Screening of a new strain of Streptomyces collinus, Lindenbein, A 19006, against Salmonella gallinarum led to the isolation of a new antibiotic. Examination of physical data and identification of hydrolysis products permitted the identification of this new metabolite as fumarylcarboxyamido-L-2,3-diaminopropionyl-L-alanine (I). The Gram-negative activity of the new antibiotic is inhibited by D-glucosamine and to a lesser extent by N-acetylglucosamine.