Open AccessThe identity of the O‐specific polysaccharide structure of Citrobacter strains from serogroups O2, O20 and O25 and immunochemical characterisation of C. youngae PCM 1507 (O2a,1b) and related strains
Author(s) -
Mieszała Małgorzata,
Lipiński Tomasz,
Kocharova Nina A,
Zatonsky George V,
Katzenellenbogen Ewa,
Shashkov Alexander S,
Gamian Andrzej,
Knirel Yuriy A
Publication year - 2003
Publication title -
fems immunology & medical microbiology
Language(s) - English
Resource type - Journals
eISSN - 1574-695X
pISSN - 0928-8244
DOI - 10.1016/s0928-8244(03)00081-6
Subject(s) - citrobacter , heteronuclear single quantum coherence spectroscopy , methylation , chemistry , strain (injury) , polysaccharide , two dimensional nuclear magnetic resonance spectroscopy , microbiology and biotechnology , biology , stereochemistry , enterobacteriaceae , biochemistry , escherichia coli , gene , anatomy
Serological studies using SDS–PAGE and immunoblotting revealed that from five strains that are ascribed to Citrobacter serogroup O2, four strains, PCM 1494, PCM 1495, PCM 1496 and PCM 1507, are reactive with specific anti‐ Citrobacter O2 serum. In contrast, strain PCM 1573 did not react with anti‐ Citrobacter O2 serum and, hence, does not belong to serogroup O2. The LPS of Citrobacter youngae O2a,1b (strain PCM 1507) was degraded under mild acidic conditions and the O‐specific polysaccharide (OPS) released was isolated by gel chromatography. Sugar and methylation analyses along with 1 H‐ and 13 C‐NMR spectroscopy, including two‐dimensional 1 H, 1 H COSY, TOCSY, NOESY and 1 H, 13 C HSQC experiments, showed that the repeating unit of the OPS has the following structure:NMR spectroscopic studies demonstrated that Citrobacter werkmanii O20 and C. youngae O25 have the same OPS structure as C. youngae O2. Sugar and methylation analyses of the core oligosaccharide fractions demonstrated structural differences in the lipopolysaccharide core regions of these strains, which may substantiate their classification in different serogroups.