Partial purification and properties of somatic antigen spontaneously released from Vibrio cholerae

The supernatant fluids from cultures of Vibrio cholerae grown for 40 h in an dialyzable medium were dialyzed, concentrated, and fractionated on agarose columns. The fractions containing most of the antigen which inhibited the vibriocidal activity of homologous antiserum were pooled, dialyzed, and concentrated to provide material with about 100 times the specific activity of the original culture supernatant. This material, containing 12 to 20% protein, 11 to 19% carbohydrate, and about 16% unbound lipid, had a mean lethal dose for mice of about 500 mug. This partially purified antigen absorbed all the vibriocidal antibody from homologous antiserum against live cultures and produced a single line of precipitation in gel diffusion tests with the same antiserum.