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Cyanobacterial toxins: A short review on phytotoxic effect in an aquatic environment
S Saqrane, B Oudra
African Journal of Environmental Science and Technology , 2011,
Abstract: Cyanobacteria are photosynthetic prokaryotes which frequently form blooms in eutrophic water bodies. Some species of cyanobacteria are able to produce toxins (cyanotoxins) that can cause aquatic environment and diverse organisms living there to be at a serious risk. One of the more serious impacts of eutrophication on aquatic ecosystems is the disappearance of submerged macrophytes and the shift to a phytoplankton-dominated state. Hence, cyanobacterial blooms may be of significant negative ecological impact. This may represent a sanitary risk due to toxin bioaccumulation and biotransfer through the food chain. So, with the increasing number of new researches made on this subject, we propose this paper to review clearly many recent and original reports that have demonstrated the effects of cyanotoxins on some biological and physiological pathways in different aquatic plants.
Green Liver Systems? for Water Purification: Using the Phytoremediation Potential of Aquatic Macrophytes for the Removal of Different Cyanobacterial Toxins from Water  [PDF]
Stephan Pflugmacher, Sandra Kühn, Sang-Hyup Lee, Jae-Woo Choi, Seungyun Baik, Kyu-Sang Kwon, Valeska Contardo-Jara
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.69161
Abstract: The protection and reasonable use of freshwater is one of the main goals for our future, as water is most important for all organisms on earth including humans. Due to pollution, not only with xenobiotics, but also with nutrients, the status of our water bodies has changed drastically. Excess nutrient load induces eutrophication processes and, as a result, massive cyanobacterial blooms during the summer times. As cyanobacteria are known to produce several toxic secondary metabolites, the so-called cyanotoxins, exhibiting hepato-, neuro- and cell-toxicity, a potential risk is given, when using this water. There is an urgent need to have a water purification system, which is able to cope with these natural toxins. Using aquatic plants as a Green Liver, the Green Liver System?, was developed, able to remove these natural pollutants. To test the ability of the Green Liver System?, several cyanobacterial toxins including artificial and natural mixtures were tested in a small-scale laboratory system. The results showed that within 7 - 14 days a combination of different aquatic macrophytes was able to remove a given toxin amount (10 μg·L-1) by 100%. The phytoremediation technology behind the Green Liver Systems? uses the simple ability of submerged aquatic plants to uptake, detoxify and store the toxins, without formation and release of further metabolites to the surrounding water.
Diversity and Impact of Prokaryotic Toxins on Aquatic Environments: A Review  [PDF]
Elisabete Valério,Sandra Chaves,Rogério Tenreiro
Toxins , 2010, DOI: 10.3390/toxins2102359
Abstract: Microorganisms are ubiquitous in all habitats and are recognized by their metabolic versatility and ability to produce many bioactive compounds, including toxins. Some of the most common toxins present in water are produced by several cyanobacterial species. As a result, their blooms create major threats to animal and human health, tourism, recreation and aquaculture. Quite a few cyanobacterial toxins have been described, including hepatotoxins, neurotoxins, cytotoxins and dermatotoxins. These toxins are secondary metabolites, presenting a vast diversity of structures and variants. Most of cyanobacterial secondary metabolites are peptides or have peptidic substructures and are assumed to be synthesized by non-ribosomal peptide synthesis (NRPS), involving peptide synthetases, or NRPS/PKS, involving peptide synthetases and polyketide synthases hybrid pathways. Besides cyanobacteria, other bacteria associated with aquatic environments are recognized as significant toxin producers, representing important issues in food safety, public health, and human and animal well being. Vibrio species are one of the most representative groups of aquatic toxin producers, commonly associated with seafood-born infections. Some enterotoxins and hemolysins have been identified as fundamental for V.?cholerae and V. vulnificus pathogenesis, but there is evidence for the existence of other potential toxins. Campylobacter spp. and Escherichia