production.


Assuntos
Cério/toxicidade , Nanopartículas Metálicas/toxicidade , Microcistinas/biossíntese , Microcystis/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Relação Dose-Resposta a Droga , Proliferação Nociva de Algas/efeitos dos fármacos , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Fotossíntese/efeitos dos fármacos
7.
Ecotoxicol Environ Saf ; 196: 110540, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32251950

RESUMO

By testing time-dependent IC50 of luteolin against Microcystis growth, this study revealed 6.5 mg/L as nearly IC50 value during prolonged stress until day 14, and explored chlorophyll-a (CLA) and phycobiliproteins (PBPs) contents, antioxidant responses and microcystin (MC)-production/-release dynamics at rising luteolin doses (0.5~2-fold IC50). Growth inhibition ratio (GIR) generally rose at rising luteolin dose, while at each dose GIR firstly increased and then leveled off or dropped. In early stage, CLA, allophycocyanin (APC), phycoerythrin (PE) and glutathione (GSH) contents, and superoxide dismutase (SOD) and catalase (CAT) activities, were increasingly stimulated at rising luteolin dose to enhance energy yield and antioxidant defense, but Microcystis was damaged more severely at rising dose, due to stress-repair imbalance. Such more severe damage in early stage, coupled with stronger PBPs-inhibition in mid-late stage, at rising dose could jointly account for rising GIR at rising dose. The CAT/GSH-stimulation persisting until late stage could alleviate cell damage in late stage, which explained for why GIR no longer increased in late stage at each luteolin dose. Besides, more MCs were produced and retained in cell to exert protective roles against luteolin-stress in early stage, but intracellular MCs decreased following inhibited MC-production by prolonged stress to decrease cell protectant. Extracellular MCs detection showed that less MCs amount existed in water phase than control along luteolin-stress, implying luteolin as eco-friendly algaecide with promising potential to remove MPM blooms and MC-risks. This is the first study to reveal the effect of various luteolin doses on MC-production/release and PBP-synthesis dynamics of Microcystis during prolonged stress. The findings shed novel views in anti-algal mechanisms of luteolin, and provided direct evidence for luteolin applied as safe agent to remediate Microcystis-dominant blooms.


Assuntos
Luteolina/farmacologia , Microcistinas/biossíntese , Microcystis/efeitos dos fármacos , Antioxidantes/metabolismo , Catalase/metabolismo , Clorofila A/metabolismo , Glutationa/metabolismo , Microcystis/enzimologia , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Ficobiliproteínas/metabolismo , Ficocianina/metabolismo , Superóxido Dismutase/metabolismo
8.
Aquat Toxicol ; 222: 105473, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32203795

RESUMO

Antibiotic contaminants have the potential to interfere with the control of cyanobacterial bloom through generating hormesis in cyanobacteria at current contamination level of ng L-1. This study investigated the influence of a mixture of four frequently detected antibiotics, amoxicillin, ciprofloxacin, sulfamethoxazole and tetracycline, during the treatment of Microcystis aeruginosa by copper sulfate (CuSO4) algaecide. CuSO4 significantly (p <  0.05) inhibited cell density, growth rate, Fv/Fm value, chlorophyll a content and microcystin production ability of M. aeruginosa in a dose-dependent manner at application doses of 0.01-0.05 mg L-1. Besides, CuSO4 inhibited oxidation-reduction process, photosynthesis and biosynthesis in M. aeruginosa at the proteomic level. Preventative application of CuSO4 to a low density (4 × 105 cells mL-1) of M. aeruginosa effectively prevented the formation of bloom at low CuSO4 doses, which is a possible route for eliminating the negative effects of CuSO4 algaecide in aquatic environments. The presence of mixed antibiotics alleviated the toxicity of CuSO4 in M. aeruginosa, through the downregulation of cation transport proteins and the upregulation of proteins related with chlorophyll a synthesis, photosynthesis, gene expression and oxidation-reduction. Mixed antibiotics also promoted microcystin synthesis in CuSO4 treated cells through the upregulation of microcystin synthetases. Mixed antibiotics significantly (p <  0.05) increased cell density, growth rate, Fv/Fm value, chlorophyll a content and microcystin production ability in CuSO4 treated cells at test concentrations of 80 and 200 ng L-1. A no-impact threshold of 20 ng L-1 for mixed antibiotics (5 ng L-1 for each antibiotic) was suggested for eliminating the interference of antibiotic contaminants on cyanobacterial bloom control.


