Influence of growth temperature on the development of Escherichia coli polysaccharide K antigens

The established seventy-one Escherichia coli polysaccharide capsular K antigenic test strains were examined for the development of the K antigen after growth at 37 degrees C and 18 degrees C. Twenty-eight K antigens were not detectable after growth of bacteria at 18 degrees C, while the remaining 43 antigens were developed at both temperatures. Most of the temperature-dependent antigens belonged to electrophoretically fast-moving K polysaccharides of rather low molecular weight, characteristically found among the common K antigens from extraintestinal disease isolates. Lipopolysaccharide O antigens were developed at both growth temperatures.