16s rRNA V1V2 region sequencing of human endometrial biopsy: SE55
DNA extraction using the Power Fecal Pro DNA kit (Qiagen, Hilden, Germany), following the manufacturers protocol using the QIAsymphony extraction device (Qiagen, Hilden, Germany). DNA concentration  assessed using the UCP probe PCR kit (Qiagen, Hilden, Germany). An extraction blank was performed as a control to monitor for potential contamination. Library preparation of the V1-V2 and V2-V3 regions of the 16S rDNA according to the manufacturers protocol using the QIAseq 16S/ITS screening and regional panels (Qiagen, Hilden, Germany). DNA quantification using the Qubit 2.0 Fluorometer and the Qubit dsDNA HS Assay (Thermo Fisher Scientific, MA, USA). DNA fragment size analyzed using the High Sensitivity D1000 kit (Agilent Technologies, Santa Clara, USA). Purified libraries were normalized and finally sequenced on the MiSeq system (Illumina Inc. San Diego, CA, USA) using v3 chemistry. A mock microbial community was used as a positive control for library preparation and sequencing. Image analysis and base calling were carried out directly on the MiSeq. Pairs of vaginal and endometrial samples from the same patient were always analyzed in parallel and within the same library preparation and sequencing run.