Genetic Aspects of the Added Carbon Dioxide Requirements of Brucella abortus . ∗

Abstract

Summary and conclusions

The results indicate that B. abortus loses its requirement for added CO₂ by spontaneous mutation at a rate of approximately 3 × 10⁻¹⁰ per cell division. Training of such cultures to dispense with their added CO₂ requirement probably consists of a selection of a spontaneously occurring mutant rather than gradual adaptation of the culture as a whole. The low mutation rate indicates a high degree of stability for CO₂ requirement in cultures of B. abortus.