Mycoplasma evolution: a review of the use of ribosomal and transfer RNA nucleotide sequences in the determination of phylogenetic relationships.

Comparison of the nucleotide sequences of "structural" RNAs (ribosomal and transfer RNA) has enabled the construction of phylogenetic trees to be achieved. Data from 16S rRNA, 5S rRNA, and tRNA from a total of eight Mollicutes (excluding T. acidophilum) including representatives of the families Mycoplasmataceae, Spiroplasmataceae, and Acholeplasmataceae, show that these families share a close relationship and a common ancestor with the gram-positive eubacteria. Thermoplasma acidophilum is a member of the kingdom Archaebacteriae and has no relationship to the other Mollicutes.