Impact of the broad‐spectrum antimicrobial peptide, lacticin 3147, on Streptococcus mutans growing in a biofilm and in human saliva

Aims: To evaluate the ability of the broad‐spectrum lantibiotic, lacticin 3147, to prevent Streptococcus mutans biofilm formation and disrupt existing biofilms. Methods and Results: Minimum inhibitory concentrations (MIC) and minimum biofilm inhibitory concentrations of purified lacticin 3147 were determined using a microdilution method. Lacticin 3147 effectively inhibited planktonic Strep. mutans, with MIC of 1·9–3·8 μmol l−1. Time‐kill kinetic studies confirmed that lacticin 3147 exhibited bactericidal activity against Strep. mutans at 38 μmol l−1 (or 10× MIC). The effect of lacticin 3147 on biofilm formation and reduction was also determined. Exposure to 6·3‐μmol l−1 lacticin 3147 (2× MIC) resulted in substantial reductions in Strep. mutans biofilm formation while lacticin 3147 was less effective against 1‐day‐old biofilms. Culture‐based analyses revealed that lacticin 3147 (50 μmol l−1) significantly inhibited Streptococcus spp. present in human saliva (P