design: DNA was extracted using a Nucleospin soil DNA extraction kit (Macherey-Nagel, Dren, Germany) following the manufacturers instructions. The V3-V4 hypervariable regions of the 16S rRNA gene were amplified using the universal primer pairs 515F (GTGCCAGCMGCCGCGGTAA) and 907R (CCGTCAATTCCTTTGAGTTT). The amplicons were gel purified, end-repaired, and Illumina-specific adaptor sequences were ligated. After quantification, each sample was individually indexed, followed by an additional purification step. Sequencing was performed on Illuminas NovaSeq 6000 platform using a paired-end 2  150 bp configuration. Approximately 20 Mb of data per sample was generated.