title: perfluorine
design: In this experiment, universal primer 338F (5 'ACTCCTACGGGAGGCAGCAG3') 806R (5 'GGACTACHVGGGTWTCTAAT 3') was used to amplify the V3-V4 region of bacterial 16S rDNA sequence. PCR amplification system consisted of 2Pro Taq 10 L, forward primer (5 mol/L)0.8 L, reverse primer (5 mol/L)0.8 L, template DNA 10ng/l, ddH2O supplementation to 20 L. The PCR reaction procedure was: predenaturation at 95  for 3 min; 30 cycles (denaturation at 95  for 30 s; Annealing at 55  for 30 s; Extend 45 s at 72 ); Finally, it was extended for 10 min at 72  C and dropped to 4  C until stopped