One way to remove genomic DNA from your preps is to precipitate the super-coiled plasmid DNA with PEG. check for the protocol in molecular cloning or current protocols. PEG will not precipitate linear or genomic DNA. Good luck.

Http://www.ncbi.nlm.nih.gov/pubmed/16209553

Are you using column-based kits (mini, midi, mega...)? They usually guarantee the elimination of genomic DNA before plasmid capture on the resin and sbsequent plasmid eluition.

Which method are you using and what kind of plasmid do you want to prepare (high/low copy, size)?

check out the protocol for plasmid isolation because it may be due to the protocol you are following chances of genomic dna contamination in plasmid isolation is rare.so please check your protocol.i can give you the protocol if you are following a wrong one.

You could run it in a gel and use Qiagen gel purification kit to purify the band of interest. Maybe you are overloading your column - using Qiagen miniprep, midi, maxi or giga I haven't had genomic DNA contamination so if you are not using one of these already maybe you could clean it up this way.

we have used DH5 alpha strain and pUC19 plasmid. even from miniprep kit we got genomic DNA contamination.

Please suggest any modification in protocol, we are using protocol from

www.protocol-online.org

After adding denaturation, alkaine solution mix it by inverting the tube repeatedly and leave it for 5minutes at room temperature . should not exceed 5minutes and transfer the tubes on ice and add Acetate solution.. Should avoid vortexing at denaturation step. Best of luck

Muneeb K Hamza, Sir if you kind enough to provide me the protocol and major modifications required.

If you want to isolate plasmid DNA, you crack your cells open and carry out a miniprep, trying very hard not to get any contaminating genomic DNA in your sample.For plasmid DNA extraction, the lysis has to be a lot more subtle than simply chewing up the cell wall with enzyme or bashing it with glass beads.

I checked the protocol you are following....i will give you my protocol just check it out.i will give you as earlier as possible.

When you perform a miniprep, it is important not to exceed with the lysis solution.

anyway, if you still have genomic contamination, you can use DNaseI, it should reduce all DNA, but genomic too. You have to try different time of incubation, not too much, otherwise you destroy also the plasmid DNA, but sufficient to eliminate the genomic.

You can do some aliquote, and incubate for different time, and check the result in a agarose gel

Thank you Muneeb K Hamza sir, my email ID is [email protected]

I prefer use the Qiagen kit and follow the procedure according to it. I had tried many times and I isolated good amount of plasmid DNA. Make sure the precipitation should not enter into the collected fluid, that makes most of contamination. Let me know, if you need I can forward the protocol.

Pradeep sir please provide Protocol, as to remove Genomic DNA contamination.

One way to remove genomic DNA from your preps is to precipitate the super-coiled plasmid DNA with PEG. check for the protocol in molecular cloning or current protocols. PEG will not precipitate linear or genomic DNA. Good luck.

Roshan Sriram , PLEASE CAN YOU SEND ME THE PROTOCOL , i AM FACING SAME PROBLEM.

A simple way to remove remaining genomic DNA in your mini/midi prep is to do yet another mini prep with your isolated DNA.

the easiest way to do that is cutting the plasmid band from the gel and recover it by using of DNA gel recovery kit. to be sure that u get it, load it again on the agarose 1%

If you have tried everything and nothing has worked so far, try using exonuclease digestion. It would not cut your plasmid but digest any open ended DNA in the prep. Following that, precipitate your DNA again, give it a wash with 70% ethanol, dry it briefly and run the gel again.