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Toxins
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Cyanobacterial Toxins: Their Occurrence, Detection and Removal
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Cyanobacterial Toxins: Their Occurrence, Detection and Removal

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

Deadline for manuscript submissions: closed (31 October 2020) | Viewed by 32702

Special Issue Editors

Prof. Dr. Christine Edwards

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Guest Editor
Robert Gordon University, Garthdee House, Garthdee Road, Aberdeen AB10 7QB, Scotland, UK
Interests: cyanotoxins; bioremediation; nature-based water treatment; advanced oxidation processes; bioactive peptides; purification and analysis
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Linda Ann Lawton

E-Mail Website
Co-Guest Editor
CyanoSol Research Group, School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, UK
Interests: cyanotoxins; bioremediation; nature-based water treatment; advanced oxidation processes; bioactive peptides; purification and analysis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Toxic cyanobacteria (planktonic and benthic) pose a threat to human, animal and ecosystem health across the world. Increasing frequency and duration of toxic blooms has been attributed to anthropogenic activity. However, in most extensive surveys and our own experience, only 50% of cyanobacterial samples analysed produced toxins and presented a hazard. In order to accurately assess the risk beyond the use of cell numbers and chlorophyll, there is an absolute need for robust, validated methods for sample preparation and analysis both in the laboratory and in the field. Methodology must also address multiple toxin groups, the associated wide array of congeners and extensive range of sample matrices (fresh and saltwater, animal and fish tissues, blood serum, urine).

Whilst identification and quantification are essential for informing stakeholder decision making, it is important to consider methods to remove cyanobacteria and their toxins, especially during production of drinking water. This may cover municipal or local water treatment systems and include a wide range of chemical, microbial and combined strategies. As toxins are particularly prevalent in developing countries, often all year round in water supplies that are severely stressed, low-cost treatment solutions are needed for the production of safe and sustainable drinking water.

We welcome research articles and up-to-date reviews that cover any of the topics addressed above.

Prof. Dr. Christine Edwards
Prof. Dr. Linda Ann Lawton
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 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

  • cyanotoxins
  • microcystin
  • cylindrospermopsin
  • BMAA
  • anatoxin-a
  • saxitoxins
  • nodularin
  • bioremediation
  • advanced oxidation
  • biosensors

Published Papers (7 papers)

