The novel structure of the core oligosaccharide backbone of the lipopolysaccharide from the Plesiomonas shigelloides strain CNCTC 80/89 (serotype O13).

•The complete new structure of P. shigelloides O13 core oligosaccharide has been established.•The presence of the glycine residue was identified by NMR and MALDI-TOF.•The position of the glycine was identified by MALDI-TOF MS/MS.