UBC Theses and Dissertations
Capsular antigens of gram-negative bacteria Altman, Eleonora
Klebsiella, Escherichia coli, Salmonella and Shigella are among the most frequently found pathogenic Enterobacteria. The classification of Salmonella and Shigella relates mainly to the O antigens which are lipopolysaccharides, whereas for Klebsiella and E. coli capsular polysaccharides (K antigens) play an important role. Approximately eighty serologically different Klebsiella strains are known of which seventy structures have been determined. The structure of the capsular polysaccharide isolated from Klebsiella serotype K50 is presented here. It is unique among the Klebsiella K antigens in having a 1 five-plus-two' repeating unit. [See Thesis for Diagram] The K antigens of Escherichia coli can be divided into three groups (A, B, L) on the basis of their thermolability, all of which comprise acidic polysaccharides. The extracellular A antigens of E. coli bear a strong similarity to the K antigens of Klebsiella. The present investigation describes the isolation and the structural analyses of acidic polysaccharides obtained from Escherichia coli 09:K28(A):H- (K28 antigen) and Escherichia coli 09:K32(A):H19 (K32 antigen). [See Thesis for Diagram] Specific bacteriophage-borne glucanases were utilized to degrade the two Escherichia coli capsular polysaccharides. E. coli K32 polysaccharide has been degraded using a purified Φ32 bacteriophage with α-glucopyranosidase activity, while E. coli K28 polysaccharide has been degraded using crude solutions of the bacteriophages Φ 28—1 and Φ 28—2 (both with α-glucopyranosidase activity), and the results have been compared.
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