Fatal dog poisoning after uptake of neurotoxic cyanobacteria associated with aquatic macrophytes in Tegeler See (Berlin, Germany) raised concerns about critical exposure of humans, especially children, to cyanotoxins produced by macrophyte associated cyanobacteria during recreational activity. From 2017 to 2021 a total of 398 samples of macrophytes washed ashore at bathing sites located at 19 Berlin lakes were analysed for anatoxins, microcystins, and cylindrospermopsins, as were 463 water samples taken in direct proximity to macrophyte accumulations. Cyanotoxins were detected in 66 % of macrophyte samples and 50 % of water samples, with anatoxins being the most frequently detected toxin group in macrophyte samples (58 %) and cylindrospermopsins in water samples (41 %). Microcoleus sp. associated with the water moss Fontinalis antipyretica was identified as anatoxin producing cyanobacterium in isolated strains as well as in field samples from Tegeler See. Anatoxin contents in macrophyte samples rarely exceeded 1 (micro)g/g macrophyte fresh weight and peaked at 9. 2 (micro)g/g f.w. Based on established toxicological points of departure, a critical anatoxin content of macrophyte samples of 3 (micro)g/g f.w. is proposed. Five samples, all taken in Tegeler See and all associated with the water moss Fontinalis antipyretica, exceeded this value. Contents and concentrations of microcystins and cylindrospermopsins did not reach critical levels. The potential exposure risks to anatoxins for children and dogs are assessed and recommendations are given. © 2022 The Authors
Cyanobacteria are favored by climate change and global warming; however, to date, mostresearch and monitoring programs have focused on planktic cyanobacteria. Benthic cyanobacte-ria blooms also increase and pose a risk to animal and human health; however, there is limitedknowledge of their occurrence, distribution and the toxins involved, especially in relation to theirplanktic conspeciï Ącs. Therefore, we analyzed the benthic and planktic life forms of cyanobacterialcommunities in 34 lakes in Germany, including a monitoring of cyanotoxins. Community analyseswere based on microscopic examination and Illumina sequencing of the 16S rRNA gene. The analysesof cyanotoxins were carried out using LC-MS/MS and ELISA. Observed benthic mats containingcyanobacteria consisted mainly of Nostocales and Oscillatoriales, being present in 35% of the lakes. Ana-toxin was the most abundant cyanotoxin in the benthic samples, reaching maximum concentrationsof 45,000Ìg/L, whereas microcystin was the predominate cyanotoxin in the open-water samples,reaching concentrations of up to 18,000Ìg/L. Based on the results, speciï Ąc lakes at risk of toxiccyanobacteria could be identiï Ąed. Our ï Ąndings suggest that monitoring of benthic cyanobacteria andtheir toxins should receive greater attention, ideally complementing existing open-water samplingprograms with little additional effort. © 2023 by the authors.
Chytrid parasites are increasingly recognized as ubiquitous and potent control agents of phytoplankton, including bloom-forming toxigenic cyanobacteria. In order to explore the fate of the cyanobacterial toxin microcystins (MCs) and assess potential upregulation of their production under parasite attack, a laboratory experiment was conducted to evaluate short- and long-term variation in extracellular and intracellular MC in the cyanobacteria Planktothrix agardhii and P. rubescens, both under chytrid infection and in the presence of lysates of previously infected cyanobacteria. MCs release under parasite infection was limited and not different to uninfected cyanobacteria, with extracellular toxin shares never exceeding 10%, substantially below those caused by mechanical lysis induced by a cold-shock. Intracellular MC contents in P. rubescens under infection were not significantly different from uninfected controls, whereas infected P. agardhii showed a 1.5-fold increase in intracellular MC concentrations, but this was detected within the first 48 hours after parasite inoculation and not later, indicating no substantial MC upregulation in cells being infected. The presence of lysates of previously infected cyanobacteria did not elicit higher intracellular MC contents in exposed cyanobacteria, speaking against a putative upregulation of toxin production induced via quorum sensing in response to parasite attack. These results indicate that chytrid epidemics can constitute a bloom decay mechanism that is not accompanied by massive release of toxins into the medium. © 2022 Elsevier
Although the use of genetically modified plants for bioremediation, or the in situ cleaning of contaminated sites, has been known for quite some time, little attention has so far been paid to the production of antibodies in plants and their ex vivo application in selective depletion. Therefore, highly affine and specific antibodies against algal toxins using microcystin as an example will be produced in plants at low cost within this research project. The basis is a monoclonal antibody (Mab 10E7, species: mouse) generated in a former research project. The sequence of the variable domains will be determined, optimized for plants and sub cloned into suitable plant transformation vectors, which already contain constant antibody sequences. In addition, a scFv fragment containing different tag sequences and fusion proteins will be constructed. Leaf-based (tobacco) as well as seed-based (barley) systems will be used.Affinity-purified plant-produced antibodies (plantibodies) will be characterized in detail for their binding properties using microtitre plate-ELISA and surface plasmon resonance (SPR). The monoclonal mouse antibody will be used as reference. To assure cost-efficiency for future applications, roughly purified fractions (sequential pH and temperature treatment followed by filtration) will be tested for the upscaling. Following immobilization of the plantibody fractions on suitable substrates, for instance membranes, porous polymer monoliths or in porous glasses, their application for depletion will be defined using model water samples spiked fortified with microcystins.
