Abstract: Objective This study aimed to evaluate the biological characteristics of a human specifically targeted antimicrobialpeptide C16LL-37 against Streptococcus mutans (S. mutans). Methods In this study, an antimicrobial peptide LL-37, apeptide derived from CSPC16 (S. mutans competence stimulating peptide), and recombinant peptide C16LL-37 were synthesized byFmoc-chemistry-based strategy. The selectivity and antibacterial activity of C16LL-37 were identified by the colony countingmethod on microbial culture plates. After treatment of C16LL-37 at 32 μmol·L^-1, the morphological changes in S. mutanswere observed by using scanning electron microscopy (SEM). In addition, enzyme-linked immunosorbent assay was used toevaluate the hemolytic activity and antibacterial activity of C16LL-37 under different conditions. Results 1) The minimuminhibitory concentration of C16LL-37 was 16 μmol·L^-1, and the minimum bactericidal concentration was 64 μmol·L^-1. 2) The survival rate of S. mutans was 3.46% after C16LL-37treatment at 64 μmol·L^-1 for 30 min, whereas it was 0% at64 μmol·L^-1 for 60 min. The survival rates of four otherkinds of bacteria were more than 60% at any time (P<0.05). 3) The morphological change in S. mutans was observedafter C16LL-37 treatment at 32 μmol·L^-1 by using SEM. S. mutans presented an irregular shape, rough surface, and evidentsplitting. 4) The hemolysis rate of C16LL-37 (≤64 μmol·L^-1) was less than 0.33%. 5) This study showed no significant influenceon the antibacterial activity of C16LL-37 under different conditions, such as temperature, pH, salinity, and trypsin atlow concentration (P>0.05). Conclusion C16LL-37 exhibited obvious specificity for S. mutans, strong antibacterial activity,low toxicity, and high stability. Thus, C16LL-37 has good potential in caries research and clinical application.

Key words: Streptococcus mutans, competence stimulating peptide, antimicrobial peptide, specifically targeted antimicrobial peptide