Structural studies of the O polysaccharides from the lipopolysaccharides of Azospirillum thiophilum BV-ST and Azospirillum griseum L-25-5w-1T.

Diazotrophic bacteria of the genus Azospirillum are known widely, because they are ubiquitous in the rhizosphere and can promote the growth and performance of nonlegume plants. Recently, more Azospirillum species have been isolated from sources other than plants or soil. We report the structures of the O polysaccharides (OPSs) from the lipopolysaccharides of the type strains A. thiophilum BV-ST (1) and A. griseum L-25-5w-1T (2), isolated from aquatic environments. Both structures have a common tetrarhamnan in the repeating-unit, which is decorated with a side xylose in the OPS of A. thiophilum BV-ST.