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Research

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19 pages, 1478 KiB  
Article
Degradation of Multiple Peptides by Microcystin-Degrader Paucibacter toxinivorans (2C20)
by Allan A. Santos, Sylvia Soldatou, Valeria Freitas de Magalhães, Sandra M. F. O. Azevedo, Dolores Camacho-Muñoz, Linda A. Lawton and Christine Edwards
Toxins 2021, 13(4), 265; https://doi.org/10.3390/toxins13040265 - 08 Apr 2021
Cited by 9 | Viewed by 4580
Abstract
Since conventional drinking water treatments applied in different countries are inefficient at eliminating potentially toxic cyanobacterial peptides, a number of bacteria have been studied as an alternative to biological filters for the removal of microcystins (MCs). Here, we evaluated the degradation of not [...] Read more.
Since conventional drinking water treatments applied in different countries are inefficient at eliminating potentially toxic cyanobacterial peptides, a number of bacteria have been studied as an alternative to biological filters for the removal of microcystins (MCs). Here, we evaluated the degradation of not only MCs variants (-LR/DM-LR/-RR/-LF/-YR), but also non-MCs peptides (anabaenopeptins A/B, aerucyclamides A/D) by Paucibactertoxinivorans over 7 days. We also evaluated the degradation rate of MC-LR in a peptide mix, with all peptides tested, and in the presence of M. aeruginosa crude extract. Furthermore, biodegradation was assessed for non-cyanobacterial peptides with different chemical structures, such as cyclosporin A, (Glu1)-fibrinopeptide-B, leucine-enkephalin, and oxytocin. When cyanopeptides were individually added, P. toxinivorans degraded them (99%) over 7 days, except for MC-LR and -RR, which decreased by about 85 and 90%, respectively. The degradation rate of MC-LR decreased in the peptide mix compared to an individual compound, however, in the presence of the Microcystis extract, it was degraded considerably faster (3 days). It was noted that biodegradation rates decreased in the mix for all MCs while non-MCs peptides were immediately degraded. UPLC–QTOF–MS/MS allowed us to identify two linear biodegradation products for MC-LR and MC-YR, and one for MC-LF. Furthermore, P. toxinivorans demonstrated complete degradation of non-cyanobacterial peptides, with the exception of oxytocin, where around 50% remained after 7 days. Thus, although P. toxinivorans was previously identified as a MC-degrader, it also degrades a wide range of peptides under a range of conditions, which could be optimized as a potential biological tool for water treatment. Full article
(This article belongs to the Special Issue Cyanobacterial Toxins: Their Occurrence, Detection and Removal)
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14 pages, 584 KiB  
Article
Development and Application of Extraction Methods for LC-MS Quantification of Microcystins in Liver Tissue
by David Baliu-Rodriguez, Daria Kucheriavaia, Dilrukshika S. W. Palagama, Apurva Lad, Grace M. O’Neill, Johnna A. Birbeck, David J. Kennedy, Steven T. Haller, Judy A. Westrick and Dragan Isailovic
Toxins 2020, 12(4), 263; https://doi.org/10.3390/toxins12040263 - 19 Apr 2020
Cited by 12 | Viewed by 3398
Abstract
A method was developed to extract and quantify microcystins (MCs) from mouse liver with limits of quantification (LOQs) lower than previously reported. MCs were extracted from 40-mg liver samples using 85:15 (v:v) CH3CN:H2O containing 200 mM ZnSO4 and [...] Read more.
A method was developed to extract and quantify microcystins (MCs) from mouse liver with limits of quantification (LOQs) lower than previously reported. MCs were extracted from 40-mg liver samples using 85:15 (v:v) CH3CN:H2O containing 200 mM ZnSO4 and 1% formic acid. Solid-phase extraction with a C18 cartridge was used for sample cleanup. MCs were detected and quantified using HPLC-orbitrap-MS with simultaneous MS/MS detection of the 135.08 m/z fragment from the conserved Adda amino acid for structural confirmation. The method was used to extract six MCs (MC-LR, MC-RR, MC-YR, MC-LA, MC-LF, and MC-LW) from spiked liver tissue and the MC-LR cysteine adduct (MC-LR-Cys) created by the glutathione detoxification pathway. Matrix-matched internal standard calibration curves were constructed for each MC (R2 ≥ 0.993), with LOQs between 0.25 ng per g of liver tissue (ng/g) and 0.75 ng/g for MC-LR, MC-RR, MC-YR, MC-LA, and MC-LR-Cys, and 2.5 ng/g for MC-LF and MC-LW. The protocol was applied to extract and quantify MC-LR and MC-LR-Cys from the liver of mice that had been gavaged with 50 µg or 100 µg of MC-LR per kg bodyweight and were euthanized 2 h, 4 h, or 48 h after final gavage. C57Bl/6J (wild type, control) and Leprdb/J (experiment) mice were used as a model to study non-alcoholic fatty liver disease. The Leprdb/J mice were relatively inefficient in metabolizing MC-LR into MC-LR-Cys, which is an important defense mechanism against MC-LR exposure. Trends were also observed as a function of MC-LR gavage amount and time between final MC-LR gavage and euthanasia/organ harvest. Full article
