The role of the microbial secondary metabolism in the cytodifferentiation of producer strains and in the ecological system is reviewed. The production of bioactive metabolites such as antibiotics seems to play a role in long‐term strategies of adaptation to environmental changes. This is reflected by characteristic features of regulation of the secondary metabolism such as catabolite repression, lack of uniform regulatory mechanisms and limited specificity of enzymes involved. The examples given may show that advantages have been taken from the knowledge of special regulatory features with regard to strain improvement and the designing of the metabolite spectrum.