Nitrogen-fixing bacterium Burkholderia brasiliensis produces a novel yersiniose A-containing O-polysaccharide.

Burkholderia brasiliensis, a Gram-negative diazotrophic endophytic bacterium, was first isolated from roots, stems, and leaves of rice plant in Brazil. The polysaccharide moiety was released by ammonolysis from the B. brasiliensis lipopolysaccharide (LPS), allowing the unambiguous characterization of a 3,6-dideoxy-4-C-(1-hydroxyethyl)-D-xylo-hexose (yersiniose A), an uncommon feature for Burkholderia LPS. The complete structure of the yersiniose A-containing O-antigen was identified by sugar and methylation analyses and NMR spectroscopy. Our results show that the repeating oligosaccharide motif of LPS O-chain consists of a branched tetrasaccharide with the following structure:-->2-alpha-d-Rhap-(1-->3)-[alpha-YerAp-(1-->2)]-alpha-D-Rhap-(1-->3)-alpha-D-Rhap-(1-->.