Effects of hydrogen peroxide on cyanobacteria and microcystins in irrigation water.

A new paper by Spoof et al. in Environmental Science and Pollution Research reports a series of experiments where lysis of cyanobacteria in abstracted lake water was induced by the use of hydrogen peroxide.

From the abstract:

This paper reports a series of experiments where lysis of cyanobacteria in abstracted lake water was induced by the use of hydrogen peroxide and the fate of released MCs was followed. The hydrogen peroxide–treated water was then used for spray irrigation of cultivated spinach and possible toxin accumulation in the plants was monitored. The water abstracted from Lake Köyliönjärvi, SW Finland, contained fairly low concentrations of intracellular MC prior to the hydrogen peroxide treatment (0.04 μgL −1 in July to 2.4 μgL −1 in September 2014). Hydrogen peroxide at sufficient doses was able to lyse cyanobacteria efficiently but released MCs were still present even after the application of the highest hydrogen peroxide dose of 20 mg L−1. No traces of MC were detected in the spinach leaves. The viability of moving phytoplankton and zooplankton was also monitored after the application of hydrogen peroxide. Hydrogen peroxide at 10 mg L−1 or higher had a detrimental effect on the moving phytoplankton and zooplankton.

The paper acknowledges CYANOCOST.


Spoof, L., Jaakkola, S., Važić, T. Važić, T., Häggqvist, K., Kirkkala, T., Ventelä, A-M., Kirkkala, T., Svirčev, Z., Meriluoto, J. Elimination of cyanobacteria and microcystins in irrigation water—effects of hydrogen peroxide treatment. Environ Sci Pollut Res (2020). https://doi.org/10.1007/s11356-019-07476-x

New research sheds light on the underlying mechanisms of 2,4 DABA neurotoxic effects

A new paper by S. Spacic et al. in Aquatic Toxicology, presents important findings with regards to the mechanisms underlying 2,4-DABA neurotoxicity. From the abstract:

“Recent studies suggest that 2,4-DABA, a neurotoxic excitatory amino acid present in virtually all environments, but predominantly in aquatic ecosystems may be a risk factor for development of neurodegenerative diseases in animals and humans. Despite its neurotoxicity and potential environmental importance, mechanisms underlying the excitatory and putative excitotoxic action of 2,4-DABA in neurons are still unexplored. We previously reported on extensive two-stage membrane depolarization and functional disturbances in leech Retzius neurons induced by 2,4-DABA. Current study presents the first detailed look into the electrophysiological processes leading to this depolarization. Intracellular recordings were performed on Retzius neurons of the leech Haemopis sanguisuga using glass microelectrodes and input membrane resistance (IMR) was measured by injecting hyperpolarizing current pulses through these electrodes. Results show that the excitatory effect 2,4-DABA elicits on neurons’ membrane potential is dependent on sodium ions. Depolarizing effect of 5·10−3 mol/L 2,4-DABA in sodium-free solution was significantly diminished by 91% reducing it to 3.26 ± 0.62 mV and its two-stage nature was abrogated. In addition to being sodium-dependent, the depolarization of membrane potential induced by this amino acid is coupled with an increase of membrane permeability, as 2,4-DABA decreases IMR by 8.27 ± 1.47 MΩ (67.60%). Since present results highlight the role of sodium ions, we investigated the role of two putative sodium-dependent mechanisms in 2,4-DABA-induced excitatory effect – activation of ionotropic glutamate receptors and the electrogenic transporter for neutral amino acids. Excitatory effect of 5·10−3 mol/L 2,4-DABA was partially blocked by 10-5 mol/L 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) a non-NMDA receptor antagonist as the first stage of membrane depolarization was significantly reduced by 2.59 ± 0.98 mV (40%), whilst second stage remained unaltered. Moreover, involvement of the sodium-dependent transport system for neutral amino acids was investigated by equimolar co-application of 5·10−3 mol/L 2,4-DABA and L-alanine, a competitive inhibitor of this transporter. Although L-alanine exhibited no effect on the first stage of membrane depolarization elicited by 2,4-DABA, it substantially reduced the second stage (the overall membrane depolarization) from 39.63 ± 2.22 mV to 16.28 ± 2.58 mV, by 58.92%. We therefore propose that the electrophysiological effect of 2,4-DABA on Retzius neurons is mediated by two distinct mechanisms, i.e. by activation of ionotropic glutamate receptor that initiates the first stage of membrane depolarization followed by the stimulation of an electrogenic sodium-dependent neutral amino acid transporter, leading to additional influx of positive charge into the cell and the second stage of depolarization.”

