Acquisition of the Oral Microbiome

Objectives: The human oral microbiome includes over 700 species of bacteria that contribute to an individual’s overall oral health status. While mature adult microbial communities have been extensively characterized, little is known about the acquisition and assembly of this complex ecosystem. Our earlier studies characterized the assembly of oral microbial communities from birth to 1 year of age. The objective of this study was to characterize the development of the oral microbiome from 1 to 14 years of age.

Methods: Salivary, supragingival, and subgingival plaque samples were collected from children and adolescents 1 -14 years of age. Bacterial community composition at the species level was determined using rRNA gene amplicon sequencing. The relationship of community composition by site and age was assessed using Bray Curtis multidimensional scaling (EnvFit), Shannon Diversity and species richness (linear regression), and relative abundance of species by age (mixed effects linear model with false discovery correction).
Results: Species richness increased with age in both supragingival (p=0.046) and subgingival (p=0.0043) sites. Several species showed significant change in abundance over time. Among the largest significant changes in supragingival sites were a decrease with age in relative abundance of Rothia and Neisseria, and an increase in Camplyobacter gracilis and Fusobacterium nucleatum. In subgingival sites Streptococcus gordonii increased and uncultivated Porphyromonas HF001 decreased with age. Using MDS plots we also found that supragingival and subgingival communities were more closely related to one another than to the profile observed in salivary samples.
Conclusions: While our previous study showed that oral microbial communities in children establish in an ordered progression during the first year of life, our current results suggest that microbial community composition continues to increase in complexity and matures in a shared and ordered sequence during early childhood and adolescence.