RESUMEN
Adsorbents with good dispersibility and high efficiency are crucial for magnetic solid-phase extraction (MSPE). In this study, flower-like magnetic nanomaterials (F-Ni@NiO@ZnO2-C) were successfully prepared by calcination of metal-organic framework (MOF) precursors that was stacked by two-dimensional (2D) nanosheet. The synthesized F-Ni@NiO@ZnO2-C has a flower-like layered structure with a large amount of pore space, promoting the rapid diffusion of targets. In addition, Zn2+ doped in MOF precursors was still retained that further produced strong metal chelation with targets. The unique structure of F-Ni@NiO@ZnO2-C was used as MSPE adsorbent, and combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for extraction of three microcystins (MCs) detection, including microcystin-LR (MC-LR), microcystin-RR (MC-RR), microcystin-YR (MC-YR). The resulting method has a detection limit of 0.2-1.0 pg mL-1, a linear dynamic range of 0.6-500.0 pg mL-1 and has good linearity (R ≥ 0.9996). Finally, the established method was applied to the highly selective enrichment of MCs in biological samples, successfully detecting trace amounts of MCs (8.4-15.0 pg mL-1) with satisfactory recovery rates (83.7-103.1 %). The results indicated that flower-like magnetic F-Ni@NiO@ZnO2-C was a promising adsorbent, providing great potential for the determination of trace amounts of MCs in biological samples.
Asunto(s)
Límite de Detección , Microcistinas , Extracción en Fase Sólida , Espectrometría de Masas en Tándem , Microcistinas/aislamiento & purificación , Microcistinas/química , Microcistinas/análisis , Extracción en Fase Sólida/métodos , Cromatografía Líquida de Alta Presión/métodos , Espectrometría de Masas en Tándem/métodos , Estructuras Metalorgánicas/química , Nanoestructuras/química , Adsorción , Carbono/química , Organismos Acuáticos/química , Animales , Reproducibilidad de los Resultados , Níquel/químicaRESUMEN
The rise in cyanobacterial blooms due to eutrophication and climate change has increased cyanotoxin presence in water. Most current water treatment plants do not effectively remove these toxins, posing a potential risk to public health. This study introduces a water treatment approach using nanostructured beads containing magnetic nanoparticles (MNPs) for easy removal from liquid suspension, coated with different adsorbent materials to eliminate cyanotoxins. Thirteen particle types were produced using activated carbon, CMK-3 mesoporous carbon, graphene, chitosan, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidised cellulose nanofibers (TOCNF), esterified pectin, and calcined lignin as an adsorbent component. The particles' effectiveness for detoxification of microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-A (ATX-A) was assessed in an aqueous solution. Two particle compositions presented the best adsorption characteristics for the most common cyanotoxins. In the conditions tested, mesoporous carbon nanostructured particles, P1-CMK3, provide good removal of MC-LR and Merck-activated carbon nanostructured particles, P9-MAC, can remove ATX-A and CYN with high and fair efficacy, respectively. Additionally, in vitro toxicity of water treated with each particle type was evaluated in cultured cell lines, revealing no alteration of viability in human renal, neuronal, hepatic, and intestinal cells. Although further research is needed to fully characterise this new water treatment approach, it appears to be a safe, practical, and effective method for eliminating cyanotoxins from water.
