title: Gut bacterial communities of common carp
design: Total microbial DNA was extracted using the HiPure Soil DNA Kit (Magen, Guangzhou, China) according to the manufacturers protocol. The V3-V4 region of the 16S ribosomal RNA gene was amplified by PCR using primers 338F: 5-ACTCCTACGGGAGGCAGCA-3 and 806R: 5-GGACTACHVGGGTWTCTAAT-3 with eight-base barcodes unique to each sample. PCR reactions were performed in a 20 mL mixture containing 4 mL of 5  Fast Pfu Buffer, 2 mL of 2.5 mM dNTPs, 0.8 mL of each primer (5 mM), 0.4 mL of FastPfu Polymerase (TransGen, China), and 10 ng of template DNA. The PCR conditions were as follows: 95 C for 2 min, followed by 27 cycles of 98 C for 10 s, 62 C for 30 s, and 68 C for 30 s, and a final extension at 68 C for 10 min. Purified PCR products were subjected to Illumina based high-throughput sequencing (Majorbio Bio-Pharm Technology, Co., Ltd., Shanghai, China).