During the sudden decrease in RNA synthesis in Streptomyces aureofaciens, i.e. around the 6th hour of cultivation, synthesis of adenosine and guanosine tetraphosphates and pentaphosphates begins. The synthesis of these nucleotides is highest during the onset of chlortetracycline production, around the 20th hour of cultivation and continues. During this phase of growth of S. aureofaciens, RNA and protein synthesis are reduced by about one order of magnitude as compared to the rate which can be observed at the beginning of cultivation, but the synthesis is not inhibited by exogenous CTC.