Nutritional control of actinorhodin production byStreptomyces coelicolor A3(2): suppressive effects of nitrogen and phosphate

Actinorhodin production inStreptomyces coelicolor A3(2) was relatively insensitive to the carbon source concentration but was elicited by nitrogen or phosphate depletion, or by a decline in the growth rate. In starch-glutamate media with nitrogen limitation, increasing the nitrogen supply delayed the onset of antibiotic synthesis and, at concentrations above 30 mM, decreased its rate. In a similar medium with phosphate limitation, increasing the initial phosphate concentration delayed actinorhodin formation and, above 2.5 mM, reduced the rate of synthesis. Experiments in which actinorhodin synthesis was elicited by phosphate depletion at various nitrogen concentrations demonstrated strong suppression by residual glutamate. Cultures in which actinorhodin biosynthesis was initiated by nitrogen depletion were not similarly suppressed by increasing amounts of residual phosphate. The results suggest that actinorhodin production inS. coelicolor A3(2) responds to interacting physiological controls, notable among which is nitrogen catabolite regulation.