Assuntos
Antibacterianos/toxicidade , Sulfato de Cobre/farmacologia , Microcistinas/biossíntese , Microcystis/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Proteoma/genética , Poluentes Químicos da Água/toxicidade , Clorofila/metabolismo , Clorofila A/metabolismo , Interações Medicamentosas , Eutrofização/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Hormese/efeitos dos fármacos , Microcystis/citologia , Microcystis/genética
9.
Chemosphere ; 249: 126147, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32062559

RESUMO

Here we report a set of experiments in which water blooming cyanobacteria Microcystis aeruginosa was repeatedly exposed to erythromycin. Growth inhibition increased with increasing erythromycin concentration (1-150 µg/L) upon first exposure. Maximum inhibition rate (76.06%), occurred under 150 µg/L erythromycin. Moreover, 96-h 50% effective concentration (EC50) was 22.97 µg/L, indicating that the growth of M. aeruginosa was affected by erythromycin under common environmental concentrations. Photosynthesis was hindered by chlorophyll and photosystem II limitations. Malondialdehyde, reactive oxygen species, and superoxide dismutase contents increased significantly under certain concentrations of erythromycin, but superoxide dismutase was suppressed by 150 µg/L erythromycin. Synthesis of intracellular and extracellular microcystins was promoted by 10-60 and by 20-60 µg/L erythromycin, respectively, but both were inhibited by 100-150 µg/L. Principal component analysis and Pearson's correlation revealed the accumulation of reactive oxygen species as the dominant mechanism of erythromycin toxicity to cells. M. aeruginosa repeatedly subjected to erythromycin exposure showed obvious resistance against the antibiotic, especially when treated twice with 60 µg/L erythromycin. The 96-h EC50 was 81.29 µg/L. As compared to the first exposure to erythromycin, photosynthetic and antioxidant activities increased, while growth inhibition and oxidation stress decreased upon multiple exposures. Production and release of microcystins were enhanced by repeated exposure to the antibiotic. Thus, erythromycin persistence in water should be examined, as repeated exposure may lead to serious environmental and human health hazards.


Assuntos
Eritromicina/toxicidade , Microcystis/efeitos dos fármacos , Antibacterianos/farmacologia , Clorofila/metabolismo , Cianobactérias/metabolismo , Eritromicina/farmacologia , Malondialdeído , Microcistinas , Estresse Oxidativo/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Espécies Reativas de Oxigênio/farmacologia , Superóxido Dismutase/metabolismo
10.
Toxicon ; 176: 47-54, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32103795

