Archaeal 16S rRNA transcript amplicon sequences
Total RNA was isolated from each of the thirty-six soil samples collected at the 0-15 cm and 15-30 cm soil layers (two soil layers x three sampling points x six sampling sites). Extractions were conducted on 2 g of soil (wet weight) by using Rneasy PowerSoil Total RNA Kit (Qiagen, Hilden, Germany) according to the manufacturers instructions. The RNA concentration and purity were assessed spectrophotometrically (Nanodrop ND-1000, Nanodrop Technologies, Inc., Wilmington, DE, USA) to determine absorbance at the following wavelengths: 230, 260, 280, and 320 nm. The concentration of isolated RNA was between 100 and 200 ng ?L-1. RNA extraction was performed in duplicate for each sample (two technical replicates) and stored at -80 C until further use. Complementary DNA (cDNA) was synthesized from a single stranded RNA isolated from soil samples using a QuantiNova Reverse Transcription Kit (Qiagen, Hilden, Germany) with integrated removal of genomic DNA contamination following the manufacturers instructions. Amplicon libraries were prepared according to the 16S Metagenomic Sequencing Library Preparation (https://support.illumina.com), using the cDNA as template in the amplification reactions and specific primers for the 16S ribosomal RNA (rRNA) gene of total archaeal and bacterial community. The pair of primers SD-Arch-0349-aS-17 (5-GYGCASCAGKCGMGAAW-3) / SD-Arch-0519-aA-16 (5-TACCGCGGCKGCTG-3) (Klindworth et al., 2013) was used to obtain amplicons of approximately 185 bp from V3 region of the 16S rRNA gene for Archaea. A fragment of approximately 390 bp of the V4 region of the 16S rRNA gene of Bacteria was amplified using the pair of primer 515F (5-GTGYCAGCMGCCGCGGTAA-3) (Parada et al., 2016) / 806R (5-GGACTACNVGGGTWTCTAA-3) (Apprill et al., 2015).