design: Aliquotes of DNAs (30 ng/L final concentration) were subjected to 16S V3-V4 rRNA gene library preparation and sequencing (Bio-Fab Research, Rome, Italy).  Illumina adapters overhang nucleotide sequences were added to the gene specific primer sequences targeting the V3-V4 region. After 16S amplification, a PCR clean-up was done to purify the V3-V4 amplicon from free primers and primerdimer species. A subsequent limited cycle amplification step was performed to add multiplexing indices and Illumina sequencing adapters by using a Nextera XT Index Kit. Finally, libraries were normalized and pooled by denoising processes and sequenced on Illumina MiSeq Platform with 2x300 bp paired-end reads. Taxonomy was assigned using home made Naive Bayesian Classifier trained on V3-V4 16S sequences of SILVA 138 database. QIIME 2 v2020.8 (Quantitative Insights Into Microbial Ecology) platform was used for microbiome analysis from raw DNA sequencing data. QIIME analysis workflow was performed by demultiplexing, quality filtering, chimera removal and taxonomic assignment.