Special Issue "Cyanotoxins in Bloom: Ever-Increasing Occurrence and Global Distribution of Freshwater Cyanotoxins from Planktic and Benthic Cyanobacteria"

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

Deadline for manuscript submissions: 31 December 2021.

Special Issue Editors

Dr. Triantafyllos Kaloudis
E-Mail Website
Guest Editor
Athens Water Supply & Sewerage Company, EYDAP SA, 11146 Athens, Greece
Interests: Cyanotoxins; cyanobacterial metabolites; cyanobacterial blooms; detection/determination of cyanotoxins; mass spectrometry; water treatment; advanced oxidation processes; environmental chemistry
Special Issues and Collections in MDPI journals
Dr. Anastasia Hiskia
E-Mail Website
Guest Editor
National Center for Scientific Research “DEMOKRITOS”, Institute of Nanoscience and Nanotechnology, Partiarchi Grigoriou E & Neapoleos 27 str., 15341, Agia Paraskevi, Athens, Greece
Interests: advanced oxidation processes; reactive oxygen species; environmental analytical chemistry; emerging pollutants; cyanotoxins; transformation products; cyanobacterial bioactive metabolites
Dr. Theodoros Triantis
E-Mail Website
Guest Editor
National Center for Scientific Research “DEMOKRITOS”, Institute of Nanoscience and Nanotechnology, Partiarchi Grigoriou E & Neapoleos 27 str., 15341, Agia Paraskevi, Athens, Greece
Interests: advanced oxidation processes; environmental analytical chemistry; cyanotoxins; transformation/degradation products of cyanotoxins; bioactive metabolites

Special Issue Information

At present, cyanobacteria and their toxins (also known as cyanotoxins) constitute a major threat for freshwater resources worldwide. Cyanotoxin occurrence in water bodies around the globe is constantly increasing, whereas emerging, less studied or completely new variants and congeners of various chemical classes of cyanotoxins, as well as their degradation/transformation products are often detected. In addition to planctic cyanobacteria, benthic cyanobacteria, in many cases, appear to be important toxin producers, although far less studied and more difficult to manage and control. This Special Issue aims to highlight novel research results on the structural diversity of cyanotoxins from planktic and benthic cyanobacteria, as well as on their expanding global geographical spread in freshwaters. In particular, the Issue welcomes research papers on :

  • Novel and improved methods of sampling, extraction, detection, and quantitation of cyanotoxins, with an emphasis on multivariant/class methods (e.g., LC-MS based techniques, in vitro assays, sensors);
  • Structural characterization of new cyanotoxins using mass spectrometry and related techniques;
  • Global occurrence of cyanotoxins, with an emphasis on emerging (e.g., saxitoxins, anatoxin-a, cylindrospermopsin) or new classes of cyanotoxins (such as anabaenopeptins, microginins, etc.) as well as first reports of cyanotoxins on water bodies in less studied regions;
  • Tranformation/degradation products of cyanotoxins formed in the environment or during conventional and advanced methods of water treatment (e.g., biodegradation, chemical oxidation).;
  • Planktic/benthic cyanotoxin producers, biotic and/or abiotic environmental factors that affect cyanotoxin production;
  • Results of monitoring programs demonstrating temporal and spatial distribution of cyanotoxins in freshwater bodies.
Dr. Triantafyllos Kaloudis
Dr. Anastasia Hiskia
Dr. Theodoros Triantis
Guest Editor

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 papers will be 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.

Keywords

  • emerging cyanotoxins
  • structural characterization
  • analysis
  • monitoring
  • mass spectrometry
  • in vitro assays
  • transformation products
  • planktic and benthic cyanobacteria

Published Papers (12 papers)

