Aims: To establish species-specific PCR and DNA probe methods for Streptococcus salivarius and to clarify the distribution of dextranase in oral isolates of Strep. salivarius.
Methods and results: A pair of PCR primers and a DNA probe were designed based on the nucleotide sequence of the dextranase gene of Strep. salivarius JCM5707. Both the PCR primer and the DNA probe specifically detected Strep. salivarius but none of the other oral streptococci (23 strains of 13 species). The primer and the probe were capable of detecting 1 pg and 1 ng of the genomic DNA, respectively, purified from Strep. salivarius JCM5707. All oral isolates (130 strains from 12 subjects) of Strep. salivarius from human saliva were positive by both methods.
Conclusion: The present PCR and DNA probe methods are highly specific to Strep. salivarius and are useful for the its detection and identification of this bacterium. The dextranase widely distributes among oral isolates of Strep. salivarius.
Significance and impact of the study: The DNA sequence of a dextranase gene present in the genome of Strep. salivarius is useful as the target DNA of the species-specific PCR and DNA probe.