algal DNA purification

[dunahayt at TCPLINK.NREL.GOV]

Hi,
We need to isolate total DNA from small volumes of large numbers of 
microalgal cultures for analysis by Southern blotting and PCR.  We've been 
using a miniprep method (obtained from the Chlamydomonas Gopher) using 
phenol/chloroform extraction, which gives decent yields, but digestion with 
restriction enzymes is usually poor.  We think this is due to carbohydrate 
contamination.  CTAB precipitation helps the digestion problem, but for 
large numbers of samples, CTAB is a nuisance, and yield is very low.  Does 
anyone know of any methods, or commercial spin columns, or anything, that 
allows easy clean up (carbohydrate removal) of genomic DNA?  I'm going to 
try the Puregene system from Gentra Systems (DNA isolation without 
phenol/chloroform), but I'm afraid that this might not address the 
carbohydrate problem.

Any info would be appreciated.

Terri Dunahay
National Renewable Energy Lab
dunahayt at tcplink.nrel.gov