Structure of the O6 antigen of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia

A polysaccharide containing d-xylose, l-rhamnose, and N-acetyl-d-glucosamine was released on mild acid hydrolysis of the lipopolysaccharide extracted from defatted cell walls of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia strain 557, the reference strain for serotype O6. By means of NMR spectroscopy and chemical degradations, the repeating unit of the polymer was identified as a branched trisaccharide with the structure shown.