DNA samples were cleaned with either the DNeasy PowerClean Pro Cleanup Kit or the Zymo Research OneStepTM PCR Inhibitor Removal Kit.(A) Results were then examined on a 1.2% TAE gel. (B) Side-by-side comparison shows that while samples processed with the DNeasy PowerClean Pro Cleanup Kit were clear, some brown color remained in those processed with the OneStep Kit, showing some residual humic substances may be present. Starting samples were brown and concentration appeared artificially high. Likewise, when looking at the ratios of 260/280 and 260/230, the starting sample had low ratios of both, showing the presence of contaminants including humic substances. Following clean-up, the DNeasy PowerClean Pro Cleanup Kit ratios of 260/280 and 260/230 increased to levels consistent with pure DNA. The concentration of DNA decreased to an average of 76.85 ng/µl. Samples cleaned with the OneStep Kit ratios of 260/280 and 260/230 remained low.
Samples described in Figure 1 were examined via RT-qPCR with a Bacillus 16S assay (1 µl of undiluted RNA or a 1:10 dilution). RNA samples were successfully amplified, confirming they were free of inhibitors at a difference of approximately 3 cycles between the undiluted and 1:10 dilution.