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Research

Jump to: Review

Article
Toxins and Other Bioactive Metabolites in Deep Chlorophyll Layers Containing the Cyanobacteria Planktothrix cf. isothrix in Two Georgian Bay Embayments, Lake Huron
Toxins 2021, 13(7), 445; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13070445 - 27 Jun 2021
Cited by 1 | Viewed by 887
Abstract
The understanding of deep chlorophyll layers (DCLs) in the Great Lakes—largely reported as a mix of picoplankton and mixotrophic nanoflagellates—is predominantly based on studies of deep (>30 m), offshore locations. Here, we document and characterize nearshore DCLs from two meso-oligotrophic embayments, Twelve Mile [...] Read more.
The understanding of deep chlorophyll layers (DCLs) in the Great Lakes—largely reported as a mix of picoplankton and mixotrophic nanoflagellates—is predominantly based on studies of deep (>30 m), offshore locations. Here, we document and characterize nearshore DCLs from two meso-oligotrophic embayments, Twelve Mile Bay (TMB) and South Bay (SB), along eastern Georgian Bay, Lake Huron (Ontario, Canada) in 2014, 2015, and 2018. Both embayments showed the annual formation of DCLs, present as dense, thin, metalimnetic plates dominated by the large, potentially toxic, and bloom-forming cyanobacteria Planktothrix cf. isothrix. The contribution of P. cf. isothrix to the deep-living total biomass (TB) increased as thermal stratification progressed over the ice-free season, reaching 40% in TMB (0.6 mg/L at 9.5 m) and 65% in South Bay (3.5 mg/L at 7.5 m) in 2015. The euphotic zone in each embayment extended down past the mixed layer, into the nutrient-enriched hypoxic hypolimnia, consistent with other studies of similar systems with DCLs. The co-occurrence of the metal-oxidizing bacteria Leptothrix spp. and bactivorous flagellates within the metalimnetic DCLs suggests that the microbial loop plays an important role in recycling nutrients within these layers, particularly phosphate (PO4) and iron (Fe). Samples taken through the water column in both embayments showed measurable concentrations of the cyanobacterial toxins microcystins (max. 0.4 µg/L) and the other bioactive metabolites anabaenopeptins (max. ~7 µg/L) and cyanopeptolins (max. 1 ng/L), along with the corresponding genes (max. in 2018). These oligopeptides are known to act as metabolic inhibitors (e.g., in chemical defence against grazers, parasites) and allow a competitive advantage. In TMB, the 2018 peaks in these oligopeptides and genes coincided with the P. cf. isothrix DCLs, suggesting this species as the main source. Our data indicate that intersecting physicochemical gradients of light and nutrient-enriched hypoxic hypolimnia are key factors in supporting DCLs in TMB and SB. Microbial activity and allelopathy may also influence DCL community structure and function, and require further investigation, particularly related to the dominance of potentially toxigenic species such as P. cf. isothrix. Full article
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Article
Cyanobacterial Toxins and Peptides in Lake Vegoritis, Greece
Toxins 2021, 13(6), 394; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13060394 - 01 Jun 2021
Viewed by 1228
Abstract
Cyanotoxins (CTs) produced by cyanobacteria in surface freshwater are a major threat for public health and aquatic ecosystems. Cyanobacteria can also produce a wide variety of other understudied bioactive metabolites such as oligopeptides microginins (MGs), aeruginosins (AERs), aeruginosamides (AEGs) and anabaenopeptins (APs). This [...] Read more.
Cyanotoxins (CTs) produced by cyanobacteria in surface freshwater are a major threat for public health and aquatic ecosystems. Cyanobacteria can also produce a wide variety of other understudied bioactive metabolites such as oligopeptides microginins (MGs), aeruginosins (AERs), aeruginosamides (AEGs) and anabaenopeptins (APs). This study reports on the co-occurrence of CTs and cyanopeptides (CPs) in Lake Vegoritis, Greece and presents their variant-specific profiles obtained during 3-years of monitoring (2018–2020). Fifteen CTs (cylindrospermopsin (CYN), anatoxin (ATX), nodularin (NOD), and 12 microcystins (MCs)) and ten CPs (3 APs, 4 MGs, 2 AERs and aeruginosamide (AEG A)) were targeted using an extended and validated