The chemical structure of the O-antigen and enterobacterial common antigen of Pectobacterium brasiliense NCPPB 4609TS.

Pectobacterium brasiliense is a widely distributed phytopathogenic bacterium that causes diseases such as soft rot and blackleg, leading to significant yield losses in potatoes as well as other vegetables and ornamental plants. Lipopolysaccharide (LPS) is an important virulence factor that plays an essential role in colonisation of plant tissues and overcoming the host defence mechanisms. The O-polysaccharide from the LPS of P. brasiliense strain NCPPB 4609TS (=CFBP 6617TS = LMG 21371TS = IFB5390) was structurally characterised using spectroscopic techniques and chemical methods. The analyses revealed that the polysaccharide repeating unit consists of Gal, GlcN and an unusual 3-amino-3,6-dideoxyglucose decorated with (R)-3-hydroxybutyric acid according to the structure shown below: In addition, another polysaccharide was isolated from bacterial cells, analysis of which led to the identification of an enterobacterial common antigen, containing N-acetyl-d-glucosamine, N-acetyl-d-mannosaminouronic acid, and 4-acetamido-4,6-dideoxy-d-galactose.