RESUMO

Cyanobacteria species are sensitive to many plant allelochemicals, such as pyrogallol. However, little attention has been paid to the relative effects of these xenobiotics on co-occurring toxigenic and non-toxigenic cyanobacterial strains, despite their co-existence in blooms. Hence, the responses of one toxigenic (TS2) and two non-toxigenic (NS1, NS2) Microcystis aeruginosa strains to pyrogallol were tested under three conditions: mono-culture and co-cultured either directly or separately by dialysis membrane. The study showed that the inhibitory effects of pyrogallol on the growth and photosynthetic yield (Fv/Fm) of either toxigenic or non-toxigenic M. aeruginosa strains were lower in direct and dialysis co-culture conditions than those in mono-culture conditions. This result indicated that chemical-mediated reciprocal effects occur between the co-existing toxigenic and non-toxigenic strains. The toxigenic M. aeruginosa strain was more sensitive to pyrogallol than the non-toxigenic strains in both mono- and co-culture systems, though whether this outcome is due to the former's toxigenic status is unclear. Intracellular microcystin-LR (MC-LR) concentrations of the toxigenic strain decreased after pyrogallol addition in both mono- and co-culture systems, whereas extracellular MC-LR concentrations increased. This finding may reflect the cell damage of M. aeruginosa because of the pyrogallol. At the same initial number of cells, the extracellular MC-LR concentration released from the same amount of TS2 cells in mono-culture was slightly higher than that in dialysis co-culture conditions. Overall, this study shows that plant allelochemicals may have the potential to reduce bloom toxicity by reducing the proportion of toxigenic cyanobacterial strains, and the effects of co-existing strains must be considered when assessing the effects of plant allelochemicals on target strains.


Assuntos
Microcistinas/toxicidade , Microcystis/efeitos dos fármacos , Pirogalol/toxicidade , Cianobactérias , Microcystis/fisiologia , Microbiologia da Água
11.
Environ Pollut ; 261: 114193, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32088440

RESUMO

Antibiotic contaminants exert stimulatory hormetic effects in cyanobacteria at low (ng L-1) concentrations, which may interfere with the control of cyanobacterial bloom in aquatic environments exhibiting combined pollution. This study investigated the influence of a mixture of four popular antibiotics (sulfamethoxazole, amoxicillin, ciprofloxacin, and tetracycline) during the application of UV-C irradiation for controlling the bloom of Microcystis aeruginosa. In the absence of antibiotics, 100-500 mJ cm-2 UV-C irradiation reduced cell density, growth rate, chlorophyll a content, Fv/Fm value and microcystin concentration in M. aeruginosa in a dose-dependent manner through the downregulation of proteins related to cell division, chlorophyll synthesis, photosynthesis and microcystin synthesis. UV-C irradiation stimulated microcystin release through the upregulation of the microcystin release regulatory protein (mcyH). The presence of 40 ng L-1 antibiotic mixture during UV-C treatment significantly reduced (p < 0.05) the treatment efficiency of 100-300 mJ cm-2 UV-C on microcystin concentration, while 80 and 160 ng L-1 antibiotic mixture significantly reduced (p < 0.05) the treatment efficiency of 100-500 mJ cm-2 UV-C on cell density and microcystin concentration. The antibiotic mixture alleviated the toxicity of UV-C on M. aeruginosa through a significant stimulation of photosynthetic activity (p < 0.05) and the upregulation of proteins involved in photosynthesis, biosynthesis, protein expression, and DNA repair. Microcystin release in UV-C-treated cyanobacterial cells was further stimulated by the antibiotic mixture through the upregulation of mcyH and four ATP-binding cassette transport proteins. The interference effects of antibiotic contaminants should be fully considered when UV-C is applied to control cyanobacterial bloom in antibiotic-polluted environments. In order to eliminate the interference effects of antibiotics, the concentration of each target antibiotic is suggested to be controlled below 5 ng L-1 before the application of UV-C irradiation.


Assuntos
Antibacterianos , Hormese , Microcystis , Raios Ultravioleta , Antibacterianos/farmacologia , Clorofila A/metabolismo , Microcistinas/metabolismo , Microcystis/efeitos dos fármacos , Microcystis/efeitos da radiação , Poluentes Químicos da Água/farmacologia
12.
Chemosphere ; 243: 125318, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995862

