Diversity and characteristics of the oral microbiome influenced by race and ethnicity.

Periodontitis disproportionately affects racial/ethnic populations. Besides social determinants contributing to disparities in periodontal health, variations of oral microbial communities may also be a key factor influencing oral immune responses. To characterize the oral microbiome from different racial/ethnic populations, we collected 161 dental plaque samples from African Americans (AAs), Caucasian Americans (CAs), and Hispanic Americans (HAs) with clinical gingival health or biofilm-induced gingivitis on an intact periodontium. Using metagenomic sequencing, we found significant difference in diversity and abundance of microbial taxa in the dental plaque samples from AA, CA, and HA groups and unique microbial species that can only be detected in a particular racial/ethnic group. Moreover, we revealed racial/ethnic associated variations in functional potential of the oral microbiome, showing that diversity and abundance of antibiotic resistant genes were greater in the oral microbiome of the AAs than those in CAs or HAs, and that the AAs exhibited higher levels of genes involving in modification of glycoconjugates, oligo- and polysaccharides. These findings indicate more complex and higher virulence potential oral microbiome in AA and HA populations, which likely contributes to higher prevalence of periodontitis in AAs and HAs.