The chemical structure of the O-polysaccharide isolated from the lipopolysaccharide of Pectobacterium brasiliense IFB5527, a phytopathogenic bacterium of high economic importance

Pectobacterium brasiliense is a widespread plant pathogenic bacterium classified to the Pectobacteriaceae family, which causes significant economic losses because of the developed soft rot and blackleg symptoms on potatoes and a wide spectrum of crops, vegetables, and ornamentals. One of the key virulence factors is a lipopolysaccharide due to its involvement in efficient colonisation of plant tissues and overcoming the host defence mechanisms. Thus, we structurally characterised the O-polysaccharide from the LPS of P. brasiliense strain IFB5527 (HAFL05) using chemical methods followed by GLC and GLC-MS as well as 1D and 2D NMR spectroscopy. The analyses revealed that the polysaccharide repeating unit consists of Fuc, Glc, GlcN and an unusual N-formylated 6-deoxy amino sugar, Qui3NFo, and has the structure shown below: