THE EXTRACELLULAR POLYSACCHARIDE OF XANTHOMONAS PHASEOLI

Abstract

The extracellular polysaccharide produced by Xanthomonas phaseoli has been purified and shown to be homogeneous by examination in the analytical ultra-centrifuge, by moving boundary electrophoresis, and by gradient precipitation with ethanol. Following hydrolysis the constituent sugars of the polysaccharide were isolated and positively identified as the crystalline derivatives of D-glucose and of D-mannose and as the crystalline lactone of D-glucuronic acid. The above hexoses were found to be present in the relative proportions of 1:1:1.The results of a preliminary investigation in which C14-labelled glucose was supplied to rapidly growing cells indicate that it is unlikely that a single six-carbon precursor is formed from which all three sugar components of the polysaccharide are synthesized directly.