Stability of Streptomyces hygrosocpicus IMET JA 6599 under different cultivation conditions in the chemostat

The stability of the macrolide antibiotic-producing strain Streptomyces hygroscopicus IMET 6599 (wild type) was in vestigated during cultivation in a chemostat with glucose limitation. No changes in the antibiotic-producing ability were found. But under special experimental conditions which consist of a sequence of nearly steady states interrupted by batch processes linked with excess of glucose, colonies with vigorous changed morphology and a green pigment after transfer to surface culture were obtained. The antibiotic activity of the wild type and of the green selectant decreased during the special experimental conditions. The formation of the green selectant is discussed in connection with changes in the glucose or energy metabolism.