Asunto(s)
Toxinas Bacterianas , Toxinas de Cianobacterias , Toxinas Marinas , Microcistinas , Purificación del Agua , Toxinas de Cianobacterias/química , Humanos , Microcistinas/toxicidad , Microcistinas/química , Microcistinas/aislamiento & purificación , Toxinas Marinas/toxicidad , Toxinas Marinas/química , Toxinas Marinas/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Toxinas Bacterianas/toxicidad , Toxinas Bacterianas/química , Toxinas Bacterianas/aislamiento & purificación , Alcaloides/química , Alcaloides/toxicidad , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/toxicidad , Tropanos/química , Tropanos/toxicidad , Tropanos/aislamiento & purificación , Nanoestructuras/química , Nanoestructuras/toxicidad , Uracilo/análogos & derivados , Uracilo/química , Uracilo/toxicidad , Cianobacterias/química , Supervivencia Celular/efectos de los fármacos , Contaminantes Químicos del Agua/toxicidad , Contaminantes Químicos del Agua/químicaRESUMEN
In the present study, algicidal bacteria cultivated in an aqueous medium were utilized as a surface modification agent to develop an efficient adsorbent for the removal of Microcystis aeruginosa. The modification considerably enhanced M. aeruginosa cell removal efficiency. Moreover, the introduction of bio-compounds ensured specificity in the removal of M. aeruginosa. Additionally, the cyanotoxin release and acute toxicity tests demonstrated that the adsorption process using the developed adsorbent is environmentally safe. Furthermore, the practical feasibility of the adsorptive removal of M. aeruginosa was confirmed through cell removal tests performed using the developed adsorbent in a scaled-up reactor (50 L and 10 tons). In these tests, the effects of the adsorbent application type, water temperature, and initial cell concentration on the M. aeruginosa removal efficiency were evaluated. The results of this study provide novel insights into the valorization strategy of biological algicides repurposed as adsorbents, and provide practical operational data for effective M. aeruginosa removal in scaled-up conditions.
Asunto(s)
Microcystis , Adsorción , Microcistinas/química , Microcistinas/metabolismo , Microcistinas/aislamiento & purificación , Cianobacterias/metabolismo , Purificación del Agua/métodosRESUMEN
The scarcity of selective adsorbents for efficient extraction and removal of microcystins (MCs) from complex samples greatly limits the precise detection and effective control of MCs. Three-dimensional covalent organic frameworks (3D COFs), characterized by their large specific surface areas and highly ordered rigid structure, are promising candidates, but suffer from lack of specific recognition. Herein, we design to engineer molecularly imprinted cavities within 3D COFs via molecularly imprinted technology, creating a novel adsorbent with exceptional selectivity, kinetics and capacity for the efficient extraction and removal of MCs. As proof-of-concept, a new CC bond-containing 3D COF, designated JNU-7, is designed and prepared for copolymerization with methacrylic acid, the pseudo template L-arginine and ethylene dimethacrylate to yield the JNU-7 based molecularly imprinted polymer (JNU-7-MIP). The JNU-7-MIP exhibits a great adsorption capacity (156 mg g-1) for L-arginine. Subsequently, the JNU-7-MIP based solid-phase extraction coupled with high performance liquid chromatography-mass spectrometry achieves low detection limit of 0.008 ng mL-1, wide linear range of 0.025-100 ng mL-1, high enrichment factor of 186, rapid extraction of 10 min, and good recoveries of 92.4%-106.5% for MC-LR. Moreover, the JNU-7-MIP can rapidly remove the MC-LR from 1 mg L-1 to levels (0.26-0.35 µg L-1) lower than the WHO recommended limit for drinking water (1 µg L-1). This work reveals the considerable potential of 3D COF based MIPs as promising adsorbents for the extraction and removal of contaminants in complex real samples.
Asunto(s)
Microcistinas , Impresión Molecular , Extracción en Fase Sólida , Contaminantes Químicos del Agua , Microcistinas/aislamiento & purificación , Microcistinas/química , Microcistinas/análisis , Adsorción , Extracción en Fase Sólida/métodos , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación , Contaminantes Químicos del Agua/análisis , Estructuras Metalorgánicas/química , Arginina/química , Polímeros Impresos Molecularmente/química , Cromatografía Líquida de Alta Presión , Límite de DetecciónRESUMEN
The present study assessed the effective use of biochar for the adsorption of two potent HAB toxins namely, Microcystin-LR (MCLR) and Saxitoxin (STX) through a combination of dosage, kinetic, equilibrium, initial pH, and competitive adsorption experiments. The adsorption results suggest that biochar has excellent capabilities for removing MCLR and STX, with STX reporting higher adsorption capacities (622.53-3507.46 µg/g). STX removal required a minimal dosage of 0.02 g/L, while MCLR removal needed 0.4 g/L for > 90%. Similarly, a shorter contact time was required for STX removal compared to MCLR for > 90% of toxin removed from water. Initial pH study revealed that for MCLR acidic conditions favored higher uptake while STX favored basic conditions. Kinetic studies revealed that the Elovich model to be most suitable for both toxins, while STX also showed suitable fittings for Pseudo-First Order and Pseudo-Second Order in individual toxin systems. Similarly, for the Elovich model the most suited kinetic model for both toxins in presence of each other. Isotherm studies confirmed the Langmuir-Freundlich model as the best fit for both toxins. These results suggest adsorption mechanisms including pore filling, hydrogen bonding, π-π interactions, hydrophobic interactions, electrostatic attraction, and dispersive interactions.
