13th International Conference on Toxic Cyanobacteria (ICTC13)
4-8 May 2025, Chania, Crete, Greece

The event was hosted in Greece by the organizing committee from the Aristotle University of Thessaloniki, NCSR Demokritos, and EYDAP SA. Over 250 scientists from 40 countries have attended and made their contribution to the conference.

Results obtained from collaborative work during CYANOMETA project were presented by several participants.

Oral presentation was given by dr. Nada Tokodi from the University of Novi Sad with the title: Metabolic profile of Raphidiopsis raciborskii extracts. The study has revealed distinct metabolite profiles in Raphidiopsis raciborskii strains from different regions. Using advanced metabolomics, researchers identified over 800 compounds in extracts from both toxic and non-toxic strains. Notably, Australian toxic strains (CS-505 and CS-506) showed a higher number of unique metabolites, suggesting strain-specific metabolic diversity. These findings highlight the untapped chemical complexity of this cyanobacterial species and its potential ecological and biotechnological relevance. Dr. Nada Tokodi also presented poster with the title: Toxicity of Raphidiopsis raciborskii extracts. Biological activity of Raphidiopsis raciborskii extracts from strains collected across Poland, Israel, and Australia was evaluated. Despite most strains being non-cyanotoxin producers, toxicological tests revealed harmful effects such as invertebrate mortality, DNA damage, and disruption of cellular communication. These findings suggest the presence of unknown bioactive compounds beyond known toxins, underlining the potential ecological and health risks posed by this widespread cyanobacterium.

Dr. Pavel Babica from the Masaryk University, Brno, Czech Republic gave more insight into the topic: Exploring the bioactive metabolites of Raphidiopsis raciborskii strains: beyond cylindrospermopsin. A comparative study of Raphidiopsis raciborskii strains from Australia, Israel, and Poland revealed that both toxin-producing and non-producing strains can exhibit strong biological activity. Several extracts showed similar cytotoxic effects on mammalian liver cells and disrupted gap junctional intercellular communication (GJIC), a key process in tissue homeostasis. Metabolomic analysis confirmed distinct chemical profiles among strains, highlighting the presence of previously unrecognized bioactive compounds with potential health risks, even in non-toxic strains.

PhD student Illés Bock from the Hungarian University of Agriculture and Life Sciences, Gödöllő, Hungary presented the following results: Assessment of lethal and sublethal effects of Raphidiopsis raciborskii extracts on zebrafish embryos using automated phenotyping method. Extracts from Raphidiopsis raciborskii strains, including both toxic and non-toxic types, were tested on zebrafish embryos to evaluate lethal and sublethal effects. Three strains caused embryo mortality, with LC50 values ranging from 20.3 to 63.2 mg/L. Sublethal effects included swim bladder non-inflation, head malformations, and body curvature. Using deep-learning-based image analysis, researchers quantified developmental disruptions. The study underscores the ecological and health risks posed by cyanobacterial metabolites, even from non-toxic strains, and demonstrates the value of zebrafish embryos as a sensitive model for environmental toxicity screening.