scholarly journals A Brief Review of the Structure, Cytotoxicity, Synthesis, and Biodegradation of Microcystins

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2147
Author(s):  
Anjali Krishnan ◽  
Xiaozhen Mou
Keyword(s):  
Health Hazard ◽  
Aquatic Organisms ◽  
Water Soluble ◽  
Cyanobacterial Blooms ◽  
Aquatic Environments ◽  
Natural Environments ◽  
Exposure Pathway ◽  
Environmental Transformation ◽  
Cyclic Heptapeptide ◽  
Harmful Cyanobacterial Blooms

Harmful cyanobacterial blooms pose an environmental health hazard due to the release of water-soluble cyanotoxins. One of the most prevalent cyanotoxins in nature is microcystins (MCs), a class of cyclic heptapeptide hepatotoxins, and they are produced by several common cyanobacteria in aquatic environments. Once released from cyanobacterial cells, MCs are subjected to physical chemical and biological transformations in natural environments. MCs can also be taken up and accumulated in aquatic organisms and their grazers/predators and induce toxic effects in several organisms, including humans. This brief review aimed to summarize our current understanding on the chemical structure, exposure pathway, cytotoxicity, biosynthesis, and environmental transformation of microcystins.

scholarly journals Inhibition of Extracellular Enzymes Exposed to Cyanopeptides

2020 ◽  
Vol 74 (3) ◽  
pp. 122-128
Author(s):  
Christine M. Egli ◽  
Regiane S. Natumi ◽  
Martin R. Jones ◽  
Elisabeth M.-L. Janssen
Keyword(s):  
Extracellular Enzymes ◽  
Heterotrophic Bacteria ◽  
Hydrolytic Enzymes ◽  
Aquatic Organisms ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
Biologically Relevant ◽  
Metabolic Functions ◽  
Harmful Cyanobacterial Blooms ◽  
Quality Assessments

Harmful cyanobacterial blooms in freshwater ecosystems produce bioactive secondary metabolites including cyanopeptides that pose ecological and human health risks. Only adverse effects of one class of cyanopeptides, microcystins, have been studied extensively and have consequently been included in water quality assessments. Inhibition is a commonly observed effect for enzymes exposed to cyanopeptides and has mostly been investigated for human biologically relevant model enzymes. Here, we investigated the inhibition of ubiquitous aquatic enzymes by cyanobacterial metabolites. Hydrolytic enzymes are utilized in the metabolism of aquatic organisms and extracellularly by heterotrophic bacteria to obtain assimilable substrates. The ubiquitous occurrence of hydrolytic enzymes leads to the co-occurrence with cyanopeptides especially during cyanobacterial blooms. Bacterial leucine aminopeptidase and alkaline phosphatase were exposed to cyanopeptide extracts of different cyanobacterial strains ( Microcystis aeruginosa wild type and microcystin-free mutant, Planktothrix rubescens) and purified cyanopeptides. We observed inhibition of aminopeptidase and phosphatase upon exposure, especially to the apolar fractions of the cyanobacterial extracts. Exposure to the dominant cyanopeptides in these extracts confirmed that purified microcystins, aerucyclamide A and cyanopeptolin A inhibit the aminopeptidase in the low mg L–1 range while the phosphatase was less affected. Inhibition of aquatic enzymes can reduce the turnover of nutrients and carbon substrates and may also impair metabolic functions of grazing organisms.

