Synergistic effect of cobalt on the induction by A-factor of the formation of aerial mycelium and anthracyclines by a blocked mutant of Streptomyces griseus.

Cobalt ions synergistically supported the inducing effect of A-factor 1a on the formation of aerial mycelium and anthracyclines by the blocked S. griseus mutant 86. This suggested an involvement of effector 1a in the transport or metabolism of this trace element. In accordance with the proposed role of 1a as an autoregulatory secondary metabolite, the parent strain S. griseus JA 3933 secreted 1a into the medium after a decrease of the specific growth rate and before the onset of antibiotic production.