LC-MS/MS protocol for the simultaneous determination of multi-class CTs and CPs. Results showed the presence of MCs (MC-LR, MC-RR, MC-YR, dmMC-LR, dmMC-RR, MC-HtyR, and MC-HilR) and CYN at concentrations of <1 μg/L, with MC-LR (79%) and CYN (71%) being the most frequently occurring. Anabaenopeptins B (AP B) and F (AP F) were detected in almost all samples and microginin T1 (MG T1) was the most abundant CP, reaching 47.0 μg/L. This is the first report of the co-occurrence of CTs and CPs in Lake Vegoritis, which is used for irrigation, fishing and recreational activities. The findings support the need for further investigations of the occurrence of CTs and the less studied cyanobacterial metabolites in lakes, to promote risk assessment with relevance to human exposure. Full article
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Article
Is the Cyanobacterial Bloom Composition Shifting Due to Climate Forcing or Nutrient Changes? Example of a Shallow Eutrophic Reservoir
Toxins 2021, 13(5), 351; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13050351 - 13 May 2021
Viewed by 1019
Abstract
Cyanobacterial blooms in eutrophic freshwater is a global threat to the functioning of ecosystems, human health and the economy. Parties responsible for the ecosystems and human health increasingly demand reliable predictions of cyanobacterial development to support necessary decisions. Long-term data series help with [...] Read more.
Cyanobacterial blooms in eutrophic freshwater is a global threat to the functioning of ecosystems, human health and the economy. Parties responsible for the ecosystems and human health increasingly demand reliable predictions of cyanobacterial development to support necessary decisions. Long-term data series help with identifying environmental drivers of cyanobacterial developments in the context of climatic and anthropogenic pressure. Here, we analyzed 13 years of eutrophication and climatic data of a shallow temperate reservoir showing a high interannual variability of cyanobacterial development and composition, which is a less occurring and/or less described phenomenon compared to recurrant monospecific blooms. While between 2007–2012 Planktothrix agardhii dominated the cyanobacterial community, it shifted towards Microcystis sp. and then Dolichospermum sp. afterwards (2013–2019). The shift to Microcystis sp. dominance was mainly influenced by generally calmer and warmer conditions. The later shift to Dolichospermum sp. was driven by droughts influencing, amongst others, the N-load, as P remained unchanged over the time period. Both, climatic pressure and N-limitation contributed to the high variability of cyanobacterial blooms and may lead to a new equilibrium. The further reduction of P-load in parallel to the decreasing N-load is important to suppress cyanobacterial blooms and ameliorate ecosystem health. Full article
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Article
Cyanotoxin Screening in BACA Culture Collection: Identification of New Cylindrospermopsin Producing Cyanobacteria
Toxins 2021, 13(4), 258; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13040258 - 03 Apr 2021
Viewed by 883
Abstract
Microcystins (MCs), Saxitoxins (STXs), and Cylindrospermopsins (CYNs) are some of the more well-known cyanotoxins. Taking into consideration the impacts of cyanotoxins, many studies have focused on the identification of unknown cyanotoxin(s)-producing strains. This study aimed to screen strains from the Azorean Bank of [...] Read more.
Microcystins (MCs), Saxitoxins (STXs), and Cylindrospermopsins (CYNs) are some of the more well-known cyanotoxins. Taking into consideration the impacts of cyanotoxins, many studies have focused on the identification of unknown cyanotoxin(s)-producing strains. This study aimed to screen strains from the Azorean Bank of Algae and Cyanobacteria (BACA) for MCs, STX, and CYN production. A total of 157 strains were searched for mcy, sxt, and cyr producing genes by PCR, toxin identification by ESI-LC-MS/MS, and cyanotoxin-producing strains morphological identification and confirmation by 16S rRNA phylogenetic analysis. Cyanotoxin-producing genes were amplified in 13 strains and four were confirmed as toxin producers by ESI-LC-MS/MS. As expected Aphanizomenon gracile BACA0041 was confirmed as an STX producer, with amplification of genes sxtA, sxtG, sxtH, and sxtI, and Microcystis aeruginosa BACA0148 as an MC-LR producer, with amplification of genes mcyC, mcyD, mcyE, and mcyG. Two nostocalean strains, BACA0025 and BACA0031, were positive for both cyrB and cyrC genes and ESI-LC-MS/MS confirmed CYN production. Although these strains morphologically resemble Sphaerospermopsis, the 16S rRNA phylogenetic analysis reveals that they probably belong to a new genus. Full article