RESUMO

Increased agricultural intensification goes with the widespread use of herbicides that adversely affect aquatic biodiversity. The effects of herbicides on toxin-producing cyanobacteria have been poorly studied. The present study aimed to investigate the toxicological and physiological effects of the herbicide clethodim on Raphidiopsis raciborskii (a.k.a. Cylindrospermopsis raciborskii) ITEPA1 and Microcystis aeruginosa BCCUSP232. On day four of the experiment, the exposure to 25 mg/L clethodim resulted in the highest cell density of R. raciborskii. Similarly, exposure to the 1, 5, 20, and 50 mg/L clethodim treatments resulted in the highest cell densities of M. aeruginosa on day 4 of the experiment. Medium effect concentrations (EC50) after 96 h of exposure of both strains to clethodim were 192.98 mg/L and 168.73 mg/L for R. raciborskii and M. aeruginosa, respectively. The presence of clethodim significantly increased the total microcystin content of M. aeruginosa compared to the control cultures. At 400 mg/L, total saxitoxins content of R. raciborskii was 27% higher than that of the control cultures on day 4. In contrast, cultures exposed to 100 mg/L clethodim had the lowest saxitoxins levels per cell quota. There was an increase in the levels of intracellular hydrogen peroxide in both species during exposure to clethodim, which was followed by significant changes (p < 0.05) in the activity of antioxidant enzymes such as peroxidase and superoxide dismutase. These results revealed that the presence of low levels of clethodim in the aquatic environment might lead to the excessive proliferation of cyanobacteria and alteration of their cyanotoxins content.


Assuntos
Cicloexanonas/farmacologia , Cylindrospermopsis/efeitos dos fármacos , Cylindrospermopsis/crescimento & desenvolvimento , Microcystis/efeitos dos fármacos , Microcystis/crescimento & desenvolvimento , Antioxidantes/metabolismo , Toxinas Bacterianas/metabolismo , Cylindrospermopsis/metabolismo , Herbicidas/farmacologia , Microcistinas/metabolismo , Microcystis/metabolismo , Peroxidases/metabolismo , Saxitoxina/metabolismo , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/farmacologia
13.
Chemosphere ; 247: 125837, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31927185

RESUMO

Application of low dosage of H2O2 at early stage of cyanobacterial life cycle is a promising route for cyanobacterial bloom mitigation, which could minimize adverse effects on non-target organisms. Besides, influence of co-existing contaminants on cyanobacterial bloom mitigation under combined pollution conditions remains unclear. This study assessed the influence of a mixture of four frequently detected antibiotics (tetracycline, sulfamethoxazole, ciprofloxacin and amoxicillin) during H2O2 treatment of Microcystis aeruginosa at early growth stage. H2O2 significantly (p < 0.05) inhibited growth rate, chlorophyll a content, Fv/Fm and rETRmax in a dose-dependent manner at low doses of 0.25-1 mg L-1, through downregulating proteins involved in cell division, cellular component organization, gene expression and photosynthesis. Although H2O2 increased microcystin content in each cyanobacterial cell through the upregulation of microcystin synthetases (mcyC and mcyF), total microcystin concentration in H2O2 treated groups was significantly (p < 0.05) reduced due to the decrease of cell density. Existence of 80 and 200 ng L-1 mixed antibiotics during H2O2 treatment facilitated the scavenging of ROS by antioxidant enzymes and significantly (p < 0.05) stimulated growth, photosynthesis, microcystin synthesis and microcystin release in H2O2 treated cells, through the upregulation of proteins involved in photosynthesis, oxidation-reduction process, biosynthesis, gene expression and transport. Mixed antibiotics increased the hazard of M. aeruginosa during H2O2 treatment, through the stimulation of microcystin synthesis and release at the proteomic level. Each target antibiotic should be controlled below 5 ng L-1 before the application of H2O2 for eliminating the interference of antibiotics on cyanobacterial bloom mitigation.