Toxicity and removal of Direct Red 28 diazo dye in living polymeric systems

2018 ◽  
Vol 69 (7) ◽  
pp. 1628-1635 ◽  
Author(s):  
Andrei Lobiuc ◽  
Stefan Olaru ◽  
Elena Iren Hancu ◽  
Naela Costica ◽  
Maria Emiliana Fortuna ◽  
...  
Keyword(s):  
Congo Red ◽  
Lemna Minor ◽  
Aquatic Organisms ◽  
Significant Inhibition ◽  
Point Of View ◽  
Water Soluble ◽  
Aquatic Environments ◽  
Polymeric Systems ◽  
Red Dye ◽  
Direct Red 28

Aquatic environments are often contaminated with various compounds, with potential toxicity towards aquatic organisms, which may enter the food chain. Azo dyes are used in various industries and contamination of waters has been reported. The present paper assesses the toxicity of the synthetic, water soluble Congo Red dye towards Lemna minor from a physiological and cytogenetical point of view. The dye was tested in 5-5000 ppm concentrations. Total frond surface, root growth and fresh mass reductions were registered from 5 ppm dye concentration, with a concentration-dependent response and calculated EC50 of 1530 ppm. Plant growth was completely inhibited above 2500 ppm. Dye accumulation was observed in tissues, along with necrosis formation. Chlorophyll a contents decreased, while carotenoid contents increased above 2500 ppm. Significant inhibition of PSII efficiency was recorded above 1000 ppm. Mitotic indices were decreased at 5 and 1000 ppm dye and were 0 at 5000 ppm. The number of chromosomal aberrations significantly increased at 5 and 1000 ppm dye. The growth medium was decontaminated up to 56% at 250 ppm dye concentration by Lemna plants. Congo Red azo dye presented toxicity towards Lemna minor, from a physiological and cyotgenetical point of view, especially at higher concentrations. In the same time, a phytoremediation potential of duckweed with respect to the tested dye was demonstrated.

Review of the Environmental Occurrence of Alkylphenols and Alkylphenol Ethoxylates

1999 ◽  
Vol 34 (1) ◽  
pp. 79-122 ◽  
Author(s):  
Donald T. Bennie
Keyword(s):  
Agricultural Soils ◽  
Degradation Products ◽  
Sewage Treatment ◽  
Aquatic Organisms ◽  
Water Soluble ◽  
Natural Environments ◽  
Limited Information ◽  
Alkylphenol Ethoxylates ◽  
Environmental Matrices ◽  
Sewage Treatment Plants

Abstract Alkylphenol ethoxylates and, in particular, nonylphenol ethoxylates have found many industrial, commercial, institutional and household uses in Canada. These nonionic surfactants are very efficient and cost effective. Their widespread use has led to the detection of the parent surfactants and their degradation products in various environmental matrices. Alkylphenol ethoxylates can be degraded aerobically and anaerobically in natural environments and sewage treatment plants.. The resulting degradation products are more persistent, more toxic, more lipophilic, less water soluble and more estrogenic than their parent compounds. This article reviews the occurrence of nonylphenol polyethoxylates and their degradation products as well as octylphenol poly-ethoxylates and their degradation products. There is limited information available about the concentrations of these substances in their original product formulations. The highest levels of the degradation products, especially nonylphenol, occur in the anaerobically digested sludge of sewage treatment plants. Sludge from these sewage treatment plants may be used as an amendment to agricultural soils. Various sewage treatment plants have wide ranges of discharged effluent concentrations of these compounds — some appear to be very efficient at removing alkylphenolics from their effluent stream. Little information is available about the fate of these substances in their receiving environment, and environmental concentrations and bioaccumulation factors of these contaminants in aquatic biota. More research is required on the uptake, persistence and bioaccumulation of alkylphenolic metabolites in fish, mussels and other aquatic organisms

scholarly journals Identification of Detoxification Esterase StrH Initiating Strobilurin Fungicides Degradation in Hyphomicrobium sp. DY-1

2021 ◽  
Author(s):  
Wankui Jiang ◽  
Qinqin Gao ◽  
Lu Zhang ◽  
Yali Liu ◽  
Mingliang Zhang ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Catalytic Efficiency ◽  
Aquatic Organisms ◽  
Degradation Process ◽  
Maximum Activity ◽  
Cyanobacterial Blooms ◽  
Strobilurin Fungicides ◽  
Novel Esterase ◽  
Esterase Gene ◽  
Harmful Cyanobacterial Blooms