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Article
Potentially Toxic Planktic and Benthic Cyanobacteria in Slovenian Freshwater Bodies: Detection by Quantitative PCR
Toxins 2021, 13(2), 133; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13020133 - 11 Feb 2021
Cited by 1 | Viewed by 630
Abstract
Due to increased frequency of cyanobacterial blooms and emerging evidence of cyanotoxicity in biofilm, reliable methods for early cyanotoxin threat detection are of major importance for protection of human, animal and environmental health. To complement the current methods of risk assessment, this study [...] Read more.
Due to increased frequency of cyanobacterial blooms and emerging evidence of cyanotoxicity in biofilm, reliable methods for early cyanotoxin threat detection are of major importance for protection of human, animal and environmental health. To complement the current methods of risk assessment, this study aimed to evaluate selected qPCR assays for detection of potentially toxic cyanobacteria in environmental samples. In the course of one year, 25 plankton and 23 biofilm samples were collected from 15 water bodies in Slovenia. Three different analyses were performed and compared to each other; qPCR targeting mcyE, cyrJ and sxtA genes involved in cyanotoxin production, LC-MS/MS quantifying microcystin, cylindrospermopsin and saxitoxin concentration, and microscopic analyses identifying potentially toxic cyanobacterial taxa. qPCR analyses detected potentially toxic Microcystis in 10 lake plankton samples, and potentially toxic Planktothrix cells in 12 lake plankton and one lake biofilm sample. A positive correlation was observed between numbers of mcyE gene copies and microcystin concentrations. Potential cylindrospermopsin- and saxitoxin-producers were detected in three and seven lake biofilm samples, respectively. The study demonstrated a potential for cyanotoxin production that was left undetected by traditional methods in both plankton and biofilm samples. Thus, the qPCR method could be useful in regular monitoring of water bodies to improve risk assessment and enable timely measures. Full article
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Article
Roles of Nutrient Limitation on Western Lake Erie CyanoHAB Toxin Production
Toxins 2021, 13(1), 47; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13010047 - 09 Jan 2021
Cited by 1 | Viewed by 2018
Abstract
Cyanobacterial harmful algal bloom (CyanoHAB) proliferation is a global problem impacting ecosystem and human health. Western Lake Erie (WLE) typically endures two highly toxic CyanoHABs during summer: a Microcystis spp. bloom in Maumee Bay that extends throughout the western basin, and a Planktothrix [...] Read more.
Cyanobacterial harmful algal bloom (CyanoHAB) proliferation is a global problem impacting ecosystem and human health. Western Lake Erie (WLE) typically endures two highly toxic CyanoHABs during summer: a Microcystis spp. bloom in Maumee Bay that extends throughout the western basin, and a Planktothrix spp. bloom in Sandusky Bay. Recently, the USA and Canada agreed to a 40% phosphorus (P) load reduction to lessen the severity of the WLE blooms. To investigate phosphorus and nitrogen (N) limitation of biomass and toxin production in WLE CyanoHABs, we conducted in situ nutrient addition and 40% dilution microcosm bioassays in June and August 2019. During the June Sandusky Bay bloom, biomass production as well as hepatotoxic microcystin and neurotoxic anatoxin production were N and P co-limited with microcystin production becoming nutrient deplete under 40% dilution. During August, the Maumee Bay bloom produced microcystin under nutrient repletion with slight induced P limitation under 40% dilution, and the Sandusky Bay bloom produced anatoxin under N limitation in both dilution treatments. The results demonstrate the importance of nutrient limitation effects on microcystin and anatoxin production. To properly combat cyanotoxin and cyanobacterial biomass production in WLE, both N and P reduction efforts should be implemented in its watershed. Full article
