unknown CTAB complex in DNA extraction - (Mar/21/2006 )

I'm extracting DNA from a sediment with CTAB. After incubating my sample for 2 hours at 65C with Lysis buffer (TE, NaPO4, NaCl, CTAB, proteinase K), and SDS, and spinning, I'm getting a weird-looking precipitate (looks like a pancake, but yellowish) on top of everything in the tube.
I'm also doing a control extraction for contamination (everything the same, but no sample = just reagents), and I'm getting also whitish precipitate, but not like a pancake.

Does anyone have an idea of what this might be?

I know that CTAB denatures and precipitates cell walls LPS and proteins - is that what my precipitate is? But what about my control?

Thanks!

Hi

What is the pH of your lysis solution? It could be that the EDTA is precipitating out if the pH is too low. The yellowish stuff in your extraction could be polyphenolics.

Cheers
Bob