Purification and properties of a soluble polymer of glucose from cultures of Acetobacter xylinum.

A soluble nondialyzable polymer of glucose was isolated and purified by selective ethanol and ammonium sulfate precipitation from the supernatant of a culture of Acetobacter xylinum which was actively producing cellulose. This polymer was heterogeneous in size with an average sedimentation constant S20,w, of the most abundant fraction of 11.1. On drying from dilute solution in water, the polymer(s) showed extended linear fibrils or aggregates of such fibrils by transmission electron microscopy. The infrared spectrum resembled closely that of cellulose II. Preparations of the lyophilized polymer were amorphous by X-ray diffraction. Composition and structure of the polymer were established by enzymatic digestion, acid hydrolysis before paper chromatography, and methylation followed by gas-liquid chromatography. Glucose was the only component of the polymer. There were few, if any, alpha 1 leads to 4 linkages between glucose residues. The polymer(s) is a linear chain of glucose units linked beta 1 leads to 4 with single glucose residues as branches at position 2 of every third glucose on the average. The possibility that this branched glucose polymer is an intermediate in cellulose biosynthesis is examined.