coli are also water contaminants and are able to produce important toxins after infecting their hosts. Other bacteria associated?with aquatic environments are emerging as toxin producers, namely Legionella?pneumophila and Aeromonas hydrophila, described as responsible for the synthesis of several exotoxins, enterotoxins and cytotoxins. Furthermore, several Clostridium species can produce potent neurotoxins. Although not considered aquatic microorganisms, they are ubiquitous in the environment and can easily contaminate drinking and irrigation water. Clostridium members are also spore-forming bacteria and can persist in hostile environmental conditions for long periods of time, contributing to their hazard grade. Similarly, Pseudomonas species are widespread in the environment. Since P. aeruginosa is an emergent opportunistic pathogen, its toxins may represent new hazards for humans and animals. This review presents an overview of the diversity of toxins produced by prokaryotic microorganisms associated with aquatic habitats and their impact on environment, life and health of humans and other animals. Moreover, important issues like the
Health Risk Assessment for Cyanobacterial Toxins in Seafood  [PDF]
Vanora Mulvenna,Katie Dale,Brian Priestly,Utz Mueller,Andrew Humpage,Glen Shaw,Graeme Allinson,Ian Falconer
International Journal of Environmental Research and Public Health , 2012, DOI: 10.3390/ijerph9030807
Abstract: Cyanobacteria (blue-green algae) are abundant in fresh, brackish and marine waters worldwide. When toxins produced by cyanobacteria are present in the aquatic environment, seafood harvested from these waters may present a health hazard to consumers. Toxicity hazards from seafood have been internationally recognised when the source is from marine algae (dinoflagellates and diatoms), but to date few risk assessments for cyanobacterial toxins in seafood have been presented. This paper estimates risk from seafood contaminated by cyanobacterial toxins, and provides guidelines for safe human consumption.
Gastroenteritis and liver carcinogenesis induced by cyanobacterial toxins
Piotr Rzymski, Barbara Poniedzia?ek, Jacek Karczewski
Polish Gastroenterology , 2011,
Abstract: Cyanobacteria (Cyanophycae, blue-green algae) are prokaryotic autotrophic microorganisms related in general to aquatic (marine and freshwater) environments. Several dozens of the species produce secondary metabolites highly toxic to mammals, including humans. Bioaccumulation of these toxic compounds in aquatic animals has been shown. Depending on the mechanism of action they can be classified as dermato-, cyto-, neuro- and hepatotoxins. Within the last group, microcystins, nodularins and cylindrospermopsins can be distinguished. Swallowing water or consuming food contaminated with cyanobacterial hepatotoxins can lead to acute gastroenteritis or even death. Promotion of carcinogenesis in hepatocytes by cyanotoxins has also been shown. Water reservoirs used for recreational purposes or as a source of food should be monitored regularly. Gastroenterologists should be aware of a potential impact of cyanotoxins on the gastrointestinal tract.
Cyanobacterial Toxins as Allelochemicals with Potential Applications as Algaecides, Herbicides and Insecticides  [PDF]
John P. Berry,Miroslav Gantar,Mario H. Perez,Gerald Berry,Fernando G. Noriega
Marine Drugs , 2008, DOI: 10.3390/md6020117
Abstract: Cyanobacteria (“blue-green algae”) from marine and freshwater habitats are known to produce a diverse array of toxic or otherwise bioactive metabolites. However, the functional role of the vast majority of these compounds, particularly in terms of the physiology and ecology of the cyanobacteria that produce them, remains largely unknown. A limited number of studies have suggested that some of the compounds may have ecological roles as allelochemicals, specifically including compounds that may inhibit competing sympatric macrophytes, algae and microbes. These allelochemicals may also play a role in defense against potential predators and grazers, particularly aquatic invertebrates and their larvae. This review will discuss the existing evidence for the allelochemical roles of cyanobacterial toxins, as well as the potential for development and application of these compounds as algaecides, herbicides and insecticides, and specifically present relevant results from investigations into toxins of cyanobacteria from the Florida Everglades and associated waterways.
