Studies on the O-antigen of Hafnia alvei PCM 1224 structurally and serologically related to the O-antigen of H. alvei 481-L

Mild hydrolysis of the lipopolysaccharide of Hafnia alvei PCM 1224 at pH 4.2 cleaved partially the O-polysaccharide chain by the glycosyl phosphate linkages to yield a phosphorylated hexasaccharide representing the repeating unit of the O-polysaccharide and higher oligosaccharides consisting of two or more repeating units. Studies of the degradation products before and after dephosphorylation by sugar and methylation analyses along with 1D and 2D 1H and 13C NMR spectroscopy, including 2D 1H,1H COSY, TOCSY, ROESY, 1H,13C HSQC, HSQC-TOCSY, and 1H,31P HMBC experiments, enabled elucidation of the following structure of the O-polysaccharide:Figure optionsDownload as PowerPoint slideThis structure is similar to that of the O-polysaccharide of H. alvei 481-L established earlier (Kubler-Kielb, J.; Vinogradov, E.; Garcia Fernandez, J. M.; Szostko, B.; Zwiefka, A.; Gamian, A. Carbohydr. Res.2006, 341, 2980–2985), which has the same sugar composition and the same main chain structure and differs in the site of attachment of α-d-Glcp only. A two-way serological cross-reactivity of the lipopolysaccharides of H. alvei PCM 1224 and 481-L with polyclonal rabbit antisera indicated the expediency of classification of both strains to the same O-serogroup.

Figure optionsDownload as PowerPoint slideHighlights
► Structure of the O-antigen of Hafnia alvei PCM 1224 has been determined.
► The main chain structure is the same as for known O-antigen of H. alvei 481-L.
► O-Antigens differ only in the site of attachment of α-d-Glc to the main chain.
► Strains PCM 1224 and 481-L share a phosphate-containing main OPS chain.
► Both strains belong to the same O-serogroup due to a serological cross-reactivity.