STUDIES ON PIGMENTATION OF SERRATIA MARCESCENS III

Abstract

An orange mutant was produced by irradiation of the parent,red strain of S. marcescens. The orange mutant is identical morphologically, culturally, and biochemically with the parent organism. The extracter pigment of the orange variant moved as a single substance when paper chromatographed in several solvent systems. It had very strong absorption in the UV spectrum, and in acid solution has a maximum at 500 mu in the visible range. UV, visible and infrared spectral examination, chemical analyses for chloride, N, and determination of molecular weight indicated that this orange pigment differed from the natural red pigment and any of its fractions. But the infrared data suggested that the mutant and natural pigments were closely related chemically. The molecular weight of the orange pigment, as determined by the Rast-Soltys cryoscopic method, was 373. An unusual property of the orange mutant was the ability to induce red pigmentation in certain white mutants produced from the same parent red strain. This phenomenon was termed syntrophic pigmentation, and the hypothesis was proposed that the biosynthetic pathways for production of natural red and orange variant pigment were identical. But the pathway was changed in the orange mutant preventing the conversion of a.precursor (s) of the pigment into red pigment. As a result of the metabolic change, the precursor (s) of the pigment accumulates in the milieu of the orange variant. The precursor (s) are utilized by the white variants to produce red pigment.