Determination of the species among mitis group of genus Streptococus using a molecular identification key

We analyzed the gene order conservation among the species of genus Streptococcus and based on this we developed a molecular identification key. The identification key was not made up based on the genes’ amino acid or nucleotide sequences but on the gene order of certain genome parts, and in this order the genes were marked with their symbols. First, we created a key to determine the groups within the genus Streptococcus using conserved synteny blocks in genomes. According to this, within those species that have a fully known genome sequence, the mitis group can be divided into two subgroups: mitis I where (S. pneumoniae, S mitis and S. oralis) and mitis II (S. gordonii, S. sanguinis and S. parasanguinis). Then we made an identification key to determine the species within the mitis subgroups. For determination of the species we chose genome parts which contain such a gene that is found in all species but the genome parts around this special gene are different in various species. Three genome parts were sufficient to determine the species correctly. These sequences were around the following genes: Xaa-pro dipeptidyl-peptidase (x-prolyl-dipeptidyl aminopeptidase) - pepX, a leucyl-tRNA synthetase - leuS and a 50S ribosomal protein L13 and 30S ribosomal protein S9 - rplM and rpsI (these are always found beside one another).