An isolate of from a brain abscess showed neuraminidase (sialidase), β-D-galactosidase, N-acetyl-β-D-glucosaminidase and N-acetyl-β-D-galactosaminidase activities. The optimal pH values of these enzymes were 5.5-6.0, 5.5-6.0, 5.0-5.5 and 5.0-5.5, respectively. The k of the enzymes varied according to whether the type of substrate was chromogenic or fluorogenic; sialidase was most active at the lowest substrate concentrations, with a k of 0.01 mM. In semi-defined medium, with porcine gastric mucin—a model glycoprotein—as the sole source of fermentable carbohydrate, levels of the glycosidases were significantly increased. Addition of glucose to the mucin-containing medium, or growth of cells in media supplemented with glucose alone, repressed glycosidic activities and the majority of these were cell-associated. cells from cultures grown with mucin were able, simultaneously, to transport sugar: phosphoenolpyruvate phosphotransferase (PTS) systems, monosaccharides which are constituents of carbohydrate side chains of glycoproteins. These cells also possessed significant levels of neuraminate-pyruvate lyase, involved in the intracellular catabolism of neuraminic acid; this was absent from cells grown with glucose. These mechanisms, collectively, may facilitate the persistence and growth of .


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