metagenome of prokaryotes:soil
DNA extraction was carried out using the DNeasy PowerLyzer PowerSoil Kit (QIAGEN) automated on the QIAGEN QIAcube (QIAGEN). The preparation of the DNA library was performed using a one-step PCR method. PCR primers used in the Earth Microbiome Project (Apprill et al., 2015, Parada et al., 2016), targeting the V4 region of 16S ribosomal RNA (rRNA), were modified to include unique dual index combinations. PCR products were amplified using the Platinum Taq DNA Polymerase High Fidelity kit (Invitrogen). Reactions were assembled using an epMotion 5075 Liquid Handler (Eppendorf). The library was sequenced using a 300 cycle Illumina MiSeq kit, using custom sequencing and index primers.  APPRILL, A., MCNALLY, S., PARSONS, R. & WEBER, L. 2015. Minor revision to V4 region SSU rRNA 806R gene primer greatly increases detection of SAR11 bacterioplankton. Aquatic Microbial Ecology, 75.  PARADA, A. E., NEEDHAM, D. M. & FUHRMAN, J. A. 2016. Every base matters: assessing small subunit rRNA primers for marine microbiomes with mock communities, time series and global field samples. Environmental Microbiology, 18, 1403-1414.