Total genomic DNA was extracted from the samples using the TGuide S96 Magnetic Soil /Stool DNA Kit. DNA passing quality assessment was fragmented. DNA fragments were further processed for end repairing, adding 3' A tail and adapter ligation. The products of proper size were selected and purified. The selected fragments were further amplified to construct the sequencing library. Qualified libraries were then processed for sequencing on Illumina platform. Raw data quality control was performed to clean reads for subsequent bioinformatics analyses. Clean reads were first assembled to predict coding genes and construct a non-redundant gene set. Function annotation, taxonomy analysis, and statistics on abundance were further performed on the base of this gene set according to existing databases. Sequences of low quality were removed by fastp software from raw tags. MEGAHIT was employed for metagenome assembly. Contigs shorter than 300 bp were removed. After assembly, QUAST was used to evaluate the assembly outputs. In coding gene prediction, MetaGeneMark (v 3.26) was applied to identify coding regions in genome at default parameter settings. MMseqs2 (v 12-113e3) was used to remove redundancy with similarity threshold at 90% and coverage threshold 80%.