Microbial Complexes in Subgingival Plaque: A Bacterial Meta-Taxonomic Study.

Area of Science:

• Microbiology
• Periodontology
• Bioinformatics

Background:

• The seminal work of Socransky et al. established a framework for understanding subgingival microbiota in periodontal health and disease.
• Technological advancements now allow for a more precise characterization of microbial diversity and dynamics.

Purpose of the Study:

• To develop a more accurate representation of subgingival microbiota diversity and dynamics using advanced sequencing and bioinformatics.
• To identify distinct microbial complexes and patterns associated with periodontal health, gingivitis, and periodontitis.

Main Methods:

• V3-V4 16S rRNA sequencing of subgingival plaque from 135 patients (healthy, gingivitis, periodontitis).
• Probabilistic assignment of sequences to unambiguous taxon groups (UTGs) using advanced bioinformatics.
• Unsupervised clustering to identify microbiota patterns and correlation analysis for bacterial community ordination.

Main Results:

• 394 unambiguous taxon groups (UTGs) were identified, with an average of 157 per sample.
• Hierarchical clustering revealed 10 UTG complexes, including Complex 6 (health-associated) and Complex 10 (disease-associated).
• Complex 10 included red complex species, Treponema, and orange complex species; Complex 6 included green, yellow, and purple complex species. Five distinct microbiota patterns related to disease progression were identified.

Conclusions:

• Ten novel UTG complexes provide a framework for understanding subgingival plaque ecology and microbial dynamics.
• Shifts in the relative abundance of these complexes signify transitions between healthy and diseased periodontal states, with intermediate patterns observed.
• Proposed use of these patterns as indicators for periodontal disease classification and risk assessment, complementing existing staging and grading systems.