ANTIBIOTIC GE37468A - A NEW INHIBITOR OF BACTERIAL PROTEIN-SYNTHESIS .3. STRAIN AND FERMENTATION STUDY

GE37468A is a new thiazolyl peptide antibiotic acting on Elongation Fa ctor Tu, produced by fermentation of Streptomyces sp. ATCC 55365. The low (<10 mg/liter) and poorly reproducible antibiotic productivity of the original soil isolate hampered the development of a scalable ferme ntation process. A tenfold increase of GE37468A productivity was achie ved by selection of spontaneous morphochromatic variants, which appear ed at high frequency in the wild type population. The higher producing ATCC 55365/O/5 colony was tyrosinase defective and blocked in the aer ial mycelium differentiation (Amy(-)Mel(-) phenotype). The fermentatio n process of this stable and purified strain was rapidly optimized to achieve a further fourfold improvement in a fed-batch process.