Determination of genome size and DNA homology between an unclassified Mycobacterium species isolated from patients with Crohn's disease and other mycobacteria.

The genome size of an unclassified Mycobacterium species, isolated from a patient with Crohn's disease, was determined by measurement of DNA renaturation kinetics as 3.1 X 10(9) Da. The percentage of DNA homology of this organism to DNA of related mycobacteria was evaluated by measurement of DNA renaturation with heterologous DNA. These studies supported the classification of this organism as Mycobacterium paratuberculosis but failed to distinguish between M. paratuberculosis and organisms of the Mycobacterium avium-intracellulare groups.