Figure 1. PCR-DGGE analysis of 16S rDNA gene fragments of ATCC type strains. (A) The PCR-amplified 16S rDNA of the ATCC type-strains shows the same 350-bp amplicons for various oral bacteria on a 1% agarose gel. (B) Denaturing gradient gel electrophoresis profiles of PCR-amplified 16S rDNA of various oral bacteria arranged from low to high %GC content. The denaturing gradient ranged from 30% to 70%.