Phylogenetic study of Staphylococcus and Macrococcus species based on partial hsp60 gene sequences

A 600 bp partial hsp60 gene sequence has been described previously as a novel genetic marker for species identification and phylogenetic studies within the genus Staphylococcus. In the present study, the 600 bp partial hsp60 gene sequences of 40 validly described Staphylococcus species and subspecies and four Macrococcus species were PCR-amplified and sequenced. Phylogenetic analysis revealed excellent concordance between the unrooted dendrograms based on partial hsp60 and 16S rRNA gene sequences. The genus Macrococcus is clearly separated from the genus Staphylococcus, but is closely related to the 'sciuri group', the only staphylococci that are cytochrome c oxidase-positive. The remaining Staphylococcus species clustered into five broad-based subdivisions, which corresponded to the 'aureus group', the 'epidermidis group', the 'haemolyticus group', the 'saprophyticus group' and the 'intermedius group'. These results agreed remarkably well with the current taxonomy of this diverse family, which is based on classical phenotypic and biochemical testing. Furthermore, pairwise sequence comparisons indicated that the hsp60 gene is more divergent and more discriminatory than the 16S rRNA gene for species differentiation among strains of the genera Staphylococcus and Macrococcus. It is concluded that the hsp60 gene may be an efficient alternative target for taxonomic and phylogenetic studies on members of these genera.