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: closed (30 November 2022) | Viewed by 15397

Special Issue Editors


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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

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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

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 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.

Keywords

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

Published Papers (5 papers)

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Research

19 pages, 3484 KiB  
Article
Cyanobacterial Harmful Bloom Lipopolysaccharides Induce Pro-Inflammatory Effects in Immune and Intestinal Epithelial Cells In Vitro
by Veronika Skočková, Ondřej Vašíček, Eliška Sychrová, Iva Sovadinová, Pavel Babica and Lenka Šindlerová
Toxins 2023, 15(3), 169; https://doi.org/10.3390/toxins15030169 - 21 Feb 2023
Cited by 3 | Viewed by 1863
Abstract
Freshwater cyanobacterial harmful blooms (CyanoHABs) produce a variety of toxic and bioactive compounds including lipopolysaccharides (LPSs). The gastrointestinal tract can be exposed to them via contaminated water even during recreational activities. However, there is no evidence of an effect of CyanoHAB LPSs on [...] Read more.
Freshwater cyanobacterial harmful blooms (CyanoHABs) produce a variety of toxic and bioactive compounds including lipopolysaccharides (LPSs). The gastrointestinal tract can be exposed to them via contaminated water even during recreational activities. However, there is no evidence of an effect of CyanoHAB LPSs on intestinal cells. We isolated LPSs of four CyanoHABs dominated by different cyanobacterial species and LPSs of four laboratory cultures representing the respective dominant cyanobacterial genera. Two intestinal and one macrophage cell lines were used to detect in vitro pro-inflammatory activity of the LPS. All LPSs isolated from CyanoHABs and laboratory cultures induced cytokines production in at least one in vitro model, except for LPSs from the Microcystis PCC7806 culture. LPSs isolated from cyanobacteria showed unique migration patterns in SDS-PAGE that were qualitatively distinct from those of endotoxins from Gram-negative bacteria. There was no clear relationship between the biological activity of the LPS and the share of genomic DNA of Gram-negative bacteria in the respective biomass. Thus, the total share of Gram-negative bacteria, or the presence of Escherichia coli-like LPSs, did not explain the observed pro-inflammatory activities. The pro-inflammatory properties of environmental mixtures of LPSs from CyanoHABs indicate their human health hazards, and further attention should be given to their assessment and monitoring. Full article
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16 pages, 1271 KiB  
Article
Measurement of Microcystin Activity in Human Plasma Using Immunocapture and Protein Phosphatase Inhibition Assay
by Brady R. Cunningham, Rebekah E. Wharton, Christine Lee, Mike A. Mojica, Logan C. Krajewski, Shirley C. Gordon, Adam M. Schaefer, Rudolph C. Johnson and Elizabeth I. Hamelin
Toxins 2022, 14(11), 813; https://doi.org/10.3390/toxins14110813 - 21 Nov 2022
Cited by 1 | Viewed by 1937
Abstract
Microcystins are toxic chemicals generated by certain freshwater cyanobacteria. These chemicals can accumulate to dangerous levels during harmful algal blooms. When exposed to microcystins, humans are at risk of hepatic injury, including liver failure. Here, we describe a method to detect microcystins in [...] Read more.
Microcystins are toxic chemicals generated by certain freshwater cyanobacteria. These chemicals can accumulate to dangerous levels during harmful algal blooms. When exposed to microcystins, humans are at risk of hepatic injury, including liver failure. Here, we describe a method to detect microcystins in human plasma by using immunocapture followed by a protein phosphatase inhibition assay. At least 279 microcystins have been identified, and most of these compounds share a common amino acid, the Adda side chain. We targeted this Adda side chain using a commercial antibody and extracted microcystins from human samples for screening and analysis. To quantitate the extracted microcystins, we fortified plasma with microcystin-LR, one of the most well-studied, commonly detected, and toxic microcystin congeners. The quantitation range for the detection of microcystin in human plasma using this method is 0.030–0.50 ng/mL microcystin-LR equivalents. This method detects unconjugated and conjugated forms (cysteine and glutathione) of microcystins. Quality control sample accuracies varied between 98.9% and 114%, with a precision of 7.18–15.8%. Finally, we evaluated plasma samples from a community health surveillance project of Florida residents living or working near harmful algae blooms. Full article
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16 pages, 2298 KiB  
Article
The Origin of Teratogenic Retinoids in Cyanobacteria
by Luděk Sehnal, Marie Smutná, Lucie Bláhová, Pavel Babica, Petra Šplíchalová and Klára Hilscherová
Toxins 2022, 14(9), 636; https://doi.org/10.3390/toxins14090636 - 15 Sep 2022
Cited by 5 | Viewed by 2106
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 [...] Read more.
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 retinoid producers and the mechanism of their biosynthesis is missing. In this study, the cultures of several taxonomically diverse species of axenic cyanobacteria were confirmed as significant producers of retinoid-like compounds. The consequent bioinformatic analysis suggested that the enzymatic background required for the biosynthesis of all-trans retinoic acid from retinal is not present across phylum Cyanobacteria. However, we demonstrated that retinal conversion into other retinoids can be mediated non-enzymatically by free radical oxidation, which leads to the production of retinoids widely detected in cyanobacteria and environmental water blooms, such as all-trans retinoic acid or all-trans 5,6epoxy retinoic acid. Importantly, the production of these metabolites by cyanobacteria in association with the mass development of water blooms can lead to adverse impacts in aquatic ecosystems regarding the described teratogenicity of retinoids. Moreover, our finding that retinal can be non-enzymatically converted into more bioactive retinoids, also in water, and out of the cells, increases the environmental significance of this process. Full article
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21 pages, 3090 KiB  
Article
Pseudanabaena galeata CCNP1313—Biological Activity and Peptides Production
by Marta Cegłowska, Karolina Szubert, Beata Grygier, Marzena Lenart, Jacek Plewka, Aleksandra Milewska, Kinga Lis, Artur Szczepański, Yuliya Chykunova, Emilia Barreto-Duran, Krzysztof Pyrć, Alicja Kosakowska and Hanna Mazur-Marzec
Toxins 2022, 14(5), 330; https://doi.org/10.3390/toxins14050330 - 6 May 2022
Cited by 2 | Viewed by 3596
Abstract
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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12 pages, 1893 KiB  
Article
Production of β-Cyclocitral and Its Precursor β-Carotene in Microcystis aeruginosa: Variation at Population and Single-Cell Levels
by Xuejian Wang, Yinjie Zhu, Delin Hou, Fei Teng, Zhonghua Cai and Yi Tao
Toxins 2022, 14(3), 201; https://doi.org/10.3390/toxins14030201 - 9 Mar 2022
Cited by 8 | Viewed by 4498
Abstract
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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