Adhesion of actinomyces isolates to experimental pellicles

Area of Science:

• Oral microbiology
• Bacterial adhesion mechanisms

Background:

• Bacterial adhesion to tooth surfaces is linked to pathogenicity.
• Actinomyces adheres via extracellular fimbriae, but bacterial contributions to the acquired pellicle are understudied.
• Previous research focused on salivary components, neglecting bacterial-derived factors.

Purpose of the Study:

• To investigate the role of cell-free glucosyltransferase (GTF) from Actinomyces viscosus in bacterial adhesion.
• To compare the adhesion properties of human and rodent isolates of A. viscosus to modified hydroxyapatite surfaces.
• To assess the impact of A. viscosus adhesion on subsequent Streptococcus mutans colonization.

Main Methods:

• Hydroxyapatite (HA) was coated with parotid saliva (sHA).
• Cell-free GTF was adsorbed onto sHA, followed by A. viscosus exposure to synthesize glucans in situ.
• Adhesion assays were performed using human and rodent A. viscosus isolates and Streptococcus mutans.

Main Results:

• Glucans synthesized in situ by GTF facilitated rodent A. viscosus adhesion.
• In situ glucans reduced human A. viscosus adhesion compared to sHA alone.
• Rodent strains, unlike human isolates, aggregated with dextrans and mutan, suggesting dextran-binding proteins.
• Rodent A. viscosus on pellicle inhibited subsequent S. mutans adhesion, while human isolates did not.

Conclusions:

• Human and rodent Actinomyces viscosus isolates exhibit distinct glucan-mediated adhesion properties.
• Bacterial-derived glucans play a significant role in Actinomyces adhesion and interspecies interactions.
• These findings highlight differences in oral biofilm formation mechanisms between human and rodent strains.