title: metagenome: subway station of China
design: DNA extraction from swabs was performed with PowerSoil DNA Isolation Kit. For the preparation of Illumina-compatible libraries of V4 region of 16S rRNA gene standard F515-R806 sequences with slight modifications were used as a primers. Amplification of each sample was performed in two replicates in 50 ul volumes by GoTaq Hot Start Colorless Master Mix (Promega).The concentration of the PCR products was measured with Pic Green, and purification of the PCR products was performed using the QIAquick PCR Purification Kit (Qiagen) for the extraction of DNA for reagent mixtures. The concentration of obtained 16S rRNA libraries in the solution was measured with Qubit fluorometer (Thermo Fisher Scientific) using Quant-iT dsDNA High-Sensitivity Assay Kit. The quality of the final libraries was assessed using the electrophoresis in agarose gel. Libraries were sequenced with MiSeq Personal Sequencing System platform of (Illumina Inc.) using paired-end 250 bp reads.