Cyanobacterial Toxins as Allelochemicals with Potential Applications as Algaecides, Herbicides and Insecticides
John P. Berry,Miroslav Gantar,Mario H. Perez,Gerald Berry
Marine Drugs , 2008,
Abstract: Cyanobacteria ( ¢ € blue-green algae ¢ € ) from marine and freshwater habitats are known to produce a diverse array of toxic or otherwise bioactive metabolites. However, the functional role of the vast majority of these compounds, particularly in terms of the physiology and ecology of the cyanobacteria that produce them, remains largely unknown. A limited number of studies have suggested that some of the compounds may have ecological roles as allelochemicals, specifically including compounds that may inhibit competing sympatric macrophytes, algae and microbes. These allelochemicals may also play a role in defense against potential predators and grazers, particularly aquatic invertebrates and their larvae. This review will discuss the existing evidence for the allelochemical roles of cyanobacterial toxins, as well as the potential for development and application of these compounds as algaecides, herbicides and insecticides, and specifically present relevant results from investigations into toxins of cyanobacteria from the Florida Everglades and associated waterways.
Influences of Cyanobacterial Toxins Microcystins on the Seedling of Plants  [PDF]
Thanh-Son Dao, Thai-Hang Le, Thanh-Luu Pham, Lan-Chi Do-Hong, Phuoc-Dan Nguyen
Journal of Environmental Protection (JEP) , 2014, DOI: 10.4236/jep.2014.51005
Abstract:

Cyanobacterial blooms associated by their toxins have been increasing in frequency in fresh water bodies throughout the world. Among the cyanobacterial toxins, microcystins (MC) are the most common and cause severe adverse impacts on plants, aquatic organisms and human beings. In this study, the effects of MC (at the concentrations of 20 and 200 μg·L-1) from field water and crude extract of cyanobacterial scum (mainly Microcystis spp.) from the Dau Tieng Reservoir, Vietnam, on the seedlings of three plants, Brassica rapa-chinensis, B. narinosa and Nasturtium officinale, were investigated for over a period of 7 days. The results showed that MC reduced the fresh weight, root and shoot length of the exposed seedlings. In addition, abnormalities of leaf shape and color of B. rapa-chinensis under exposure to MC were observed. The results implied that MC were taken up and might be accumulated in the seedlings possessing potential risk to consumers as seedlings of these plants are a common food source for Vietnamese. To the best of our knowledge, this is the first report on the effects of MC on B. rapa-chinensis, B. narinosa and N. officinale.

Toxins produced in cyanobacterial water blooms - toxicity and risks
Luděk Bláha, Pavel Babica, Blahoslav Mar álek
Interdisciplinary Toxicology , 2009, DOI: 10.2478/v10102-009-0006-2
Abstract: Cyanobacterial blooms in freshwaters represent a major ecological and human health problem worldwide. This paper briefly summarizes information on major cyanobacterial toxins (hepatotoxins, neurotoxins etc.) with special attention to microcystins - cyclic heptapeptides with high acute and chronic toxicities. Besides discussion of human health risks, microcystin ecotoxicology and consequent ecological risks are also highlighted. Although significant research attention has been paid to microcystins, cyanobacteria produce a wide range of currently unknown toxins, which will require research attention. Further research should also address possible additive, synergistic or antagonistic effects among different classes of cyanobacterial metabolites, as well as interactions with other toxic stressors such as metals or persistent organic pollutants.
On the Chemistry, Toxicology and Genetics of the Cyanobacterial Toxins, Microcystin, Nodularin, Saxitoxin and Cylindrospermopsin  [PDF]
Leanne Pearson,Troco Mihali,Michelle Moffitt,Ralf Kellmann,Brett Neilan
Marine Drugs , 2010, DOI: 10.3390/md8051650
Abstract: The cyanobacteria or “blue-green algae”, as they are commonly termed, comprise a diverse group of oxygenic photosynthetic bacteria that inhabit a wide range of aquatic and terrestrial environments, and display incredible morphological diversity. Many aquatic, bloom-forming species of cyanobacteria are capable of producing biologically active secondary metabolites, which are highly toxic to humans and other animals. From a toxicological viewpoint, the cyanotoxins span four major classes: the neurotoxins, hepatotoxins, cytotoxins, and dermatoxins (irritant toxins). However, structurally they are quite diverse. Over the past decade, the biosynthesis pathways of the four major cyanotoxins: microcystin, nodularin, saxitoxin and cylindrospermopsin, have been genetically and biochemically elucidated. This review provides an overview of these biosynthesis pathways and additionally summarizes the chemistry and toxicology of these remarkable secondary metabolites.
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