Structural and Interaction Studies of Bacterial Polysaccharides by NMR Spectroscopy

An introduction to bacterial polysaccharides and the methods for structural determination are described in the first two parts of the thesis. In a structural elucidation of bacterial polysaccharides NMR experiments are important as is component analysis. A short description of immunochemical methods such as enzyme immunoassays is included. Two NMR techniques used for interaction studies, trNOE and STD NMR, are also discussed. The third part of the thesis discusses and summarizes the results from the included papers. The structures of the exopolysaccharides produced by two lactic acid bacteria are determined by one- and two dimensional NMR experiments. One is a heteropolysaccharide produced by Streptococcus thermophilus and the other a homopolysaccharide produced by Propionibacterium freudenreichii. The structure of an acidic polysaccharide from a marine bacterium with two serine residues in the repeating unit is also investigated. The structural and immunological relationship between two O-antigenic polysaccharides from Escherichia coli strain 180/C3 and O5 is discussed and investigated. Finally, interaction studies of an octasaccharide derived from the Salmonella enteritidis O-antigen and a bacteriophage are described which were performed with NMR experiments.

Epistemic marking and multiple perspective : an introduction

This paper discusses forms of epistemic marking that instantiate multiple perspective constructions (see Evans 2005). Such forms express the speaker’s and the addressee’s simultaneous epistemic perspectives from the point of view of the speaker, crucially relying on the assumptions of the speaker with regard to the addressee’s knowledge. The analysis of forms considers established semanto-pragmatic concepts, such as semantic scope, mitigation strategies and communicative intention (as marked by sentence-type) in the exploration of forms. In addition, the notion of knowledge asymmetry is discussed alongside the concepts of epistemic status and stance as tools for a semantic analysis of investigated forms