Incorporation of C14-labeled substrates into violacein.

Previous studies on the physiological aspects of violacein biosynthesis (DeMoss and Evans, 1959) suggested that only L-tryptophan would serve as the primary source of carbon for pigment formation by Chromobacterium violaceum. In view of the pigment structure suggested by Ballantine et al. (1958), 5-[3-(5-hydroxyindolyl)]-3-(3-isatinyl)-2-pyrrolone, it seemed advisable to determine the actual source of the pigment carbon, and to determine if the pyrrolone residue is formed via an independent metabolic pathway. The data presented suggest that tryptophan is probably the sole precursor of violacein carbon; furthermore, the formation of the pyrrolone moiety is a process involving tryptophan metabolism and does not involve the mediation of the glycine-suceinate pathway for pyrrole synthesis described by Shemin (1955).