Effect of Propolis on Streptococcus mutans Biofilm Formation

Objective: To evaluate the susceptibility of  S. mutans during growth as a biofilm in the presence of different concentrations of propolis. Material and Methods: Three different  concentrations of ethanolic extract of propolis  (10%, 5%,  and  2.5 %) w ere used to  evaluate i ts  potential to attenuate the biofilm  formation  of  S. mutans (ATCC 25175) on  microplates. A crystal violet staining method  was performed  to measure  the  optical density (OD) of  the  biofilm biomass after  3  h  and 18 h time periods. All the experiments were performed in triplicate, and the obtained data were expressed as mean ± standard deviation. A two-tailed Student’s t-test was used to determine the different abilities of biofilm formation between the treated and control groups of the bacteria film in the presence of propolis. A p-value of 0.05) to those of  the  control ( S. mutans grown in  tryptic soy broth + 1% sucrose ) .  Conclusion: A ll the tested concentrations of propolis  added  to the growth medium did not  inhibit the biofilm formation of  S. mutans .  Since biofilms consist of bacterial  cells and extracellular  matrices , we  hypothesize that the extracellular matrix  may have interfered with the antimicrobial properties of the tested propolis.