Identification of new genomospecies in the mycobacterium terrae complex

Members of the Mycobacterium terrae complex are slow-growing, non-chromogenic acidfast
bacilli found in the natural environment and occasionally in clinical material. These genetically
closely-related members are difficult to differentiate by conventional phenotypic
and molecular tests. In this paper we describe the use of whole genome data for the identification
of four strains genetically similar to Mycobacterium sp. JDM601, a newly identified
member of the M. terrae complex. Phylogenetic information from the alignment of genomewide
orthologous genes and single nucleotide polymorphisms show consistent clustering of
the four strains together with M. sp. JDM601 into a distinct clade separate from other rapid
and slow growing mycobacterial species. More detailed inter-strain comparisons using average
nucleotide identity, tetra-nucleotide frequencies and analysis of synteny indicate that
our strains are closely related to but not of the same species as M. sp. JDM601. Besides
the 16S rRNA signature described previously for the M. terrae complex, five more hypothetical
proteins were found that are potentially useful for the rapid identification of mycobacterial
species belonging to the M. terrae complex. This paper illustrates the versatile utilization of
whole genome data for the delineation of new bacterial species and introduces four new
genomospecies to add to current members in the M. terrae complex.