Species identification and phylogenetic relationships based on partial HSP60 gene sequences within the genus Staphylococcus

The phylogenetic relationships among 36 validly described species or subspe cies within the genus Staphylococcus were investigated by cloning and seque ncing their 60 kDa heat-shock protein (HSP60) genes using a set of universa l degenerate HSP60 PCR primers. The cloned partial HSP60 DNA sequences from nine Staphylococcus aureus strains were highly conserved (97-100 % DNA seq uence similarity; mean 98 %), indicating that the HSP60 gene of multiple is olates within the same species have little microheterogeneity. At the subsp ecies level, DNA sequence similarity among members of S. aureus, Staphyloco ccus schleiferi, Staphylococcus cohnii and Staphylococcus capitis ranged fr om 91 to 98 %, At the interspecies level, sequence similarity among 23 dist inct species of staphylococci ranged from 74 to 93 % (mean 82 %). By compar ison, the highest sequence similarity of Bacillus subtilis and Escherichia coli with members within the genus Staphylococcus was only 70 and 59 %, res pectively. Importantly, phylogenetic analysis based on the neighbour-joinin g distance method revealed remarkable concordance between the tree derived from partial HSP60 gene sequences and that based on genomic DNA-DNA hybridi zation, while 16S rRNA gene sequences correlated less well. The results dem onstrate that DNA sequences from the highly conserved and ubiquitous HSP60 gene offer a convenient and accurate tool for species-specific identificati on and phylogenetic analysis of staphylococci.