Preparation of purified polysaccharides from Rhizobium.

A method is described for the preparation of purified polysaccharides from strains of Rhizobium in quantities large enough so that with an exhaustive purification scheme enough product is recovered for various characterization purposes. When steps in the purification process are eliminated, much larger amounts of crude gum are obtained. Organisms were grown in liquid medium and the crude gum was precipitated along with the bacterial cells by a quaternary ammonium complexing agent. This precipitate was dissolved in salt solution, reprecipitated with ethanol or ethanol-acetone mixtures several times, followed by pressure filtration with membrane filters. The same procedure should be applicable to commercial scale production in large fermentors if a use for the gum could be shown. The method also should be suitable for other organisms with similar growth habits.