Interactive forces between co-aggregating and non-co-aggregating oral bacterial pairs

Area of Science:

• Microbiology
• Biophysics
• Dental Research

Background:

• Dental plaque develops through adhesive interactions between diverse bacterial strains and species.
• These interactions are driven by Lifshitz-Van der Waals and acid-base forces, overcoming electrostatic repulsion.
• The influence of temperature on these forces is significant, yet direct measurements of forces between co-aggregating and non-co-aggregating pairs are lacking.

Purpose of the Study:

• To quantify and compare the interactive forces between co-aggregating and non-co-aggregating bacterial pairs.
• To investigate the effect of temperature (10°C, 22°C, 40°C) on these bacterial adhesive forces.

Main Methods:

• Utilized atomic force microscopy (AFM) to measure forces between bacterial pairs.
• Immobilized Actinomyces naeslundii 147 on AFM cantilevers and streptococci on glass surfaces.
• Measured repulsive forces upon approach and adhesive forces upon retraction.

Main Results:

• A repulsive force was observed upon approach for both co-aggregating and non-co-aggregating pairs.
• Upon retraction, co-aggregating pairs exhibited significantly larger adhesive forces and energies compared to non-co-aggregating pairs.
• The adhesive interactions for the co-aggregating pair were weakest at 40°C.

Conclusions:

• Bacterial co-aggregation is characterized by distinct adhesive forces measurable by AFM.
• Temperature critically influences the strength of adhesive interactions in bacterial plaque formation.
• Understanding these forces provides insights into the mechanisms of dental plaque development.