Effects of harmful cyanobacteria on the freshwater pathogenic free-living amoeba Acanthamoeba castellanii

► Grazing is a major factor influencing cyanobacterial population dynamics. ► Free-living amoebae have been described grazing efficiently on cyanobacteria. ► Cyanobacteria may produce toxic secondary metabolites for amoeba grazers. ► Cyanobacterial protein-phosphatase inhibitors may drive toxic effects on amoebae. ► Cyanobacterial toxicity is of utmost importance to comprehend interactions between these organisms.