library_construction_protocol: According to manufacturer's instruction of QIAamp DNA Micro Kit (QIAGEN, Hilden, Germany), BALF and BB samples were respectively used to extract DNA. Qubit 4.0 (Thermo Fisher Scientific, MA, USA) was used to measure extracted DNA concentrations. QIAseq Ultralow Input Library Kit (QIAGEN, Hilden, Germany) was used to construct metagenomics libraries[27]. Inspected and qualified library was sequenced on Nextseq 550 platform (Illumina, San Diego, USA). On average, about 1580 million reads were obtained for each sample.