Lysis Ofmicrocystis Aeruginosa(kütz.) Bybdellovibrio‐like Bacteria1

Cells ofMicrocystis aeruginosa(Kützing), collected from water‐blooms of Lake Varese, were lysed byBdellovibrio‐like bacteria. The cells were lysed only after penetration. The cyanobacteria and lysing bacteria were characterized by a fibrous glycocalyx. Once the host cell was penetrated, the bacteria remained localized mainly between the host cell wall and cytoplasmic membrane, which appeared partially thickened. Cell lysis began by breakdown of cell structures. The cell wall appeared broken at many sites, and in completely lysed cells, was partially interrupted. The lysis ofMicrocystisby bacteria could be one of the causes of the death of algal blooms.