Strobilurin fungicides are widely used in agricultural production due to their broad-spectrum and fungal mitochondrial inhibitory activities. However, their massive application has detained the growth of eukaryotic algae and increased the collateral damage in freshwater systems, notably the harmful cyanobacterial blooms (HCBs). In this study, a strobilurin fungicide-degrading strain Hyphomicrobium sp. DY-1 was isolated and characterized successfully. Moreover, a novel esterase gene strH responsible for the de-esterification of strobilurin fungicides was cloned, and the enzymatic properties of StrH were studied. For trifloxystrobin, StrH displayed the maximum activity at 50°C and pH 7.0. The catalytic efficiency (kcat/Km) of StrH for different strobilurin fungicides were 196.32±2.30 μM−1·s−1 (trifloxystrobin), 4.64±0.05 μM−1·s−1 (picoxystrobin), 2.94±0.02 μM−1·s−1 (pyraclostrobin), and (2.41±0.19)×10−2 μM−1·s−1 (azoxystrobin). StrH catalyzed the de-esterification of a variety of strobilurin fungicides generating the corresponding parent acid to achieve the detoxification of strobilurin fungicides and relieve strobilurin fungicides growth inhibition on Chlorella. This research will provide insight into the microbial remediation of strobilurin fungicides-contaminated environments. IMPORTANCE Strobilurin fungicides have been widely acknowledged as an essential group of pesticides worldwide. So far, their residues and toxic effects on aquatic organisms have been reported in different parts of the world. Microbial degradation could eliminate xenobiotics from the environment. Therefore, the degradation of strobilurin fungicides by microorganisms has also been reported. However, little is known about the involvement of enzyme or gene in strobilurin fungicides degradation. In this study, a novel esterase gene strH responsible for the detoxification of strobilurin fungicides was cloned in the newly isolated strain Hyphomicrobium sp. DY-1. This degradation process detoxifies the strobilurin fungicides and relieves their growth inhibition on Chlorella.

Research on Allelochemicals with Material Properties Exuded by Submerged Freshwater Macrophyte Elodea nuttallii

2014 ◽  
Vol 1023 ◽  
pp. 71-74 ◽  
Author(s):  
Yun Ni Gao ◽  
Li Ping Zhang ◽  
Bi Yun Liu ◽  
Yong Yuan Zhang ◽  
Zhen Bin Wu
Keyword(s):  
Phenolic Acids ◽  
High Growth ◽  
Aquatic Organisms ◽  
High Growth Rate ◽  
Cyanobacterial Blooms ◽  
Elodea Nuttallii ◽  
Inhibitory Effects ◽  
Methanol Fraction ◽  
Culture Density ◽  
Harmful Cyanobacterial Blooms

Elodea nuttallii is well-known for its successful invasion to Europe and Asia. In addition to its high growth rate and nutrient storage capacity, chemical defense was recently found to play an important role in excluding other aquatic organisms. To reveal the chemical nature of its allelopathic effects on cyanobacterial development, extraction of plant exudates with different solvents and eluted procedures followed by 72h bioassays with Microcystis aeruginosa was conducted. The results showed that the fraction eluted with methanol exhibited the strongest inhibitory effects, which indicated that the anti-cyanobacterial active allelochemicals released by E.nuttallii was hydrophilic. Then ten phenolic acids were identified in the purified methanol fraction of Elodea exudates by GC-MS analysis. Quantification of the four phenolic acids therein showed the release contents were lower than 10μg/L when E.nuttallii was cultivated at 10g FW/L, which increased with the increasing culture density. When the culture density was 100g FW/L, the detected contents of vanillic acid, protocatechuic acid, ferulic acid and caffeic acid in E.nuttallii culture water were 23.41μg/L, 17.56 μg/L, 12.31 μg/L and 18.93μg/L, respectively. These results were helpful to understand the allelopathy mechanisms of E.nuttallii in aquatic ecosystems and useful in control of harmful cyanobacterial blooms.

