Characterization of subgingival plaque microbiota in patients with severe periodontitis using full-length 16S rRNA gene sequencing.

Periodontitis is a widespread global health issue with significant systemic health implications. Subgingival plaque microbiota is considered its driving factor. Thus, accurate profiling of the microbiota is essential for understanding the etiology of periodontitis. We investigated the subgingival plaque, supragingival plaque, and tongue microbiota in 34 patients with severe periodontitis using PacBio long-read sequencing of the full-length 16S ribosomal RNA gene and amplicon sequence variant (ASV) analysis. The alpha and beta diversities of subgingival and supragingival plaque microbiota were distinct from those of tongue microbiota. Despite their distinct bacterial compositions, the tongue and plaque microbiota shared an average of 20 ASVs per participant, accounting for approximately 13% and 38% of the tongue and plaque microbiota, respectively. Comparative microbiota analysis across these oral niches identified 17 species that were specifically enriched in the subgingival plaque. They accounted for 18.9 ± 20.2% (mean ± SD) of the subgingival plaque microbiota and predominantly consisted of Porphyromonas gingivalis, Parvimonas micra, and Mogibacterium timidum. Altogether, we demonstrate a high-resolution profile of the subgingival microbiota, thereby providing information to improve our understanding of the complex etiology of periodontitis.