Asunto(s)
Carbón Orgánico , Toxinas Marinas , Microcistinas , Saxitoxina , Purificación del Agua , Microcistinas/química , Microcistinas/aislamiento & purificación , Carbón Orgánico/química , Saxitoxina/química , Toxinas Marinas/química , Adsorción , Cinética , Purificación del Agua/métodos , Concentración de Iones de Hidrógeno , Contaminantes Químicos del Agua/químicaRESUMEN
A novel Ag3PO4/ZnWO4-modified graphite felt electrode (AZW@GF) was prepared by drop coating method and applied to photoelectrocatalytic removal of harmful algae. Results showed that approximately 99.21% of chlorophyll a and 91.57% of Microcystin-LR (MCLR) were degraded by the AZW@GF-Pt photoelectrocatalytic system under the optimal operating conditions with a rate constant of 0.02617 min-1 and 0.01416 min-1, respectively. The calculated synergistic coefficient of photoelectrocatalytic algal removal and MC-LR degradation by the AZW@GF-Pt system was both larger than 1.9. In addition, the experiments of quenching experiments and electron spin resonance (ESR) revealed that the photoelectrocatalytic reaction mainly generated â¢OH and â¢O2- for algal removal and MC-LR degradation. Furthermore, the potential pathway for photoelectrocatalytic degradation of MC-LR was proposed. Finally, the photoelectrocatalytic cycle algae removal experiments were carried out on AZW@GF electrode, which was found to maintain the algae removal efficiency at about 91% after three cycles of use, indicating that the photoelectrocatalysis of AZW@GF electrode is an effective emergency algae removal technology.
Asunto(s)
Electrodos , Grafito , Toxinas Marinas , Microcistinas , Compuestos de Plata , Grafito/química , Grafito/efectos de la radiación , Microcistinas/química , Microcistinas/aislamiento & purificación , Catálisis , Compuestos de Plata/química , Fosfatos/química , Óxidos/química , Técnicas Electroquímicas , Tungsteno/química , Clorofila A/química , Zinc/química , Purificación del Agua/métodos , Clorofila/química , Procesos Fotoquímicos , Floraciones de Algas NocivasRESUMEN
Microcystins (MCs) are cyclic heptapeptidic toxins produced by many cyanobacteria. Microcystins can be accumulated in various matrices in two forms: a free cellular fraction and a covalently protein-bound form. To detect and quantify the concentration of microcystins, a panel of techniques on various matrices (water, sediments, and animal tissues) is available. The analysis of MCs can concern the free or the total (free plus covalently bound) fractions. Free-form analyses of MCs are the most common and easiest to detect, whereas total-form analyses are much less frequent and more complex to achieve. The objective of this review is to summarize the different methods of extraction and analysis that have been developed for total forms. Four extraction methods were identified: MMPB (2-methyl-3-methoxy-4-phenylbutyric acid) method, deconjugation at basic pH, ozonolysis, and laser irradiation desorption. The study of the bibliography on the methods of extraction and analysis of the total forms of MCs showed that the reference method for the subject remains the MMPB method even if alternative methods and, in particular, deconjugation at basic pH, showed results encouraging the continuation of the methodological development on different matrices and on naturally-contaminated samples.
Asunto(s)
Técnicas de Química Analítica , Cianobacterias , Microcistinas/análisis , Microcistinas/aislamiento & purificación , Animales , AguaRESUMEN
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.
