Gerald Cagle

Identification ofEscherichia coli spheroplasts by the fluorescent-antibody staining technique

Spheroplasts ofEscherichia coli were produced by penicillin or lysozyme-ethylenediaminetetraacetic acid and examined by the direct fluorescent-antibody staining technique. Most spheroplasts stained with somatic-O fluorescent antibody exhibited brilliant peripheral fluorescence with localized areas of irregular staining. Electron micrographs showed that these spherical structures had considerable amounts of cell wall fragments associated with them. Two strains ofE. coli employed in the present study required different concentrations of penicillin for the conversion of all cells in an exponential culture to spheroplasts. Slight differences in lysozyme sensitivity were also encountered with these strains. The direct fluorescent-antibody staining technique was effective for the rapid identification ofE. coli spheroplasts in mixed cultures.