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Cecal contents of conventional and germfree rats were examined for glycosidases which may have a role in degrading glycoprotein oligosaccharides. Utilizing p-nitrophenylglycosides as substrates, we identified glycosidases in bacteria-free supernatants from cecal contents which act on beta-linkages. These cecal glycosidases appear to be of bacterial origin since: (1) direct comparisons of the enzymes in similar contents from germfree rats showed negligible activities; (2) most of the glycosidase levels in bacterial extracts were at least as high as those of soluble supernatants; and (3) disk gel electrophoresis of contents and bacterial extracts revealed in both preparations a beta-N-acetylglucosaminidase band with similar Rfs. Also, the blood group B antigenicity of germfree cecal glycoproteins was greatly decreased by conventional cecal contents. These findings indicate that beta-galactosidase and beta-N-acetylgalactosaminidase in cecal contents are bacterial in origin, and they may have a role in the bacterial catabolism of intestinal glycoproteins.

Intestinal mucin glycoproteins were examined for their ability to sustain growth of pathogenic shigella. Inoculation of germfree cecal mucin glycoproteins with Shigella flexneri 4b resulted at 48 h in a 940-fold increase in the enteropathogen concentration. Investigation in vitro of enzymatic degradation by the pathogen led to the identification of a blood group B-degrading glycosidase produced by the bacteria. In in vivo experiments, fecal supernatants of mice monocontaminated with S. flexneri 4b contained an alpha-galactosidase active against the p-nitrophenyl-glycoside. This fecal alpha-galactosidase peaked 5 days after shigella contamination, showing 2.8 +/- 1.4 mU of enzyme activity per mg of protein. Contaminated fecal supernatants similarly destroyed the blood group B reactivity of cecal mucin glycoproteins. These data suggested that S. flexneri 4b could proliferate within ileocolonic environment by enzymatically degrading mucin glycoprotein sugars.

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