Studies on the Extracellular Polysaccharides (EPS) Produced in vitro by Pseudomonas phaseolicola

Native EPS produced by Pseudomonas syringae pv. phaseolicola in vitro was separated by ion exchange chromatography on DEAE fractogel into three different polysaccharide fractions. A neutral polysaccharide eluting with the void volume yielded only fructose upon hydrolysis and exhibited an IR spectrum similar to authentic levan. At about 300 mM KCl a mannuronan eluted. Comparison with authentic alginate by IR spectroscopy, elution behaviour during DEAE-fractogel column chromatography, and monomer composition (mannuronic acid and traces of guluronic acid) confirmed the identity of this fraction as a bacterial alginate. It contained about 56 mol% acetyl groups. A third polysaccharide eluted at about 160 mM KCl. Its monomeric composition (rhamnose, fucose, glucose, and amino sugars), elution behaviour upon DEAE-fractogel column chromatography, and TLC patterns, closely resembled the sugar moiety of lipopolysaccharides (LPS) from, Pseudomonas syringae pv. phaseolicola. The protein component of crude EPS represented a fourth macromolecular fraction. It was not covalently linked to any of the polysaccharides since it could be removed from the EPS by phenol extraction.