title: DES3_sw
design: The total DNA information of microbial community in each water sample was extracted using the CTAB methods. The purified DNA for amplifications reactions. The fragment of V4 hypervariable domains of bacterial 16S rRNA genes were PCR amplified using the universal primers 515F and 806R . All DNA PCR reactions were carried out in a 50mL reaction volume, containing 25mL of 2* Taq PCR mix, 3mL Primer F (10 mM), 3 mL Primer FR (10 mM), 3 mL diluted DNA and 16 mL dd H2O tub system. The cycling processes include pre-denaturation for 60 s at 98 , followed by 34 cycles of denaturation at 94  for 60 s, annealing at 57  for 45 s, extension at 72  for 60 s, and a final extension at 72  for 10min. After the amplification reactions, PCR products were checked in 2 % agarose gel by electrophoresis and then stored at -20  and sequenced on an Illumina HiSeq X Ten platform using the 2  254 bp paired-end read protocol at Novogene Company ( Beijing, China). The representative sequences for each OTU were packed for annotating corresponding taxonomic information for each sequence using the SILVA high quality ribosomal RNA database.