The paper acknowledges CYANOCOST.


Svetolik Spasic, Marija Stanojevic, Jelena Nesovic Ostojic, Sanjin Kovacevic, Jasna Todorovic, Marko Dincic, Vladimir Nedeljkov, Milica Prostran, Srdjan Lopicic (2020).
Two distinct electrophysiological mechanisms underlie extensive depolarization elicited by 2,4 diaminobutyric acid in leech Retzius neurons. Aquatic Toxicology 220, 105398.


Frontiers topic: Global Intensification of Cyanobacterial Blooms: The Driving Forces and Mitigation Approaches

This Frontiers Research Topic presents research papers and reviews that explore novel approaches expanding our understanding of the development of toxic phytoplankton blooms and their immense performance in a changing environment, with particular focus on Microcystis sp. It aims to address various aspects of cyanobacterial blooms including the following:

• abiotic and biotic drivers of cyanobacteria blooms

• biological role of secondary metabolites, including cyanotoxins, in the bloom’s lifecycle,

• allelopathic and info-chemical interactions between microorganisms involved in toxic blooms,

• competition in host/parasite interactions, including cy-anophages,

• novel strategies for mitigation of cyanobacterial blooms.

Topic Editors:

Aaron Kaplan, Hebrew University of Jerusalem, Israel),
Rainer Kurmayer, University of Innsbruck, Austria,
Assaf Sukenik, Kinneret Limnological Laboratory, Israel Oceanographic and Limnological Research, Leon H. Charney School of Marine Sciences, University of Haifa, Migdal, Israel.

Deadline for submission of abstracts: 01 April 2020.

Link to the webpage of this Frontiers Topic


NaToxAq Conference call for abstracts (Brno, 10-12 June 2020)

Natural toxins can pose varying degrees of risk towards ecosystems and even human health. Natural Toxins: Environmental Fate and Safe Water Supply is the first international conference focusing solely on the topic of natural compounds affecting the quality of our water resources and drinking water. The conference provides a unique platform to present latest findings in plenum and develop new ideas among experts and young researchers, setting the direction for future research in this rapidly evolving field and help guide water legislation.

A call for abstracts in now open, with deadline on January 30, 2020.

Visit the NaToxAq Conference webpage.

Download the conference flyer.


Special Issue “Selected Papers from the 11th International Conference on Toxic Cyanobacteria” – Toxins

Dear Colleagues,

The International Conference on Toxic Cyanobacteria is a periodic summit of an international community focusing on the study of cyanotoxins and toxic cyanobacteria. The next ICTC 11 will be held in Kraków, Poland, 5–10 May, 2019.

The Local Organizing Committee agreed with Toxins to call for a Special Issue related to the research presented during ICTC 11. The submitted articles should contain recent and most important findings discussed during the conference including: the occurrence of toxic/invasive cyanobacteria in the context of climate changes; ecology of cyanobacteria with special emphasis on abiotic and biotic factors which regulate their growth and/or toxin production; physiological function, environmental significance and biotechnological application of secondary cyanometabolites; physiology and molecular biology of cyanobacteria; toxicity and harmful effects; risk identification and water management.

Link to the special issue: https://www.mdpi.com/journal/toxins/special_issues/Conference_Toxic_Cyanobacteria

Additional links to the conference which you may find useful: http://ictc11.org/special-issues/

On behalf of the Local Organizing Committee

Dr. Dariusz Dziga
Guest Editor

SETAC Europe 2020 Session: Marine and Freshwater Pelagic and Benthic Harmful Algal Blooms

SETAC Europe 30th Annual meeting will take place on 3-7 May 2020 in Dublin, Ireland.

A Session on “Marine and Freshwater Pelagic and Benthic Harmful Algal Blooms: Toxins Production, Detection, Fate, Effects, Monitoring and Management” (Co-chairs Triantafyllos Kaloudis, James Lazorchack) is scheduled under “Track 6”. 

You can submit your abstracts by 27 November 2019.

Link to the session (Track 6).