Assuntos
Antibacterianos/farmacologia , Peróxido de Hidrogênio/farmacologia , Microcystis/efeitos dos fármacos , Proteômica/métodos , Amoxicilina/farmacologia , Clorofila A , Ciprofloxacino/metabolismo , Cianobactérias/efeitos dos fármacos , Microcistinas/biossíntese , Microcystis/metabolismo , Oxirredução , Fotossíntese/efeitos dos fármacos , Sulfametoxazol/metabolismo
14.
Ecotoxicol Environ Saf ; 189: 109976, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31767457

RESUMO

Eastern China is a typical region that suffers from harmful cyanobacterial blooms. Numerous studies have focused on bloom formation mechanisms; however, the detailed mechanisms remained unclear. Our study explored the influence of four metal ions (Ca, Cu, Pb and Cd) on Microcystis aeruginosa to determine their effects on bloom formation. We found that Ca concentrations higher than 100 mg L-1 contributed to cyanobacterial bloom formation. The presence of Ca triggered the anti-oxidation process and promoted the secretion of extracellular polysaccharides, thus inducing aggregation of algal cells and enhancing their buoyancy 2.1-fold more than the control (p<0.05). The reverse regulation of dissolved CO2 to bicarbonate by carbonic anhydrase formed a large amount of carbonate and decreased the growth rate by 38-56%. Cu (>0.1 mg L-1) presented significant toxicity to algal cells while Pb (>1 mg L-1) suppressed the algal growth rate due to the acidic condition. Cd (<0.1 mg L-1) exhibited no apparent toxicity to the algae. Furthermore, as the buoyancy increased, Cd was likely to facilitate the formation of cyanobacterial blooms, which needs further research. These findings can provide a theoretical basis for eutrophic lake management and contribute to the development of water quality and wastewater discharge standards.


Assuntos
Cádmio/farmacologia , Cálcio/farmacologia , Cobre/farmacologia , Chumbo/farmacologia , Microcystis/crescimento & desenvolvimento , China , Eutrofização , Microcystis/efeitos dos fármacos
15.
Environ Pollut ; 256: 113444, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31676094

RESUMO

Microcystis blooms and their secondary metabolites microcystins (MCs) occurred all over the world, which have damaged aquatic ecosystems and threatened public health. Techniques to reduce the Microcystis blooms and MCs are urgently needed. This study aimed to investigate the algicidal and inhibitory mechanisms of a red pigment prodigiosin (PG) against the growth and MC-producing abilities of Microcystis aeruginosa (M. aeruginosa). The numbers of Microcystis cells were counted under microscope. The expression of microcystin synthase B gene (mcyB) and concentrations of MCs were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme linked immunosorbent assay (ELISA) methods, respectively. The inhibitory effects of PG against M. aeruginosa strain FACHB 905 with 50% algicidal concentration (LC50) at 120 h was 0.12 µg/mL. When M. aeruginosa cells exposed to 0.08 µg/mL, 0.16 µg/mL, 0.32 µg/mL PG, the expression of mcyB of M. aeruginosa was down-regulated 4.36, 8.16 and 18.51 times lower than that of the control at 120 h. The concentrations of total MC (TMC) also were 1.66, 1.72 and 5.75 times lower than that of the control at 120 h. PG had high algicidal effects against M. aeruginosa, with the activities of superoxide dismutase (SOD) initially increased and then decreased after 72 h, the contents of malondialdehyde (MDA) increase, the expression of mcyB gene down-regulation, and MCs synthesis inhibition. This study was first to report the PG can simultaneously lyse Microcystis cells, down-regulate of mcyB expression and inhibit MCs production effectively probably due to oxidative stress, which indicated PG poses a great potential for regulating Microcystis blooms and MCs pollution in the environment.


