Isolation of an exopolysaccharide-producing bacterium, Sphingomonas sp. CS101, which forms an unusual type of sphingan.

An exopolysaccharide-producing Gram negative bacterium was isolated and determined to be a Sphingomonas sp. (CS101). A sugar composition analysis of an exopolysaccharide indicated that the Sphingomonas sp. CS101 secreted an exopolysaccharide composed of glucose, mannose, fucose, and rhamnose in the ratio of 2.1:1.1:1.0:0.1, suggesting that this exoplysaccharide is an unusual type of sphingan family. The mean molecular weight of the exopolysaccharide was determined to be 4.2x10(5) Da by size exclusion chromatography coupled with multi-angle laser-light scattering (SEC/MALLS) analysis. An exopolysaccharide was produced up to 17 g/l (pH 7; 30 degrees C) with the optimal medium condition over 4 days of cultivation.