Harmful algal blooms (HABs) in freshwater and marine systems are defined as an assemblage of eukaryotic or prokaryotic plankton which have the potential to cause negative health, ecological or economic impacts. These negative impacts are caused by mechanisms that include, but are not limited to, public health and environmental risks from toxin(s) production, light attenuation, diurnal swings in pH and dissolved oxygen, offensive tastes and odors, and impaired visual aesthetics. Examples of some of the major toxins found in various combinations are: (a) prokaryotes (cyanobacteria) – microcystins, cylindrospermopsins, anatoxins, nodularin and saxitoxins; and (b) eukaryotes (dinoflagellates, diatoms, chrysophytes and raphidophytes) euglenophysins, prymensins, brevetoxins, ciguatoxins, saxitoxins and domoic acid. In recent years, there has been new information about the potential threat of benthic (attached and/or buried) toxin-producing cyanobacteria and algae. However, there are still many uncertainties about planktonic and benthic cyanobacteria/algae and the nature of their benthic/pelagic life stages. There is also some uncertainty concerning whether there is a greater risk to aquatic life due to the effects of filamentous and matt forming toxin and non-toxin producing algae on feeding inhibition and smothering. What are the current knowledge gaps related to blooms of benthic cyanobacteria/algae on substrates (attached) and/or in sediment (buried)? What research is required to address these gaps? Do we have enough knowledge to develop mitigation plans and predictive models? What tools are available to track and monitor benthic cyanobacteria/algae and their associated toxins in freshwater and marine environments, and are these fit for purpose? What information do we need to make informed risk assessments and are our current tools/techniques sufficient? How should we best incorporate ‘omics techniques into benthic cyanobacterial/algal research? What are the risks of filamentous of matt forming cyanobacteria and algae? What are the current regulations available to address both benthic and pelagic HABS and what are the current difficulties in managing the conditions that contribute to toxin production? To help address these questions, the objective of this session is to exchange information on the distribution, detection, identification, , occurrence and interaction of both benthic and planktonic cyanobacteria and algae and their associated toxins and finally management tools or approaches to reduce occurrence of blooms.


Special Issue “Harmful Cyanobacteria and Their Metabolites” – Applied Sciences

Dear Colleagues,

The ongoing eutrophication of aquatic ecosystems has increased cyanobacterial blooms and also intensified the problems caused by the blooms. Harmful cyanobacteria and their toxic metabolites are known to cause health concerns in humans, animals, and plants, and water-users continue to experience cyanobacterial hazards and nuisance in Europe and other parts of the world as evidenced by some recent events.

The Special Issue “Harmful Cyanobacteria and Their Metabolites” in the journal Applied Sciences has a wide scope and it is intended to address some of the gaps in our knowledge concerning the management of cyanobacterial problems. It deals with, e.g., the occurrence of harmful cyanobacteria, methods for the analysis of noxious cyanometabolites, fate/impact/health effects of cyanotoxins, as well as management measures related to harmful cyanobacteria.

Some examples of work relevant for the Special Issue includes manuscripts on toxic invasive cyanobacteria; occurrence of toxic cyanobacteria in less-studied environments; cyanobacterial adaptations to climate change especially in relation to toxin production; cyanobacterial production of taste and odor compounds; management of harmful cyanobacteria in protected ecosystems; exposure assessment and effects of cyanotoxins in aquatic and terrestrial organisms including humans; novel methods for monitoring and analysis of cyanotoxins; prevention and control measures for the elimination of cyanobacterial problems. Review papers promoting international initiatives for the management of cyanobacterial problems may also be considered if presented with a strong scientific rationale but the potential authors of such papers are encouraged to contact the Guest Editors in advance.

Dr. Jussi Meriluoto
Dr. Nada Tokodi
Guest Editors

Link to the webpage of the Issue.

Download the flyer of the Issue.

First study to show that microginins are genotoxic

Abstract from a paper by Ujvarosi et al. (2019), published in Chemospere :

