*2.2. Genomic DNA Extraction*

The following molecular and sequencing procedures were performed in an outside outsourcing research laboratory. Genomic DNA (gDNA) was isolated from the dental plaque samples using a DNA extraction kit for bacteria (iNtRON Biotechnology, Seongnam, Korea) following the manufacturer's protocol. The collected samples were treated with lysozyme at 37 ◦C for 15 min and lysed with a buffer containing proteinase K and RNase A at 65 ◦C for 15 min. The lysates were mixed with a binding buffer and then passed through resin columns for purification. The harvested g DNA from the samples was quantified using a NanoDrop ND-1000 spectrophotometer (Thermo Scientific, Waltham, MA, USA).
