Modulation of Streptococcus mutans Adherence to Hydroxyapatite by Engineered Salivary Peptides

Since the modification of the proteinaceous components of the Acquired Enamel Pellicle (AEP) could influence the adhesion of Streptococcus mutans, the most cariogenic bacteria, to dental surfaces, we assessed if engineered salivary peptides would affect the adherence and modulate the bacterial proteome upon adherence. Single-component AEPs were formed onto hydroxyapatite (HAp) discs by incubating them with statherin, histatin-3, DR9, DR9-DR9, DR9-RR14, RR14, and parotid saliva. Then, the discs were inoculated with S. mutans UA159 and the bacteria were allowed to adhere for 2 h, 4 h, and 8 h (n = 12/treatment/time point). The number of bacteria adhered to the HAp discs was determined at each time point and analyzed by two-way ANOVA and Bonferroni tests. Cell-wall proteins were extracted from adhered, planktonic, and inoculum (baseline) bacteria and proteome profiles were obtained after a bottom-up proteomics approach. The number of adhered bacteria significantly increased over time, being the mean values obtained at 8 h, from highest to lowest, as follows: DR9-RR14 > statherin > RR14 = DR9-DR9 > DR9 = histatin3 > saliva (p < 0.05). Treatments modulated the bacterial proteome upon adherence. The findings suggested a potential use of our engineered peptide DR9-DR9 to control S. mutans biofilm development by reducing bacterial colonization.