(This article belongs to the Special Issue Cyanobacterial Toxins: Their Occurrence, Detection and Removal)
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14 pages, 1075 KiB  
Article
Ultra-Trace Analysis of Cyanotoxins by Liquid Chromatography Coupled to High-Resolution Mass Spectrometry
by Daria Filatova, Oscar Núñez and Marinella Farré
Toxins 2020, 12(4), 247; https://doi.org/10.3390/toxins12040247 - 11 Apr 2020
Cited by 17 | Viewed by 4012
Abstract
The increasing frequency of episodes of harmful algal blooms of cyanobacterial origin is a risk to ecosystems and human health. The main human hazard may arise from drinking water supply and recreational water use. For this reason, efficient multiclass analytical methods are needed [...] Read more.
The increasing frequency of episodes of harmful algal blooms of cyanobacterial origin is a risk to ecosystems and human health. The main human hazard may arise from drinking water supply and recreational water use. For this reason, efficient multiclass analytical methods are needed to assess the level of cyanotoxins in water reservoirs and tackle these problems. This work describes the development of a fast, sensitive, and robust analytical method for multiclass cyanotoxins determination based on dual solid-phase extraction (SPE) procedure using a polymeric cartridge, Oasis HLB (Waters Corporation, Milford, MA, USA), and a graphitized non-porous carbon cartridge, SupelcleanTM ENVI-CarbTM (Sigma-Aldrich, St. Louis, MO, USA), followed by ultra-high-performance liquid chromatography high-resolution mass spectrometry (SPE-UHPLC-HRMS). This method enabled the analysis of cylindrospermopsin, anatoxin-a, nodularin, and seven microcystins (MC-LR, MC-RR, MC-YR, MC-LA, MC-LY, MC-LW, MC-LF). The method limits of detection (MLOD) of the validated approach were between 4 and 150 pg/L. The analytical method was applied to assess the presence of the selected toxins in 21 samples collected in three natural water reservoirs in the Ter River in Catalonia (NE of Spain) used to produce drinking water for Barcelona city (Spain). Full article
(This article belongs to the Special Issue Cyanobacterial Toxins: Their Occurrence, Detection and Removal)
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16 pages, 2390 KiB  
Article
Effects of Microcystin-LR on Metabolic Functions and Structure Succession of Sediment Bacterial Community under Anaerobic Conditions
by Qin Ding, Kaiyan Liu, Zhiquan Song, Rongli Sun, Juan Zhang, Lihong Yin and Yuepu Pu
Toxins 2020, 12(3), 183; https://doi.org/10.3390/toxins12030183 - 15 Mar 2020
Cited by 17 | Viewed by 3025
Abstract
Microcystins (MCs), which are produced by harmful cyanobacteria blooms, pose a serious threat to environmental health. However, the effect of MCs on the bacterial community under anaerobic conditions is still unclear. This study examined the dynamic changes of MC-degrading capacity, metabolic activity, and [...] Read more.
Microcystins (MCs), which are produced by harmful cyanobacteria blooms, pose a serious threat to environmental health. However, the effect of MCs on the bacterial community under anaerobic conditions is still unclear. This study examined the dynamic changes of MC-degrading capacity, metabolic activity, and structure of the bacterial community in lake sediment repeatedly treated with 1 mg/L microcystin-LR (MC-LR) under anaerobic conditions. The results showed that the MC-degrading capacity of the bacterial community was increased nearly three-fold with increased treatment frequency. However, the metabolic profile behaved in exactly opposite trend, in which the overall carbon metabolic activity was inhibited by repeated toxin addition. Microbial diversity was suppressed by the first addition of MC-LR and then gradually recovered. The 16S amplicon sequencing showed that the dominant genera were changed from Exiguobacterium and Acinetobacter to Prosthecobacter, Dechloromonas, and Agrobacterium. Furthermore, the increase in the relative abundance of Dechloromonas, Pseudomonas, Hydrogenophaga, and Agrobacterium was positively correlated with the MC-LR treatment times. This indicates that they might be responsible for MC degradation under anaerobic conditions. Our findings reveal the relationship between MC-LR and the sediment bacterial community under anaerobic conditions and indicate that anaerobic biodegradation is an effective and promising method to remediate MCs pollution. Full article
(This article belongs to the Special Issue Cyanobacterial Toxins: Their Occurrence, Detection and Removal)
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Review

