G1
High-quality, clean data were obtained from the raw sequences after a series of data filtration steps. Rfam (http://rfam.sanger.ac.uk) was used for the removal of rRNAs and tRNAs. The remaining reads were then mapped to intergenic regions of the reference genome of S. mutans UA159 with high sequence similarity (mismatch 1) using the BurrowsWheeler Alignment tool (BWA) (http://bio-bwa.sourceforge.net/).