mi·​cro·​cys·​tin ˌmī-krə-ˈsi-stin How to pronounce microcystin (audio)
: any of various toxins that are produced by freshwater cyanobacteria (genus Microcystis, especially M. aeruginosa), have hepatotoxic effects in animals including humans, and may occur in large quantities and contaminate water supplies during algal blooms (see bloom entry 2 sense 1d)
… two water samples from a Toledo treatment plant tested positive for microcystin, a toxin possibly caused by an algae bloom in Lake Erie. Residents were told not to drink, or even boil, the water tainted with microcystin, which can cause nausea and impair liver function.Lauren Raab
When cyanobacteria die, they release microcystin, and scientists have found that remaining cyanobacteria respond to the molecule by making more of their own.Carl Zimmer

Examples of microcystin in a Sentence

Recent Examples on the Web The city has spent more than a billion dollars to upgrade its stormwater system and water-treatment plant, including improvements to filter and eliminate microcystin and a buoy with special sensors that monitor the extent of algal blooms near the city’s water-intake pipe in Lake Erie. Tim Folger, National Geographic, 17 Nov. 2020 Microcystis, which is the most common bloom forming genus of cyanobacteria, can form a layer of green scum in Lake Erie and releases a toxin called microcystin. Miriam Marini, Detroit Free Press, 31 July 2021 The ban continued today, as further testing revealed evidence of the toxin microcystin in a drinking water plant. Tom Yulsman, Discover Magazine, 4 Aug. 2014 The most significant chunk of that money - $715,992 – will be spent on a University of Toledo project to develop and test the use of microcystin degrading bacteria to remove and degrade bloom toxins from drinking water. cleveland, 28 Oct. 2021 The one at Barker's Island included two species not seen in the open water blooms and the toxin microcystin. Arkansas Online, 24 Oct. 2021 The marina struggled with algae outbreaks this past spring and into summer with a particularly potent bloom in April showing microcystin levels 100 times higher than what’s considered harmful to humans. Kimberly Miller, orlandosentinel.com, 24 Oct. 2021 The one at Barker’s Island included two species not seen in the open water blooms and the toxin microcystin. Morgan Greene, chicagotribune.com, 15 Oct. 2021 Phosphorus feeds blue-green algae called cyanobacteria that produce a toxin called microcystin that can be deadly to animals and humans. Peter Krouse, cleveland, 16 July 2021 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'microcystin.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


New Latin Microcystis, a species of cyanobacteria (from micro- micro- + Greek kýstis "pouch, bladder") + -in entry 1 — more at cyst

First Known Use

1965, in the meaning defined above

Time Traveler
The first known use of microcystin was in 1965

Dictionary Entries Near microcystin

Cite this Entry

“Microcystin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/microcystin. Accessed 6 Dec. 2023.

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