library_construction_protocol: The DNA extraction and purification was performed using a Zymo Research BIOMICS DNA Microprep Kit (D4301, USA) following the manufacturer's instructions, with a blank control (DNA negative water) included in the process. Nucleic acid integrity was verified through electrophoresis, and the concentration and purity of each DNA sample was determined on a Tecan F200 plate reader after stained with PicoGreen. The V4 region of 16S rRNA gene was amplified using primers 515F (5-GTGYCAGCMGCCGCGGTAA-3) and 806R (5-GGACTACHVGGGTWTCTAAT-3) primers, and KOD-Plus-Neo DNA Polymerase (TOYOBO, Japan). PCR thermocycling conditions included an initial denaturation at 94oC for 1 min, followed by 30 cycles of 94oC for 20 s, 52oC for 30 s, and 72oC for 30 s, with a final extension step at 72oC for 5 min. The DNA negative control was also included for each PCR plate. PCR products were visualized on 1% agarose gels and quantified using a Qubit 2.0 Fluorometer (Thermo Fisher Scientific, USA). All the samples meet the following criteria: (1) high DNA integrity; (2) DNA concentrations > 10 ng/microL; (3) DNA total quality > 100 ng. Blank controls showed no visible bands and had a DNA amount of less than 1 ng/microL. The sequencing library was constructed using a NEBNext Ultra II DNA Library Prep Kit (BioLabs, New England). High-throughput sequencing was performed on a NovaSeq 6000 platform (PE250) by Rhonin Biotechnology Co., Ltd. (Chengdu, China).