I have cut out the interested bands out with blades, cut them into piece and wash them with NF water, stored them in NF water in 4 degree overnight, redo PCR and check with agarose gel, then rerun DGGE to confirm the purity of the bands.

However I found that around 70% of samples gives no signal at the original bands positions while gives other noises, two unrelated bands at the top part almost exist in every samples, what maybe the reasons and how can I solve it?

Thank you very much.