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Article
Mass Occurrence of Anatoxin-a- and Dihydroanatoxin-a-Producing Tychonema sp. in Mesotrophic Reservoir Mandichosee (River Lech, Germany) as a Cause of Neurotoxicosis in Dogs
Toxins 2020, 12(11), 726; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12110726 - 20 Nov 2020
Cited by 1 | Viewed by 1010
Abstract
In August 2019, three dogs died after bathing in or drinking from Mandichosee, a mesotrophic reservoir of the River Lech (Germany). The dogs showed symptoms of neurotoxic poisoning and intoxication with cyanotoxins was considered. Surface blooms were not visible at the time of [...] Read more.
In August 2019, three dogs died after bathing in or drinking from Mandichosee, a mesotrophic reservoir of the River Lech (Germany). The dogs showed symptoms of neurotoxic poisoning and intoxication with cyanotoxins was considered. Surface blooms were not visible at the time of the incidents. Benthic Tychonema sp., a potential anatoxin-a (ATX)-producing cyanobacterium, was detected in mats growing on the banks, as biofilm on macrophytes and later as aggregations floating on the lake surface. The dogs’ pathological examinations showed lung and liver lesions. ATX and dihydroanatoxin-a (dhATX) were detected by LC-MS/MS in the stomachs of two dogs and reached concentrations of 563 and 1207 µg/L, respectively. Anatoxins (sum of ATX and dhATX, ATXs) concentrations in field samples from Mandichosee ranged from 0.1 µg/L in the open water to 68,000 µg/L in samples containing a large amount of mat material. Other (neuro)toxic substances were not found. A molecular approach was used to detect toxin genes by PCR and to reveal the cyanobacterial community composition by sequencing. Upstream of Mandichosee, random samples were taken from other Lech reservoirs, uncovering Tychonema and ATXs at several sampling sites. Similar recent findings emphasize the importance of focusing on the investigation of benthic toxic cyanobacteria and applying appropriate monitoring strategies in the future. Full article
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Article
Is a Central Sediment Sample Sufficient? Exploring Spatial and Temporal Microbial Diversity in a Small Lake
Toxins 2020, 12(9), 580; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12090580 - 09 Sep 2020
Cited by 1 | Viewed by 1294
Abstract
(1) Background: Paleolimnological studies use sediment cores to explore long-term changes in lake ecology, including occurrences of harmful cyanobacterial blooms. Most studies are based on single cores, assuming this is representative of the whole lake, but data on small-scale spatial variability of microbial [...] Read more.
(1) Background: Paleolimnological studies use sediment cores to explore long-term changes in lake ecology, including occurrences of harmful cyanobacterial blooms. Most studies are based on single cores, assuming this is representative of the whole lake, but data on small-scale spatial variability of microbial communities in lake sediment are scarce. (2) Methods: Surface sediments (top 0.5 cm) from 12 sites (n = 36) and two sediment cores were collected in Lake Rotorua (New Zealand). Bacterial community (16S rRNA metabarcoding), Microcystis specific 16S rRNA, microcystin synthetase gene E (mcyE) and microcystins (MCs) were assessed. Radionuclide measurements (210Pb, 137Cs) were used to date sediments. (3) Results: Bacterial community, based on relative abundances, differed significantly between surface sediment sites (p < 0.001) but the majority of bacterial amplicon sequence variants (88.8%) were shared. Despite intense MC producing Microcystis blooms in the past, no Microcystis specific 16S rRNA, mcyE and MCs were found in surface sediments but occurred deeper in sediment cores (approximately 1950′s). 210Pb measurements showed a disturbed profile, similar to patterns previously observed, as a result of earthquakes. (4) Conclusions: A single sediment core can capture dominant microbial communities. Toxin producing Microcystis blooms are a recent phenomenon in Lake Rotorua. We posit that the absence of Microcystis from the surface sediments is a consequence of the Kaikoura earthquake two years prior to our sampling. Full article
