A Polysaccharide Produced by the Crown-Gall Organism

In previous studies of the nutrition and carbon metabolism of the crowngall organism, Phgtomonas tumejczciens (Smith and Town) Bergey et al., it was found that a considerable quantity of unidentified material was produced when the organism was grown in synthetic medium (1,2).Because of the pathogenicity of this organism its metabolic products are of special interest.The unidentified material has therefore been investigated with the result that a polysaccharide has been isolated in apparently pure form.This polysaccharide is distinct from the gum produced by this organism and studied by Conner et al. (3).It is a major metabolic product and is excreted into the medium.Under the conditions employed for growth it accounted for 15 to 20 per cent of the sugar metabolized and amounted to 40 or 50 per cent of the previously unidentified material.This product is also of interest because of its relatively low molecular weight and its high degree of solubility in water, The preparation and chemical studies of this polysaccharide are presented below.EXPERIMENTAL Total reducing sugar was determined by the method of Stiles, Peterson, and Fred (4).For iodometric estimation of aldoses the procedure of Hinton and Macara (5) was used.Carbon analyses on bacterial cultures were made by the wet combustion method of Heck (6).Nitrogen was determined by a micromethod described by Johnson (7).Optical rotations were measured at room temperature with a Schmidt and Haensch polarimeter, No. 52b, with monochromatic light.Culture and Medium-The culture, Phytomonas tumejaciens A-6, was the progeny of a single cell (8).Its pathogenicity was checked at intervals by inoculation of tomato plants and by the subsequent development of galls.The synthetic medium contained sucrose 2, urea 0.05, potassium