Microcystin

Microcystins — or cyanoginosins — are a class of toxins produced by certain freshwater blue-green algae. Over 50 different microcystins have been discovered so far, of which microcystin-LR is the most common. Chemically they are cyclic heptapeptides produced through nonribosomal peptide synthases. Microcystins — or cyanoginosins — are a class of toxins produced by certain freshwater blue-green algae. Over 50 different microcystins have been discovered so far, of which microcystin-LR is the most common. Chemically they are cyclic heptapeptides produced through nonribosomal peptide synthases. Cyanobacteria can produce microcystins in large quantities during algal blooms which then pose a major threat to drinking and irrigation water supplies, and the environment at large. Microcystins — or cyanoginosins — are a class of toxins produced by certain freshwater cyanobacteria; primarily Microcystis aeruginosa but also other Microcystis, as well as members of the Planktothrix, Anabaena, Oscillatoria and Nostoc genera. Over 50 different microcystins have been discovered so far, of which microcystin-LR is the most common. Chemically they are cyclic heptapeptides produced through nonribosomal peptide synthases. Microcystin-LR is the most toxic form of over 80 known toxic variants, and is also the most studied by chemists, pharmacologists, biologists, and ecologists. Microcystin-containing 'blooms' are a problem worldwide, including China, Brazil, Australia, South Africa, the United States and much of Europe. Hartebeespoort Dam in South Africa is one of the most contaminated sites in Africa, and possibly in the world. Microcystins contain several uncommon non-proteinogenic amino acids such as dehydroalanine derivatives and the uncommon β-amino acid ADDA. Microcystins covalently bond to and inhibit protein phosphatases PP1 and PP2A and can thus cause pansteatitis. The microcystin-producing Microcystis is a genus of freshwater cyanobacteria and thrives in warm water conditions, especially in stagnant waters. The EPA predicted in 2013 that climate change and changing environmental conditions may lead to harmful algae growth and may negatively impact human health. Algal growth is also encouraged through the process of eutrophication (oversupply of nutrients). In particular, dissolved reactive phosphorus promotes algal growth. Humans are exposed by swallowing, skin contact with or inhaling contaminated water.Microcystins are chemically stable over a wide range of temperature and pH, possibly as a result of their cyclic structure.Microcystin-producing bacteria algal blooms can overwhelm the filter capacities of water treatment plants. Some evidence shows the toxin can be transported by irrigation into the food chain, In 2011, a record outbreak of blooming microcystis occurred in Lake Erie, in part related to the wettest spring on record, and expanded lake bottom dead zones, reduced fish populations, fouled beaches, and the local tourism industry which generates more than $10 billion in revenue annually. In August 2014, the City of Toledo, Ohio detected unsafe levels of microcystin in its water supply due to harmful algal blooms in Lake Erie, the shallowest of the Great Lakes. The city issued an advisory to approximately 500,000 people that the water was not safe for drinking or cooking. An Ohio state task force found that Lake Erie received more phosphorus than any other Great Lake, both from crop land, due to the farming practices, and from urban water-treatment centres