Asunto(s)
Alcaloides/aislamiento & purificación , Araceae/metabolismo , Toxinas Marinas/aislamiento & purificación , Microcistinas/aislamiento & purificación , Tropanos/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Biodegradación Ambiental , Biomasa , Clorofila A/metabolismo , Cianobacterias/metabolismo , Toxinas de Cianobacterias , Conductividad Eléctrica , Concentración de Iones de Hidrógeno , Iones , Cinética , FotosíntesisRESUMEN
Microcystins (MCs), produced by Microcystis sp, are the most commonly detected cyanotoxins in freshwater, and due to their toxicity, worldwide distribution, and persistence in water, an improvement in the monitoring programs for their early detection and removal from water is necessary. To this end, we investigate the performance of three covalent organic frameworks (COFs), TpBD-(CF3)2, TpBD-(NO2)2, and TpBD-(NH2)2, for the adsorption of the most common and/or toxic MC derivatives, MC-LR, MC-RR, MC-LA, and MC-YR, from water. While MC-LR and MC-YR can be efficiently adsorbed using all three COF derivatives, high adsorption efficiencies were found for the most lipophilic toxin, MC-LA, with TpBD-(NH2)2, and the most hydrophilic one, MC-RR, with TpBD-(NO2). Theoretical calculations revealed that MC-LA and MC-RR have a tendency to be located mainly on the COF surface, interacting through hydrogen bonds with the amino and nitro functional groups of TpBD-(NH2)2 and TpBD-(NO2)2, respectively. TpBD-(NO2)2 outperforms the adsorbent materials reported for the capture of MC-RR, resulting in an increase in the maximum adsorption capacity by one order of magnitude. TpBD-(NH2)2 is reported as the first efficient adsorbent material for the capture of MC-LA. Large differences in desorption efficiencies were observed for the MCs with different COFs, highlighting the importance of COF-adsorbate interactions in the material recovery. Herein we show that efficient capture of these toxins from water can be achieved through the proper selection of the COF material. More importantly, this study demonstrates that by careful choice of COF functionalities, specific compounds can be targeted or excluded from a group of analogues, providing insight into the design of more efficient and selective adsorbent materials.
Asunto(s)
Estructuras Metalorgánicas/química , Microcistinas/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Microcystis/química , Modelos Moleculares , Purificación del Agua/métodosRESUMEN
Cyanobacterial blooms and the associated release of cyanotoxins pose problems for many conventional water treatment plants due to their limited removal by typical unit operations. In this study, a conventional water treatment process consisting of coagulation, flocculation, sedimentation, filtration, and sludge dewatering was assessed in lab-scale experiments to measure the removal of microcystin-LR and Microcystis aeruginosa cells using liquid chromatography with mass spectrometer (LC-MS) and a hemacytometer, respectively. The overall goal was to determine the effect of recycling cyanotoxin-laden dewatered sludge supernatant on treated water quality. The lab-scale experimental system was able to maintain the effluent water quality below relevant the United States Environmental Protection Agency (US EPA) and World Health Organisation (WHO) standards for every parameter analyzed at influent concentrations of M. aeruginosa above 106 cells/mL. However, substantial increases of 0.171 NTU (Nephelometric Turbidity Unit), 7 × 104 cells/L, and 0.26 µg/L in turbidity, cyanobacteria cell counts, and microcystin-LR concentration were observed at the time of dewatered supernatant injection. Microcystin-LR concentrations of 1.55 µg/L and 0.25 µg/L were still observed in the dewatering process over 24 and 48 h, respectively, after the initial addition of M.aeruginosa cells, suggesting the possibility that a single cyanobacterial bloom may affect the filtered water quality long after the bloom has dissipated when sludge supernatant recycling is practiced.
