Floyd Dewhirst, DDS, PhD

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Floyd Dewhirst was deciphering the oral microbiome before the term microbiome was created. Dewhirst’s long-term research focus has been to define the diversity, genetic capability and pathogenic potential of organisms present in the human oral cavity.

Dewhirst has used 16S rRNA gene sequence information for cultured and as-yet-uncultured oral microbes to identify oral bacteria and place them into an organized taxonomic framework. This effort has resulted in the identification of approximately 700 species or phylotypes of human oral bacteria that are described in the Human Oral Microbiome Database (HOMD – http://www.homd.org). This database contains important phylogenetic, genomic and bibliographic information for each species, as well as bioinformatics tools to examine their genomes. Many isolates for previously unnamed or uncultured bacteria have been identified and made available to the scientific community through deposit in national type culture collections. The availability of these strains and their genome information has facilitated scientists worldwide to study them.

“Prior to this work, there was no reliable way to identify the bacteria that could not be grown,” said Dewhirst. “We now have molecular tools to easily identify currently uncultivated bacteria and investigators can now study their associations with health and disease.”

Dewhirst’s current research focus includes culturing the remaining 35% of oral bacteria that have resisted cultivation. His group has cultured strains representing more than 20 previously uncultured oral species in the past three years including more than 20 strains of bacteria representing four species of the Saccharibacteria (TM7) phylum. In collaboration with the Borisy group at Forsyth, he is seeking to expand genomic information for human oral bacterial species through analysis of metapangenomic sequence information. His ultimate goal is to have full pangenomic information for all species that comprise the oral microbiome.