Plant leaves were examined for bacteria capable of producing polysaccharide extracellularly. A bacterium identified as belonging to genus Enterobacter efficiently produced polysaccharide. Polysaccharide productivity was optimal in medium which included sucrose, peptone, MgSO4.7H(2)O, and yeast extract; the conversion ratio of sucrose to the product was about 30% (w/w). The theological and gelling properties of partially purified polysaccharides were similar to those of xanthan gum. The polysaccharides could be separated into two types by ion exchange chromatography. The sugar constituents of both polysaccharides wore glucose, mannose, rhamnose, galacturonic acid, and glucuronic acid, although their respective molar ratios were different.