Asunto(s)
Agua Potable/microbiología , Floraciones de Algas Nocivas , Toxinas Marinas/aislamiento & purificación , Microcistinas/aislamiento & purificación , Microcystis/aislamiento & purificación , Aguas del Alcantarillado/microbiología , Microbiología del Agua , Purificación del Agua , Calidad del Agua , Precipitación Química , Cromatografía Liquida , Filtración , Espectrometría de Masas , Microcystis/crecimiento & desarrollo , Microcystis/metabolismo , Nefelometría y TurbidimetríaRESUMEN
In the last decade, it has become evident that complex mixtures of cyanobacterial bioactive substances, simultaneously present in blooms, often exert adverse effects that are different from those of pure cyanotoxins, and awareness has been raised on the importance of studying complex mixtures and chemical interactions. We aimed to investigate cytotoxic and genotoxic effects of complex extracts from laboratory cultures of cyanobacterial species from different orders (Cylindrospermopsis raciborskii, Aphanizomenon gracile, Microcystis aeruginosa, M. viridis, M. ichtyoblabe, Planktothrix agardhii, Limnothrix redekei) and algae (Desmodesmus quadricauda), and examine possible relationships between the observed effects and toxin and retinoic acid (RA) content in the extracts. The cytotoxic and genotoxic effects of the extracts were studied in the human hepatocellular carcinoma HepG2 cell line, using the MTT assay, and the comet and cytokinesis-block micronucleus (cytome) assays, respectively. Liquid chromatography electrospray ionization mass spectrometry (LC/ESI-MS) was used to detect toxins (microcystins (MC-LR, MC-RR, MC-YR) and cylindrospermopsin) and RAs (ATRA and 9cis-RA) in the extracts. Six out of eight extracts were cytotoxic (0.04-2 mgDM/mL), and five induced DNA strand breaks at non-cytotoxic concentrations (0.2-2 mgDM/mL). The extracts with genotoxic activity also had the highest content of RAs and there was a linear association between RA content and genotoxicity, indicating their possible involvement; however further research is needed to identify and confirm the compounds involved and to elucidate possible genotoxic effects of RAs.
Asunto(s)
Alcaloides/toxicidad , Chlorophyta/metabolismo , Cianobacterias/metabolismo , Daño del ADN , Microcistinas/toxicidad , Micronúcleos con Defecto Cromosómico/inducido químicamente , Tretinoina/toxicidad , Alcaloides/aislamiento & purificación , Supervivencia Celular/efectos de los fármacos , Cromatografía Liquida , Ensayo Cometa , Toxinas de Cianobacterias , Células Hep G2 , Humanos , Microcistinas/aislamiento & purificación , Pruebas de Micronúcleos , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masas en Tándem , Tretinoina/aislamiento & purificaciónRESUMEN
Freshwater cyanobacterial blooms are becoming increasingly problematic microbiological pollutants, especially for the water resource and surface natural lakes. Cyanobacterial blooms, which produce toxins and microcystins, negatively affect the quality of water, animal, and human health, and they have also negative impact on recreational activities. The effect of electrochemically prepared potassium ferrate (green oxidation agent) on the water polluted by cyanobacteria and cyanotoxins was studied. The two most frequently occurring cyanobacterial genus Microcystis and Anabaena and the most toxic and abundant microcystin MC-LR were successfully inactivated and treated by ferrate. Potassium ferrates were applied at different conditions, such as varied hydrodynamics flow of samples, pH, and Fe(VI) concentrations. High detected elimination efficiency was consequently tested on the real water matrix from microbiological polluted natural lake Sastín-Gazárka in Slovakia. The ferrate application leads to the better chemical, biological, microbiological, and ecotoxicological outcomes.
Asunto(s)
Cianobacterias/aislamiento & purificación , Hierro , Lagos , Microcistinas/aislamiento & purificación , Animales , Eslovaquia , AguaRESUMEN
The ZnO-based visible-LED photocatalytic degradation and mineralization of two typical cyanotoxins, microcystin-LR (MC-LR), and anatoxin-A were examined. Al-doped ZnO nanoparticle photocatalysts, in Al:Zn ratios between 0 and 5 at.%, were prepared via sol-gel method and exhaustively characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and nitrogen adsorption-desorption isotherms. With both cyanotoxins, increasing the Al content enhances the degradation kinetics, hence the use of nanoparticles with 5 at.% Al content (A5ZO). The dosage affected both cyanotoxins similarly, and the photocatalytic degradation kinetics improved with photocatalyst concentrations between 0.5 and 1.0 g L-1. Nevertheless, the pH study revealed that the chemical state of a species decisively facilitates the mutual interaction of cyanotoxin and photocatalysts. A5ZO nanoparticles achieved better outcomes than other photocatalysts to date, and after 180 min, the mineralization of anatoxin-A was virtually complete in weak alkaline medium, whereas only 45% of MC-LR was in neutral conditions. Moreover, photocatalyst reusability is clear for anatoxin-A, but it is adversely affected for MC-LR.
