Antimicrobial Activity of Statherin and its Derivatives on Cariogenic Bacteria

Methods: Whole statherin and 13 shortened derivatives (all at 100µg ml ^-1) were tested for their ability to kill Streptococcus mutans, Lactobacillus casei and Actinomyces naeslundii. Derivatives included 5 C-terminal, 5 N-terminal and 3 mid-portion peptides. Bacterial suspensions in phosphate buffered saline (approx. 1 x 10⁶ colony forming units ml ^-1) were added to peptide solutions and control saline at a ratio of 1:100. Incubation of mixtures was carried out at 37ºC under aerobic conditions with shaking at 200 rpm. Samples were taken at 0, 30, 60, 90 and 120 min and plated to obtain colony counts after incubation at 37ºC for 48h.

Results: None of the peptide derivatives showed any antimicrobial activity against the 3 species tested. However, A. naeslundii was shown to be susceptible (74% reduction in mean count) to the whole molecule.

Conclusion: In conclusion, 13 shortened derivatives of statherin demonstrated no antimicrobial properties against 3 species of cariogenic bacteria. It is hypothesised that certain species of bacteria are not susceptible to the antimicrobial action of statherin and will more readily colonise the tooth surface.