Precipitation appears after adding sodium acetate but before adding cold ethanol - (Sep/10/2009 )

Hi, everyone. I am extracting some genomic DNA from some soil samples. But I found some white stuff in the bottom of the mirco tube imediately after adding NaAc to it, but I had not yet added cold ethanol. When I votex the tube, the white stuff disappeared.

Can anyone tell me how did this all come out?

Thanks.

fzhang on Sep 10 2009, 07:31 PM said:

Exactly how far through the protocol were you. For that matter, exactly what was your protocol?

fzhang on Sep 10 2009, 04:31 AM said:

I have that happen as well. I don't know what the cause of it is. I do know that swirling or inverting it causes it to disappear.

can anyone help?

fzhang on Sep 12 2009, 02:16 AM said:

What's your protocol please?

swanny on Sep 14 2009, 01:18 PM said:

After adding one volume of chloroform isoamyl alcohol (24:1) to my crude DNA solution, I pipette the upper aqueous phase to another tube. Then I added 0.1 volume of 3M sodium acetate to this solution. Right then some white stuff like precipiation appeared in the lower part of the volume. If I inverted the tube, this white stuff would readily vanish.

Thanks a lot, swanny.

is your NaAcetate ice cold AND you are using CTAB in one of the previous steps? If yes: you should keep your samples on ice before removing the supernatant. CTAB preciptiates at low temps (lower than app. 10-15°C). Therefore it will vanish again, when warm enough.
Keeping you samples cold will allow you to remove the CTAB from your DNA...good for PCR, as CTAB is a strong inhibitor.

gebirgsziege on Sep 14 2009, 02:50 PM said:

Thanks. But neither did I use CTAB nor put my samples on the ice. It's wierd, right?

lot of polysaccarides or glycoproteins?