Asunto(s)
Aluminio/química , Toxinas Marinas/aislamiento & purificación , Nanopartículas del Metal/química , Microcistinas/aislamiento & purificación , Procesos Fotoquímicos , Tropanos/aislamiento & purificación , Óxido de Zinc/química , Catálisis , Toxinas de Cianobacterias , Concentración de Iones de Hidrógeno , Cinética , Luz , Fotoquímica , Fotólisis , Contaminantes Químicos del Agua/aislamiento & purificaciónRESUMEN
Microcystis is a widespread freshwater cyanobacterium that can produce microcystin, a potent hepatotoxin harmful to animals and humans. Therefore, it is crucial to monitor for the presence of toxigenic Microcystis spp. to provide early warning of potential microcystin contamination. Microscopy, which has been used traditionally to identify Microcystis spp., cannot differentiate toxigenic from non-toxigenic Microcystis. We developed a PCR-based method to detect toxigenic Microcystis spp. based on detection of the microcystin synthetase C (mcyC) gene and 16S rRNA gene. Specificity was validated against toxic and nontoxic M. aeruginosa strains, as well as 4 intergeneric freshwater cyanobacterial strains. Analytical sensitivity was as low as 747 fg/µL genomic DNA (or 3 cells/µL) for toxic M. aeruginosa. Furthermore, we tested 60 water samples from 4 farm ponds providing drinking water to swine facilities in the midwestern United States using this method. Although all water samples were positive for Microcystis spp. (i.e., 16S rRNA gene), toxigenic Microcystis spp. were detected in only 34 samples (57%). Seventeen water samples contained microcystin (0.1-9.1 µg/L) determined with liquid chromatography-mass spectrometry, of which 14 samples (82%) were positive for mcyC. A significant correlation was found between the presence of toxigenic Microcystis spp. and microcystin in water samples (p = 0.0004). Our PCR method can be a low-cost molecular tool for rapid and specific identification of toxigenic Microcystis spp. in farm ponds, improving detection of microcystin contamination, and ensuring water safety for farm animals.
Asunto(s)
Microcistinas/aislamiento & purificación , Microcystis/aislamiento & purificación , Reacción en Cadena de la Polimerasa/veterinaria , Estanques/microbiología , Proteínas Bacterianas/análisis , Toxinas Bacterianas/análisis , Eutrofización , Granjas , Medio Oeste de Estados Unidos , Reacción en Cadena de la Polimerasa/métodos , ARN Bacteriano/análisis , ARN Ribosómico 16S/análisisRESUMEN
Harmful algal blooms formed by colony-forming cyanobacteria deteriorate water resources by producing cyanotoxins, which frequently occur at high intracellular concentrations. We aimed to localize toxic microcystins (MCs) and bioactive anabaenopeptins (APs) at the subcellular level under noninvasive conditions. Since both metabolites are synthesized nonribosomally, the relaxed specificity of key enzymes catalyzing substrate activation allowed chemical labeling through a standard copper-catalyzed click chemistry reaction. The genera Planktothrix and Microcystis specifically incorporated unnatural amino acids such as N-propargyloxy-carbonyl-L-lysine or O-propargyl-L-tyrosine, resulting in modified AP or MC peptides carrying the incorporated alkyne moiety. The labeled cells were quantitatively differentiated from the unlabeled control cells. MCs and APs occurred intracellularly as distinct entities showing a cell-wide distribution but a lowered spatial overlap with natural autofluorescence. Using the immunofluorescence technique, colocalization with markers of individual organelles was utilized to relate the distribution of labeled MCs to cellular compartments, e.g., using RbcL and FtsZ (cytosol) and PsbA (thylakoids). The colocalization correlation coefficients calculated pairwise between organelles and autofluorescence were highly positive as opposed to the relatively low positive indices derived from labeled MCs. The lower correlation coefficients imply that only a portion of the labeled MC molecules were related spatially to the organelles in the cell.
