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. mutan s 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  <   0·05) with an approximate 4‐log reduction in viability compared with the control. Conclusions:  These results indicate that lacticin 3147 may be an effective therapy against Strep. mutans and was shown to substantially attenuate its ability to form a biofilm. Significance and Impact of the Study:  Lacticin 3147 has the potential to be a useful adjunct to traditional oral therapeutic approaches in addition to its use as a bioactive ingredient for food applications.