diversity of human commensal microflora
Targeted gene survey from oral microflora
A good definition of commensal microflora and understanding of its relation to health is essential in preventing and combating disease. We hypothesized that the species richness of human commensal oral microflora is currently underestimated. Saliva and supragingival plaque was sampled from 71 and 98 healthy adults, respectively. Amplicons from the V6 hypervariable region of the small subunit ribosomal RNA gene were generated by PCR, pooled into saliva and plaque pools and sequenced using the Genome Sequencer 20 system at 454 Life Sciences. Evaluation of the data consisted of taxonomic and rarefaction analyses.  Among 197,600 sequences, nearly 29,000 were identified as unique V6 tag sequences, representing 22 phyla and about 5,600 and 10,000 species-level phylotypes in saliva and plaque, respectively. This work gives a radically new insight in the diversity of human commensal oral microflora, which, with an estimated number of 26,200 phylotypes, is considerably higher than previously reported.  454 sequence data is available from the Short Read Archive (SRA): <a href="ftp://ftp.ncbi.nih.gov/pub/TraceDB/ShortRead/SRA001159 ">SRA001159</a>.