Studies on pigmentation of serratia marcescens. III. The characteristics of an orange variant.

The production of color variants of Serratia marcescens by means of ultraviolet light irradiation has been reported by Labrum and Bunting (1953). These variants exhibited several shades of pink, orange, or white pigmentation, and differed markedly from the natural or wild-type red color. Rizki (1954a) demonstrated that several of these pink, orange, and white variants were capable of inducing red color in each other. This same observation was reported by us for orange and white variants (Williams and Green, 1954). The variants capable of inducing red pigmentation evidently produced a diffusible substance which caused the production of red color in reactive strains (Rizki, 1954a; Williams and Green, 1954). The study of the relationship existing between inducing and susceptible variants is important for an understanding of the biosynthesis of prodigiosin, the natural red pigment of S. marcescens. Coincident to such a study is an investigation of the pigments of the variants. Rizki (1954b) presented ultraviolet and visible spectra for an extract of orange variant pigment. The present report describes the orange mutant produced in our laboratory, and the characteristics of its pigment.