scholarly journals Phytoremediation of CYN, MC-LR and ANTX-a from Water by the Submerged Macrophyte Lemna trisulca

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 699
Author(s):  
Małgorzata Kucała ◽  
Michał Saładyga ◽  
Ariel Kaminski
Keyword(s):  
Electrical Conductivity ◽  
Chlorophyll A ◽  
Growth And Development ◽  
Cyanobacterial Blooms ◽  
Biotechnological Potential ◽  
Intracellular Pool ◽  
Ph Values ◽  
Bg11 Medium ◽  
Total Pool ◽  
Harmful Cyanobacterial Blooms

Cyanotoxins are harmful to aquatic and water-related organisms. In this study, Lemna trisulca was tested as a phytoremediation agent for three common cyanotoxins produced by bloom-forming cyanobacteria. Cocultivation of L. trisulca with Dolichospermum flos-aquae in BG11 medium caused a release of the intracellular pool of anatoxin-a into the medium and the adsorption of 92% of the toxin by the plant—after 14 days, the total amount of toxin decreased 3.17 times. Cocultivation with Raphidopsis raciborskii caused a 2.77-time reduction in the concentration of cylindrospermopsin (CYN) in comparison to the control (62% of the total pool of CYN was associated with the plant). The greatest toxin limitation was noted for cocultivation with Microcystis aeruginosa. After two weeks, the microcystin-LR (MC-LR) concentration decreased more than 310 times. The macrophyte also influenced the growth and development of cyanobacteria cells. Overall, 14 days of cocultivation reduced the biomass of D. flos-aquae, M. aeruginosa, and R. raciborskii by 8, 12, and 3 times, and chlorophyll a concentration in comparison to the control decreased by 17.5, 4.3, and 32.6 times, respectively. Additionally, the macrophyte stabilized the electrical conductivity (EC) and pH values of the water and affected the even uptake of cations and anions from the medium. The obtained results indicate the biotechnological potential of L. trisulca for limiting the development of harmful cyanobacterial blooms and their toxicity.

scholarly journals A Review on Fish Sensory Systems and Amazon Water Types With Implications to Biodiversity

2021 ◽  
Vol 8 ◽  
Author(s):  
Elio de Almeida Borghezan ◽  
Tiago Henrique da Silva Pires ◽  
Takehide Ikeda ◽  
Jansen Zuanon ◽  
Shiro Kohshima
Keyword(s):  
Aquatic Organisms ◽  
Sensory Systems ◽  
Spatial Distance ◽  
Fish Diversity ◽  
Aquatic Environments ◽  
Water Types ◽  
Local Adaptations ◽  
Freshwater Organisms ◽  
Research Perspectives ◽  
Lighting Environment

The Amazon has the highest richness of freshwater organisms in the world, which has led to a multitude of hypotheses on the mechanisms that generated this biodiversity. However, most of these hypotheses focus on the spatial distance of populations, a framework that fails to provide an explicit mechanism of speciation. Ecological conditions in Amazon freshwaters can be strikingly distinct, as it has been recognized since Alfred Russel Wallace’s categorization into black, white, and blue (= clear) waters. Water types reflect differences in turbidity, dissolved organic matter, electrical conductivity, pH, amount of nutrients and lighting environment, characteristics that directly affect the sensory abilities of aquatic organisms. Since natural selection drives evolution of sensory systems to function optimally according to environmental conditions, the sensory systems of Amazon freshwater organisms are expected to vary according to their environment. When differences in sensory systems affect chances of interbreeding between populations, local adaptations may result in speciation. Here, we briefly present the limnologic characteristics of Amazonian water types and how they are expected to influence photo-, chemical-, mechano-, and electro-reception of aquatic organisms, focusing on fish. We put forward that the effect of different water types on the adaptation of sensory systems is an important mechanism that contributed to the evolution of fish diversity. We point toward underexplored research perspectives on how divergent selection may act on sensory systems and thus contribute to the origin and maintenance of the biodiversity of Amazon aquatic environments.

