Structural studies of some bacterial lipopolysaccharides and extracellular polysaccharides using NMR spectroscopy and mass spectrometry

The thesis presents structural studies of the O-specific chains from lipopolysaccharides, LPS, isolated from the bacteria Hafnia alvei strain PCM 1200, PCM 1203 and PCM 1205 and Plesiomonas shigelloides strain CNCTC 144/92 (O74:H5) as well as studies of extracellular polysaccharides, EPS, isolated from Butyrivibrio fibrisolvens strains I1 and 12. The main methods used, alone or in combination, for solving the structures have been chemical degradation procedures, mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. In the studies of Hafnia alvei it was established that the O-deacetylated O-specific polysaccharide isolated from LPS from H. alvei strains 1200 and 1203 possess the same composition and sequence as the O-deacetylated H. alvei strain 1205, i.e. a glycerol teichoic acid-like polymer having a repeating unit composed of a pentasaccharide unit. Serological tests revealed immunochemical similarities between the LPS of the Hafnia alvei strains PCM 1200, 1203 and 1205. In the studies of Plesiomonas shigelloides strain CNCTC 144/92 it was concluded that the O-specific chain is composed of a trisaccharide repeating unit with the following structure: [->2)-b-D-Quip3NHR-(1->3)-a-L-Rhap2OAc-(1->3)-a-D-FucpNAc-(1->] in which the R was determined as 3-hydroxy-2,3-dimethyl-5-oxo-pyrrolidine-2-carboxylic acid. The structure of the core part of the LPS was determined to be composed of a non-phosphorylated octasaccharide. The structure elucidation of the EPS produced by Butyrivibrio fibrisolvens strain I1 revealed a hexasaccharide repeating unit with a unique substituent consisting of glucitol phosphate where the glucitol was 4,6 substituted to a pyruvic acid acetal. The structure elucidation of the EPS produced by Butyrivibrio fibrisolvens strain 12 also revealed a hexasaccharide repeating unit with a unique substituent of glyceric acid phosphate where the glyceric acid was substituted with a glutamic acid