title: Soil bacterial communities affected by agricultural practices 51A
design: Metagenomic DNA was extracted from 3 g soil (6 times from 0.5 g) with a technique described by Ceja–Navarro et al. (Appl. Environ. Microbiol. 2010). Primers 8–F (5´–AGA GTT TGA TCI TGG CTC A– 3´) and 556–R (5´ –TGC CAG IAG CIG CGG TAA– 3´), 10 pb multiplexed and containing the Roche 454 pyrosequencing adaptors Lib–L, were used to amplify the region V1–V3 of the 16S rRNA gene from the metagenomic DNA. All samples were amplified in triplicate, pooled in equal amounts, and purified Sequencing was done by Macrogen Inc. (DNA Sequencing Service, Seoul, Korea) by using a Roche GS–FLX Titanium 454 pyrosequencer (Roche, Mannheim, Germany) and the instructions of the manufacturer for amplicon sequencing.