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Article
Insight into Unprecedented Diversity of Cyanopeptides in Eutrophic Ponds Using an MS/MS Networking Approach
Toxins 2020, 12(9), 561; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12090561 - 31 Aug 2020
Cited by 8 | Viewed by 1419
Abstract
Man-made shallow fishponds in the Czech Republic have been facing high eutrophication since the 1950s. Anthropogenic eutrophication and feeding of fish have strongly affected the physicochemical properties of water and its aquatic community composition, leading to harmful algal bloom formation. In our current [...] Read more.
Man-made shallow fishponds in the Czech Republic have been facing high eutrophication since the 1950s. Anthropogenic eutrophication and feeding of fish have strongly affected the physicochemical properties of water and its aquatic community composition, leading to harmful algal bloom formation. In our current study, we characterized the phytoplankton community across three eutrophic ponds to assess the phytoplankton dynamics during the vegetation season. We microscopically identified and quantified 29 cyanobacterial taxa comprising non-toxigenic and toxigenic species. Further, a detailed cyanopeptides (CNPs) profiling was performed using molecular networking analysis of liquid chromatography-tandem mass spectrometry (LC-MS/MS) data coupled with a dereplication strategy. This MS networking approach, coupled with dereplication, on the online global natural product social networking (GNPS) web platform led us to putatively identify forty CNPs: fourteen anabaenopeptins, ten microcystins, five cyanopeptolins, six microginins, two cyanobactins, a dipeptide radiosumin, a cyclooctapeptide planktocyclin, and epidolastatin 12. We applied the binary logistic regression to estimate the CNPs producers by correlating the GNPS data with the species abundance. The usage of the GNPS web platform proved a valuable approach for the rapid and simultaneous detection of a large number of peptides and rapid risk assessments for harmful blooms. Full article
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Article
Cylindrospermopsin- and Deoxycylindrospermopsin-Producing Raphidiopsis raciborskii and Microcystin-Producing Microcystis spp. in Meiktila Lake, Myanmar
Toxins 2020, 12(4), 232; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12040232 - 07 Apr 2020
Cited by 7 | Viewed by 1190
Abstract
Meiktila Lake is a shallow reservoir located close to Meiktila city in central Myanmar. Its water is used for irrigation, domestic purposes and drinking water. No detailed study of the presence of cyanobacteria and their potential toxin production has been conducted so far. [...] Read more.
Meiktila Lake is a shallow reservoir located close to Meiktila city in central Myanmar. Its water is used for irrigation, domestic purposes and drinking water. No detailed study of the presence of cyanobacteria and their potential toxin production has been conducted so far. To ascertain the cyanobacterial composition and presence of cyanobacterial toxins in Meiktila Lake, water samples were collected in March and November 2017 and investigated for physico-chemical and biological parameters. Phytoplankton composition and biomass determination revealed that most of the samples were dominated by the cyanobacterium Raphidiopsis raciborskii. In a polyphasic approach, seven isolated cyanobacterial strains were classified morphologically and phylogenetically as R. raciborskii, and Microcystis spp. and tested for microcystins (MCs), cylindrospermopsins (CYNs), saxitoxins and anatoxins by enzyme-linked immunosorbent assay (ELISA) and liquid chromatography–mass spectrometry (LC–MS). ELISA and LC–MS analyses confirmed CYNs in three of the five Raphidiopsis strains between 1.8 and 9.8 μg mg−1 fresh weight. Both Microcystis strains produced MCs, one strain 52 congeners and the other strain 20 congeners, including 22 previously unreported variants. Due to the presence of CYN- and MC-producing cyanobacteria, harmful effects on humans, domestic and wild animals cannot be excluded in Meiktila Lake. Full article
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Review

