title: metagenome:human vaginal swab
design: 600 l of each vaginal sample was added with 7.2 l lysozyme (RT410-TA, TIANGEN BIOTECH, Beijing, China) for wall-breaking reaction. Then, 250 L 0.5 mm glass beads were attached to a horizontal platform on a vortex mixer and agitated vigorously at 2800-3200 rpm for 30 min. 0.3 mL sample was separated into a new 1.5 mL microcentrifuge tube, and the total bacterial genomic DNA was extracted using the TIANMicrobe Pathogen DNA/RNA Extraction Kit (Magnetic Bead Method) (NG550-01, TIANGEN BIOTECH, Beijing, China) following the manufacturers instructions. Then, DNA libraries were constructed through DNA-fragmentation, end-repair, adapter-ligation and PCR amplification81. The DNA concentration of the libraries was measured using the Qubit  dsDNA HS Assay Kit (Thermo Fisher Scientific, Waltham, MA, USA). The libraries were qualified with Agilent 2100 Bioanalyzer using Agilent High Sensitivity DNA Kit, and equivalent doublestranded DNA libraries were pooled and transformed into a singlestranded circular DNA library through DNA denaturation and circularization. DNA nanoballs were generated from singlestranded circular DNA by rolling circle amplification, then qualified with Invitrogen Qubit 2.0 Fluorometer (Thermo Fisher Scientific, Foster City, CA), and loaded onto the flow cell for sequencing with Paired-End 150 on the MGISEQ200 platform (BGI Genomics, Shenzhen, Guangdong, China).