Asunto(s)
Toxinas Bacterianas/aislamiento & purificación , Cianobacterias/química , Microcistinas/aislamiento & purificación , Péptidos Cíclicos/aislamiento & purificación , Aminoácidos/química , Aminoácidos/metabolismo , Toxinas Bacterianas/química , Química Clic , Cianobacterias/crecimiento & desarrollo , Cianobacterias/metabolismo , Agua Dulce/química , Floraciones de Algas Nocivas , Microcistinas/química , Péptidos Cíclicos/químicaRESUMEN
Microcystins (MCs) are potent toxins produced by environmental cyanobacterial blooms. The present study evaluated the effects of a Microcystis aeruginosa cyanobacterial lysate containing 0.1, 1, and 10 µg L-1 MC-LR equivalent in the C. elegans Bristol N2 wild-type and the effects caused by equivalent concentrations of a MC-LR standard. The lysate was prepared from a culture of toxic strain (RST9501) originated from the Patos Lagoon Estuary (RS, Brazil). The minimal concentration necessary to cause significant effects in C. elegans under exposure to M. aeruginosa lysate or to MC-LR standard were, respectively, 10 and 0.1 µg L-1 MC-LR equivalent for growth and 10 and 1 µg L-1 MC-LR equivalent for fertility. Reproduction (ie, brood size) was only affected by the exposure to 10 µg L-1 MC-LR standard and was not affected by the lysate. The nematodes that were exposed to lysate containing 1 µg L-1 MC-LR equivalent or MC-LR were also analyzed for pharyngeal pumping and gene expression using RT-qPCR. The worms' rhythmic contractions of the pharynx were similarly affected by the lysate containing 1 µg L-1 of MC-LR equivalent and the MC-LR standard. The MC-LR standard caused down-regulation of genes related to growth (daf-16), fertility (spe-10), and biotransformation (gst-2). This is the first study to evaluate the effects of a toxic cyanobacterial lysate using the C. elegans model. This study suggests the organism as a potential biotest to evaluate toxicity of natural waters containing M. aeruginosa cells and to environmental risk assessment associated to cyanobacterial bloom events.
Asunto(s)
Caenorhabditis elegans/efectos de los fármacos , Microcistinas/toxicidad , Microcystis/química , Contaminantes Químicos del Agua/toxicidad , Animales , Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiología , Conducta Alimentaria/efectos de los fármacos , Expresión Génica/efectos de los fármacos , Toxinas Marinas , Microcistinas/aislamiento & purificación , Microcystis/metabolismo , Reproducción/efectos de los fármacos , Contaminantes Químicos del Agua/aislamiento & purificaciónRESUMEN
[D-Leu1]MC-LY (1) ([M + H]+m/z 1044.5673, Δ 2.0 ppm), a new microcystin, was isolated from Microcystis aeruginosa strain CPCC464. The compound was characterized by 1H and 13C NMR spectroscopy, liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS) and UV spectroscopy. A calibration reference material was produced after quantitation by 1H NMR spectroscopy and LC with chemiluminescence nitrogen detection. The potency of 1 in a protein phosphatase 2A inhibition assay was essentially the same as for MCLR (2). Related microcystins, [D-Leu1]MC-LR (3) ([M + H]+m/z 1037.6041, Δ 1.0 ppm), [D-Leu1]MC-M(O)R (6) ([M + H]+m/z 1071.5565, Δ 2.0 ppm) and [D-Leu1]MC-MR (7) ([M + H]+m/z 1055.5617, Δ 2.2 ppm), were also identified in culture extracts, along with traces of [D-Leu1]MC-M(O2)R (8) ([M + H]+m/z 1087.5510, Δ 1.6 ppm), by a combination of chemical derivatization and LC-HRMS/MS experiments. The relative abundances of 1, 3, 6, 7 and 8 in a freshly extracted culture in the positive ionization mode LC-HRMS were ca. 84, 100, 3.0, 11 and 0.05, respectively. These and other results indicate that [D-Leu1]-containing MCs may be more common in cyanobacterial blooms than is generally appreciated but are easily overlooked with standard targeted LC-MS/MS screening methods.
