The objective of this study was to develop PCR primers that are specific for Streptococcus sanguinis, Streptococcus parasanguinis, and Streptococcus gordonii. We designed the S. sanguinis-, S. parasanguinis-, and S. gordonii- specific primers, Ssa21-F3/Ssa21-R2, Spa17-F/Spa17-R, and Sgo41-F1/Sgo41-R1 respectively, based on the nucleotide sequences of the Ssa21, Spa17, and Sgo41 DNA probes that were screened using inverted dot blot hybridization (IDBH). The species-specificity of these primers was as- sessed against 43 strains of mitis group streptococci, in- cluding clinical strains of S. sanguinis, S. parasanguinis, and S. gordonii. The resulting PCR data revealed that species-specific amplicons had been obtained from all strains of the target species tested, and that none of these amp- licons occurred in any other strains from other species. These results suggest that the Ssa21-F3/Ssa21-R2, Spa17- F/Spa17-R, and Sgo41-F1/Sgo41-R1 primers may be useful in detecting S. sanguinis, S. parasanguinis, and S. gordonii at the species level, respectively.

Mitis group streptococci (MGS) were classified based on the nucleotide sequences 16S rRNA gene (16S rDNA) and comprised 13 Streptococcus species. However, 16S rDNA homogeneity among MGS was too high to discriminate between clinical strains at the species level, notably between Streptococcus mitis, Streptococcus oralis, Streptococcus pneumoniae, and Streptococcus pseudopneumoniae. The purpose of this study was to discriminate between 37 strains of MGS isolated from Korean oral cavities using phylogenetic analysis of the DNA-dependant RNA polymerase beta‐subunit gene (rpoB). 16S rDNA and rpoB from clinical strains of MGS were sequenced using the dideoxy chain termination method and analyzed using MEGA version 5 software. The resulting phylogenetic data showed that the rpoB sequences could delineate clinical strains of MGS at the species level. Phylogenetic analysis of rpoB is therefore a useful approach for dentifying MGS at the species level.

지렁이과 (family Megascolecidae) 왕지렁이속 (genus Amynthas) 그룹을 rDNA ITS 유전자를 이용하여 계통 유연관계를 알아보고자 하였다. 2과 10속에서 26종의 DNA 염기서열을 이용하여 종간 계통적 유연관계를 MP (Maximum Parsimony), NJ (Neighbor Joining), QP (Quartet Puzzling)로 계통도를 작성하였다. 염기서열이 확보된 Megascolecidae (지렁이과)의 국내외