Effect of Glucose and Amino Acids on Expression of K99 Antigen in Escherichia coli

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Abstract
K99 antigen production by enterotoxigenic E. coli strains of bovine origin was investigated by slide agglutination and in vitro attachment to intestinal villi. Work with 2 strains (B41 and B44) showed that on minimal medium M2, K99 antigen was not repressed by a high concentration of glucose (2% wt/vol). Growth on synthetic or complex medium did not affect K99 antigen detection, which was independent of capsular antigens, and its synthesis was not repressed by Casamino acids or glucose. A survey of 12 strains revealed 2 groups: in 1 group K99 antigen production was constitutive on basal medium without glucose, and in the 2nd group K99 antigen was produced only in the presence of glucose. Immunoelectrophoresis patterns, and the results of slide agglutination and attachment tests, were dependent upon K99 type, whereas hemagglutination patterns were not.