Microginins (MGs) are bioactive metabolites mainly produced by Microcystis spp., (Cyanobacteria) commonly found in eutrophic environments. In this study, the cytotoxic and genotoxic activities of four MG congeners (MG FR3, MG GH787, cyanostatin B, MGL 402) and a well characterized cyanobacterial extract B-14-01 containing these metabolites were evaluated in the human hepatocellular carcinoma (HepG2) cell line. The cytotoxicity was measured with the MTT assay, while genotoxicity was studied with the comet, γH2AX and cytokinesis block (CBMN) micronucleus assays. The viability of cells after 24 h was significantly affected only by the extract, whereas after 72 h a concentration dependent decrease in cell proliferation was observed for the extract and tested microginins, with MGL 402 being the most potent and MG FR3 the least potent congener. The extract and all tested congeners induced DNA strand breaks after 4 and 24 h exposure. The most potent was the extract, which induced concentration and time dependent increase in DNA damage at concentrations ≥0.01 μg mL−1. Among microginins the most potent was MGL 402 (increase in DNA strand breaks at ≥ 0.01 μg mL−1) and MG FR3 was the least potent (increase in DNA strand breaks at ≥ 1 μg mL−1). However, no induction of DNA double strand breaks was observed after 24 and 72-h exposure to the cyanobacterial extract or MGs. Induction of genomic instability was observed in cells exposed to MG GH787, cyanostatin B and the extract B-14-01. This study is the first to provide the evidence that microginins exert genotoxic activity.

The paper is a product of joined research by groups in Slovenia and Hungary and features CYANOCOST members Bojana Zegura, Gabor Vasas, Klara Hercog, Metka Filipic. The authors acknowledge CYANOCOST.


Andrea Zsuzsanna Ujvárosi, Klara Hercog, Milán Riba, Sándor Gonda, Metka Filipič, Gábor Vasas, Bojana Žegura (2019). “The cyanobacterial oligopeptides microginins induce DNA damage in the human hepatocellular carcinoma (HepG2) cell line”, Chemosphere, Volume 240,  https://doi.org/10.1016/j.chemosphere.2019.124880.


Exciting PhD position at the Research Department for Limnology, Mondsee, Austria

Harmful algal blooms formed by cyanobacteria (cyanoHABs) not only deteriorate ecosystem services but cause significant economic losses because of managing and treating drinking water and food supplies. Among those toxins, most prominent are the microcystins (and related peptides), i.e. by inhibiting eukaryotic protein phosphatases 1 and 2A of higher organisms. Intracellular toxic peptides can be released into the surrounding environment either through cell lysis or through active transport out of the cell.
One possibility to investigate cyanotoxins on the individual cell level is the so-called bioorthogonal labeling. In vivo labeling of cyanotoxins/peptides is based on the discovery of unspecific key enzymes involved in the synthesis pathway of those compounds which also can use non-natural functional groups as precursors. The resulting modified molecule is subsequently labeled by a fluorophore through a so-called click chemistry reaction. We will perform cyanotoxin/peptide labeling and high resolution imaging to localize, quantify and reveal inter/intracellular peptide storage and release using various isolates varying substantially in intra- and extracellular toxic peptide content (0-60% of the total content).
The tasks of this position will include (i) the integration of the data on cyanotoxin/peptide localization, and labeling of metabolites, (ii) experiments on strain-specific variation and stress-induced variation. The PhD candidate will be responsible for collecting the data on peptide localization using high resolution microscopy and further analysis using advanced imaging software, as well as to analyze the strain-specific and stress induced variation under controlled laboratory conditions.

Download the full call (pdf).

Further Information: Assoc. Prof. Dr. Rainer Kurmayer
Research Department for Limnology Mondsee, University of Innsbruck, Austria
email: rainer.kurmayer@uibk.ac.at
For application please send a motivation letter together with a CV (in English) until 15 September 2019.



New marine cyanobacteria species found by Cyanolab in Aegean sea

A new paper by Konstantinou et al. from Cyanolab AUTH (Head: Dr. Spyros Gkelis), published in Journal of Phycology. The authors propose a novel marine genus Leptothoe gen. nov. and describe three new sponge-associated species:  Le. sithoniana, Le. kymatousa, and Le.  spongobia, based on a combination of molecular, chemical and morphological approach. The new sponge-associated Leptothoe species show distinct characters compared to other marine Leptolyngbyaceae, reinforcing the investigation of cyanobacterial diversity associated with sponges. Interestingly, Leptothoe spongobia TAU-MAC 1115 isolated from the sponge Acanthella acuta was shown to produce microcystin-RR indicating that microcystin production among marine cyanobacteria could be more widespread than previously determined.


Konstantinou, D., Voultsiadou, E., Panteris, E., Zervou, S. K., Hiskia, A., & Gkelis, S. (2019). Leptothoe, a new genus of marine cyanobacteria (Synechococcales) and three new species associated with sponges from the Aegean Sea. Journal of phycology.  https://doi.org/10.1111/jpy.12866