Streptococcus mutans transcriptome in the presence of sodium fluoride and sucrose

Abstract Objective Considering the diverse mechanisms by which fluoride could affect oral bacteria, this study evaluated the effect of sodium fluoride on Streptococcus mutans transcriptome in the presence of sucrose. Methods S. mutans UA159 was cultured in 3 different types of media: medium control[TY], sucrose control[TY_S], and sodium fluoride sucrose test[TY_S_NaF]. Triplicates of each group were sampled at exponential phase 3 h after inoculation, total RNA was isolated, mRNA enriched and cDNA paired-end sequenced (Illumina Hi-Seq2500). Results Genes related to S. mutans adhesion( gtf B and gtf C), acidogenicity and sugar transport were up-regulated in the presence of sucrose(TY_S) and sucrose/fluoride(TY_S_NaF), whereas gene dltA, D-alanine-activating enzyme, which is related to regulation of non-PTS sugar internalization was down-regulated. Up-regulation of the scrA gene and the PTS fructose-and mannose system, as well as functions such as those involved in stress and defence responses and peptidases; and down-regulation of lacACDG and pyruvate formate-lyase were observed in the TY_S_NaF group, as compared to TY_S group. Conclusions The presence of NaF has decreased the overall gene expression level in S. mutans . However, its major effect seems to be the inducing of expression of genes involved in some PEP:PTS systems and other metabolic transporters which imply specific cellular internalisation of sugars.