16S seq of human milk
The microbiota metagenomic DNA was extracted from 5 ml milk samples using a QIAamp Fast DNA stool Mini Kit (Qiagen, Venlo, The Netherlands). Barcoded specific bacterial primers 338F (5-ACTCCTACGGGAGGCAGCA-3) and 806R(5-GGACTACHVGGGTWTCTAAT-3) [1] were used to PCR amplify the variable region 3-4 (V3-V4) of the 16S rRNA gene. Construction of sequencing libraries and paired-end sequencing was performed on an Illumina NovaSeq6002 platform at Biomarker Technologies Co, Ltd. (Beijing, China) adhering to standard protocols.