Assuntos
Desinfetantes/toxicidade , Microcystis/efeitos dos fármacos , Prodigiosina/toxicidade , Ecossistema , Malondialdeído/metabolismo , Microcistinas/metabolismo , Microcystis/metabolismo , Reação em Cadeia da Polimerase em Tempo Real
16.
Environ Sci Pollut Res Int ; 27(1): 873-881, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31820237

RESUMO

Pre-oxidation in water treatment is considered an effective method to enhance the removal of algal cells and their exuded organic matters. However, pre-oxidation also alters the characteristics of algae and consequently influences disinfection processes. The existing studies mainly focused on the stationary growth phase, but little is known for the exponential and declined phases. The objectives of this study were to examine the effects of pre-ozonation on the integrity of algal cells, the release of algal organic matters, and the formation of disinfection by-products like N-nitrosodimethylamine (NDMA) from Microcystis aeruginosa (M. aeruginosa) at three growth phases. The results demonstrated that pre-ozonation was efficient to inactivate M. aeruginosa cells. The severity of M. aeruginosa cell damage increased as the ozone dosage increased from 0.5 to 2.0 mg/L. The damage of cell membranes resulted in the release of intracellular organic matters. Excitation-emission matrix spectra (EEMS) analysis indicated that ozone mainly reacted with soluble microbial products (SMP). With the increase of ozone concentration, although the trend of NDMA formation was similar for all three growth phases, more production of NDMA by algal cells was observed at the declined phase. In the post-disinfection process, chloramine showed the potential as a more suitable disinfectant than chlorination after pre-ozonation to minimize the NDMA formation. Therefore, appropriate pre-ozonation is beneficial to reduce the NDMA formation from exponential algae, while has no significant change during both stationary and declined phases.


Assuntos
Dimetilnitrosamina/análise , Microcystis/fisiologia , Ozônio/química , Cloraminas , Desinfetantes/farmacologia , Desinfecção , Halogenação , Microcystis/efeitos dos fármacos , Oxirredução , Ozônio/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos
17.
Ecotoxicol Environ Saf ; 190: 110080, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31855790

RESUMO

Elevated UV-B radiation due to ozone layer depletion may prevent the growth of bloom-forming cyanobacteria in aquatic environments, while antibiotic contaminants may cause effects opposite to that of UV-B due to hormesis. This study investigated the influence of a quaternary antibiotic mixture on Microcystis aeruginosa after UV-B radiation through a 15-day exposure test. UV-B radiation extended the lag phase of M. aeruginosa at doses of 600 and 900 mJ/cm2, and significantly (p < 0.05) reduced the growth rate and the Fv/Fm value at doses of 300-900 mJ/cm2. Although UV-B radiation significantly (p < 0.05) stimulated the microcystin production ability in each cyanobacterial cell, the total microcystin concentration still significantly (p < 0.05) decreased due to the reduction of cell density. Mixed antibiotics and UV-B regulated the proteomic expression profile of M. aeruginosa in different manners. UV-B radiation upregulated 19 proteins and downregulated 49 proteins in M. aeruginosa, while mixed antibiotics upregulated 45 proteins and downregulated 25 proteins in UV-B treated cells. Mixed antibiotics significantly (p < 0.05) stimulated growth and photosynthesis, increased cell density and microcystin concentration, and reduced oxidative stress in UV-B treated cells through the upregulation of proteins involved in photosynthesis, biosynthesis, cell division, oxidation-reduction, gene expression and microcystin synthesis. This study verified the hypothesis that antibiotics accelerated the recovery of M. aeruginosa from UV-B induced damage. A safe threshold of 20 ng/L was suggested for mixed antibiotics (5 ng/L for each antibiotic), in order to eliminate the stimulatory effects of antibiotics on bloom-forming cyanobacteria.


Assuntos
Antibacterianos/farmacologia , Microcystis/efeitos dos fármacos , Microcystis/efeitos da radiação , Raios Ultravioleta , Microcistinas/metabolismo , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Fotossíntese/efeitos dos fármacos , Proteômica
18.
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
19.
Bioorg Med Chem ; 27(24): 115159, 2019 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-31699453

