WT2
Extraction of total bacterial DNA from intestinal samples was used for high-throughput sequencing in grass carp: 200-300 mg of intestinal contents were extracted, centrifuged to collect the precipitate, added to 750 L of SL1 buffer and 150 L of SX buffer, and ground for 5 min. The solution was placed in a thermomixer, lysed at 65 C for 13 min; centrifuged at 12000 rpm for 10 min, and SL3 buffer was added to the supernatant and incubated at 20 C for 5 min, centrifuged at 12000 rpm for 10 min. Then, the supernatant was added to an inhibitor removal column, centrifuged at 12000 rpm for 2 min, and then, the filtrate was mixed with 250 L of SB buffer, transferred to the binding column, and centrifuged at 12000 rpm for 2 min. Next, 700 L of buffer SW1, SW2 and 100 L of eluent SE were mixed together, and after washing, the mixture was incubated for 5 min, and centrifuged at 12000 rpm for 5 min to elute DNA. The samples were tested by a Bioanalyzer system 2100 (Agilent, Palo Alto, USA) and then subjected to sequencing by a PacBio platform and data analysis.