The production, isolation, and characterization of a grisein‐like sideromycin complex

Streplomyces griscus var. X‐2455 produces an antibiotic complex which is active in vitro against a number of gram‐positive and gram‐negative bacteria and in mice against systemic infections caused by K , pneumoniae and D , pneumoniac . In view of the favorable chemotherapeutic index and the broad in vitro spectrum of crude concentrates, isolation of the pure antibiotic complex and the individual constituents was undertaken. The antibiotics referred to as Ho 5‐2667, Ro 7‐7730, and Ho 7‐7731 can be differentiated by tle, ultraviolet light absorption spectra, and in vitro antibacterial activities. They all contain iron and may be classified as sideromycins. From antibiotic concentrates an antibacterially inactive substance was isolated and identified as N ‐acetyltyramine.