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27 pages, 1424 KiB  
Review
A Review of Nephrotoxicity of Microcystins
by Shuaishuai Xu, Xiping Yi, Wenya Liu, Chengcheng Zhang, Isaac Yaw Massey, Fei Yang and Li Tian
Toxins 2020, 12(11), 693; https://doi.org/10.3390/toxins12110693 - 31 Oct 2020
Cited by 34 | Viewed by 3534
Abstract
Cyanobacterial blooms triggered by eutrophication and climate change have become a global public health issue. The toxic metabolites microcystins (MCs) generated by cyanobacteria can accumulate in food chain and contaminate water, thus posing a potential threat to human and animals health. Studies have [...] Read more.
Cyanobacterial blooms triggered by eutrophication and climate change have become a global public health issue. The toxic metabolites microcystins (MCs) generated by cyanobacteria can accumulate in food chain and contaminate water, thus posing a potential threat to human and animals health. Studies have suggested that aside liver, the kidney may be another target organ of MCs intoxication. Therefore, this review provides various evidences on the nephrotoxicity of MCs. The review concludes that nephrotoxicity of MCs may be related to inhibition of protein phosphatases and excessive production of reactive oxygen species, cytoskeleton disruption, endoplasmic reticulum stress, DNA damage and cell apoptosis. To protect human from MCs toxic consequences, this paper also puts forward some directions for further research. Full article
(This article belongs to the Special Issue Cyanobacterial Toxins: Their Occurrence, Detection and Removal)
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32 pages, 463 KiB  
Review
A Mini-Review on Detection Methods of Microcystins
by Isaac Yaw Massey, Pian Wu, Jia Wei, Jiayou Luo, Ping Ding, Haiyan Wei and Fei Yang
Toxins 2020, 12(10), 641; https://doi.org/10.3390/toxins12100641 - 04 Oct 2020
Cited by 61 | Viewed by 6615
Abstract
Cyanobacterial harmful algal blooms (CyanoHABs) produce microcystins (MCs) which are associated with animal and human hepatotoxicity. Over 270 variants of MC exist. MCs have been continually studied due of their toxic consequences. Monitoring water quality to assess the presence of MCs is of [...] Read more.
Cyanobacterial harmful algal blooms (CyanoHABs) produce microcystins (MCs) which are associated with animal and human hepatotoxicity. Over 270 variants of MC exist. MCs have been continually studied due of their toxic consequences. Monitoring water quality to assess the presence of MCs is of utmost importance although it is often difficult because CyanoHABs may generate multiple MC variants, and their low concentration in water. To effectively manage and control these toxins and prevent their health risks, sensitive, fast, and reliable methods capable of detecting MCs are required. This paper aims to review the three main analytical methods used to detect MCs ranging from biological (mouse bioassay), biochemical (protein phosphatase inhibition assay and enzyme linked immunosorbent assay), and chemical (high performance liquid chromatography, liquid chromatography-mass spectrometry, high performance capillary electrophoresis, and gas chromatography), as well as the newly emerging biosensor methods. In addition, the current state of these methods regarding their novel development and usage, as well as merits and limitations are presented. Finally, this paper also provides recommendations and future research directions towards method application and improvement. Full article
(This article belongs to the Special Issue Cyanobacterial Toxins: Their Occurrence, Detection and Removal)
21 pages, 1008 KiB  
Review
A Mini Review on Microcystins and Bacterial Degradation
by Isaac Yaw Massey and Fei Yang
Toxins 2020, 12(4), 268; https://doi.org/10.3390/toxins12040268 - 21 Apr 2020
Cited by 69 | Viewed by 6731
Abstract
Microcystins (MCs) classified as hepatotoxic and carcinogenic are the most commonly reported cyanobacterial toxins found in the environment. Microcystis sp. possessing a series of MC synthesis genes (mcyA-mcyJ) are well documented for their excessive abundance, numerous bloom occurrences and MC producing capacity. About [...] Read more.
Microcystins (MCs) classified as hepatotoxic and carcinogenic are the most commonly reported cyanobacterial toxins found in the environment. Microcystis sp. possessing a series of MC synthesis genes (mcyA-mcyJ) are well documented for their excessive abundance, numerous bloom occurrences and MC producing capacity. About 246 variants of MC which exert severe animal and human health hazards through the inhibition of protein phosphatases (PP1 and PP2A) have been characterized. To minimize and prevent MC health consequences, the World Health Organization proposed 1 µg/L MC guidelines for safe drinking water quality. Further the utilization of bacteria that represent a promising biological treatment approach to degrade and remove MC from water bodies without harming the environment has gained global attention. Thus the present review described toxic effects and bacterial degradation of MCs. Full article
(This article belongs to the Special Issue Cyanobacterial Toxins: Their Occurrence, Detection and Removal)
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