, 1993). rpoA-specific primers were designed based on rpoA nucleotide sequences of S. pneumoniae (GenBank accession number AM286896), S. oralis (GenBank accession number AM269658), and S. mitis (GenBank accession number AM269625) in the public database using the primer3 program (Rozen & Skaletsky, 2000) with default settings. The primer sequences were rpoA – F (5′-CACAGTTCCAGGTGTTCGTG-3′; positions 47–66) and rpoA – R: (5′-TGCTGAAAGCCCTAAAGCAT-3′;
positions 472–491). The primers used for the PCR amplification and sequencing of the 16S rRNA gene were derived from conserved regions of previously described 16S rRNA gene sequences of eubacteria: 27F (5′-AGAGTTTGATCMTGGCTCAG-3; positions 8–27, Escherichia coli) and 1525R (5′-AAGGAGGTGWTCCARCC-3′; complementary to PLX-4720 position 1525–1509, E. coli) (Lane, 1991). PCR was performed with 100 ng of genomic DNA template in 25 μL reaction mixtures containing 1 mM each primer, 2.5 μL reaction buffer, 0.2 mM dNTPs, 1.5 mM MgCl2,
and 2.5 U Taq polymerase (Roche Diagnostics, Indianapolis, IN). Amplification was carried out in a GeneAmp PCR system 2700 (Applied Biosystems, Foster City, CA) with the following learn more primary PCR cycling conditions: initial denaturation at 94 °C for 5 min; 35 cycles at 94 °C for 30 s, 64 °C for 30 s, and 72 °C for 30 s; and a final extension at 72 °C for 10 min. Electrophoresis of each PCR product in 1.2% SeaKem LE agarose gels (FMC Bioproducts, Rockland, ME) was performed, followed by ethidium bromide staining. The results were viewed under a GelDoc XR image-analysis system (BioRad, Hercules, CA). Partial rpoA gene (445 bp) and nearly complete
16S rRNA gene (c. 1500 bp) sequences were directly sequenced Dichloromethane dehalogenase using a BigDye terminator cycle sequencing kit (Applied Biosystems) and an automatic DNA sequencer (model 3730; Applied Biosystems). The resultant sequences were aligned using the clustalx program (Thompson et al., 1994) and computer-assisted phylogenetic trees were constructed using the neighbor-joining algorithm (Saitou & Nei, 1987), least-squares (Fitch & Margoliash, 1967), and maximum-likelihood (Felsenstein, 1981) methods from the phylip suite of programs (Felsenstein, 1989). Evolutionary distance matrices were generated using the neighbor-joining method described by Jukes & Cantor (1969) and tree topology was evaluated using bootstrap analysis (Felsenstein, 1985) of the neighbor-joining dataset with the seqboot and consense programs from the phylip package. The nucleotide sequences obtained in this study were deposited in the NCBI GenBank under accession numbers GU045377–GU045404 for rpoA and GU045405–GU045432 for the 16S rRNA gene. Both rpoA and 16S rRNA genes were successfully amplified from the genomic DNA of all 28 streptococci strains. The estimated size of the amplified PCR products was 445 bp for the N-terminal region of rpoA and about 1500 bp for the 16S rRNA gene.