Special Issue "Cyanobacterial Toxin and Secondary Metabolite Detection, Fate and Toxicity Assessment"

A special issue of Toxins (ISSN 2072-6651). This special issue belongs to the section "Marine and Freshwater Toxins".

Deadline for manuscript submissions: 30 November 2022 | Viewed by 2517

Special Issue Editors

Dr. Elisabeth Janssen
E-Mail Website
Guest Editor
Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Dübendorf, Switzerland
Interests: analytical chemistry; environmental fate processes; photochemistry; natural toxins; extracellular enzymes; organic micropollutants
Dr. Pavel Babica
E-Mail Website
Guest Editor
1. Masaryk University, Faculty of Science, RECETOX, Brno, Czech Republic
2. Institute of Botany, Department of Experimental Phycology and Ecotoxicology, Brno, Czech Republic
Interests: cyanobacterial toxins; cyanotoxin environmental fate and monitoring; environmental toxicology; in vitro toxicology; toxicity mechanisms; human health risks

Special Issue Information

Dear Colleagues,

Around the globe, the frequency and intensity of cyanobacteria in surface waters is increasing. At the same time, cyanotoxins and bioactive secondary metabolites from cyanobacteria are equally prevalent. However, we still lack a comprehensive understanding of exposure concentrations, fate processes, toxic effects, and treatment options for a wide range of these natural chemicals. The variety of toxins and metabolites requires diverse methods for their identification and to study their toxicity and behavior in environmental and engineered systems.

This Special Issue aims to highlight novel research on toxins and secondary metabolites produced by cyanobacteria, with focus on

  • Analytical methods for identification and quantification (e.g., integrative sampling techniques, analytical procedures, data processing workflows, LC–MS-based techniques, in vitro tests, rapid assessment tools, sensors)
  • Occurrence in surface waters or simulated field conditions (e.g., production dynamics, local fingerprints, spatial and temporal distribution, correlation with other monitoring parameters)
  • Behavior in environmental and engineered systems (e.g., sorption and sedimentation, (photo)oxidation, biotransformation, transformation products, advanced oxidation)
  • Toxicity to aquatic organisms and human health hazards and effects (e.g., acute toxicity, sublethal and chronic effects, behavior effects, bioassays, and cell-based assays)
  • Assessment and management of ecological and human health risks of cyanobacteria and cyanotoxins (e.g., assessment of cyanotoxin exposures, recreational or drinking or irrigation water safety, bloom mitigation, removal of cyanobacteria and cyanotoxin in drinking water treatment)
  • New discoveries of secondary metabolites from cyanobacteria (e.g., new compound discoveries, literature analysis of discovered compounds)

Dr. Elisabeth Janssen
Dr. Pavel Babica
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a double-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxins is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.


  • cyanobacteria
  • cyanotoxins
  • secondary metabolites
  • identification
  • transformation
  • toxicity
  • mass spectrometry

Published Papers (2 papers)

