The influence of pH of the culture medium on the sensitivity of Mycoplasma gallisepticum antigens for use in certain serological tests.

Mycoplasma gallisepticum antigens were prepared from organisms cultured in broth medium with glucose. The influence of period of growth, pH of the medium and duration of incubation at low pH (5.0) on the sensitivity of these antigens was determined in certain tests. The most sensitive antigen for the serum plate test was harvested after no more than 8 hr. incubation at pH 5.0. Sensitivity in serum plate, haemagglutination and gel diffusion tests was impaired if organisms were incubated at pH 5.0 for long periods. Antigens prepared from buffered broth medium were found to be at least as sensitive as those from unbuffered medium for the haemagglutination and gel precipitation tests, but considerably less so for the serum plate test.