Analysis of the RNA samples described in figure 1 using 16S rRNA gene universal primers and a one-step qRT-PCR kit reveals DNA levels before and after treatment. Using 1 µl of the treated or untreated RNA from each sample, qRT-PCR was run. Treatment of RNA samples reduced DNA 5 logs (>15 cycles), placing it below the level of background DNA in the qPCR kit (red line). Assay efficiency is shown by the standard curve (grey lines) to be at 99%.
Samples were treated using the DNase Max Kit and a competitor's kit to compare residual DNase activity using a DNase-free certification assay. All manufacturer's protocols were followed. The negative control (lane 5) did not receive DNase. The attached agarose gel results are after a 1 hour incubation at 37°C and an activation period of 5 minutes at 65°C. DNase was successfully removed by the DNase Max Removal Resin (lanes 3-4). DNase remained in the samples treated with competitor's resin (lanes 1-2).
The RNeasy PowerSoil Total Kit was used to extract RNA from two different soils. The resulting product was then treated with the DNase Max Kit to remove any lingering DNA. Genomic DNA was effectively removed from the RNA samples, as seen in the agarose gel images.