RESUMO

Harmful cyanobacteria bloom (HCB) has occurred frequently in recent years and it is urgent to develop novel algicides to deal with this problem. In this paper, a series of novel thiamin diphosphate (ThDP) analogs 5a-5g were designed and synthesized targeting cyanobacterial pyruvate dehydrogenase complex E1 (Cy-PDHc E1). Our results showed that compounds 5a-5g have higher inhibitory activities against Cy-PDHc E1 (IC50 9.56-3.48 µM) and higher inhibitory activities against two model cyanobacteria strains Synechocystis sp PCC6803 (EC50 2.03-1.58 µM) and Microcystis aeruginosa FACHB905 (EC50 1.86-0.95 µM). Especially, compound 5b displayed highest inhibitory activities (IC50 = 3.48 µM) against Cy-PDHc E1 and powerful inhibitory activities against cyanobacteria Synechocystis sp PCC6803 (EC50 = 1.58 µM) and Microcystis aeruginosa FACHB905 (EC50 = 1.04 µM). Moreover, the inhibitory activities of compound 5b were even higher than those of copper sulfate (EC50 = 2.02 and 1.71 µM separately) which has been widely used as algicide against cyanobacteria PCC6803 and FACHB905. The more important was that compound 5b display much higher inhibitory selectivity between Cy-PDHc E1 (Inhibitory rate 97.4%) and porcine PDHc E1 (Inhibitory rate 11.8%) under the same concentration (100 µM). The inhibition kinetic experiment and molecular docking research showed that compound 5b can inhibit Cy-PDHc E1 by occupying the ThDP-binding pocket and then blocking Cy-PDHc E1 bound to ThDP as competitive inhibitor. The imagines of SEM and TEM showed that cellular microstructures were heavily destroyed under compound 5b stress. Our results demonstrated compound 5b could be taken as a potential lead compound targeting Cy-PDHc E1 to obtain environment-friendly algicide for harmful cyanobacterial blooms control.


Assuntos
Inibidores Enzimáticos/farmacologia , Microcystis/efeitos dos fármacos , Piruvato Desidrogenase (Lipoamida)/antagonistas & inibidores , Synechocystis/efeitos dos fármacos , Tiamina/análogos & derivados , Tiamina/farmacologia , Animais , Sítios de Ligação , Descoberta de Drogas , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Modelos Moleculares , Estrutura Molecular , Conformação Proteica , Relação Estrutura-Atividade , Suínos , Tiamina/química
20.
Environ Sci Pollut Res Int ; 26(31): 32255-32265, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31598929

RESUMO

Microcystis aeruginosa, a species of freshwater cyanobacteria, is known to be one of the dominant species causing cyanobacterial harmful algal blooms (CyanoHABs). M. aeruginosa blooms have the potential to produce neurotoxins and peptide hepatotoxins, such as microcystins and lipopolysaccharides (LPSs). Currently, technologies for CyanoHAB control do not provide any ultimate solution because of the secondary pollution associated with the control measures. In this study, we attempted to use the peptide HPA3NT3-A2, which has been reported to be nontoxic and has antimicrobial properties, for the development of an eco-friendly control against CyanoHABs. HPA3NT3-A2 displayed significant algicidal effects against M. aeruginosa cells. HPA3NT3-A2 induced cell aggregation and flotation (thereby facilitating harvest), inhibited cell growth through sedimentation, and eventually destroyed the cells. HPA3NT3-A2 had no algicidal effect on other microalgal species such as Haematococcus pluvialis and Chlorella vulgaris. Additionally, HPA3NT3-A2 was not toxic to Daphnia magna. The algicidal mechanism of HPA3NT3-A2 was intracellular penetration. The results of this study suggest the novel possibility of controlling CyanoHABs using HPA3NT3-A2.


Assuntos
Antibacterianos/farmacologia , Chlorella vulgaris/efeitos dos fármacos , Cianobactérias/química , Daphnia/efeitos dos fármacos , Água Doce/microbiologia , Proliferação Nociva de Algas/efeitos dos fármacos , Microalgas/efeitos dos fármacos , Microcystis/efeitos dos fármacos , Animais , Antibacterianos/química , Chlorella vulgaris/química , Cianobactérias/efeitos dos fármacos , Microcistinas
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