A new water-soluble polysaccharide (WSP) was isolated from a culture of Acetobacter xylinum NCI 1005 grown on sucrose. The structure of the WSP was analysed by nuclear magnetic resonance spectroscopy and determined to be a beta-(2-->6)-linked polyfructan, which is structurally different from the polymer synthesized from glucose instead of sucrose by the same strain. The discovery of this new polysaccharide has revealed that the bacterium is able to synthesize two different kinds of water-soluble polysaccharides.