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Pseudanabaena galeata CCNP1313—Biological Activity and Peptides Production
Toxins 2022, 14(5), 330; https://doi.org/10.3390/toxins14050330 - 06 May 2022
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Even cyanobacteria from ecosystems of low biodiversity, such as the Baltic Sea, can constitute a rich source of bioactive metabolites. Potent toxins, enzyme inhibitors, and anticancer and antifungal agents were detected in both bloom-forming species and less commonly occurring cyanobacteria. In previous work [...] Read more.
Even cyanobacteria from ecosystems of low biodiversity, such as the Baltic Sea, can constitute a rich source of bioactive metabolites. Potent toxins, enzyme inhibitors, and anticancer and antifungal agents were detected in both bloom-forming species and less commonly occurring cyanobacteria. In previous work on the Baltic Pseudanabaena galeata CCNP1313, the induction of apoptosis in the breast cancer cell line MCF-7 was documented. Here, the activity of the strain was further explored using human dermal fibroblasts, African green monkey kidney, cancer cell lines (T47D, HCT-8, and A549ACE2/TMPRSS2) and viruses (SARS-CoV-2, HCoV-OC43, and WNV). In the tests, extracts, chromatographic fractions, and the main components of the P. galeata CCNP1313 fractions were used. The LC-MS/MS analyses of the tested samples led to the detection of forty-five peptides. For fourteen of the new peptides, putative structures were proposed based on MS/MS spectra. Although the complex samples (i.e., extracts and chromatographic fractions) showed potent cytotoxic and antiviral activities, the effects of the isolated compounds were minor. The study confirmed the significance of P. galeata CCNP1313 as a source of metabolites with potent activity. It also illustrated the difficulties in assigning the observed biological effects to specific metabolites, especially when they are produced in minute amounts. Full article
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Production of β-Cyclocitral and Its Precursor β-Carotene in Microcystis aeruginosa: Variation at Population and Single-Cell Levels
Toxins 2022, 14(3), 201; https://doi.org/10.3390/toxins14030201 - 09 Mar 2022
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Bloom-forming cyanobacteria produce and release odorous compounds and pose threats to the biodiversity of aquatic ecosystem and to the drinking water supply. In this study, the concentrations of β-cyclocitral in different bacterial growth phases were investigated using GC–MS to determine the growth stage [...] Read more.
Bloom-forming cyanobacteria produce and release odorous compounds and pose threats to the biodiversity of aquatic ecosystem and to the drinking water supply. In this study, the concentrations of β-cyclocitral in different bacterial growth phases were investigated using GC–MS to determine the growth stage of Microcystis aeruginosa at high risk for β-cyclocitral production. Moreover, the synchronicity of the production of β-cyclocitral and its precursor β-carotene at both population and single-cell levels was assessed. The results indicated that β-cyclocitral was the main odorous compound produced by M. aeruginosa cells. The intracellular concentration of β-cyclocitral (Cβ-cc) as well as its cellular quota (Qβ-cc) increased synchronously in the log phase, along with the increase of cell density. However, they reached the maximum values of 415 μg/L and 10.7 fg/cell in the late stationary phase and early stationary phase, respectively. The early stage of the stationary phase is more important for β-cyclocitral monitoring, and the sharp increase in Qβ-cc is valuable for anticipating the subsequent increase in Cβ-cc. The molar concentrations of β-cyclocitral and β-carotene showed a linear relationship, with an R2 value of 0.92, suggesting that the production of β-cyclocitral was linearly dependent on that of β-carotene, especially during the log phase. However, the increase in Qβ-cc was slower than that in β-carotene during the stationary phase, suggesting that β-cyclocitral production turned to be carotene oxygenase-limited when the growth rate decreased. These results demonstrate that variations of β-cyclocitral production on a single-cell level during different bacterial growth phases should be given serious consideration when monitoring and controlling the production of odorous compounds by M. aeruginosa blooms. Full article
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: A fast and reliable LC-MS/MS method for the quantification of saxitoxin in blood plasma samples
Authors: Klára Odehnalová1, Petra Přibilová1,2, Blahoslav Maršálek1, Pavel Babica1,3,*
Affiliation: 1 Institute of Botany, Czech Academy of Sciences, Lidická 25/27, 60200 Brno, Czech Republic 2 Institute of Chemistry and Technology of Environmental Protection, Faculty of Chemistry, Brno University of Technology, Purkyňova 118, 612 00 Brno, Czech Republic 3 RECETOX, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic
Abstract: Saxitoxin is a highly poisonous toxin produced by cyanobacteria and marine dinoflagellates, that can cause acute animal and human intoxications. It is difficult to characterize the poisoning based on symptoms, so a rapid diagnostic assessment is necessary to confirm the source and character of intoxication. Thus, we developed a fast and simple method of saxitoxin extraction based on plasma sample acidification and its precipitation by acetonitrile, followed by quantification using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our approach serves the results by one hour with lower limits of detection of 5.0 ng/mL. Within-run and between-run precision experiments showed good reproducibility with less than 15 % values. Standard curves for calibration were linear with correlation coefficients higher than 0.98 across the assay calibration range (5 to 200 ng/mL). Although the high ionization suppression of analyte in this simple sample procedure occurred, we demonstrated by participating in proficiency testing that the assay was 100 % accurate in determining the presence or absence of this toxin in human plasma specimens, with recovery values higher than 86 %. We conclude that our simple method of saxitoxin determination in human plasma can quickly and reliably diagnose its exposure.

Title: The origin of teratogenic retinoids in cyanobacteria
Authors: Ludek Sehnal, Marie Smutná, Lucie Blahova, Pavel Babica, Petra Šplíchalová, Klara Hilscherova*
Affiliation: RECETOX, Faculty of Science, Masaryk University, Kotlarska 2, Brno, Czech Republic
Abstract: Although information about the occurrence and distribution of retinoids in the environment is scarce, cyanobacterial water blooms have been identified as a significant source of these small molecules. Despite the confirmed presence of retinoids in the freshwater blooms dominated by cyanobacteria and their described teratogenic effects, reliable identification of retinoids producers and the mechanism of their biosynthesis is missing. Using bioinformatic, molecular and chemical approaches, this study focuses on the confirmation of cyanobacteria as retinoids producers and elucidation of retinoid biosynthesis in cyanobacteria. The cultures of several taxonomically diverse species of cyanobacteria, where axenicity has been verified by 16S rRNA sequencing, were confirmed as significant producers of retinoid-like compounds. Consequent bioinformatic analysis documented that the enzymatic background required for the biosynthesis of all- trans retinoic acid from retinal is not present across phylum Cyanobacteria. However, we demonstrated experimentally that retinal conversion into other retinoids can be mediated non-enzymatically by free radical oxidation, which leads to the production of retinoid compounds widely detected in cyanobacteria and water bloom affected aquatic environment, such as all- trans retinoic acid, 9/13 cis retinoic acid, or all- trans 5,6epoxy retinoic acid. Importantly, production of these metabolites by cyanobacteria in association with mass development of water blooms can lead to adverse impacts in aquatic ecosystems regarding described teratogenicity of retinoids, especially in areas where occurrence of water blooms coincides with early development of aquatic vertebrates and invertebrates. Moreover, our finding that retinal can be converted by reactive oxygen species into more bioactive retinoids also in water, out of the cells, increases the environmental significance of this process.

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