Phylogeny of the genus Mycobacterium: many doubts, few certainties.

The genus Mycobacterium is characterized by very limited interspecies genetic variability and this makes the definition of a robust phylogeny problematic. In this study a twofold phylogenetic approach was adopted. Phylogenetic trees were constructed using as targets the almost complete 16S rRNA gene sequences and the concatenated amino acid sequences coded by fragments of hsp65 and rpoB genes. The comparison of the results made it possible to identify clusters of species sharing common phylogenetic pathway but for the majority of mycobacteria the definition of a robust phylogeny remained unreached.