Increased production of saframycin A and isolation of saframycin S

This paper reports on an increased production of saframycin A, which is a satellite antibiotic to streptothricin and a trace component in the culture of Streptomyces lavendulae No. 314. Some improvement in the yield of the antibiotic was attained by supplementing the standard medium with two end-products of metabolic pathways related to saframycin biosynthesis. A further significant increase of saframycin A potency could be attained by addition of NaCN to the culture broth. Finally, a drastic degradation of saframycin A in the culture was successfully prevented by maintaining the pH lower than 5.5 after peak production of the antibiotic. The combined application of these improvements resulted in approximately 1,000-fold increase in saframycin A production as compared with the parental level. The precursor of saframycin A in the culture, which yielded saframycin A upon cyanation was isolated, characterized and named saframycin S. Physicochemical properties of saframycin S were described and structural formulae were discussed.