A bacterium, Ikeda-3, that was isolated from the wastewater of a winery was found to produce floating and precipitating exopolysaccharides (EPSs) when grown aerobically in a medium containing sucrose as the sole carbon source. The concentrations of floating and precipitating EPSs were approximately 2.7 g/l and 0.6 g/l, respectively, in a mini-jar fermentor after incubations of the bacterium at 15 degrees C for 5 d in a synthetic medium containing 1% sucrose, 0.01% CaCO3, 0.05% MgSO4, 0.05% K2HPO4, 0.0001% Na2MoO4, 0.05% peptone and 0.82% bicine. A component analysis of two types of EPS suggested that they represent a novel type of sphingan composed of glucose, rhamnose, mannose and mannuroic acid. Glucoronic acid, which is commonly found in sphingans, was absent. From physiological, biochemical and chemotaxonomic characterization, phylogenetic analysis and DNA-DNA relatedness, Ikeda-3 was identified as Novosphingobium rosa. To our knowledge the production of EPS by N. rosa is reported here for the first time.