Ciliate Nassula sp. grazing on a microcystin-producing cyanobacterium (Planktothrix agardhii): impact on cell growth and in the microcystin fractions

► Interactions of free-living ciliates and toxic cyanobacteria. ► Ciliates can survive and grow on toxic diet of Planktothrix agardhii over an extended period of time. ► These primary consumers feeding on MC-containing cyanobacteria shifted the balance between the microcystin fractions (unbound vs bound).