The cyanobacterium Synechocystis produces toxins that often lead to its own demise. The biologists Stefan Kopfmann and Prof. Dr. Wolfgang Hess from the University of Freiburg have determined the logic governing this mechanism. The cyanobacterium Synechocystis produces several toxins. However, most of the time they cannot become active because the unicellular organism usually only produces them together with an antitoxin that neutralizes their poisonous effect.