What is "microcystin"

n. (context biochemistry English) Any of a class of cyclic oligopeptide hepatotoxins produced by cyanobacterium

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.

Microcystins can be produced in large quantities during algal blooms and pose a major threat to drinking and irrigation water supplies, as well as the environment at large.