Jump to: Research

Review
Anabaenopeptins: What We Know So Far
Toxins 2021, 13(8), 522; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13080522 - 27 Jul 2021
Viewed by 389
Abstract
Cyanobacteria are microorganisms with photosynthetic mechanisms capable of colonizing several distinct environments worldwide. They can produce a vast spectrum of bioactive compounds with different properties, resulting in an improved adaptative capacity. Their richness in secondary metabolites is related to their unique and diverse [...] Read more.
Cyanobacteria are microorganisms with photosynthetic mechanisms capable of colonizing several distinct environments worldwide. They can produce a vast spectrum of bioactive compounds with different properties, resulting in an improved adaptative capacity. Their richness in secondary metabolites is related to their unique and diverse metabolic apparatus, such as Non-Ribosomal Peptide Synthetases (NRPSs). One important class of peptides produced by the non-ribosomal pathway is anabaenopeptins. These cyclic hexapeptides demonstrated inhibitory activity towards phosphatases and proteases, which could be related to their toxicity and adaptiveness against zooplankters and crustaceans. Thus, this review aims to identify key features related to anabaenopeptins, including the diversity of their structure, occurrence, the biosynthetic steps for their production, ecological roles, and biotechnological applications. Full article
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Review
Co-Occurrence of Cyanobacteria and Cyanotoxins with Other Environmental Health Hazards: Impacts and Implications
Toxins 2020, 12(10), 629; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins12100629 - 01 Oct 2020
Cited by 5 | Viewed by 1521
Abstract
Toxin-producing cyanobacteria in aquatic, terrestrial, and aerial environments can occur alongside a wide range of additional health hazards including biological agents and synthetic materials. Cases of intoxications involving cyanobacteria and cyanotoxins, with exposure to additional hazards, are discussed. Examples of the co-occurrence of [...] Read more.
Toxin-producing cyanobacteria in aquatic, terrestrial, and aerial environments can occur alongside a wide range of additional health hazards including biological agents and synthetic materials. Cases of intoxications involving cyanobacteria and cyanotoxins, with exposure to additional hazards, are discussed. Examples of the co-occurrence of cyanobacteria in such combinations are reviewed, including cyanobacteria and cyanotoxins plus algal toxins, microbial pathogens and fecal indicator bacteria, metals, pesticides, and microplastics. Toxicity assessments of cyanobacteria, cyanotoxins, and these additional agents, where investigated in bioassays and in defined combinations, are discussed and further research needs are identified. 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: Influence of Biotope and Biotic Factors on Cyanobacteria Abundance, Genotype and Toxin Production

Authors: Maria Iasmina MOZA and Carmen POSTOLACHE

Abstract: 

Environmental genetics-related modern methods are shown as important indicators of various cyanotoxins syntheses, and their knowledge and use are critically analyzed. Microcystins and other cyanotoxins loads and syntheses are related to different drivers, like various chemical elements and compounds (especially nutrients, such as nitrogen and phosphorus, and their ratio), then to the light, conductivity, temperature, and other climatical and hydrological factors, to which spatial and geographical features (such as the surface of the water bodies) have to be added. The biotic relationships include different specific and supraspecific, uni- and bilateral links between the cyanobacteria, and subsequently their synthesized toxins, and protozoans (or protoctists), chromists, macrophytes, different systematical and ecological groups of zooplankton, and others. The importance of, but also the gaps in, the knowledge and the scarcity of studies involving ectocrines mediated interactions between different groups of algae and plants are highlighted. The paper ends with an interesting classification of lakes' trophicity, illustrated with conceptual diagrams, based on possible scenarios of cyanobacteria behavior.

 

Title: Abiotic drivers of cyanobacteria blooms in Danube Delta lakes

Authors: Maria Iasmina MOZA, Carmen POSTOLACHE, Ana Maria BENEDEK, Mirela MOLDOVEANU, Alina DUMITRACHE, Francesco POMATI and Piet SPAAK

Abstract: Cyanobacteria mass development, especially in freshwater ecosystems, is a global concern and understanding its underlying mechanisms is an important goal of freshwater ecology. Lakes in Danube Delta, one of the most important complex of freshwater ecosystems in Europe, experienced in the past decades different intensities of cyanobacteria blooms. Conditions that favor or precede this phenomenon are still poorly understood. We conducted a study on the effects of several environmental factors on cyanobacteria abundance and genus composition, covering many lakes and several lake types in the Danube Delta during three seasons (spring, summer and autumn) in 2013 and 2014. We also evaluated the response (positive or negative) of each cyanobacteria genus to these factors and highlighted how nutrient availability influenced them. We found that cyanobacteria genera responded to pH, oxygen saturation, light, ammonium, conductivity, temperature and nitrate. Although these environmental variables are significant (p=0.001), they only explain 14.75% of the variation in abundance of cyanobacteria genera. Furthermore, our study showed that abiotic environmental predictors explained three times better the cyanobacteria community structure compared to the spatial lakes distribution in Danube Delta. These findings suggest the greater importance of environmentally driven assembly mechanism, as opposed to the dispersal assembly mechanism. This study is among the first to investigate cyanobacteria in the Danube Delta’s different lakes in a repeated and standardized design and it showed that mass occurrence of cyanobacteria were less severe than expected based on earlier studies.

 

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