Effects of Thyme Essential Oil on Streptococcus Sanguinis Biofilm

Objectives: To evaluate the effects of Thyme essential oil on Streptococcus sanguinis biofilm formation.
Methods: S. sanguinis SK36 strain and Thyme essential oil were used in this experimental study. Minimum inhibitory concentration (MIC) and minimum bactericide concentration (MBC) assays of the essential oil were performed. Biofilm formation assay was conducted using human saliva from a healthy adult. Then, transcriptional analysis of genes was performed from S. sanguinis biofilm exposed to Thyme essential oil [MIC]. Quantitative PCR (qPCR) was performed with a StepOne Real-time PCR system. Data were analyzed by comparing mean from at least three independent experiments using a nonparametric Kruskal-Wallis test with Dunn’s post hoc test.
Results: MIC of Thyme essential was 0.72mg/mL, and MBC was 0.36mg/mL. There was no statistical difference of expression of the following genes: vick, vicR, spxB, gftP, eno, mecA, ptsG, piliA, piliB, piliC and ssapcsB between the group exposed to Thyme essential oil vs. control group (p>0.05).
Conclusions: The use of Thyme essential oil may not have effects on Streptococcus sanguinis biofilm formation. Thus, new essential oils should be evaluated to determine their potential effects on S. sanguinis, and on other microorganisms related to oral diseases.