Paired-end MiSeq of 16S bacteria: PCR Sequencing water blank
DNA from soil samples was extracted via the Qiagen DNeasy PowerSoil Kit (Germantown, MD), following manufacturers instructions. Sequencing was performed in the Ge- netics Core at the University of Arizona, and polymerase chain re- action (PCR) parameters included denaturation at 98 C for 5 min, 34 cycles of denaturation at 50 C for 30 sec, annealing at 72 C for 1 min, and an extension at 72 C for 5 min. For bacteria and archaea, the V4 region of the 16S rRNA gene was amplified us- ing primers 515F and 806R.