IRON DEFICIENCY-INDUCED TETRACYCLINE PRODUCTION IN SUBMERGED CULTURESBY STREPTOMYCES-AUREOFACIENS

Streptomyces aureofaciens ATCC 10762 grown in rotary-shaken submerged cultures produced substantial amounts of tetracycline only when the de fined medium was deprived of iron. The biosynthesis of tetracycline wa s inhibited either by free iron at concentrations above 1-2 mu mol l(- 1), or by chelated iron provided by the siderophores of this bacterial strain. Late static iron-containing cultures allowed cell differentia tion and sporulation and led to tetracyclines synthesis. A nitrosoguan idine-induced mutant able to synthesize tetracycline in the presence o f iron in shaken submerged cultures was isolated and compared to the w ild-type strain. However, no constitutive siderophore-mediated iron tr ansport occurred in the mutant. These results suggest the involvement of a putative iron-controlled repressor in the biosynthesis of these s econdary metabolites during vegetative growth and primary metabolism o f the bacterium.