[Nucleotide makeup of the DNA of fast-growing mycobacteria and related microorganisms]

The melting points of DNA were used to determine the nucleotide composition of DNA from the following microorganisms with a high growth rate: Mycobacterium phlei, M. smegmatis, M. fortuitum, Nocardia asteroides, the organism of the "rhodochrous"--N. opaca group, and organisms related to strain "Mycobacterium" rhodochrous ATCC 13808. M. fortuitum had a higher mol% G+C (67.5--69.5) than M. phlei (66.9--67.5) and M. smegnatis (64.4--68.1); the strains of M. smegmatis were characterized by the most heterogeneous nucleotide composition of DNA. The organisms of the "rhodochrous" complex (mol% G+C=69.5--72.2) were closer to N. asteroides (mol% G+C=72.5--73.5) than to the mycobacteria with a high growth rate.