ACTINORHODIN AND UNDECYLPRODIGIOSIN PRODUCTION IN WILD-TYPE AND RELA MUTANT STRAINS OF STREPTOMYCES-COELICOLOR A3(2) GROWN IN CONTINUOUS-CULTURE

The effects of growth rate and nutrient feed rate on the production of actinorhodin (Act) and undecylprodigiosin (Red) were determined in St reptomyces coelicolor A3(2) and in a congenic relA null-mutant known t o be deficient in ppGpp synthesis and antibiotic production under cond itions of nitrogen limitation. In the relA(+) strain, Act production w as inversely related to specific growth rate in continuous cultures li mited by glucose, ammonium, or phosphate. while Red biosynthesis was o ptimal at 0.05 h(-1) regardless of the specific nutrient limitation. P roduction of Act and Red in the relA mutant was lower than that of the parental strain, particularly under conditions of glucose- and ammoni um-limitation, indicating an important and general role for ppGpp in d etermining the onset of the antibiotic biosynthesis under conditions o f nutrient limitation. At constant growth rate, but with varying nutri ent feed rates, the specific rate of Act production was adversely infl uenced by increasing levels of glucose, ammonium, and phosphate, with phosphate having the greatest inhibitory effect. Under the same condit ions, the specific rate of Red production was stimulated by increasing glucose levels, but markedly decreased by increased levels of phospha te. (C) 1998 Federation of European Microbiological Societies. Publish ed by Elsevier Science B.V. All rights reserved.