The Exopolysaccharides of Klebsiella Serotype 2 Strains as Substrates for Phage-induced Polysaccharide Depolymerases

SUMMARY: A phage-induced enzyme has been used to hydrolyse the exopolysaccharides prepared from nine Klebsiella serotype 2 strains. In each case, the major product was a tetrasaccharide with chemical composition corresponding to the carbohydrate repeating unit of the polysaccharide. The tetrasaccharides also contained formate, sometimes with acetate or pyruvate. As the terminal reducing sugar in each tetrasaccharide was mannose, the enzyme is a mannosidase hydrolysing the d-mannosyl 1 → 4 d-glucose linkage.The enzyme is highly specific, being inactive against carboxyl-reduced type 2 polysaccharide and against polysaccharides from a number of other Klebsiella strains of different serotype. In contrast, similar phage-induced enzymes from Klebsiella aerogenes serotype 54 strains hydrolyse both type 2 and type 54 polysaccharides, yielding the same products from type 2 material as does the homologous enzyme. No further polysaccharides among those currently tested acted as substrates for the phage-induced enzymes.