Abstract
Two new 7-formamidocephalosporins have been isolated as their acetyl derivatives (SQ 28, 516 and SQ 28, 517) from fermentations of a Flavobacterium sp. SC 12, 154. Structure 1 was deduced for SQ 28, 516 from its spectroscopic properties while structure 2 was proposed for SQ 28, 517. SQ 28, 516 exhibits weak antibacterial activity.