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Microcistinas/aislamiento & purificación , Microcystis , Cromatografía Liquida , Microcistinas/química , Proteína Fosfatasa 2/antagonistas & inhibidores , Espectroscopía de Protones por Resonancia Magnética , Espectrometría de Masas en TándemRESUMEN
Adsorbent Fe3O4/chitosan was successfully synthesized for the removal of microcystin-LR and characterized by Scanning electron microscope, Fourier transform infra-red, thermogravimetric analysis and vibrating sample magnetometer. The effects of reaction conditions, including pH, temperature and ratio of Fe3O4 to chitosan on microcystin-LR adsorption capacity were investigated by the Box-Behnken response surface methodology design, and the optimal adsorption conditions were determined. The adsorption properties of microcystin-LR were examined by adsorption kinetics, isothermal and thermodynamics experiments. The results demonstrated that Fe3O4/chitosan was successfully prepared and the maximum adsorption capacity of microcystin-LR was under optimum conditions in which pH value was 5.53, temperature was 40 °C and the ratio of Fe3O4 to chitosan was 1:1.39. The data revealed that kinetics was fitted well with the pseudo-second-order model, Langmuir isotherm model was more appropriate for describing than the Freundlich isotherm model and the adsorption of microcystin-LR was a spontaneous process. The material maintained good adsorption capacity after five cycles. The results suggested that Fe3O4/chitosan was an efficient and low-cost adsorbent for removing microcystin-LR from polluted water.
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Quitosano/química , Compuestos Férricos/química , Toxinas Marinas/química , Toxinas Marinas/aislamiento & purificación , Microcistinas/química , Microcistinas/aislamiento & purificación , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Concentración de Iones de Hidrógeno , Cinética , TemperaturaRESUMEN
The presence of cyanobacteria in drinking water, aquatic foods and bathing water has created a significant major problem to global public health as these toxins induce damage in various organ including liver, cardiovascular, intestinal and central nervous systems. Although the morphologic, phylogenetic and toxicogenetic characteristics of cyanobacteria were identified in several lakes in China, many freshwater sources such as Dong Ting Lake, Hunan Province, China remain to be determined. Since the presence of these cyanobacteria may potentially affect human health, the aim of this study was to isolate, identify and characterize the most frequent occurring bloom-forming cyanobacteria in Dong Ting Lake, Hunan Province, China, which can provide information on the safety of utilization of this water source for drinking water, agriculture and recreation. Samples collected from the surface water of Dong Ting Lake were subjected to serial dilution in the lab for morphological analysis. Data demonstrated the morphological features were 2-5 µm diameters with rounded shapes and green color resembling Microcystis sp. The isolated cyanobacterial strain obtained from surface water samples in Dong Ting Lake was termed Microcystis sp. YFM2. The MC concentration was detected by enzyme-linked immunosorbent assay (ELISA) and found to be 92.88 µg/107 cells in Microcystis sp. YFM2. By polymerase chain reaction (PCR) results indicated that Microcystis sp. YFM2 isolated from Dong Ting Lake contained synthetase genes (mcyA-C). Our findings indicated that the dominant cyanobacteria Microcystis sp. YFM2 isolated from the freshwater Dong Ting Lake demonstrated morphologic, phylogenetic and toxicogenetic properties resembling a toxin generating cyanobacterium. Based upon this knowledge, it is essential to monitor the use of this Lake for future domestic, agricultural and recreational purposes.
Asunto(s)
Monitoreo del Ambiente/métodos , Lagos/microbiología , Microcistinas/aislamiento & purificación , Microcystis/clasificación , Microcystis/genética , China , FilogeniaRESUMEN
This study develops a novel electrochemical sensing platform for microcystin-LR (MC-LR) detection. This aptasensor comprises the hybridization of double aptamer to its complementary strand (CS) on the surface of electrode and generation of an Infinity-shaped DNA structure in the absence of target by terminal deoxynucleotidyl transferase (TdT). The formation of Infinity-shaped construction leads to the development of an ultrasensitive aptasensor for MC-LR detection. In the presence of MC-LR, double aptamer is dissociated from its CS because of its high affinity for MC-LR and leaves the surface of electrode. Subsequently, no Infinity-shaped structure is formed following the introduction of TdT and a strong current signal is observed. The proposed method was employed for specific detection of MC-LR in the range from 60 pM to 1000â¯nM with a detection limit of 15 pM. The credibility of the approach was confirmed by detection of MC-LR in real samples like serum and tap water samples. This study provides a new aptasensor for detection of MC-LR as well as other toxin analysis.