Cyanobacteria are known to produce a wide array of metabolites, including various classes of toxins. Among these, hepatotoxins (Microcystins), neurotoxins (Anatoxin-A and PSP toxins) or cytotoxins (Cylindrospermopsins) have been subjected to numerous, individual studies during the past twenty years. Reports of toxins co-occurrences, however, remain scarce in the literature. The present work is an inventory of cyanobacteria with a particular focus on Nostocales and their associated toxin classes from 2007 to 2010 in ten lakes used for drinking water production in France. The results show that potential multiple toxin producing species are commonly encountered in cyanobacteria populations. Individual toxin classes were detected in 75% of all samples. Toxin co-occurrences appeared in 40% of samples as two- or three-toxin combinations (with 35% for the microcystinsâ€Ìanatoxin combination), whereas four-toxin class combinations only appeared in 1% of samples. Toxin co-occurrences could be partially correlated to species composition and water temperature. Peak concentrations however could never be observed simultaneously and followed distinct, asymmetrical distribution patterns. As observations are the key for preventive management and risk assessment, these results indicate that water monitoring should search for all four toxin classes simultaneously instead of focusing on the most frequent toxins, i.e., microcystins Quelle: https://www.mdpi.com
Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains. Quelle: https://www.mdpi.com
TOXIC will focus on the reduction of the human health risk due to the occurrence of potentially toxic cyanobacteria and cyanotoxins in drinking water sources. The proposed project contains multidisciplinary aspects ranging from raw water monitoring and cyanotoxin identification and analysis to the behaviour of cyanobacteria and their toxins during water treatment processes, including cost evaluation, application and exploitation of the results by potential end-users. With respect to the WHO Guideline Value of 1.0 ug/L for microcystin-LR in drinking water, TOXIC will provide tools for early warning in the case of massive algal blooms as well as cost-effective and problem-driven treatment approaches. An Internet-based cyanobacteria platform, 'Best practise' guidance for raw water monitoring, analysis and treatment as well as a commercially available software package far treatment simulation will expected as highlighted project results.
Cyanobakterien ('Blaualgen') produzieren oft erhebliche Mengen toxischer cyclischer Heptapeptide (Microcystine; MCYST). Diese Verbindungen sind hinsichtlich ihrer Biochemie und ihrer Öko- und Humantoxikologie ziemlich gut untersucht. Studien zur ökologischen Relevanz von MCYST für die Produzenten sind demgegenüber eher selten. Die MCYST-produzierenden Cyanobakterien überwintern im Sediment der Gewässer, steigen im Frühjahr aktiv in die Freiwasserzone auf, wachsen dort und sedimentieren dann im Spätsommer/Herbst unter 'Mitnahme' der MCYST. Eine mögliche Variabilität der ökologischen Funktion von MCYST wurde im bisherigen Projektverlauf auf die Prozesse Wachstum sowie die Übergangsprozesse Aufstieg und Sedimentation eingeschränkt. Über eine MCYST-Massenbilanz und Laborexperimente sollen diese Prozesse näher charakterisiert werden. Die Arbeiten konzentrieren sich (1) auf die Rolle von MCYST während des Aufsteigens der Startpopulation, (2) auf die Steuerung der MCYST-Produktion während des exponentiellen Wachstums (Hypothese: MCYST erhöht die Effizienz der C-Assimilation), (3) die Rolle von MCYST bei der Sedimentation. Die Ergebnisse könnten Möglichkeiten zur zielgerichteten Unterdrückung der Toxinproduktion im Rahmen der Wassergütebewirtschaftung aufzeigen.
Objective/Problems to be solved: Water is becoming an increasingly scarce resource throughout the world and furthermore, many of these limited supplies have become nutrient enriched, supporting the growth of toxic cyanobacteria. These organisms produce extremely toxic naturally occurring compounds that frequently cause the death of both wild and domestic animals via ingestion of contaminated water. The death of patients undergoing dialysis has also been reported as a result of water used in their treatment being contaminated with the cyanotoxin microcystin-LR. In recognition of the potential risk to human health posed by cyanotoxins the World Health Organisation has now established a maximum limit of 1 Ag l-1 of microcystin-LR in drinking water. Cyanotoxins are very stable and traditional water treatment processes will not destroy them. There is also growing concern over contamination of water by pathogenic bacteria including E. coli O157 that has been associated with a number of high profile health incidents. The proposed revised Drinking Water Directive 98/83/EC will characterise high priority water pollutants. Toxin-producing algae have been specifically highlighted as a potential key hazardous pollutant. It has been identified that work needs to be carried out in developing expertise on these species and how to deal with them in drinking water. The new directive will also include a requirement to verify the efficiency of disinfection. This research proposal includes the development of such a device on the water treatment unit: The European Commission Task Force on Environment-Water identified 10 priority areas (so called 'action lines') for EU collaborative research and development in the area of freshwater. Action line 3 specifically highlights toxin-producing algae as a potential key hazardous pollutant and identified that work needs to be carried out developing expertise on these species and how to deal with them in drinking water. It also specifically mentions inadequate treatment of drinking water as being a potential problem. Action line 4 details the requirement to develop water treatment technologies for, among other things, the disinfection of drinking water. Photocatalytic oxidation is an advanced water treatment sub-technology specifically identified as an area where research should be concentrated. Scientific objectives and approach: The problems of contamination of drinking water by cyanotoxins and E. coli will be investigated using semiconductor photocatalysis. The objective of this project is to develop a method primarily for dealing with cyanotoxins in drinking water. In addition the destruction of the pathogenic micro-organism, E. coli, will also be investigated. A novel biosensor will be developed for the on-line detection of cyanotoxins in water... Prime Contractor: The Robert Gordon Unversity, School of Mechanical and Offshore Engineering; Aberdeen/Scotland.
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