Variability of the microcystin synthetase gene cluster

Abstract In populations of Planktothrix, microcystin-producers and non-producers, which are morphologically identical, coexist. In order to develop a basis for the reliable detection of microcystin producers in field samples with polymerase chain reaction (PCR) based methods, we studied the presence and variability of eight regions of the mcy gene cluster in 46 Planktothrix strains, including both microcystin-producing and non-producing ones. PCR-amplification products for two mcy gene regions were also found in non-microcystin-producing strains, indicating the existence of natural mutants. PCR-products of the other regions studied were only detected in microcystin-producing strains. Two of these mcy-amplicons were variable in sequence and length. Four gene regions remained that were conserved and specific for microcystin-producing Planktothrix strains, and thus qualified to detect the respective chemotypes in environmental samples

Cyanotoxins associated with macrophytes in Berlin (Germany) water bodies – Occurrence and risk assessment

Publisher Copyright: © 2022Fatal 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 cy-anobacterium in isolated strains as well as in field samples from Tegeler See. Anatoxin contents in macrophyte samples rarely exceeded 1 mu g/g macrophyte fresh weight and peaked at 9.2 mu g/g f.w. Based on established toxicological points of departure, a critical anatoxin content of macrophyte samples of 3 mu 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 concentra-tions 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.Peer reviewe

Combating cyanobacterial proliferation by avoiding or treating inflows with high P load—experiences from eight case studies

Increased external nutrient loads of anthropogenic origin, especially those of phosphorus (P), were one of the major causes of eutrophication during the first half of the twentieth century in Europe. They led to deterioration of lake ecosystems, particularly including noxious blooms of (potentially toxic) cyanobacteria. From the 1970–1980s, strategies to decrease the phosphorus loads from sewage were increasingly implemented, among them are the ban of phosphates in detergents, the expansion of sewer systems and improvement in wastewater treatment to remove nutrients. Case studies of eight lakes, whose response to point source reduction of phosphorus was observed over decades, show that a pronounced reduction of the phosphorus load from point sources can be achieved either by the diversion of inflows carrying high loads, by upgraded sewage treatment, or by phosphorus precipitation in the major tributary directly before its inflow into the water body. Outcomes demonstrate that in order to effectively control cyanobacterial blooms, the measures taken need to reduce in-lake concentrations of total phosphorus below 20–50 µg L−1, with this threshold varying somewhat between lakes depending in particular on hydromorphological and biological conditions. Whether and when load reduction succeeds in controlling cyanobacteria depends primarily on the load remaining after remediation and on the water residence time

Különböző országokból származó cianobaktérium populációk toxicitása

7 Microcystis és 2 Planktothrix toxintermelő cianobaktérium minta vizsgálatára került sor, melyek a Velencei tóból, Braziliából és Németországból származnak. A minták egy része a természetben gyűjtött biomassza, míg másik része törzsizolátum. A toxicitás detektálására Thamnotox kittet, patkány májsejtvonalat, egértesztet alkalmaztunk. Az eredményeket összevetettük a HPLC-s analízis eredményeivel, mely szerint a brazil mintákban microcystin LR forma, vagyis a legtoxikusabb variáns nem fordult elő. A magyar és német minták egyaránt tartalmazták mindhárom vizsgált microcystin formát (LR, RR, YR), azonban a magyar mintákban az LR forma koncentrációja egy nagyságrenddel nagyobb volt, mint a német mintákban. Toxicitásban a magyar és brazil minták mutattak hasonlóságot, bár a brazil minták nem tartalmaztak LR variánst, de az RR forma koncentrációja olyan magas volt (12,5 és 14,8 mg/g), hogy ez jelentkezett a hasonló toxicitásban. A német minták alacsonyabb toxicitása a kisebb toxintartalommal magyarázható. A korreláció a Thamnotox teszt eredmények és az egérteszt eredmények között igen szoros (r: 0,967), míg a teljes toxin koncentráció és az egérteszt között 0,473, ugyanígy a teljes toxin koncentráció és a Thamnotoxkit teszt között (r: 0,680) jóval gyengébb az összefüggés. Hasonló eredményre jutottunk a májsejtekre kifejtett toxikus hatással kapcsolatban is. A biomassza kivonatok toxikusabbnak tűnnek, mint az a microcystin tartalommal magyarázható lenne, tehát feltételezhető, hogy a már ismert toxinokon kívül más toxikus hatású vegyületekkel is kell számolnunk a cianobaktériumoknál

A collaborative evaluation of LC-MS/MS based methods for BMAA analysis: soluble bound BMAA found to be an important fraction.

Exposure to β-Ν-methylamino-l-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compared. A CYANOCOST initiated workshop was organized aimed at training scientists in BMAA analysis, creating mutual understanding and paving the way towards interlaboratory comparison exercises. During this workshop, we tested different methods (extraction followed by derivatization and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis, or directly followed by LC-MS/MS analysis) for trueness and intermediate precision. We adapted three workup methods for the underivatized analysis of animal, brain and cyanobacterial samples. Based on recovery of the internal standard D3BMAA, the underivatized methods were accurate (mean recovery 80%) and precise (mean relative standard deviation 10%), except for the cyanobacterium Leptolyngbya. However, total BMAA concentrations in the positive controls (cycad seeds) showed higher variation (relative standard deviation 21%-32%), implying that D3BMAA was not a good indicator for the release of BMAA from bound forms. Significant losses occurred during workup for the derivatized method, resulting in low recovery ( < 10%). Most BMAA was found in a trichloroacetic acid soluble, bound form and we recommend including this fraction during analysis

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

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.Peer reviewe