PHS3
Approximately 5 ml saliva was sampled from one periodontally healthy people and used for DNA isolation. Total DNA was quantified using a Qubit Fluorometer (Invitrogen) before sheared into about 180 bp fragments with a Covaris Focused-ultrasonicator (Covaris). Libraries were prepared on the sheared fragments using a TruSeq Sample Preparation Kit v2 (Illumina) according to the manufacturer's instructions. Fragment size and integrity of the libraries were assessed by a Fragment Analyzer (Advanced Analytical Technologies). Libraries were sequenced with 2×101 bp paired-end (PE) on an Illumina HiSeq 2000 platform.