The thesis for a candidate's degree by speciality 03.00.07 - microbiology. Institute of Microbiology and Virology named by D.K. Zabolotny of National Academy of Sciences of Ukraine, Kyiv, 2005. Candidate's thesis is dedicated to investigation of lipopolysaccharides (LPS) of Rahnella aquatilis. Six strains (33071 - type, 1-95, 2-95, 3-95, 2-87, and 3-88 ) were isolated from different sources, and their LPS were characterised on structure - function level. The analyses of monosaccharides showed us, that the predominant monosacharides in LPS of investigated strains were rhamnose, mannose, and galactose. Mild acid hydrolysis was used for receiving individual structural components of LPS molecule. R. aquatilis strains 33071, 3-95, 2-87, 3-88 contained two high molecular fractions of O-specific polysaccharide (OPS): 1 and 1*. The predominant monosaccharides of OPS were galactose, fucose, rhamnose, mannose and glucose. The majority of core-olygosaccharides were represented by galactose and glucose. All investigated strains were devided into four chemotypes by their OPS monosaccharide composition, and into nine chemotypes by their core olygosaccharide composition. By fatty acids composition all LPS were the similar. The predominant fatty acid was 3-oxytetradecanoic- diagnostic for Enterobacteriaceae. Tetradecanoic, dodecanoic and hexadecanoic were also detected. At first, the OPS structure of investigated R. aquatilis strains were established. It was identified 5 types of OPS structure, which were unique. The structure of OPS were represented by linear or branched hetero- or homopolysaccharides, which include mono-, three-, hexa- (or hepta-) saccharides repeating units. OPS of some strains tested included more than one type of oligosaccharide, which were different by their structure. On the basis of O-antigenicity of LPS, strains investigated were devided in to three serogroups: the first include the type strain 33071, the second - strains 1-95, 2-95, 3-95, 2-87, the third - strain 3-88. LPS of all investigated strains are pyrogenic and toxic. Chemical modifications of LPS by N,O-deacylation and dephosphorylation lead to the complete loss of their toxicity and pyrogenicity. Key words: lipopolysaccharides, fatty acids composition, structure of OPS, serogroup, toxicity, pyrogenicity, N,O-deacylation, dephosphorylation LPS, Rahnella aquatilis.