scholarly journals Resilience of Microbial Communities after Hydrogen Peroxide Treatment of a Eutrophic Lake to Suppress Harmful Cyanobacterial Blooms

2021 ◽  
Vol 9 (7) ◽  
pp. 1495
Author(s):  
Tim Piel ◽  
Giovanni Sandrini ◽  
Gerard Muyzer ◽  
Corina P. D. Brussaard ◽  
Pieter C. Slot ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Microbial Community ◽  
Microbial Communities ◽  
Microbial Community Composition ◽  
Glycoside Hydrolases ◽  
Microbial Community Analysis ◽  
Cyanobacterial Blooms ◽  
Temporary Increase ◽  
Low Concentrations ◽  
Harmful Cyanobacterial Blooms

Applying low concentrations of hydrogen peroxide (H2O2) to lakes is an emerging method to mitigate harmful cyanobacterial blooms. While cyanobacteria are very sensitive to H2O2, little is known about the impacts of these H2O2 treatments on other members of the microbial community. In this study, we investigated changes in microbial community composition during two lake treatments with low H2O2 concentrations (target: 2.5 mg L−1) and in two series of controlled lake incubations. The results show that the H2O2 treatments effectively suppressed the dominant cyanobacteria Aphanizomenon klebahnii, Dolichospermum sp. and, to a lesser extent, Planktothrix agardhii. Microbial community analysis revealed that several Proteobacteria (e.g., Alteromonadales, Pseudomonadales, Rhodobacterales) profited from the treatments, whereas some bacterial taxa declined (e.g., Verrucomicrobia). In particular, the taxa known to be resistant to oxidative stress (e.g., Rheinheimera) strongly increased in relative abundance during the first 24 h after H2O2 addition, but subsequently declined again. Alpha and beta diversity showed a temporary decline but recovered within a few days, demonstrating resilience of the microbial community. The predicted functionality of the microbial community revealed a temporary increase of anti-ROS defenses and glycoside hydrolases but otherwise remained stable throughout the treatments. We conclude that the use of low concentrations of H2O2 to suppress cyanobacterial blooms provides a short-term pulse disturbance but is not detrimental to lake microbial communities and their ecosystem functioning.

The effects of a water-soluble alpha tetra-substituted zinc phthalocyanine derivative onArthrospira platensis-M2 strain

2018 ◽  
Vol 22 (08) ◽  
pp. 686-692 ◽  
Author(s):  
Armağan Günsel ◽  
Hatice Tunca ◽  
Ahmet T. Bilgiçli ◽  
Ali Doğru ◽  
M. Nilüfer Yaraşir ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Biomass Accumulation ◽  
Arthrospira Platensis ◽  
Water Soluble ◽  
Zinc Phthalocyanine ◽  
Natural Environments ◽  
Oxygen Species ◽  
Sod Activity ◽  
Future Studies

In this study, we have analyzed the effect a newly synthesized water-soluble alpha tetra-substituted zinc phthalocyanine (Pc) compound on superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) activities and biomass accumulation in the Arthrospira platensis-M2 strain to test whether this compound could be used as an algaecide or not. We found that lower concentrations (3 μg mL[Formula: see text] and 6 μg mL[Formula: see text] of Pc compound were not toxic to algae cells, as indicated by enduring biomass accumulation during the study (7 days). Higher Pc concentrations, however, were toxic and inhibited biomass accumulation. This inhibition appeared on the fourth day and persisted during the study. At higher Pc concentrations, SOD activity decreased significantly, but APX and GR activity were not affected. These results may show that Pc applications did not cause the accumulation of reactive oxygen species in Arthrospira platensis-M2 cells. Our result suggests that higher Pc concentrations did not cause oxidative stress but biomass accumulation inhibited, possibly due to some different toxicity mechanism(s), which should be carried out in the future studies. As a result, we may offer use of this compound as a means to keep under control algal populations in natural environments.

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