Calcium modulates interactions between bacteria and hydroxyapatite.

Area of Science:

• Biomaterials Science
• Microbiology
• Surface Chemistry

Background:

• Bacterial adhesion to biomaterials like hydroxyapatite is influenced by surface characteristics.
• The role of aqueous medium composition, specifically ion concentration, on this adhesion is less understood.

Purpose of the Study:

• To investigate the effect of calcium ion (Ca2+) concentration on the adhesion of Streptococcus mutans and three Lactobacillus species to hydroxyapatite.
• To correlate adhesion changes with bacterial strain-specific surface properties.

Main Methods:

• Studied adhesion of Streptococcus mutans, Lactobacillus fermentum, Lactobacillus salivarius, and Lactobacillus casei on powdered hydroxyapatite.
• Varied the calcium ion (Ca2+) concentration in the aqueous medium.
• Assessed bacterial surface properties including hydrophobicity and electrophoretic mobility.

Main Results:

• Adhesion varied significantly with Ca2+ concentration, depending on the bacterial strain.
• Increased Ca2+ enhanced adhesion for Lactobacillus fermentum, Lactobacillus salivarius, and Streptococcus mutans (at low Ca2+).
• Lactobacillus casei showed high adhesion independent of Ca2+, with minimal ion effect.

Conclusions:

• Calcium ions mediate bacterial adhesion to hydroxyapatite, with strain-specific responses.
• Bacterial hydrophobicity and surface electrical properties influence Ca2+-dependent adhesion.
• Findings provide insights into controlling bacterial colonization on hydroxyapatite biomaterials.