Mycobacterium ulcerans and other mycolactone-producing mycobacteria should be considered a single species

The new species assignations for MPM have not considered their genomic context and have been based on variable phenotypic characteristics (such as colony morphology and in vitro growth rates) and limited, monophyletic rRNA, hsp65, or rpoB analyses, which have shown these mycobacteria have a few unique nucleotide sequences when compared to a small number of allele sequences in GenBank. In practice, a prokaryotic species is considered to be a group of strains (including the type strain) that is characterised by a certain degree of phenotypic consistency, showing greater than 97% 16S rRNA gene-sequence identity and greater than 70% DDH [16].